Technology Information!!!

ThinkPad

2008-06-30T12:40:00.000+07:00

ThinkPad is a brand of portable laptop and notebook personal computers originally designed, manufactured and sold by IBM. Since early 2005, the ThinkPad range has been manufactured and marketed by Lenovo, which purchased the IBM PC division.

History
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IBM introduced the first three ThinkPad models, the 700, 700C, 700T, in October 1992. The 700C used the Microsoft Windows 3.1 operating system, 25 MHz 486SLC processor, 120 MB hard disk drive, the industry's first 10.4" TFT color display, 2.2" x 11.7" x 8.3" dimension (56 x 297 x 210 mm), and 3 kg (6.5 lb) weight, cost US$ 4,350. The design of the commercial versions differed significantly from the prototype's keyboard-less tablet design. The bright red TrackPoint, embedded in the keyboard, enabled the notebook to be used on an airline tray table without a mouse. An IBM researcher conceived the title "ThinkPad" from a corporate-issued leather-bound pocket notebook with the corporate motto 'Think' embossed on the cover. The name met disagreements from the IBM corporate naming committee because the nomenclature system for the IBM computers was then numerical; however, the brand name "ThinkPad" was kept as the press showed appreciation for the title. The first ThinkPads were very successful, and soon collected more than 300 awards for design and quality.

The ThinkPad 750 flew aboard the Space Shuttle Endeavor during a mission to repair the Hubble Space Telescope on December 2, 1993. The ThinkPad 750C's task was to run a NASA test program which determined if radiation inherent in the space environment causes memory anomalies in the 750C or generates other unexpected problems. In 1995, the average number used was five, and in 1999 the average number was nine. Throughout 2006, a ThinkPad A31p was being used in the Service Module Central Post of the International Space Station and seven ThinkPad A31p laptops were in service in orbit aboard the International Space Station.

ThinkPads have been praised for exceptional build quality, system reliability, and services throughout their decade and a half of presence in the consumer market. The original design was a collaboration between Tom Hardy, corporate manager of the IBM Design Program, Italian-based designer Richard Sapper (noted then for the design of the Tizio lamp and later commissioned to design a ballpoint for Lamy) and Kazuhiko Yamazaki, lead notebook designer at IBM's Yamato Design Center in Japan. Sapper proposed a design inspired by the Shōkadō bentō, a traditional black-lacquered Japanese lunch box.

The fold-out butterfly keyboard, which appeared in the ThinkPad 701 series, is widely considered a design masterpiece and is on display at the Museum of Modern Art in New York. The ThinkPad 760 series also included an unusual keyboard design; the keyboard was elevated by two arms riding on small rails on the side of the screen, tilting the keyboard to achieve a more ergonomic design.

The 755CV featured another interesting design quirk: the screen could be separated from the lid, allowing it to be used to project the computer display using an overhead projector, before data projectors were commonplace.

Lenovo purchase
In 2005 the Chinese manufacturer of ThinkPads, Lenovo, purchased the brand from IBM, in a multi-year deal whereby IBM still helps in the marketing and support of these products.

* Added Magnesium-alloy chassis roll cage to reduce motherboard flex caused by holding the laptop one handed on a corner.
* Added Carbon Fibre Reinforced Plastic to 15" ThinkPad Models.
* Reintroduced a line of Tablet PCs based on the X series.
* Moved the physical location of GPU to the edge of motherboard near hinge, further reduce the chance of solders come loose caused by motherboard flex.
* Introduced Widescreen displays with the Z series of ThinkPads and added the option of Widescreen to the T series models.
* Brought back a consumer friendly laptop under the Z series line of ThinkPads.
* Added rubber cushion to the hard drive tray to reduce vibration and to absorb shock.
* Added the Windows key to all models of the 60- and 61-series making all the Windows shortcuts possible. (Although possible before with the keyboard remapping utility)
* Added Magnesium-alloy lid roll cage for a sturdier lid while replacing the lid material from magnesium-alloy to plastic for better wireless signal reception.
* Official support for Linux.
* Added drain holes starting with the T60 series.
* Ported the ThinkPad keyboard into stand-alone keyboards for desktop PCs in PS/2 or USB flavor.
* Added user forum on its website where actual Thinkpad developers and engineers view and reply to posts.

Features
Traditionally black, ThinkPads have commonly featured magnesium, carbon fiber reinforced plastic or titanium composite cases. The ThinkPad has introduced many innovations, including the TrackPoint pointing device. ThinkLight, an LED keyboard light at the top of the LCD screen, Active Protection System, an accelerometer sensor which detects when a ThinkPad is falling and shuts the hard drive down to prevent damage, Roll-cage design to eliminate motherboard flex, Biometric fingerprint reader, Client Security Solution, which improves security using a built-in TPM and facilitates deployment in corporate environment and drain holes to help reduce damages to the keyboard and components from accidental spillage.

Model information
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ThinkPad S30 and S31
Japan & Taiwan-only Pentium III model with no CD drive, a 10-inch (250 mm) screen, 256MB Maximum RAM, PCMCIA slot, CF slot, 2 USB 1.1 ports, Firewire port, RJ11 and RJ45, and a keyboard with English and Japanese shared keys. Battery with built-in stand, long life 5 hr run. HDD 20 GB upgradeable to 160 GB tested. Some models have built-in WiFi. BIOS are interchangeable in S30 and S31 and tested to work. The latest known BIOS is 1.82.
ThinkPad 235
The Japan-only ThinkPad 235 (or Type 2607), is an interesting product because it is a progeny of the IBM/Ricoh RIOS project. Also known as Clavius or Chandra2, it contains unusual features like the presence of 3 PCMCIA slots and the use of dual camcorder batteries as a source of power. Features an Intel Pentium MMX 233 MHz CPU, support for up to 160 MB of EDO memory, and a built-in 2.5-inch (64 mm) hard drive with UDMA support. Hitachi markets Chandra2 as the Prius Note 210.
ThinkPad 240
The ultraportable ThinkPad 240 (X, Z) started with an Intel Celeron and went up to the 600 MHz Intel Pentium III. The RAM was expandable to 320 MB max with a bios update. With a 10.4-inch (260 mm) screen and an 18 mm key pitch (A standard key pitch is 19mm). They were also one of the first ThinkPad series to contain a built-in Mini PCI card slot (form factor 3b). The 240s have no optical drives and an external floppy drive. An optional extended battery sticks out the bottom like a bar and props up the back of the notebook. Weighing in at 2.9 pounds (1.3 kg) these were the smallest and lightest ThinkPads ever made.
ThinkPad 300 series
The 300 series (300, 310, 340, 350, 360, 365, 380, 385, 390 (all with various sub-series)) was a long-running value series starting at the 386SL/25 processor, all the way to the Pentium III 450. They were a bit large and slower than the more full-featured models but offered a less expensive ThinkPad.
ThinkPad 500 series
The 500 series (500, 510, 560 (E, X, Z), 570 (E)) were the main line of the ultraportable ThinkPads. Starting with the 486SX2-50 Blue Lightning to the Pentium III 500, these machines had only a hard disk onboard. Any other drives were external (or in the 570's case in the ultrabase). They weighed in at around 4 pounds (1.8 kg) and because of their excellent design are still in use today.
ThinkPad 600 series
The 600 series (600, 600E and 600X) are the direct predecessors of the T series, and are legendary for their portability, comfortable keyboard, and sturdy construction. The 600 series packed a 12.1" SVGA or a 13.3" XGA TFT LCD, Pentium MMX, Pentium II or III processor, full-sized keyboard, and optical bay into a package weighing roughly 2.3 kg (5 lb). IBM was able to create this light, fully featured machine by using lightweight but strong carbon fibre composite plastics. The battery shipped with some 600 series models had a manufacturing defect that left it vulnerable to memory effect and resulted in poor battery life, but this problem can be avoided by use of a third-party battery.
ThinkPad 700 series
The 700 series (700, 701, 720, 730 (tablet), 750, 755, 760, 765, 770 (many with sub-models)) were the cutting-edge Intel-based ThinkPads. They featured the best screens, largest hard drives and fastest processors available at the time. This was the first successful ThinkPad introduced in 1992 (the first ThinkPad was a tablet PC without a keyboard and a mouse).
ThinkPad 800 series
The ThinkPad 800 series (800/820/821/822/823/850/851/860) were unique in that they were based on the PowerPC architecture, rather than the Intel x86 architecture. They all used the PowerPC 603e CPU, at speeds of 100 MHz, or 166 MHz in the 860 model. The 800 may have used a 603, and it is unclear if the 800 was experimental or not. All units used SCSI 2 instead of IDE hard disks. The units are believed to have all been extremely expensive, as the 850 cost upwards of $12,000. The 800 series can run Windows NT 3.5 (probably 4.0 as well), OS/2, AIX 4.14, Solaris Desktop 2.5.1 PowerPC Edition, and Linux.
ThinkPad TransNote
The ThinkPad TransNote was a pen-based PC in a notebook. Data could be entered through the keyboard, TrackPoint, paper notepad (with writing sensor below), or the screen via stylus. This ThinkPad expanded on IBM's previous pen based notebooks (360P(E), 730T(E), and 750(P)).
ThinkPad T20 series
Comprising the T20, T21, T22 and T23, these were Mobile Pentium III or Mobile Pentium III-M, sub-5 lb (2.3 kg) class machines. Contained processors ranging from 0.18 micrometre Mobile Pentium III 650 MHz to 0.13 micrometre Mobile Pentium III-M 1.20 GHz. Typically had 14.1-inch (360 mm) XGA screens, Ultrabay 2000 optical drives, S3 Savage/IX-MV graphics chip and Cirrus Logic CS 4614/22/24 sound chips; although variations along the line existed. Introduced the ThinkLight, a LED mounted inside the upper screen lip that illuminates the keyboard (activated with Fn-PgUp, the extreme diagonal keys); and titanium-reinforced and rubberized screen lids. Used MiniPCI form factor cards, which could be modem and/or Ethernet. With the T23, an internal WiFi antenna became available, so WiFi miniPCI cards could be used. These models did not contain the active hard drive protection or touchpad pointing device which appeared in later models. They were clad in black non-slip rubber with embedded glitter. The case lid had tabs along the edge that interlocked with depressions in the lower case when closed, to reduce case flexing. Comparatively more stylish, functional, and rugged machines; and easy to disassemble for repair or upgrades.
ThinkPad T30
Features include an Intel Mobile Pentium 4 processor ranging from 1.6 GHz to 2.4 GHz. A T30 may accommodate up to a 2.4 GHz processor with the latest BIOS and Embedded Controller upgrades. Graphics are provided by ATI Radeon Mobility 7500 hardware with 16 MB of discrete video memory, which supports external widescreen resolutions. Users have even reported success with output resolutions of 1920x1200 via DVI on the optional Port Replicator II docking station, although IBM claims a limit of 1280x1024 due to a weak TMDS transmitter. The T30 was available with a 14.1-inch (360 mm) screen, with resolutions of 1024 x 768 and 1400 x 1050. DVI video output is available with the optional Port Replicator II docking station, but resolution is officially limited to 1280x1024. Features available include the embedded security subsystem, UltraNav touchpad, 256 MB standard memory (1 GB maximum according to IBM manual, but it has been reported to accept 2 GB of RAM), a 20, 40 or 60 GB hard disk, Ultrabay Plus drive, wireless, and Bluetooth. The T30 also contains a miniPCI slot usable for a wireless card. The shell is titanium-reinforced composite. The whole package was a bit heavier and thicker than the T4x series.
ThinkPad R40 series
This line of notebooks comprised the R40 and the R40e. These had Mobile Celeron, Pentium 4-M or Pentium M processors, depending on sub-variant.
ThinkPad T40 series
Includes the T40, T41, T42, T43, and associated "p" series (for "performance"; e.g., T43p). A typical 14.1-inch (360 mm) T4x weighs 2.2 kg (4.9 lb), slightly less than the 600 series, and features an Intel Pentium M Processor (ranging from the Intel Pentium M at 1.3 GHz to the Intel Pentium M 770 at 2.13 GHz), a 14.1 or 15-inch (380 mm) LCD (XGA, SXGA+), an integrated GPU (Intel Graphics Media Adapter 900) or a discrete GPU (Radeon x300, 7500, 9000, Fire GL 9000, 9600, Fire GL T2, X300, and Fire GL V3200), and a hard drive ranging in size from 30 to 100 GB with the Active Protection System to protect the hard drive (T41 and later models). "p" (mobile workstation) models are also available with a 14-inch (360 mm) SXGA+ or a 15-inch (380 mm) SXGA+/UXGA FlexView display with wide viewing angle and high density IPS technology. These 15-inch (380 mm) display models weigh slightly more than their lesser brethren, with optical drive and battery, at 2.7 kg (5.9 lb). All T4x models use either 6-cell or 9-cell lithium-ion batteries, as well as an optional 4-cell Ultrabay Slim lithium-polymer battery. The 9-cell battery gives a runtime of 5+ hours and a crease allowing the notebook to lay flat on an airplane tray-table. Some T42 and T43 models feature a biometric security system with built-in fingerprint reader. Some types of the model also had the option to include Bluetooth support. The T40 was IBM's first ThinkPad to use the Pentium M "Banias" CPU. The T42 employed a Pentium M "Dothan" processor with a 400 MHz frontside bus, while the T43 used a later revision Dothan running a 533 MHz FSB.
ThinkPad R50 series
Based on the T40 series, this line of notebooks includes the R50, R50e, R50p, R51, R51e and R52. This series of notebooks is available with fingerprint-readers and uses many components also found in T40-series models, such as batteries, keyboards and planars (system boards). The R51e and the R52, both based on the T43 system board, are the first R-series notebook to utilize DDR2-memory and include a SATA-controller, however uses only PATA-harddrives.
ThinkPad T60 series
Includes the T60, T61; and associated "p" series (for "performance"; e.g. T60p); intended as the next generation of the T4x Series ThinkPads; this is the first T Series ThinkPad to include the Intel Core Duo "Yonah" Technology, and later the Intel Core 2 Duo "Merom" Mobile technology; and the first T-series ThinkPads to come in widescreen resolution. This model has a VMX-enabled BIOS (although the lowest end Intel Core CPUs themselves do not support VMX, such as the T5500), meaning that running fully virtualised operating systems via Xen or VMware is possible. The T61, announced in May 2007, features a widescreen resolution as the default resolution, and incorporates the Intel Santa Rosa platform having a fully 64-bit chipset, and is the first T-series ThinkPad to have an integrated web camera (optional), smart card reader (optional), and media card reader (optional). Furthering innovation founded in the T60, the T61 also sports a top-cover roll cage, aside from the magnesium roll cage inside the main chassis. T61 extra features include a fingerprint reader (some models) and a new improved framing (all models).
ThinkPad X20 series
Pentium III Mobile, sub-4 lb machines. Contained Pentium III-M processors ranging from 500 MHz to 1.13 GHz. 12.1 inch XGA screens, and ATI Rage Mobility M1 (X20, X21) or Radeon Mobility M6 (X22, X23, X24) graphics chips. Used miniPCI form factor cards, which supports modem and/or Ethernet. With the X22 and later machines, provisions for wireless networking support are built into the chassis. Ultrabay 2000 optical drive support can be fitted via the Ultrabase portable docking station option, and extended batteries can give the series a 5-hour running time.
ThinkPad X30 series
Pentium III Mobile (X30), Pentium M Banias (X31) or Pentium M Dothan (X32), 12.1 inch XGA screens, dedicated Graphic Chip (ATI M6 with 16 MB, which means no shared memory is cut from the RAM), Bluetooth on some models (upgradable), WLAN (802.11b, b/g or even a/b/g), FireWire, CompactFlash card slot. No built-in optical drive. Lots of options like second battery, Mediaslice (for battery and UltraBay), port replicators, docking stations (some with a PCI slot).
ThinkPad X40 Series
An example of the lightweight X series, weighing in at 1.2 kg (2.7 lb), 25% lighter than its predecessor, the X31. The last variant of the X40 series, the X41 Tablet, was the first ThinkPad tablet PC since the original pen-based ThinkPad. It is the lightest 12" Tablet PC with a keyboard from any manufacturer. It was also the final released ThinkPad designed by IBM before the brand was purchased by Lenovo.
ThinkPad X60 series
Includes the X60 and X61, with their associated "s" and "Tablet" series. The X60 is first X Series ThinkPad to feature Intel chips using the Intel Core architecture. The Core Duo L2400 (Low Voltage) CPU on the X60s model achieves 7+ hours of battery life on standard benchmarks, and can reach around 10 hours under light use, when using the extended-life battery. Note this model lacks a built-in optical drive, unlike the larger T60. The X61, like the T61, also is the first X-series ThinkPad to use Intel's Santa Rosa platform.
ThinkPad Z60 series
This is the first ThinkPad to feature a widescreen (16:10 aspect ratio) display. The Z Series is also the first ThinkPad equipped with a titanium lid (on some models). Integrated WWAN and/or webcam also found on some configurations. The series includes, as of 2006, the Z60 and Z61; the latter of which is the first Z Series ThinkPad with Intel "Yonah" Dual Core Technology. The processor supports Intel VT; this is disabled in the BIOS but can be turned on thanks to a BIOS update. Running fully virtualised operating systems via Xen or VMware is therefore possible.
ThinkPad X300
Codenamed "Kodachi". Released February 26, 2008. Distinguished from other ultraportables by its usage of LED backlighting, removable battery, solid state drive, and integrated DVD burner, it is the flagship model for the X-series. It also integrates GPS, WWAN, and a webcam in the top lid. The thickest part of the notebook is 2.34 cm (0.92 inches)and the thinnest part is 1.85 cm (0.73 inches).

Reception
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Both IBM and Lenovo-manufactured ThinkPads have been recognized by the press for their reliability. Laptop Magazine states that the ThinkPad has the highest-quality laptop computer keyboard available. The ThinkPad was ranked #1 in reliability and support according to PC Magazine's 2007 Survey. The Lenovo ThinkPad is the PC Magazine 2006 Reader's Choice for PC based laptops, and ranked number 1 in Support for PC based laptops. The ThinkPad Series is the first product line that has received PC World's Hall of Fame award. The ThinkPad X Tablet series is PC Magazine Editor's Choice for tablet PCs. The 3.5 lb (1.6 kg) ThinkPad X60s is ranked number 1 in ultraportable laptops by PC World. It lasted 8 hours and 21 minutes on a single charge with its 8 cell battery. The Lenovo ThinkPad X60s Series is on PC World's Top 100 Product of 2006. The 2005 PC World Reliability and Service survey ranked ThinkPad products ahead of all other brands for reliability. In the 2004 survey, they were ranked second (behind eMachines) Lenovo was named the most environment-friendly company in the electronics industry by Greenpeace in 2007. Lenovo ThinkPad T60p received the Editor's Choice award for Mobile Graphic Workstation from PC Magazine. Lenovo ThinkPad X60 is the PC Magazine Editor's Choice among ultra portable laptops.

Criticism
There have been concerns and complaints about the service, support, hardware, and security before and after Lenovo acquired the ThinkPad line. For example:

* IBM EasyServ has been outsourced to Solectron. The default depot repair is now handled by Solectron, and there have been complaints about unsatisfactory repairs and charges from users.
* Many who ordered T60s or T61s between May 9 and May 24, 2007, did not receive their orders when promised due to a variety of problems at Lenovo.
* Lenovo in Canada has a buggy ordering system that causes delayed delivery time and results in customer's frustration
* Many IBM ThinkPad models give a no-1802 error when trying to install "unauthorized" wireless cards. This prevents users from starting up their computers unless the wireless mini-PCI card is removed, or an IBM-authorized card is used. However, there are workaround patches.

MacBook Air

2008-06-30T11:57:00.002+07:00

The MacBook Air is a thin, lightweight, Apple Macintosh MacBook notebook computer featuring an optional solid-state hard drive. The Air has a 13.3-inch, widescreen LED backlit display, with 1280 x 800 screen resolution. The Air weighs 3.0 pounds (1.36 kg), and is 0.76 inches (1.93 cm) at its thickest point and 0.16 inches (0.4 cm) at its thinnest.

Apple CEO Steve Jobs introduced the MacBook Air at the Macworld Conference & Expo on January 15, 2008. Apple describes it as the "world's thinnest notebook", although there have been thinner models in the past and newer, thinner, laptops have been announced.

Overview
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To reduce the computer's size and weight, Apple omitted certain features long standard on its laptops. It is Apple's first notebook since the PowerBook 2400c without a built-in removable media drive. Users may purchase an external USB SuperDrive, or use bundled Remote Disc software to access the optical drive of another computer, but only for installing software. It is the first subcompact laptop offered by Apple since the full-featured 12" PowerBook G4 was discontinued in 2006.

Similarly to the PowerBook Duo series which preceded it, it lacks many features of the larger MacBooks, including a security slot and an Ethernet port, (although a USB-to-Ethernet adapter may be purchased separately). The MacBook Air offers a single USB port and, unlike the Duo, it provides for no other means of expansion or port replication. Like the entry-level MacBook, The MacBook Air lacks Cardbus and ExpressCard slots, both standard features in older and newer laptops. The device lacks a FireWire port, and as such OS X 10.5 Leopard does not require a FireWire port.

The Air is Apple's first laptop computer to be offered with an optional solid-state hard drive. ArsTechnica found "moderate" performance improvements of the 64 GB solid-state drive over the standard 80 GB hard drive in tests. The Air comes with 2 GB RAM memory as standard.

The CPU is an Intel Core 2 Duo chip, which was specially redesigned for the MacBook Air, reducing the physical chip packaging's size by 60 percent. While the processor is unique, it has been criticized for being under-powered and older-generation technology.

The laptop has the magnetic latch system of the MacBook and an aluminum casing like the MacBook Pro. The oversized trackpad offers iPhone-like Multi-Touch gestures, an improvement over previous MacBook trackpads. Among the gestures are pinching, swiping, and rotating.

The MacBook Air is pre-loaded with Mac OS X v10.5 and iLife '08.

Remote Disc

The MacBook Air can wirelessly access the optical drive of another Mac or Windows PC that has the Remote Disc program installed, allowing the installation of applications from a CD or DVD. It can also reinstall the system software from the included installation DVD. Remote Disc supports netbooting, so the MacBook Air can boot from its installation DVD in another computer's drive.

User-serviceability
Unlike the rest of the MacBook family, the MacBook Air has no directly user-replaceable parts. Its hard drive, memory, and battery are enclosed within the casing, with memory soldered directly to the motherboard. The MacBook Air's battery is not easily replaceable, enclosed in a manner similar to the iPod and related Apple product lines. The hard drive is not soldered and can be replaced through a non-trivial disassembly procedure. Relatively expensive solid-state drives (SSDs) are commercially available. As part of out-of-warranty service, Apple offers to replace the battery for a fee. It may be possible for the end user to replace the battery, though it is unclear whether this process would void the notebook's warranty. Users looking to replace batteries through third-party vendors will need to wait until replacement batteries are made available for this model.

Environmental impact
The MacBook Air has an all-aluminum case, a mercury- and arsenic-free LCD glass substrate, PVC-free internal cables, and the majority of circuit boards free of brominated flame retardants. Greenpeace, which had previously criticized Apple for its ecological practices, stated that the "greener" MacBook Air is a step towards what it considers necessary improvements.

Concerns about overheating and CPU-lockup

Several MacBook Air users since the release of the first generation product have complained of problems with severe overheating, causing CPU lockup. This effect appears to be exacerbated in warmer climates, such as northern Australia. A software update released by Apple in early March which attempted to fix the problem had mixed results. The problem seems to appear when undergoing system-intensive tasks such as video playback, video chatting, or playing games.

Turning the integrated fans to full speed by using third-party software or using USB-powered cool-pads does not cool down the notebook sufficiently to prevent core-shutdowns; undervolting the CPU however solves the MacBook Air's problems with overheating and CPU-lockups in most cases.

Criticism
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The MacBook Air has been criticized by Ryan Block of Engadget for its high price compared to other notebooks of similar specification, with him suggesting that a premium is being paid for its form factor.

The Macbook Air has also been criticized for the difficulty in accessing the headphone and USB port. Because of tight clearance, some devices, including some headphone jacks and 3G USB cellular modems will not fit, requiring users to purchase either a powered USB hub or an extension cable in order to use their devices.

As seen in the specification section, the Macbook Air lacks a Firewire port. It does not support Target Disk Mode of any kind, which would have enabled it to be used as an external hard drive for quick data transfers.

4G

2007-10-31T19:12:00.000+07:00

4G (also known as beyond 3G), an acronym for Fourth-Generation Communications System, is a term used to describe the next step in wireless communications. A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an "Anytime, Anywhere" basis, and at higher data rates than previous generations. There is no formal definition for what 4G is; however, there are certain objectives that are projected for 4G.

These objectives include: that 4G will be a fully IP-based integrated system. This will be achieved after wired and wireless technologies converge and will be capable of providing 100 Mbit/s and 1 Gbit/s speeds both indoors and outdoors, with premium quality and high security. 4G will offer all types of services at an affordable cost.

Objective and Approach
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Objectives
4G is being developed to accommodate the quality of service (QoS) and rate requirements set by forthcoming applications like wireless broadband access, Multimedia Messaging Service, video chat, mobile TV, High definition TV content, DVB, minimal service like voice and data, and other streaming services for "anytime-anywhere". The 4G working group has defined the following as objectives of the 4G wireless communication standard:

-A spectrally efficient system (in bits/s/Hz and bit/s/Hz/site),
-High network capacity: more simultaneous users per cell,
-A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R,
-A data rate of at least 100 Mbit/s between any two points in the world,
-Smooth handoff across heterogeneous networks,
-Seamless connectivity and global roaming across multiple networks,
-High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc)
-Interoperability with existing wireless standards, and
-An all IP, packet switched network.
In summary, the 4G system should dynamically share and utilise network resources to meet the minimal requirements of all the 4G enabled users.

Approaches
As described in 4G consortia including WINNER, WINNER - Towards Ubiquitous Wireless Access, and WWRF, a key technology based approach is summarized as follows, where Wireless-World-Initiative-New-Radio (WINNER) is a consortium to enhance mobile communication systems.

Consideration points
-Coverage, radio environment, spectrum, services, business models and deployment types, users

Principal technologies
-Baseband techniques
--OFDM: To explot the frequency selective channel property
--MIMO: To attain ultra high spectral efficiency
--Turbo principle: To minimize the required SNR at the reception side
-Adaptive radio interface
-Modulation, MIMO spatial processing including multi-antenna and multi-user MIMO, relaying including fixed relay networks (FRNs) and the cooperative relaying concept, multi-mode protocol
It introduces a single new ubiquitous radio access system concept, which is flexible to a variety levels of beyond 3G wireless systems.

Wireless System Evolution
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First generation: Almost all of the systems from this generation were analog systems where voice was considered to be the main traffic. These systems could often be listened to by third parties. some of the standards are NMT, AMPS, Hicap, CDPD, Mobitex, DataTac

Second generation: All the standards belonging to this generation are commercial centric and they are digital in form. Around 60% of the current market is dominated by European standards. The second generation standards are GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, and WiDEN.

Third generation: To meet the growing demands in the number of subscribers (increase in network capacity), rates required for high speed data transfer and multimedia applications, 3G standards started evolving. The systems in this standard are basically a linear enhancement of 2G systems. They are based on two parallel backbone infrastructures, one consisting of circuit switched nodes, and one of packet oriented nodes. The ITU defines a specific set of air interface technologies as third generation, as part of the IMT-2000 initiative. Currently, transition is happening from 2G to 3G systems. As a part of this transition, lot of technologies are being standardized. From 2G to 3G: 2.75G - EDGE and EGPRS, 3G - CDMA 2000,W-CDMA or UMTS (3GSM), FOMA, 1xEV-DO/IS-856, TD-SCDMA, GAN/UMA. Similarly from 3G to 4G: 3.5G - HSDPA, HSUPA, Super3G - HSOPA/LTE

Fourth generation: According to the 4G working groups, the infrastructure and the terminals of 4G will have almost all the standards from 2G to 4G implemented. Even though the legacy systems are in place to be adopted in 4G for the existing legacy users, going forward the infrastructure will however only be packet based, all-IP. Also, some proposals suggest having an open platform where the new innovations and evolutions can fit. The technologies which are being considered as pre-4G are used in the following standard version: WiMax, WiBro, 3GPPLong Term Evolution and 3GPP2 Ultra Mobile Broadband.

Components
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Access schemes
As the wireless standards evolved, the access techniques used also exhibited increase in efficiency, capacity and scalability. The first generation wireless standards used plain TDMA and FDMA. In the wireless channels, TDMA proved to be less efficient in handling the high data rate channels as it requires large guard periods to alleviate the multipath impact. Similarly, FDMA consumed more bandwidth for guard to avoid inter carrier interference. So in second generation systems, one set of standard used the combination of FDMA and TDMA and the other set introduced a new access scheme called CDMA. Usage of CDMA increased the system capacity and also placed a soft limit on it rather than the hard limit. Data rate is also increased as this access scheme is efficient enough to handle the multipath channel. This enabled the third generation systems to used CDMA as the access scheme IS-2000, UMTS, HSXPA, 1xEV-DO, TD-CDMA and TD-SCDMA. The only issue with the CDMA is that it suffers from poor spectrum flexibility and scalability.

Recently, new access schemes like Orthoganal FDMA, Single Carrier FDMA, Interleaved FDMA and Multi-carrier code division multiple access are gaining more importance for the next generation systems. WiMax is using OFDMA in the downlink and in the uplink. For the next generation UMTS, OFDMA is being considered for the downlink. By contrast, IFDMA is being considered for the uplink since OFDMA contributes more to the PAPR related issues and results in nonlinear operation of amplifiers. IFDMA provides less power fluctuation and thus avoids amplifier issues. Similarly, MC-CDMA is in the proposal for the IEEE 802.20 standard. These access schemes offer the same efficiencies as older technologies like CDMA. Apart from this, scalability and higher data rates can be achieved.

The other important advantage of the above mentioned access techniques is that they require less complexity for equalization at the receiver. This is an added advantage especially in the MIMO environments since the spatial multiplexing transmission of MIMO systems inherently requires high complexity equalization at the receiver.

In addition to improvements in these multiplexing systems, improved modulation techniques are being used. Whereas earlier standards largely used Phase-shift keying, more efficient systems such as 64QAM are being proposed for use with the 3GPP Long Term Evolution standards.

IPv6
Unlike 3G, which is based on two parallel infrastructures consisting of circuit switched and packet switched network nodes respectively, 4G will be based on packet switching only. This will require low-latency data transmission.

It is generally believed that 4th generation wireless networks will support a greater number of wireless devices that are directly addressable and routable. Therefore, in the context of 4G, IPv6 is an important network layer technology and standard that can support a large number of wireless-enabled devices. By increasing the number of IP addresses, IPv6 removes the need for Network Address Translation (NAT), a method of sharing a limited number of addresses among a larger group of devices.

In the context of 4G, IPv6 also enables a number of applications with better multicast, security, and route optimization capabilities. With the available address space and number of addressing bits in IPv6, many innovative coding schemes can be developed for 4G devices and applications that could aid deployment of 4G networks and services.

Advanced Antenna Systems
The performance of radio communications obviously depends on the advances of an antenna system, refer to smart or intelligent antenna. Recently, multiple antenna technologies are emerging to achieve the goal of 4G systems such as high rate, high reliability, and long range communications. In the early 90s, to cater the growing data rate needs of data communication, many transmission schemes were proposed. One technology, spatial multiplexing, gained importance for its bandwidth conservation and power efficiency. Spatial multiplexing involves deploying multiple antennas at the transmitter and at the receiver. Independent streams can then be transmitted simultaneously from all the antennas. This increases the data rate into multiple folds with the number equal to minimum of the number of transmit and receive antennas. This is called MIMO (as a branch of intelligent antenna). Apart from this, the reliability in transmitting high speed data in the fading channel can be improved by using more antennas at the transmitter or at the receiver. This is called transmit or receive diversity. Both transmit/receive diversity and transmit spatial multiplexing are categorized into the space-time coding techniques, which does not necessary require the channel knowledge at the transmit. The other category is closed-loop multiple antenna technologies which use the channel knowledge at the transmitter.

Software-Defined Radio (SDR)
SDR is one form of open wireless architecture (OWA). Since 4G is a collection of wireless standards, the final form of a 4G device will constitute various standards. This can be efficiently realized using SDR technology, which is categorized to the area of the radio convergence.

Developments
--------------------------------------
The Japanese company NTT DoCoMo has been testing a 4G communication system prototype with 4x4 MIMO called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo recently reached 5 Gbit/s with 12x12 MIMO while moving at 10 km/h, and is planning on releasing the first commercial network in 2010.

Digiweb, an Irish fixed and wireless broadband company, has announced that they have received a mobile communications license from the Irish Telecoms regulator, ComReg. This service will be issued the mobile code 088 in Ireland and will be used for the provision of 4G Mobile communications.

Pervasive networks are an amorphous and presently entirely hypothetical concept where the user can be simultaneously connected to several wireless access technologies and can seamlessly move between them (See handover, IEEE 802.21). These access technologies can be Wi-Fi, UMTS, EDGE, or any other future access technology. Included in this concept is also smart-radio (also known as cognitive radio technology) to efficiently manage spectrum use and transmission power as well as the use of mesh routing protocols to create a pervasive network.

Sprint plans to launch 4G services in trial markets by the end of 2007 with plans to deploy a network that reaches as many as 100 million people in 2008.... and has announced WiMax service called Xohm. Tested in Chicago, this speed was clocked at 100 Mbit/s.

Verizon Wireless announced on September 20, 2007 that it plans a joint effort with the Vodafone Group to transition its networks to the 4G standard LTE. The time of this transition has yet to be announced.

The German WiMAX operator Deutsche Breitband Dienste (DBD) has launched WiMAX services (DSLonair) in Magdeburg and Dessau. The subscribers are offered a tariff plan costing 9.95 euros per month offering 2 Mbit/s download / 300 kbit/s upload connection speeds and 1.5 GB monthly traffic. The subscribers are also charged a 16.99 euro one-time fee and 69.90 euro for the equipment and installation.DBD received additional national licenses for WiMAX in December 2006 and have already launched the services in Berlin, Leipzig and Dresden.

American WiMAX services provider Clearwire made its debut on Nasdaq in New York on March 8, 2007. The IPO was underwritten by Merrill Lynch, Morgan Stanley and JP Morgan. Clearwire sold 24 million shares at a price of $25 per share. This adds $600 million in cash to Clearwire, and gives the company a market valuation of just over $3.9 billion.

Applications
--------------------------------------
The killer application of 4G is not clear, though the improved bandwidths and data throughput offered by 4G networks should provide opportunities for previously impossible products and services to be released. Perhaps the "killer application" is simply to have mobile always on Internet, no walled garden and reasonable flat rate per month charge. Existing 2.5G/3G/3.5G phone operator based services are often expensive, and limited in application.

Already at rates of 15-30 Mbit/s, 4G should be able to provide users with streaming high-definition television. At rates of 100 Mbit/s, the content of a DVD, for example a movie, can be downloaded within about 5 minutes for offline access.

Pre-4G Wireless Standards
--------------------------------------
According to a Visant Strategies study there will be multiple competitors in this space:

-WiMAX - 7.2 million units by 2010 (May include fixed and mobile)
-Flash-OFDM - 13 million subscribers in 2010 (only Mobile)
-3GPP Long Term Evolution of UMTS in 3GPP - valued at US$2 billion in 2010 (~30% of the world population)
-UMB in 3GPP2
-IEEE 802.20
Fixed WiMax and Mobile WiMax are different systems, as of July 2007, all the deployed WiMax is "Fixed Wireless" and is thus not yet 4G (IMT-advanced) although it can be seen as one of the 4G standards being considered.

CentOS

2007-10-19T14:03:00.000+07:00

CentOS is a freely-available Linux distribution that is based on Red Hat's commercial product: Red Hat Enterprise Linux (RHEL). This rebuild project strives to be 100% binary compatible with the upstream product and, within its mainline and updates, not to vary from that goal. Additional software archives hold later versions of such packages, along with other Free and Open Source Software RPM-based packages. CentOS stands for Community ENTerprise Operating System.

RHEL is largely composed of free and open source software, but is made available in a usable, binary form (such as on CD-ROM or DVD-ROM) only to paying subscribers. As required, Red Hat releases all source code for the product publicly under the terms of the GNU General Public License and other licenses. CentOS developers use that source code to create a final product that is very similar to RHEL and freely available for download and use by the public, but not maintained or supported by Red Hat. There are other distributions derived from RHEL's source as well, but they have not attained the surrounding community that CentOS has built; CentOS is generally the one most current with Red Hat's changes.

CentOS' preferred software updating tool is based on yum, although support for use of an up2date variant exists. Each may be used to download and install both additional packages and their dependencies, and also to obtain and apply periodic and special (security) updates from repositories on the CentOS Mirror Network.

CentOS can be used as an X Window System-based desktop but, like RHEL, is targeted primarily at the server market. Some hosting companies rely on CentOS working together with the cPanel Control Panel.

Versioning scheme
-----------------------------------------
-CentOS version numbers have two parts, a major version and a minor version. The major version corresponds to the version of Red Hat Enterprise Linux from which the source packages used to build CentOS are taken. The minor version corresponds to the update set of that Red Hat Enterprise Linux version from which the source packages used to build CentOS are taken. For example, CentOS 4.4 is built from the source packages from Red Hat Enterprise Linux 4 update 4. CentOS refers to the source as "PNAELV" (Prominent North American Enterprise Linux Vendor), which is an acronym referring to Red Hat, coined in response to questions raised by Red Hat's legal counsel in a letter to project members regarding possible trademark issues.
-Since mid-2006, starting with RHEL 4.4 (formerly known as RHEL 4.0 update 4), Red Hat have adopted a versioning convention identical to that of CentOS, e.g., RHEL 4.5 or RHEL 3.9. See this Red Hat Knowledge Base article for more information.

NTT DoCoMo

2007-10-01T01:45:00.000+07:00

NTT DoCoMo, Inc. (株式会社エヌ・ティ・ティ・ドコモ, Kabushiki-gaisha Enutiti Dokomo?, TYO: 9437, NYSE: DCM, LSE: NDCM) is the predominant mobile phone operator in Japan. The name is officially an abbreviation of the phrase Do Communications Over the Mobile Network, and is also a play on dokomo, meaning “everywhere” in Japanese.

DoCoMo was spun off from Nippon Telegraph and Telephone (NTT) in August 1991 to take over the mobile cellular operations. DoCoMo provides 2G (MOVA) PDC cellular services in 800 MHz and 1.5 GHz bands (total 34 MHz bandwidth), and 3G (FOMA) W-CDMA services in the 2 GHz (1945-1960 MHz) band. Its businesses also include PHS (Paldio), paging, and satellite. DoCoMo has announced that its PHS services will be phased out over the next few years.

DoCoMo provides phone, video phone (FOMA and Some PHS), i-mode (internet), and mail (i-mode mail, Short Mail, and SMS) services.

Customers
-----------------------------
NTT DoCoMo is a subsidiary of Japan's incumbent telephone operator NTT. The majority of NTT-DoCoMo's shares are owned by NTT (which is 31% to 55% government-owned). While some NTT shares are publicly traded, control of the company by Japanese interests (Government and civilian) is guaranteed by the number of shares available to buyers. It provides wireless voice and data communications to many subscribers in Japan. NTT DoCoMo is the creator of W-CDMA technology as well as mobile i-mode service.

NTT DoCoMo has more than 50 million customers, which means more than half of Japan’s cellular market. The company provides a wide variety of mobile multimedia services. These include i-mode which provides e-mail and internet access to over 50 million subscribers, and FOMA, launched in 2001 as the world's first 3G mobile service based on W-CDMA.

In addition to wholly owned subsidiaries in Europe and North America, the company is expanding its global reach through strategic alliances with mobile and multimedia service providers in Asia-Pacific and Europe. NTT DoCoMo is listed on the Tokyo (9437), London (NDCM), and New York (DCM) stock exchanges.

Services
-----------------------------------------------------
i-mode
i-mode is NTT DoCoMo’s proprietary mobile internet platform and as of October 2006 boasts 47 million customers in Japan. This excludes overseas users over networks in 15 other countries, as of November 2005, through i-mode licensing agreements with cellular phone operators.

With i-mode, mobile phone users get benefits such as mobile reservations, supporting secure transactions and keeping up to date with the latest information. They're able to get easy access to thousands of Internet sites, as well as specialized services such as e-mail, online shopping, Mobile Banking, ticket reservations, and restaurant reviews. Mobile users can access sites from anywhere in Japan, and at unusually low rates, because their charges are based on the volume of data transmitted, not the airtime. NTT DoCoMo's i-mode network structure not only provides access to i-mode and i-mode-compatible content through the Internet, but also provides access through a dedicated leased-line circuit for added security. Doja the Java environment specification for i-mode adds further functionality.

Takeshi Natsuno won the Wharton Infosys Business Transformation Award in 2002 for his innovative strategical work on i-mode.
FOMA
DoCoMo was the first mobile operator in the world to commercially roll-out 3G mobile communications. DoCoMo's 3G services are marketed under the brand FOMA. At present (2005) FOMA uses wCDMA technology with a data rate of 384 kbit/s. Since DoCoMo was the first carrier to roll out 3G network technology, DoCoMo used technologies different from the European UMTS standards, which were not ready early enough for DoCoMo's roll-out. Recently DoCoMo is working to modify FOMA to conform fully with UMTS standards over time.

HSDPA
DoCoMo is working to upgrade the data rates towards 14.4 Mbit/s using HSDPA. Up to 3.6 Mbit/s per cell in the downlink service has launched in August 2005

Ownership
-----------------------------------------------------
NTT DoCoMo's shares are publicly traded on several stock exchanges, with the major shareholder (over 55%) being Japan's incumbent operator NTT. NTT is also a publicly traded corporation and the majority share holder is the Government of Japan.

R&D
-----------------------------------------------------
While most mobile operators globally do not perform any significant R&D and rely on equipment suppliers for the development and supply of new communication equipment, NTT DoCoMo continues the NTT tradition of very extensive R&D efforts. It was mainly DoCoMo's strong R&D investments which allowed DoCoMo to introduce 3G communications and i-mode data services long before such services were introduced anywhere else in the world.

DoCoMo's investments outside Japan
-----------------------------------------------------
NTT DoCoMo has a wide range of foreign investments. However, NTT DoCoMo was not successful in investing in foreign carriers. DoCoMo had invested very large multi-billion dollar amounts in KPN, Hutchison Telecom (included 3, Hutch, etc.), KTF, AT&T Wireless, and had to write-off or sell all these investments in foreign carriers. As a result, DoCoMo booked a total of about US$ 10 billion in losses, while during the same time DoCoMo's Japan operations were profitable.

Access DoCoMo outside Japan
-----------------------------------------------------

DoCoMo/Vodafone PDC phones
PDC phones do not work in foreign countries. PDC is deployed only in Japan.
Most DoCoMo "FOMA" phones (except roaming-ready models) and Vodafone Japan 802N, 703N and 905SH
These are W-CDMA-only phones, so they cannot be used with GSM networks. Also note that they cannot be used with a foreign operator's subscription because they do not accept other operators' SIM cards.
Vodafone 3G phones (except 802N, 703N and 905SH) and DoCoMo "FOMA" roaming-ready phones These phones will work with foreign GSM networks (with the exception of the 903i and 904i series which only have WCDMA roaming capability). However, they cannot be used with a foreign operator's subscription until they are unlocked. This can be done for the N900iG, the M1000, and most of the Vodafone-branded 3G phones (except the 904SH and the 705SH).
KDDI phones can not be used outside Japan, with the exception of the Global Passport models. Those cannot be used locally on non-Japanese networks, however, because of the use of a non-standard ESN (5 letters followed by 6 numbers).
Much like U.S. CDMA phones, Japanese phones are designed for their respective operators (except recent Vodafone 3G phones) and will not work with a foreign operator's subscription. In other words, the fact that a Japanese phone is technically capable of working in a foreign country does not mean it can be used with a local operator's service out of the box.

High-Definition Multimedia Interface (HDMI)

2007-09-16T16:57:00.000+07:00

The High-Definition Multimedia Interface (HDMI) is a licensable audio/video connector interface for transmitting uncompressed, encrypted digital streams. HDMI connects DRM-enforcing digital audio/video sources, such as a set-top box, a Blu-ray Disc player, a PC running Windows Vista, a video game console, or an AV receiver, to a compatible digital audio device and/or video monitor, such as a digital television (DTV). HDMI began to appear in 2006 on prosumer HDTV camcorders and high-end digital still cameras.

It represents the DRM alternative to consumer analog standards such as RF (coaxial cable), composite video, S-Video, SCART, component video and VGA, and digital standards such as DVI (DVI-D and DVI-I).

General notes
--------------------------------------------
HDMI supports any TV or PC video format, including standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It is independent of the various DTV standards such as ATSC, and DVB (-T,-S,-C), as these are encapsulations of the MPEG movie data streams, which are passed off to a decoder, and output as uncompressed video data on HDMI. HDMI encodes the video data into TMDS for transmission digitally over HDMI.

Devices are manufactured to adhere to various versions of the specification, where each version is given a number, such as 1.0 or 1.3. Each subsequent version of the specification uses the same cables, but increases the throughput and/or capabilities of what can be transmitted over the cable. For example, previously, the maximum pixel clock rate of the interface was 165 MHz, sufficient for supporting 1080p at 60 Hz or WUXGA (1920x1200), but HDMI 1.3 increased that to 340 MHz, providing support for WQXGA (2560x1600) and beyond across a single digital link. See also: HDMI Versions.

HDMI also includes support for 8-channel uncompressed digital audio at 192 kHz sample rate with 24 bits/sample as well as any compressed stream such as Dolby Digital, or DTS. HDMI supports up to 8 channels of one-bit audio, such as that used on Super Audio CDs at rates up to 4x that used by Super Audio CD. With version 1.3, HDMI now also supports lossless compressed streams such as Dolby TrueHD and DTS-HD Master Audio.

HDMI is backward-compatible with the single-link Digital Visual Interface carrying digital video (DVI-D or DVI-I, but not DVI-A) used on modern computer monitors and graphics cards. This means that a DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable, but the audio and remote control features of HDMI will not be available. Additionally, without support for High-bandwidth Digital Content Protection (HDCP) on the display, the signal source may prevent the end user from viewing or recording certain restricted content.

In the U.S., HDCP-support is a standard feature on digital TVs with built-in digital (ATSC) tuners, (it does not feature on the cheapest digital TVs, as they lack HDMI altogether). Among the PC-display industry, where computer displays rarely contain built-in tuners, HDCP support is absent from many models. For example, the first LCD monitors with HDMI connectors did not support HDCP, and few compact-LCD monitors (17" or smaller) support HDCP.

The HDMI Founders include consumer electronics manufacturers Hitachi, Matsushita Electric Industrial (Panasonic/National/Quasar), Philips, Sony, Thomson (RCA), Toshiba, and Silicon Image. Digital Content Protection, LLC (a subsidiary of Intel) is providing HDCP for HDMI. In addition, HDMI has the support of major motion picture producers Fox, Universal, Warner Bros., and Disney, and system operators DirecTV and EchoStar (Dish Network) as well as CableLabs and Samsung.

Specifications
--------------------------------------------
HDMI defines the protocol and electrical specifications for the signaling, as well as the pin-out, electrical and mechanical requirements of the cable and connectors.

Connectors
The HDMI Specification has expanded to include three connectors, each intended for different markets.

The standard Type A HDMI connector has 19 pins, with bandwidth to support all SDTV, EDTV and HDTV modes and more. The plug outside dimensions are 13.9 mm wide by 4.45 mm high. Type A is electrically compatible with single-link DVI-D.

A higher resolution version called Type B is defined in HDMI 1.0. Type B has 29 pins (21.2 mm wide), allowing it to carry an expanded video channel for use with very high-resolution future displays, such as WQSXGA (3200x2048). Type B is electrically compatible with dual-link DVI-D, but is not in general use.

The Type C mini-connector is intended for portable devices. It is smaller than Type A (10.42 mm by 2.42 mm) but has the same 19-pin configuration.

Cable
The HDMI cable can be used to carry video, audio, and/or device-controlling signals (CEC). Adaptor cables, from Type A to Type C, are available.

TMDS channel
The Transition Minimized Differential Signaling (TMDS) channel:

-Carries video, audio, and auxiliary data via one of three modes called the Video Data Period, the Data Island Period, and the Control Period. During the Video Data Period, the pixels of an active video line are transmitted. During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets. The Control Period occurs between Video and Data Island periods.
-Signaling method: Formerly according to DVI 1.0 spec. Single-link (Type A HDMI) or dual-link (Type B HDMI).
-Video pixel rate: 25 MHz to 340 MHz (Type A, as of 1.3) or to 680 MHz (Type B). Video formats with rates below 25 MHz (e.g. 13.5 MHz for 480i/NTSC) transmitted using a pixel-repetition scheme. From 24 to 48 bits per pixel can be transferred, regardless of rate. Supports 1080p at rates up to 120 Hz and WQSXGA.
-Pixel encodings: RGB 4:4:4, YCbCr 4:4:4 (8–16 bits per component); YCbCr 4:2:2 (12 bits per component)
-Audio sample rates: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz.
-Audio channels: up to 8.
-Audio streams: any IEC61937-compliant stream, including high bitrate (lossless) streams (Dolby TrueHD, DTS-HD Master Audio).

Consumer Electronics Control channel
The Consumer Electronics Control (CEC) channel is optional to implement, but wiring is mandatory. The channel:

-Uses the industry standard AV Link protocol.
-Used for remote control functions.
-One-wire bidirectional serial bus.
-Defined in HDMI Specification 1.0, updated in HDMI 1.2a, and again in 1.3a (added timer and audio commands).
This feature is used in two ways:

-To allow the user to command and control multiple CEC-enabled boxes with one remote control, and
-To allow individual CEC-enabled boxes to command and control each other, without user intervention.
An example of the latter is to allow the DVD player, when the drawer closes with a disk, to command the TV and the intervening A/V Receiver (all with CEC) to power-up, select the appropriate HDMI ports, and auto-negotiate the proper video mode and audio mode. No remote control command is needed. Similarly, this type of equipment can be programmed to return to sleep mode when the movie ends, perhaps by checking the real-time clock. For example, if it is later than 11:00 p.m., and the user does not specifically command the systems with the remote control, then the systems all turn off at the command from the DVD player.

Alternative names for CEC are Anynet (Samsung), BRAVIA Theatre Sync (Sony), Regza Link (Toshiba), RIHD (Onkyo) and Viera Link/EZ-Sync (Panasonic/JVC).

Content protection
-According to High-bandwidth Digital Content Protection (HDCP) Specification 1.2.
-Beginning with HDMI CTS 1.3a, any system which implements HDCP must do so in a fully-compliant manner. HDCP compliance is itself part of the requirements for HDMI compliance.
-The HDMI repeater bit, technically the HDCP repeater bit, controls the authentication and switching/distribution of an HDMI signal.

Versions
--------------------------------------------

Devices are manufactured to adhere to various versions of the specification, where each version is given a revision number. Each subsequent version of the specification uses the same cables, but increases the throughput and capabilities of what can be transmitted over that cable. The need for a new HDMI cable if you already have one really depends on the cable (which also has a HDMI rating). The main thing to consider is if any current cable would be able to handle the increased bandwidth—for example the 10.2 Gbit/s that comes with version 1.3. Cable compliance testing is included in the HDMI Compliance Test Specification (see TESTID 5-3), with "Category 1" and "Category 2" defined in the HDMI Specification 1.3a (Section 4.2.6).

A product listed as having an HDMI version does not necessarily mean that it will have all of the features listed under the version classification, indeed some of the features are optional. For example in HDMI v1.3 it is optional to support the xvYCC wide color standard. This means if you have bought a camcorder that supports the wide color space (which for example is branded by Sony as "x.v.Color") you have to specifically check that the display supports both HDMI v1.3 and the xvYCC wide color standard.

HDMI 1.0
Released December 2002.

-Single-cable digital audio/video connection with a maximum bitrate of 4.9 Gbit/s. Supports up to 165 Mpixel/s video (1080p60 Hz or UXGA) and 8-channel/192 kHz/24-bit audio.

HDMI 1.1
Released May 2004.

-Added support for DVD Audio.

HDMI 1.2
Released August 2005.

-Added support for One Bit Audio, used on Super Audio CDs, up to 8 channels.
-Availability of HDMI Type A connector for PC sources.
-Ability for PC sources to use native RGB color-space while retaining the option to support the YCbCr CE color space.
-Requirement for HDMI 1.2 and later displays to support low-voltage sources.

HDMI 1.2a
Released December 2005.

-Fully specifies Consumer Electronic Control (CEC) features, command sets, and CEC compliance tests.

HDMI 1.3
Released 22 June 2006.

-Increases single-link bandwidth to 340 MHz (10.2 Gbit/s)
-Optionally supports 30-bit, 36-bit, and 48-bit xvYCC with Deep Color or over one billion colors, up from 24-bit sRGB or YCbCr in previous versions.
-Incorporates automatic audio syncing (Audio video sync) capability.
-Optionally supports output of Dolby TrueHD and DTS-HD Master Audio streams for external decoding by AV receivers. TrueHD and DTS-HD are lossless audio codec formats used on HD DVDs and Blu-ray Discs. If the disc player can decode these streams into uncompressed audio, then HDMI 1.3 is not necessary, as all versions of HDMI can transport uncompressed audio.
-Availability of a new mini connector for devices such as camcorders.

HDMI 1.3a
Released 10 November 2006.

-Cable and Sink modifications for Type C
-Source termination recommendation
-Removed undershoot and maximum rise/fall time limits.
-CEC capacitance limits changed
-RGB video quantization range clarification
-CEC commands for timer control brought back in an altered form, audio control commands added.
-Concurrently released compliance test specification included.

HDMI 1.3b
Testing specification released 26 March 2007.

Cable length
--------------------------------------------
The HDMI specification does not define a maximum cable length. As with all cables, signal attenuation becomes too high at a certain length. Instead, HDMI specifies a minimum performance standard. Any cable meeting that specification is compliant. Different construction quality and materials will enable cables of different lengths. In addition, higher performance requirements must be met to support video formats with higher resolutions and/or frame rates than the standard HDTV formats.

The signal attenuation and intersymbol interference caused by the cables can be compensated by using Adaptive Equalization.

HDMI 1.3 defined two categories of cables: Category 1 (standard or HDTV) and Category 2 (high-speed or greater than HDTV) to reduce the confusion about which cables support which video formats. Using 28 AWG, a cable of about 5 metres (~16 ft) can be manufactured easily and inexpensively to Category 1 specifications. Higher-quality construction (24 AWG, tighter construction tolerances, etc.) can reach lengths of 12 to 15 metres (~39 to 49 ft). In addition, active cables (fiber optic or dual Cat-5 cables instead of standard copper) can be used to extend HDMI to 100 metres or more. Some companies also offer amplifiers, equalizers and repeaters that can string several standard (non-active) HDMI cables together.

HDMI and high-definition optical media players
--------------------------------------------
Both introduced in 2006, Blu-ray Disc and HD DVD offer new high-fidelity audio features that require HDMI for best results. Dolby Digital Plus (DD+), Dolby TrueHD and DTS-HD Master Audio use bitrates exceeding TOSLINK's capacity. HDMI 1.3 can transport DD+, TrueHD, and DTS-HD bitstreams in compressed form. This capability would allow a preprocessor or audio/video receiver with the necessary decoder to decode the data itself, but has limited usefulness for HD DVD and Blu-ray.

HD DVD and Blu-ray permit "interactive audio", where the disc-content tells the player to mix multiple audio sources together, before final output. Consequently, most players will handle audio-decoding internally, and simply output LPCM audio all the time. Multichannel LPCM can be transported over an HDMI 1.1 (or higher) connection. As long as the audio/video receiver (or preprocessor) supports multi-channel LPCM audio over HDMI, and supports HDCP, the audio reproduction is equal in resolution to HDMI 1.3. However, many of the cheapest AV receivers do not support audio over HDMI and are often labeled as "HDMI passthrough" devices.

Note that all of the features of an HDMI version may not be implemented in products adhering to that version since certain features of HDMI, such as Deep Color and xvYCC support, are optional.

Criticism
--------------------------------------------
Among manufacturers, the HDMI specification has been criticized as lacking in functional usefulness. The public specification devotes many pages to the lower-level protocol layers (physical, electrical, logical); there is inadequate documentation for the system framework. HDMI-peripherals include audio/video sources, audio-only receivers, audio-video receivers, video-only receivers, repeaters (which have more downstream ports than upstream ports), and switchers (which have more upstream ports than downstream ports). The specification stops short of offering examples of system behavior involving multiple HDMI-devices, leaving implementation to the product engineer's interpretation. Even between devices which use chips from Silicon Image (a promoter and supplier of HDMI IP and silicon), interoperability is not assured. The industry is working to improve through plugfest events (i.e. manufacturer conferences) and more comprehensive design-validation services.

Another criticism of HDMI is that the connectors are not as robust as previous display connectors. Currently most devices with HDMI capability are utilizing surface-mount connectors rather than through-hole or reinforced connectors, making them more susceptible to damage from exterior forces. Tripping over a cable plugged into an HDMI port can easily cause damage to that port.

Closed captioning problems
According to the HDMI Specification, all video timings carried across the link for standard video modes (such as 720p, 1080i, etc.) must have horizontal and video timings matching those defined in the CEA-861D Specification. Since those definitions allow only for the visual portion of the frame (or field, for interlaced video modes), there is no line transmitted for closed captions. Line 21 is not part of the transmitted data as it is in analog modes. For HDMI it is but one of the non-data lines in the vertical blanking interval.

Although an HDMI display is allowed to define a 'native mode' for video, which could expand the active line count to encompass Line 21, most MPEG decoders cannot format a digital video stream to include extra lines—they send only vertical blanking. Even if it were possible, the closed captioning character codes would have to be encoded in some way into the pixel values in Line 21. This would then require the receiver logic in the display to decode those codes and construct the captions.

It is possible, although not standardized, that some measure of content in text form can be transmitted from Source to Sink using CEC commands, or using InfoFrame packets. Again, as there is no standardized format for such data it would likely work only between a source and sink system from the same manufacturer. Such uniqueness goes against the standardization mission of HDMI, which is focused in part on interoperability.

Of course, it is possible that a future enhancement of the HDMI Specification may encompass closed caption transport.

From Wikipedia, the free encyclopedia

Multiprotocol Label Switching (MPLS)

2007-09-13T15:36:00.000+07:00

In computer networking and telecommunications, Multi Protocol Label Switching (MPLS) is a data-carrying mechanism that belongs to the family of packet-switched networks. MPLS operates at an OSI Model layer that is generally considered to lie between traditional definitions of Layer 2 (data link layer) and Layer 3 (network layer), and thus is often referred to as a "Layer 2.5" protocol. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, SONET, and Ethernet frames.

Background
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A number of different technologies were previously deployed with essentially identical goals, such as frame relay and ATM. MPLS is now replacing these technologies in the marketplace, mostly because it is better aligned with current and future technology needs.

In particular, MPLS dispenses with the cell-switching and signaling-protocol baggage of ATM. MPLS recognizes that small ATM cells are not needed in the core of modern networks, since modern optical networks (as of 2001) are so fast (at 10 Gbit/s and well beyond) that even full-length 1500 byte packets do not incur significant real-time queuing delays (the need to reduce such delays, to support voice traffic, having been the motivation for the cell nature of ATM).

At the same time, it attempts to preserve the traffic engineering and out-of-band control that made frame relay and ATM attractive for deploying large-scale networks.

MPLS was originally proposed by a group of engineers from Ipsilon_Networks, but their "IP Switching" technology, which was defined only to work over ATM, did not achieve market dominance. Cisco Systems, Inc. introduced a related proposal, not restricted to ATM transmission, called "Tag Switching" when it was a Cisco proprietary proposal, and was renamed "Label Switching" when it was handed over to the IETF for open standardization. The IETF work involved proposals from other vendors, and development of a consensus protocol that combined features from several vendors' work.

One original motivation was to allow the creation of simple high-speed switches, since for a significant length of time it was impossible to forward IP packets entirely in hardware. However, advances in VLSI have made such devices possible. Therefore the advantages of MPLS primarily revolve around the ability to support multiple service models and perform traffic management. MPLS also offers a robust recovery framework that goes beyond the simple protection rings of synchronous optical networking (SONET/SDH).

While the traffic management benefits of migrating to MPLS are quite valuable (better reliability, increased performance), there is a significant loss of visibility and access into the MPLS cloud for IT departments.

How MPLS works
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MPLS works by preappending packets with an MPLS header, containing one or more 'labels'. This is called a label stack.

Each label stack entry contains four fields:

-a 20-bit label value.
-a 3-bit field for QoS priority (experimental).
-a 1-bit bottom of stack flag. If this is set, it signifies the current label is the last in the stack.
-an 8-bit TTL (time to live) field.
These MPLS labeled packets are switched after a Label Lookup/Switch instead of a lookup into the IP table. As mentioned above, when MPLS was conceived, Label Lookup and Label Switching was faster than a RIB lookup because it could take place directly within the switched fabric and not the CPU.

The entry and exit points of an MPLS network are called Label Edge Routers (LER), which, respectively, push an MPLS label onto the incoming packet and pop it off the outgoing packet. Routers that perform routing based only on the label are called Label Switch Routers (LSR). In some applications, the packet presented to the LER already may have a label, so that the new LSR pushes a second label onto the packet. For more information see Penultimate Hop Popping.

In the specific context of a MPLS based Virtual Private Network (VPN), LSRs that function as ingress and/or egress routers to the VPN. are often called PE (Provider Edge) routers. Devices that function only as transit routers are similarly called P (Provider) routers. See RFC2547. The job of a P router is significantly easier than that of a PE router, so they can be less complex and may be more dependable because of this.

When an unlabeled packet enters the ingress router and needs to be passed on to an MPLS tunnel, the router first determines the forwarding equivalence class the packet should be in, and then inserts one or more labels in the packet's newly created MPLS header. The packet is then passed on to the next hop router for this tunnel.

When a labeled packet is received by an MPLS router, the topmost label is examined. Based on the contents of the label a swap, push (impose) or pop (dispose) operation can be performed on the packet's label stack. Routers can have prebuilt lookup tables that tell them which kind of operation to do based on the topmost label of the incoming packet so they can process the packet very quickly. In a swap operation the label is swapped with a new label, and the packet is forwarded along the path associated with the new label.

In a push operation a new label is pushed on top of the existing label, effectively "encapsulating" the packet in another layer of MPLS. This allows the hierarchical routing of MPLS packets. Notably, this is used by MPLS VPNs.

In a pop operation the label is removed from the packet, which may reveal an inner label below. This process is called "decapsulation". If the popped label was the last on the label stack, the packet "leaves" the MPLS tunnel. This is usually done by the egress router, but see PHP below.

During these operations, the contents of the packet below the MPLS Label stack are not examined. Indeed transit routers typically need only to examine the topmost label on the stack. The forwarding of the packet is done based on the contents of the labels, which allows "protocol independent packet forwarding" that does not need to look at a protocol-dependent routing table and avoids the expensive IP longest prefix match at each hop.

At the egress router, when the last label has been popped, only the payload remains. This can be an IP packet, or any of a number of other kinds of payload packet. The egress router must therefore have routing information for the packet's payload, since it must forward it without the help of label lookup tables. An MPLS transit router has no such requirement.

In some special cases, the last label can also be popped off at the penultimate hop (the hop before the egress router). This is called Penultimate Hop Popping (PHP). This may be interesting in cases where the egress router has lots of packets leaving MPLS tunnels, and thus spends inordinate amounts of CPU time on this. By using PHP, transit routers connected directly to this egress router effectively offload it, by popping the last label themselves.

MPLS can make use of existing ATM network infrastructure, as its labeled flows can be mapped to ATM virtual circuit identifiers, and vice-versa.

Installing and removing MPLS paths
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There are two standardized protocols for managing MPLS paths: CR-LDP (Constraint-based Routing Label Distribution Protocol) and RSVP-TE, an extension of the RSVP protocol for traffic engineering. Also an extension of BGP protocol can be used to manage MPLS path.

An MPLS header does not identify the type of data carried inside the MPLS path. If one wants to carry two different types of traffic between the same two routers, with different treatment from the core routers for each type, one has to establish a separate MPLS path for each type of traffic.

Comparison of MPLS versus IP
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MPLS cannot be compared to IP as a separate entity because it works in conjunction with IP and IP's IGP routing protocols. MPLS gives IP networks simple traffic engineering, the ability to transport Layer 3 (IP) VPNs with overlapping address spaces, and support for Layer 2 pseudo wires (with Any Transport Over MPLS, or ATOM - see Martini draft). Routers with programmable CPUs and without TCAM/CAM or another method for fast lookups may also see a limited increase in the performance.

MPLS relies on IGP routing protocols to construct its label forwarding table, and the scope of any IGP is usually restricted to a single carrier for stability and policy reasons. As there is still no standard for carrier-carrier MPLS it is not possible to have the same MPLS service (Layer2 or Layer3 VPN) covering more than one operator.

MPLS local protection
In the event of a network element failure when recovery mechanisms are employed at the IP layer, restoration may take several seconds which is unacceptable for real-time applications (such as VoIP). In contrast, MPLS local protection meets the requirements of real-time applications with recovery times comparable to those of SONET rings (up to 50ms).

Comparison of MPLS versus ATM
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While the underlying protocols and technologies are different, both MPLS and ATM provide a connection-oriented service for transporting data across computer networks. In both technologies connections are signaled between endpoints, connection state is maintained at each node in the path and encapsulation techniques are used to carry data across the connection. Excluding differences in the signaling protocols (RSVP/LDP for MPLS and PNNI for ATM) there still remain significant differences in the behavior of the technologies.

The most significant difference is in the transport and encapsulation methods. MPLS is able to work with variable length packets while ATM transports fixed-length (53 byte) cells. Packets must be segmented, transported and re-assembled over an ATM network using an adaption layer, which adds significant complexity and overhead to the data stream. MPLS, on the other hand, simply adds a label to the head of each packet and transmits it on the network.

Differences exist, as well, in the nature of the connections. An MPLS connection (LSP) is uni-directional - allowing data to flow in only one direction between two endpoints. Establishing two-way communications between endpoints requires a pair of LSPs to be established. Because 2 LSPs are required for connectivity, data flowing in the forward direction may use a different path from data flowing in the reverse direction. ATM point-to-point connections (Virtual Circuits), on the other hand, are bi-directional, allowing data to flow in both directions over the same path (bi-directional are only svc ATM connections; pvc ATM connections are uni-directional).

Both ATM and MPLS support tunnelling of connections inside connections. MPLS uses label stacking to accomplish this while ATM uses Virtual Paths. MPLS can stack multiple labels to form tunnels within tunnels. The ATM Virtual Path Indicator (VPI) and Virtual Circuit Indicator (VCI) are both carried together in the cell header, limiting ATM to a single level of tunnelling.

The biggest single advantage that MPLS has over ATM is that it was designed from the start to be complementary to IP. Modern routers are able to support both MPLS and IP natively across a common interface allowing network operators great flexibility in network design and operation. ATM's incompatibilities with IP require complex adaptation making it largely unsuitable in today's predominantly IP networks.

MPLS deployment
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MPLS is currently in use in large "IP Only" networks, and is standardized by IETF in RFC 3031.

In practice, MPLS is mainly used to forward IP datagrams and Ethernet traffic. Major applications of MPLS are Telecommunications traffic engineering and MPLS VPN.

Competitors to MPLS
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MPLS can exist in both IPv4 environment (IPv4 routing protocols) and IPv6 environment (IPv6 routing protocols). The major goal of MPLS development - the increase of routing speed - is no longer relevant because of the usage of ASIC, TCAM and CAM based switching. Therefore the major usage of MPLS is to implement limited traffic engineering and Layer 3/Layer 2 “service provider type” VPNs over existing IPv4 networks. The only competitors to MPLS are technologies like L2TPv3 that also provide services such as service provider Layer 2 and Layer 3 VPNs.

IEEE 1355 is a completely unrelated technology that does something similar in hardware.

IPv6 references: Grosetete, Patrick, IPv6 over MPLS, Cisco Systems 2001; Juniper Networks IPv6 and Infranets White Paper; Juniper Networks DoD's Research and Engineering Community White Paper.

From Wikipedia, the free encyclopedia

Thaicom 4 (IPSTAR)

2007-09-13T15:30:00.000+07:00

Thaicom 4, also known as IPSTAR, is a broadband satellite built by Space Systems/Loral (SS/L) for Shin Satellite and was the heaviest commercial satellite launched as of August 2005. It was launched on August 11, 2005 from the European Space Agency's spaceport in French Guiana onboard the Ariane rocket. The satellite had a launch mass of 6486 kilograms. Thaicom 4 is from SS/L’s LS-1300 line of spacecraft.

The IPSTAR broadband satellite was designed for high-speed, 2-way broadband communication over an IP platform and is to play an important role in the broadband Internet/multimedia revolution and the convergence of information and communication technologies.

The satellite's 45 Gbit/s bandwidth capacity, in combination with its platform’s ability to provide an immediately available, high-capacity ground network with affordable bandwidth, allows for rapid deployment and flexible service locations within its footprint.

The IPSTAR system is comprised of a gateway earth station communicating over the IPSTAR satellite to provide broadband packet-switched communications to a large number of small terminals with network star configuration.

A wide-band data link from the gateway to the user terminal employs an Orthogonal Frequency Division Multiplexing (OFDM) with a Time Division Multiplex (TDM) overlay. These forward channels employ highly efficient transmission methods, including Turbo Product Code (TPC) and higher order modulation (L-codes) for increased system performance.

In the terminal-to-gateway direction (or return link), the narrow-band channels employ the same efficient transmission methods. These narrow-band channels operate in different multiple-access modes based on bandwidth-usage behavior, including Slotted-ALOHA, ALOHA, and TDMA for STAR return link waveform.

Spot Beam Coverage

Traditional satellite technology utilizes a broad single beam to cover entire continents and regions. With the introduction of multiple narrowly focused spot beams and frequency reuse, IPSTAR is capable of maximizing the available frequency for transmissions. Increasing bandwidth by a factor of twenty compared to traditional Ku-band satellites translates into better efficiencies. Despite the higher costs associated with spot beam technology, the overall cost per circuit is considerably lower as compared to shaped beam technology.

Dynamic Power Allocation

IPSTAR's Dynamic Power Allocation optimizes the use of power among beams and allocates a power reserve of 20 percent to be allocated to beams that may be affected by rain fade, thus maintaining the link.

From Wikipedia, the free encyclopedia

Storage area network (SAN)

2007-09-09T19:36:00.000+07:00

In computing, a storage area network (SAN) is an architecture to attach remote computer storage devices (such as disk arrays, tape libraries and optical jukeboxes) to servers in such a way that, to the operating system, the devices appear as locally attached. Although cost and complexity is dropping, as of 2007, SANs are still uncommon outside larger enterprises.

By contrast to a SAN, network-attached storage (NAS) uses file-based protocols such as NFS or SMB/CIFS where it is clear that the storage is remote, and computers request a portion of an abstract file rather than a disk block.

Network types
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Most storage networks use the SCSI protocol for communication between servers and disk drive devices. However, they do not use SCSI low-level physical interface (e.g. cables), as its bus topology is unsuitable for networking. To form a network, a mapping layer is used to other low-level protocols:

-Fibre Channel Protocol (FCP), mapping SCSI over Fibre Channel. Currently the most common. Comes in 1 Gbit/s, 2 Gbit/s, 4 Gbit/s, 8 Gbit/s, 10 Gbit/s variants.
-iSCSI, mapping SCSI over TCP/IP.
-HyperSCSI, mapping SCSI over Ethernet.
-FICON mapping over Fibre Channel (used by mainframe computers).
-ATA over Ethernet, mapping ATA over Ethernet.
-SCSI and/or TCP/IP mapping over InfiniBand (IB).

Storage sharing
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The driving force for the SAN market is rapid growth of highly transactional data that require high speed, block-level access to the hard drives (such as data from email servers, databases, and high usage file servers). Historically, enterprises were first creating "islands" of high performance SCSI disk arrays. Each island was dedicated to a different application and visible as a number of "virtual hard drives" (or LUNs).

SAN essentially enables connecting those storage islands using a high-speed network.

However, an operating system still sees SAN as a collection of LUNs and is supposed to maintain its own file systems on them. Still, the most reliable and most widely used are the local file systems, which cannot be shared among multiple hosts. If two independent local file systems resided on a shared LUN, they would be unaware of the fact, would have no means of cache synchronization and eventually would corrupt each other. Thus, sharing data between computers through a SAN requires advanced solutions, such as SAN file systems or clustered computing.

Despite such issues, SANs help to increase storage capacity utilization, since multiple servers share the same growth reserve on disk arrays.

In contrast, NAS allows many computers to access the same file system over the network and synchronizes their accesses. Lately, the introduction of NAS heads allowed easy conversion of SAN storage to NAS.

Benefits
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Sharing storage usually simplifies storage administration and adds flexibility since cables and storage devices do not have to be physically moved to move storage from one server to another.

Other benefits include the ability to allow servers to boot from the SAN itself. This allows for a quick and easy replacement of faulty servers since the SAN can be reconfigured so that a replacement server can use the LUN of the faulty server. This process can take as little as half an hour and is a relatively new idea being pioneered in newer data centers. There are a number of emerging products designed to facilitate and speed up this process still further. For example, Brocade offers an Application Resource Manager product which automatically provisions servers to boot off a SAN, with typical-case load times measured in minutes. While this area of technology is still new, many view it as being the future of the enterprise datacenter.

SANs also tend to enable more effective disaster recovery processes. A SAN could span a distant location containing a secondary storage array. This enables storage replication either implemented by disk array controllers, by server software, or by specialized SAN devices. Since IP WANs are often least costly method of long-distance transport, the Fibre Channel over IP (FCIP) and iSCSI protocols have been developed to allow SAN extension over IP networks. The traditional physical SCSI layer could only support a few meters of distance - not nearly enough to ensure business continuance in a disaster. Demand for this SAN application has increased dramatically after the September 11th attacks in the United States, and increased regulatory requirements associated with Sarbanes-Oxley and similar legislation.

Consolidation of disk arrays economically accelerated advancement of some of their advanced features. Those include I/O caching, snapshotting, volume cloning (Business Continuance Volumes or BCVs).

SAN infrastructure
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SANs often utilize a Fibre Channel fabric topology - an infrastructure specially designed to handle storage communications. It provides faster and more reliable access than higher-level protocols used in NAS. A fabric is similar in concept to a network segment in a local area network. A typical Fibre Channel SAN fabric is made up of a number of Fibre Channel switches.

Today, all major SAN equipment vendors also offer some form of Fibre Channel routing solution, and these bring substantial scalability benefits to the SAN architecture by allowing data to cross between different fabrics without merging them. These offerings use proprietary protocol elements, and the top-level architectures being promoted are radically different. They often enable mapping Fibre Channel traffic over IP or over SONET/SDH.

Compatibility
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One of the early problems with Fibre Channel SANs was that the switches and other hardware from different manufacturers were not entirely compatible. Although the basic storage protocols FCP were always quite standard, some of the higher-level functions did not interoperate well. Similarly, many host operating systems would react badly to other operating systems sharing the same fabric. Many solutions were pushed to the market before standards were finalized and vendors innovated around the standards.

The combined efforts of the members of the Storage Networking Industry Association (SNIA) improved the situation during 2002 and 2003. Today most vendor devices, from HBAs to switches and arrays, interoperate nicely, though there are still many high-level functions that do not work between different manufacturers’ hardware.

SANs at home
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SANs are primarily used in large scale, high performance enterprise storage operations. It would be unusual to find a single disk drive connected directly to a SAN. Instead, SANs are normally networks of large disk arrays. SAN equipment is relatively expensive, therefore, Fibre Channel host bus adapters are rare in desktop computers. The iSCSI SAN technology is expected to eventually produce cheap SANs, but it is unlikely that this technology will be used outside the enterprise data center environment. Desktop clients are expected to continue using NAS protocols such as CIFS and NFS. The exception to this may be remote storage replication.

SANs in the Media and Entertainment
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Video editing workgroups require very high data rates. Outside of the enterprise market, this is one area that greatly benefits from SANs.

Per-node bandwidth usage control, sometimes referred to as quality-of-service (QoS), is especially important in video workgroups as it lets you ensure a fair and prioritized bandwidth usage across your network. Avid Unity and Tiger Technology MetaSAN are specifically designed for video networks and offer this functionality.

Storage virtualization and SANs
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Storage virtualization refers to the process of completely abstracting logical storage from physical storage. The physical storage resources are aggregated into storage pools, from which the logical storage is created. It presents to the user a logical space for data storage and transparently handles the process of mapping it to the actual physical location. This is of course naturally implemented inside each modern disk array, using vendor's proprietary solution. However, the goal is to virtualize multiple disk arrays, made by different vendors, scattered over the network, into a single monolithic storage device, which can be managed unifromly.

Surface Computing (Microsoft Surface)

2007-09-09T02:17:00.000+07:00

Microsoft Surface is a forthcoming product from Microsoft which is developed as a software and hardware combination technology that allows a user, or multiple users, to manipulate digital content by the use of natural motions, hand gestures, or physical objects. It was announced on May 29, 2007 at D5, and is expected to be released by commercial partners in November 2007. Initial customers will be in the hospitality businesses, such as restaurants, hotels, retail, and public entertainment venues.

Overview
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Surface is essentially a Windows Vista PC tucked inside a black table base, topped with a 30-inch touchscreen in a clear acrylic frame. Five cameras that can sense nearby objects are mounted beneath the screen. Users can interact with the machine by touching or dragging their fingertips and objects such as paintbrushes across the screen, or by setting real-world items tagged with special barcode labels on top of it.

Surface has been optimized to respond to 52 touches at a time. During a demonstration with a reporter, Mark Bolger, the Surface Computing group's marketing director, "dipped" his finger in an on-screen paint palette, then dragged it across the screen to draw a smiley face. Then he used all 10 fingers at once to give the face a full head of hair.

In addition to recognizing finger movements, Microsoft Surface can also identify physical objects. Microsoft says that when a diner sets down a wine glass, for example, the table can automatically offer additional wine choices tailored to the dinner being eaten.

Prices will reportedly be $5,000 to $10,000 per unit. However Microsoft said it expects prices to drop enough to make consumer versions feasible in 3 to 5 years.

The machines, which Microsoft debuted May 30, 2007 at a technology conference in Carlsbad, California, are set to arrive in November in T-Mobile USA stores and properties owned by Starwood Hotels & Resorts Worldwide Inc. and Harrah's Entertainment Inc.

History
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The technology behind Surface is called Multi-touch. It has at least a 25-year history, beginning in 1982, with pioneering work being done at the University of Toronto (multi-touch tablets) and Bell Labs (multi-touch screens). The product idea for Surface was initially conceptualized in 2001 by Steven Bathiche of Microsoft Hardware and Andy Wilson of Microsoft Research. In October 2001, a virtual team was formed with Bathiche and Wilson as key members, to bring the idea to the next stage of development.

In 2003, the team presented the idea to the Microsoft Chairman Bill Gates, in a group review. Later, the virtual team was expanded and a prototype nicknamed T1 was produced within a month. The prototype was based on an IKEA table with a hole cut in the top and a sheet of architect vellum used as a diffuser. The team also developed some applications, including pinball, a photo browser and a video puzzle. Over the next year, Microsoft built more than 85 early prototypes for Surface. The final hardware design was completed in 2005.

A similar concept was used in the 2005 Science Fiction movie The Island, by Sean Bean's character "Merrick". As noted in the DVD commentary, the director Michael Bay stated the concept of the device came from consultation with Microsoft during the making of the movie. One of the film's technology consultant's associates from MIT later joined Microsoft to work on the Surface project.

Surface was unveiled by Microsoft CEO Steve Ballmer on May 29, 2007 at The Wall Street Journal's D: All Things Digital conference in Carlsbad, California.Surface Computing is part of Microsoft's Productivity and Extended Consumer Experiences Group, which is within the Entertainment & Devices division. The first few companies to deploy Surface will include Harrah's Entertainment, Starwood Hotels & Resorts Worldwide, T-Mobile and a distributor, International Game Technology.

Features
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Microsoft notes four main components being important in Surface's interface: direct interaction, multi-touch contact, a multi-user experience, and object recognition. The device also enables drag and drop digital media when wi-fi enabled devices are placed on its surface such as a Microsoft Zune, cellular phones, or digital cameras.

Surface features multi-touch technology that allows a user to interact with the device at more than one point of contact. For example, using all of their fingers to make a drawing instead of just one. As an extension of this, multiple users can interact with the device at once.

The technology allows non-digital objects to be used as input devices. In one example, a normal paint brush was used to create a digital painting in the software. This is made possible by the fact that, in using cameras for input, the system does not rely on restrictive properties required of conventional touchscreen or touchpad devices such as the capacitance, electrical resistance, or temperature of the tool used (see Touchscreen).

The computer's "vision" is created by a near-infrared, 850-nanometer-wavelength LED light source aimed at the surface. When an object touches the tabletop, the light is reflected to multiple infrared cameras with a net resolution of 1280 x 960, allowing it to sense, and react to items touching the tabletop.

Surface will ship with basic applications, including photos, music, virtual concierge, and games, that can be customized for the customers.

Specifications
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Surface is a 30-inch (76 cm) display in a table-like form factor, 22 inches (56 cm) high, 21 inches (106 cm) deep, and 84 inches (214 cm) wide. The Surface tabletop is acrylic, and its interior frame is powder-coated steel. The software platform runs on Windows Vista and has wired Ethernet 10/100, wireless 802.11 b/g, and Bluetooth 2.0 connectivity.

Electronic Product Code

2007-09-09T02:11:00.000+07:00

The Electronic Product Code, (EPC), is a family of coding schemes created as an eventual successor to the bar code. The EPC was created as a low-cost method of tracking goods using RFID technology. It is designed to meet the needs of various industries, while guaranteeing uniqueness for all EPC-compliant tags. EPC tags were designed to identify each item manufactured, as opposed to just the manufacturer and class of products, as bar codes do today. The EPC accommodates existing coding schemes and defines new schemes where necessary.

The EPC was the creation of the MIT Auto-ID Center, a consortium of over 120 global corporations and university labs. The EPC system is currently managed by EPCglobal, Inc., a subsidiary of GS1, creators of the UPC barcode.

The Electronic Product Code promises to become the standard for global RFID usage, and a core element of the proposed EPCglobal Network.

Structure
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All EPC numbers contain a header identifying the encoding scheme that has been used. This in turn dictates the length, type and structure of the EPC. EPC encoding schemes frequently contain a serial number which can be used to uniquely identify one object.

EPC Version 1.3 supports the following coding schemes:

-General Identifier (GID) GID-96
-a serialized version of the GS1 Global Trade Item Number (GTIN) SGTIN-96 SGTIN-198
-GS1 Serial Shipping Container Code (SSCC) SSCC-96
-GS1 Global Location Number (GLN), SGLN-96 SGLN-195
-GS1 Global Returnable Asset Identifier (GRAI) GRAI-96 GRAI-170
-GS1 Global Individual Asset Identifier (GIAI) GIAI-96 GIAI-202 and
-DOD Construct DoD-96

From Wikipedia, the free encyclopedia

Near Field Communication

2007-09-06T00:19:00.000+07:00

Near Field Communication or NFC, is a short-range wireless technology which enables the communication between devices over a short distance (hands width). The technology is primarily aimed at usage in mobile phones.

NFC is compatible with the existing contactless infrastructure already in use for public transportation and payment.

Essential specifications
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-Works by magnetic field induction. It operates within the globally available and unlicensed RF band of 13.56 MHz.
-Working distance: 0-20 centimeters
-Speed: 106 kbit/s, 212 kbit/s or 424 kbit/s
-There are two modes:
-Passive Communication Mode: The Initiator device provides a carrier field andthe target device answers by modulating existing field. In this mode, the Target device may draw its operating power from the Initiator-provided electromagnetic field, thus making the Target device a transponder.
-Active Communication Mode: Both Initiator and Target device communicate by generating their own field. In this mode, both devices typically need to have a power supply.
-NFC can be used to configure and initiate other wireless network connections such as Bluetooth, Wi-Fi or Ultra-wideband.
A patent licensing program for NFC is currently under development by Via Licensing Corporation, an independent subsidiary of Dolby Laboratories.

Uses and applications
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NFC technology is currently mainly aimed at being used with mobile phones. There are three main use cases for NFC:

-card emulation: the NFC device behaves like an existing contactless card)
-reader mode: the NFC device is active and read a passive RFID tag, for example for interactive advertising)
-P2P mode: two NFC devices are communicating together and exchanging information.)
Plenty of applications will be possible such as:

-Mobile ticketing in public transport - an extension of the existing contactless infrastructure.
-Mobile Payment - the mobile phone acts as a debit/ credit payment card.
-Smart poster - the mobile phone is used to read RFID tags on outdoor billboards in -order to get info on the move.
-Bluetooth pairing - in the future pairing of Bluetooth 2.1 devices with NFC support will be as easy as bringing them close together and accepting the pairing. The process of activating Bluetooth on both sides, searching, waiting, pairing and authorization will be replaced by a simple "touch" of the mobile phones.
Other applications in the future could include:

-Electronic tickets – airline tickets, concert/event tickets, and others
-Electronic money
-Travel cards
-Identity documents
-Mobile commerce
-Electronic keys – car keys, house/office keys, hotel room keys, etc

Standardization bodies & industry projects
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Standards
It was approved as an ISO/IEC standard on December 8, 2003 and as an ECMA standard later on.

NFC is an open platform technology standardized in ECMA-340 and ISO/IEC 18092. These standards specify the modulation schemes, coding, transfer speeds and frame format of the RF interface of NFC devices, as well as initialization schemes and conditions required for data collision-control during initialization-for both passive and active NFC modes. Furthermore, they also define the transport protocol, including protocol activation and data-exchange methods. Air interface for NFC is standardized in:

-ISO/IEC 18092/ECMA-340 : Near Field Communication Interface and Protocol-1(NFCIP-1)
-ISO/IEC 21481/ECMA-352 : Near Field Communication Interface and Protocol-2 (NFCIP-2)
NFC Forum has in addition defined a common data format called NDEF, which can be used to store and transport different kinds of items, ranging from any MIME-typed object to ultra-short RTD -documents, such as URLs.

NDEF is conceptually very similar to MIME. It is a dense binary format of so-called "records", in which each record can hold a different type of object. By convention, the type of the first record defines the context of the entire message.

NFC Forum
The NFC Forum is a non-profit industry association founded on March 18, 2004 by NXP Semiconductors, Sony Corporation and Nokia Corporation to advance the use of NFC short-range wireless interaction in consumer electronics, mobile devices and PCs. The NFC Forum will promote implementation and standardization of NFC technology to ensure interoperability between devices and services. In July 2007, there were over 115 members of the NFC Forum.

GSMA
The GSM Association (GSMA) is the global trade association representing 700 mobile phone operators across 218 countries of the world.

They have launched two initiatives:

-the Mobile NFC initiative: fourteen mobile network operators, who together represent 40% of the global mobile market back NFC and are working together to develop NFC applications. They are Bouygues Télécom, China Mobile, Cingular Wireless, KPN, Mobilkom Austria, Orange, SFR, SK Telecom, Telefonica Móviles España, Telenor, TeliaSonera, Telecom Italia Mobile (TIM), Vodafone and 3 .
On 13th February 2007, they published a white paper on NFC to give the point of view of mobile operators on the NFC ecosystem .

-the Pay buy mobile initiative seeks to define a common global approach to using Near Field Communications (NFC) technology to link mobile devices with payment and contactless systems. To date, 30 mobile operators have joined this initiative.

StoLPaN
StoLPaN (‘Store Logistics and Payment with NFC’) is a pan-European consortium supported by the European Commission’s Information Society Technologies program. StoLPaN will examine the as yet untapped potential for bringing together the new kind of local wireless interface, NFC and mobile communication.

Other standardization bodies
Other standardization bodies are involved in NFC:

-ETSI / SCP (Smart Card Platform) to specify the interface between the SIM card and the NFC chipset.
-Global Platform to specify a multi-application architecture of the secure element.
-|EMVCo for the impacts on the EMV payment applications.

High-definition television

2007-08-30T14:43:00.000+07:00

High-definition television (HDTV) is a digital television broadcasting system with a significantly higher resolution than traditional formats (NTSC, SECAM, PAL). While some early analog HDTV formats were broadcast in Europe and Japan, HDTV is usually broadcast digitally, because digital television (DTV) broadcasting requires much less bandwidth if it uses enough video compression. HDTV technology was first introduced in the US during the 1990s by a group of electronics companies called the Digital HDTV Grand Alliance.

History
--------------------------------------------
High-Definition television was first developed by Nippon Hōsō Kyōkai, and was unveiled in 1969. However, the system did not become mainstream until the late 1990s.

In the early 2000s, a number of high-definition television standards were competing for the still-developing niche markets.

Three HDTV standards are currently defined by the International Telecommunication Union (ITU-R BT.709). They include 1080i (1,080 actively interlaced lines), 1080p (1,080 progressively scanned lines), and 720p (720 progressively scanned lines). All standards use a 16:9 aspect ratio, leading many consumers to the incorrect conclusion of equating widescreen television with HDTV. All current HDTV broadcasting standards are encompassed within the ATSC and DVB specifications.

HDTV is also capable of "theater-quality" audio because it uses the Dolby Digital (AC-3) format to support "5.1" surround sound. It should be noted that while HDTV is more like a theater in quality than conventional television, 35 mm and 70 mm film projectors used in theaters still have the highest resolution and best viewing quality on very large screens. Many HDTV programs are produced from movies on film as well as content shot in HD video.

The term "high-definition" can refer to the resolution specifications themselves, or more loosely to media capable of similar sharpness, such as photographic film and digital video. As of July 2007, HDTV saturation in the US has reached 30 percent – in other words, three out of every ten American households own at least one HDTV. However, only 44 percent of those that do own an HDTV are actually receiving HDTV programming, as many consumers are not aware that they must obtain special receivers to receive HDTV from cable or satellite, or use ATSC tuners to receive over-the-air broadcasts; others may not even know what HDTV is.

HDTV Sources
--------------------------------------------
The rise in popularity of large screens and projectors has made the limitations of conventional Standard Definition TV (SDTV) increasingly evident. An HDTV compatible television set will not improve the quality of SDTV channels. To get a better picture HDTV televisions require a High Definition (HD) signal. Typical sources of HD signals are as follows:

-Over the air with an antenna. Most cities in the US with major network affiliates broadcast over the air in HD. To receive this signal an HD tuner is required. Most newer HDTV televisions have a HD tuner built in. For HDTV televisions without a built in HD tuner, a separate set-top HD tuner box can be rented from a cable or satellite company or purchased.
-Cable television companies often offer HDTV broadcasts as part of their digital broadcast service. This is usually done with a set-top box or CableCARD issued by the cable company. Alternatively one can usually get the network HDTV channels for free with basic cable by using a QAM tuner built into their HDTV or set-top box. Some cable carriers also offer HDTV on-demand playback of movies and commonly viewed shows.
-Satellite-based TV companies, such as Optimum, DirecTV, Sky Digital, Virgin Media (in the UK and Ireland) and Dish Network, offer HDTV to customers as an upgrade. New satellite receiver boxes and a new satellite dish are often required to receive HD content.
-Video game systems, such as the Xbox (NTSC only), Xbox 360, and Playstation 3, can output an HD signal.
-Two optical disc standards, Blu-ray and HD DVD, can provide enough digital storage to store hours of HD video content.

Notation
--------------------------------------------
In the context of HDTV, the formats of the broadcasts are referred to using a notation describing:

-The number of lines in the vertical display resolution.
-Whether progressive scan (p) or interlaced scan (i) are used. Progressive scan redraws all the lines (a frame) of a picture in each refresh. Interlaced scan redraws every second line (a field) in one refresh and the remaining lines in a second refresh. Interlaced scan increases picture resolution while saving bandwidth but at the expense of some flicker or other artifacts.
-The number of frames or fields per second.
The format 720p60 is 1280 × 720 pixels, progressive encoding with 60 frames per second (60 Hz). The format 1080i50 is 1920 × 1080 pixels, interlaced encoding with 50 fields (25 frames) per second. Often the frame or field rate is left out, indicating only the resolution and type of the frames or fields, and leading to confusion. Sometimes the rate is to be inferred from the context, in which case it can usually be assumed to be either 50 or 60, except for 1080p which is often used to denote either 1080p24, 1080p25 or 1080p30 at present but will also denote 1080p50 and 1080p60 in the future.

A frame or field rate can also be specified without a resolution. For example 24p means 24 progressive scan frames per second and 50i means 25 interlaced frames per second, consisting of 50 interlaced fields per second. Most HDTV systems support some standard resolutions and frame or field rates. The most common are noted below.

Changes in notation
The terminology described above was invented for digital systems in the 1990s. A digital signal encodes the color of each pixel, or dot on the screen as a series of numbers. Before that, analog TV signals encoded values for one monochrome, or three-color signals as they scanned a screen continuously from line to line. By comparison, radio encodes an analog signal of the sound to be sent to an amplified speaker, typically up to 20 kHz, but video signals are in the MHz range, which is why they are much higher in the broadcast spectrum than audio radio. Analog video signals have no true "pixels" to measure horizontal resolution. The vertical scan-line count included off-screen scan lines with no picture information while the CRT beam returned to the top of the screen to begin another field. Thus NTSC was considered to have "525 lines" even though only 486 of them had a picture (625/576 for PAL). Similarly the Japanese MUSE system was called "1125 line", but is only 1035i by today's measuring standards. This change was made because digital systems have no need of blank retrace lines unless the signal was converted to analog to drive a CRT.

Standard resolutions

When resolution is considered, both the resolution of the transmitted signal and the (native) displayed resolution of a TV set are taken into account. Digital NTSC- and PAL/SECAM-like signals (480i60 and 576i50 respectively) are transmitted at a horizontal resolution of 720 or 704 "pixels". However these transmitted DTV "pixels" are not square, and have to be stretched for correct viewing. PAL TV sets with an aspect ratio of 4:3 use a fixed pixel grid of 768 × 576 or 720 × 540; with an aspect ratio of 16:9 they use 1440 x 768, 1024 × 576 or 960 × 540; NTSC ones use 640 × 480 and 852 × 480 or, seldom, 720 × 540. High Definition usually refers to one million pixels or more.

In Australia, the 576p50 format is also considered a HDTV format, as it has doubled temporal resolution though the use of progressive scanning. Thus, a number of Australian networks broadcast a 576p signal as their High-definition DVB-T signal, while others use the more conventional 720p and 1080i formats. Technically, however, the 576p format is defined as Enhanced-definition television.

Standard frame or field rates
23.977p (allow easy conversion to NTSC)
24p (cinematic film)
25p (PAL, SECAM DTV progressive material)
30p (NTSC DTV progressive material)
50p (PAL, SECAM DTV progressive material)
60p (NTSC DTV progressive material)
50i (PAL & SECAM)
60i (NTSC, PAL-M)

Comparison with SDTV
HDTV has at least twice the linear resolution of standard-definition television (SDTV), thus allowing much more detail to be shown compared with analog television or regular DVD. In addition, the technical standards for broadcasting HDTV are also able to handle 16:9 aspect ratio pictures without using letterboxing or anamorphic stretching, thus further increasing the effective resolution for such content.

Format considerations
--------------------------------------------
The optimum formats for a broadcast depends on the type of media used for the recording and the characteristics of the content. The field and frame rate should match the source, as should the resolution. On the other hand, a very high resolution source may require more bandwidth than is available in order to be transmitted without loss of fidelity. The lossy compression that is used in all digital HDTV storage/transmission systems will then cause the received picture to appear distorted when compared to the uncompressed source.

Photographic film destined for the theater typically has a high resolution and is photographed at 24 frames per second. Depending on the available bandwidth and the amount of detail and movement in the picture, the optimum format for video transfer is thus either 720p24 or 1080p24. When shown on television in countries using PAL, film must be converted to 25 frames per second by speeding it up by 4.1 percent. In countries using the NTSC standard, 30 frames per second, a technique called 3:2 pulldown is used. One film frame is held for three video fields, (1/20 of a second) and then the next is held for two video fields (1/30 of a second) and then the process repeats, thus achieving the correct film rate with two film frames shown in 1/12 of a second.

See also: Telecine
Older (pre-HDTV) recordings on video tape such as Betacam SP are often either in the form 480i60 or 576i50. These may be upconverted to a higher resolution format (720i), but removing the interlace to match the common 720p format may distort the picture or require filtering which actually reduces the resolution of the final output.

See also: Deinterlacing
Non-cinematic HDTV video recordings are recorded in either 720p or 1080i format. The format used depends on the broadcast company (if destined for television broadcast); however, in other scenarios the format choice will vary depending on a variety of factors. In general, 720p is more appropriate for fast action as it uses progressive scan frames, as opposed to 1080i which uses interlaced fields and thus can have a degradation of image quality with fast motion.

In addition, 720p is used more often with Internet distribution of HD video, as all computer monitors are progressive, and most graphics cards do a poor job of de-interlacing video in real time. 720p video also has lower storage and decoding requirements than 1080i or 1080p.

In North America, Fox, My Network TV (also owned by Fox), ABC, and ESPN (ABC and ESPN are both owned by Disney) currently broadcast 720p content. NBC, Universal HD (both owned by General Electric), CBS, PBS, The CW, HBO, Showtime, Starz!, MOJO HD, HDNet ,TNT, and Discovery HD Theater currently broadcast 1080i content.

In the United Kingdom on Sky Digital, there are BBC HD, Sky One HD, Sky Arts HD, Sky Movies HD1 & 2, Sky Sports HD1,2 & X, Discovery HD, National Geographic Channel HD, The History Channel HD & Sky Box Office HD1 & 2. With MTV HD, FX HD, Living HD Rush HD, Ultra HD & Eurosport HD to come in the near future. BBC HD is also available on Virgin Media

Technical details
--------------------------------------------

MPEG-2 is most commonly used as the compression codec for digital HDTV broadcasts. Although MPEG-2 supports up to 4:2:2 YCbCr chroma subsampling and 10-bit quantization, HD broadcasts use 4:2:0 and 8-bit quantization to save bandwidth. Some broadcasters also plan to use MPEG-4 AVC, such as the BBC which is trialing such a system via satellite broadcast, which will save considerable bandwidth compared to MPEG-2 systems. Some German broadcasters already use MPEG-4 AVC together with DVB-S2 (Pro 7, Sat.1 and Premiere). Although MPEG-2 is more widely used at present, it seems likely that in the future all European HDTV may be MPEG-4 AVC, and Ireland and Norway, which have not yet begun any digital television broadcasts, are considering MPEG-4 AVC for SD Digital as well as HDTV on terrestrial broadcasts.

HDTV is capable of "theater-quality" audio because it uses the Dolby Digital (AC-3) format to support "5.1" surround sound. The pixel aspect ratio of native HD signals is a "square" 1.0, in which each pixel's height equals its width. New HD compression and recording formats such as HDV use rectangular pixels to save bandwidth and to open HDTV acquisition for the consumer market. For more technical details see the articles on HDV, ATSC, DVB, and ISDB.

Television studios as well as production and distribution facilities, use HD-SDI SMPTE 292M interconnect standard (a nominally 1.485 Gbit/s, 75-ohm serial digital interface) to route uncompressed HDTV signals. The native bitrate of HDTV formats cannot be supported by 6-8 MHz standard-definition television channels for over-the-air broadcast and consumer distribution media, hence the widespread use of compression in consumer applications. SMPTE 292M interconnects are generally unavailable in consumer equipment, partially due to the expense involved in supporting this format, and partially because consumer electronics manufacturers are required (typically by licensing agreements) to provide encrypted digital outputs on consumer video equipment, for fear that this would aggravate the issue of video piracy.

Newer dual-link HD-SDI signals are needed for the latest 4:4:4 camera systems (Sony HDC-F950 & Thomson Viper), where one link/coax cable contains the 4:2:2 YCbCr info and the other link/coax cable contains the additional 0:2:2 CbCr information.

Advantages of HDTV expressed in non-engineering terms
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High-definition television (HDTV) potentially offers a much better picture quality than standard television. HD's greater clarity means the picture on screen can be less blurred and less fuzzy. HD also brings other benefits such as smoother motion, richer and more natural colors, surround sound, and the ability to allow a variety of input devices to work together. However, there are a variety of reasons why the best HD quality is not usually achieved. The main problem is a lack of HD input. Many cable and satellite channels and even some "high definition" channels are not broadcast in true HD. Also, image quality may be lost if the television is not properly connected to the input device or not properly configured for the input's optimal performance.

Almost all commercially available HD is digital, so the system cannot produce a snowy or washed out image from a weak signal, effects from signal interference, such as herringbone patterns, or vertical rolling. HD digital signals will either deliver an excellent picture, a picture with noticeable pixelation, a series of still pictures, or no picture at all. Any interference will render the signal unwatchable. As opposed to a lower-quality signal one gets from interference in an analogue television broadcast, interference in a digital television broadcast will freeze, skip, or display "garbage" information.

With HDTV the lack of imperfections in the television screen often seen on traditional television is another reason why many prefer high definition to analog. As mentioned, problems such as snow caused from a weak signal, double images from ghosting or multi-path and picture sparkles from electromagnetic interference are a thing of the past. These problems often seen on a conventional television broadcast just do not occur on HDTV.

HD programming and films will be presented in 16:9 widescreen format (although films created in even wider ratios will still display "letterbox" bars on the top and bottom of even 16:9 sets). Older films and programming that retain their 4:3 ratio display will be presented in a version of letterbox commonly called "pillar box," displaying bars on the right and left of 16:9 sets (rendering the term "fullscreen" a misnomer). While this is an advantage when it comes to playing 16:9 movies, it creates the same disadvantage when playing 4:3 television shows that standard televisions have playing 16:9 movies. A way to address this is to zoom the 4:3 image to fill the screen or reframe its material to 14:9 aspect ratio, either during preproduction or manually in the TV set.

The colors will generally look more realistic, due to their greater bandwidth. The visual information is about 2-5 times more detailed overall. The gaps between scanning lines are smaller or invisible. Legacy TV content that was shot and preserved on 35 mm film can now be viewed at nearly the same resolution as that at which it was originally photographed. A good analogy for television quality is looking through a window. HDTV offers a degree of clarity that is much closer to this.

The "i" in these numbers stands for "interlaced" while the "p" stands for "progressive". With interlaced scan, the 1,080 lines are split into two, the first 540 being "painted" on a frame, followed by the second 540 painted on another frame. This method reduces the bandwidth and raises the frame rate to 50-60 per second. A progressive scan displays all 1,080 lines at the same time at 60 frames per second, using more bandwidth. (See: An explanation of HDTV numbers and laymens glossary)

Dolby Digital 5.1 surround sound is broadcast along with standard HDTV video signals, allowing full surround sound capabilities. (Standard broadcast television signals usually only include monophonic or stereophonic audio. Stereo broadcasts can be encoded with Dolby Surround, an early home video surround format.) Both designs make more efficient use of electricity than SDTV designs of equivalent size, which can mean lower operating costs. LCD is a leader in energy conservation.

Disadvantages of HDTV expressed in non-engineering terms
--------------------------------------------
HDTV is the answer to a question few consumers were asking. Viewers will have to upgrade their TVs in order to see HDTV broadcasts, incurring household expense in the process. Adding a new aspect ratio makes for consumer confusion when their display is capable of one or more ratios but must be switched to the correct one by the user. Traditional standard definition TV shows, when displayed correctly on an HDTV monitor, will have empty display areas to the left and right of the image. Many consumers aren't satisfied with this unused display area and choose instead to distort their standard definition shows by stretching them horizontally to fill the screen, giving everything a too-wide or not-tall-enough appearance. Alternately, they'll choose to zoom the image which removes content that was on the top and bottom of the original TV show.

Early systems
--------------------------------------------
The term "high definition" was used to describe the electronic television systems of the late 1930s and 1940s beginning with the former British 405-line black-and-white system, introduced in 1936; however, this and the subsequent 525-line U.S. NTSC system, established in 1941, were high definition only in comparison with previous mechanical and electronic television systems, and NTSC, along with the later European 625-line PAL and SECAMs, is described as standard definition today.

On the other hand, the 819-line French black-and-white television system introduced after World War II arguably was high definition in the modern sense, as it had a line count and theoretical maximum resolution considerably higher than those of the 625-line systems introduced across most of postwar Europe. However, it required far more bandwidth than other systems, and was switched off in 1986, a year after the final British 405-line broadcasts.

Japan was the only country where commercial analog HDTV was launched and had some success. In other places, such as Europe, analog (HD-MAC) HDTV failed. Finally, although the United States experimented with analog HDTV (there were about 10 proposed formats), it soon moved towards a digital approach.

Ultra-wideband

2007-08-28T15:06:00.000+07:00

Ultra-wideband (UWB, ultra-wide band, ultraband, etc.) is a radio technology that can be used for short-range high-bandwidth communications by using a large portion of the radio spectrum in a way that doesn't interfere with other more traditional 'narrow band' uses. It also has applications in radar imaging , precision positioning and tracking technology.

Ultra-Wideband (UWB) may be used to refer to any radio technology having bandwidth exceeding the lesser of 500 MHz or 20% of the arithmetic center frequency, according to Federal Communications Commission (FCC). This article discusses the meaning of Ultra-wideband in the field of radio communications.

Overview
------------------------------------------
Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth (>500 MHz) that should, in theory and under the right circumstances, be able to share spectrum with other users. A February 14, 2002 Report and Order by the FCC authorizes the unlicensed use of UWB in 3.1–10.6 GHz. This is intended to provide an efficient use of scarce radio bandwidth while enabling both high data rate personal-area network (PAN) wireless connectivity and longer-range, low data rate applications as well as radar and imaging systems. More than four dozen devices have been certified under the FCC UWB rules, the vast majority of which are radar, imaging or positioning systems. Deliberations in the International Telecommunication Union Radiocommunication Sector (ITU-R) have resulted in a Report and Recommendation on UWB in November of 2005. National jurisdictions around the globe are expected to act on national regulations for UWB very soon. The UK regulator Ofcom announced a similar decision on 9 August 2007.

Ultra Wideband was traditionally accepted as pulse radio, but the FCC and ITU-R now define UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% of the center frequency. Thus, pulse-based systems—wherein each transmitted pulse instantaneously occupies the UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in orthogonal frequency-division multiplexing (OFDM) fashion—can gain access to the UWB spectrum under the rules. Pulse repetition rates may be either low or very high. Pulse-based radars and imaging systems tend to use low repetition rates, typically in the range of 1 to 100 megapulses per second. On the other hand, communications systems favor high repetition rates, typically in the range of 1 to 2 giga-pulses per second, thus enabling short-range gigabit-per-second communications systems. Each pulse in a pulse-based UWB system occupies the entire UWB bandwidth, thus reaping the benefits of relative immunity to multipath fading (but not to intersymbol interference), unlike carrier-based systems that are subject to both deep fades and intersymbol interference.

The FCC power spectral density emission limit for UWB emitters operating in the UWB band is -41.3 dBm/MHz. This is the same limit that applies to unintentional emitters in the UWB band, the so called Part 15 limit. However, the emission limit for UWB emitters can be significantly lower (as low as -75 dBm/MHz) in other segments of the spectrum.

A significant difference between traditional radio transmissions and UWB radio transmissions is that traditional transmissions transmit information by varying the power/frequency/and or phase of a sinusoidal wave. UWB transmissions can transmit information by generating radio energy at specific time instants and occupying large bandwidth thus enabling a pulse-position or time-modulation. But also information can be imparted (modulated) on UWB signals (pulses) by encoding the polarity of the pulse, the amplitude of the pulse, and/or also by using orthogonal pulses. UWB pulses can be sent sporadically at relatively low pulse rates to support time/position modulation, but can also be sent at rates up to the inverse of the UWB pulse bandwidth. Pulse-UWB systems have been demonstrated at channel pulse rates in excess of 1.3 giga-pulses per second using a continuous stream of UWB pulses (Continuous Pulse UWB or "C-UWB"), supporting forward error correction encoded data rates in excess of 675 Mbit/s. Such a pulse-based UWB method using bursts of pulses is the basis of the IEEE 802.15.4a draft standard and working group, which has proposed UWB as an alternative PHY layer.

One of the valuable aspects of UWB radio technology is the ability for a UWB radio system to determine "time of flight" of the direct path of the radio transmission between the transmitter and receiver to a high resolution. With a two-way time transfer technique distances can be measured to high resolution as well as to high accuracy by compensating for local clock drifts and inaccuracies.

Another valuable aspect of pulse-based UWB is that the pulses are very short in space (less than 60 cm for a 500 MHz wide pulse, less than 23 cm for a 1.3 GHz bandwidth pulse), so most signal reflections do not overlap the original pulse, and thus the traditional multipath fading of narrow band signals does not exist. However, there still is inter-pulse interference for fast pulse systems which can be mitigated by coding techniques.

Technical discussion
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One performance measure of a radio in applications like communication, positioning, location, tracking, radar, is the channel capacity for a given bandwidth and signaling format. Channel capacity is the theoretical maximum possible number of bits per second of information that can be conveyed through one or more links in an area. According to the Shannon-Hartley theorem, channel capacity of a properly encoded signal is proportional to the bandwidth of the channel and to the logarithm of signal to noise ratio (SNR)—assuming the noise is additive white Gaussian noise (AWGN). Thus channel capacity increases linearly by increasing bandwidth of the channel to the maximum value available, or equivalently in a fixed channel bandwidth by increasing the signal power exponentially. By virtue of the huge bandwidths inherent to UWB systems, the huge channel capacities can be achieved without invoking higher order modulations that need very high SNR to operate.

Ideally, the receiver signal detector should be matched to the transmitted signal in bandwidth, signal shape and time. Any mismatch results in loss of margin for the UWB radio link.

Channelization (sharing the channel with other links) is a complex problem subject to many practical variables. Typically two UWB links can share the same spectrum by using orthogonal time-hopping codes for pulse-position (time-modulated) systems, or orthogonal pulses and orthogonal codes for fast-pulse based systems.

Current forward error correction (FEC) technology; as demonstrated recently in some very high data rate UWB pulsed systems, like LDPC (Low Density Parity Coding), perhaps in combination with Reed-Solomon codes, can provide channel performance approaching the Shannon limit. When stealth is required, some UWB formats (mainly pulse-based) can fairly easily be made to look like nothing more than a slight rise in background noise to any receiver that is unaware of the signal’s complex pattern.

Multipath (distortion of a signal because it takes many different paths to the receiver) is an enemy of narrow-band radio--it causes fading where wave interference is destructive. Some UWB systems use "rake" receiver techniques to recover multipath generated copies of the original pulse to improve performance on receiver. Other UWB systems use channel equalization techniques to achieve the same purpose. Narrowband receivers can use similar techniques, but are limited due to the poorer resolution capabilities of narrowband systems.

There has been much concern over the interference of narrow band signals and UWB signals that share the same spectrum; traditionally the only radio technology that operated using pulses was spark gap transmitters; which were banned due to excessive interference. However, UWB is much lower power. The subject was extensively covered in the proceedings that led to the adoption of the FCC rules in the US, and also in the 6 meetings relating to UWB of the ITU-R that led to the ITU-R Report and Recommendations on UWB technology. In particular, many common pieces of equipment emit impulsive noise (notably hair dryers) and the argument was successfully made that the noise floor would not be raised excessively by wider deployment of wideband transmitters of low power.

Applications
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Due to the extremely low emission levels currently allowed by regulatory agencies, UWB systems tend to be short-range and indoors. However, due to the short duration of the UWB pulses, it is easier to engineer extremely high data rates, and data rate can be readily traded for range by simply aggregating pulse energy per data bit using either simple integration or by coding techniques. Conventional OFDM technology can also be used subject to the minimum bandwidth requirement of the regulations. High data rate UWB can enable wireless monitors, the efficient transfer of data from digital camcorders, wireless printing of digital pictures from a camera without the need for an intervening personal computer, and the transfer of files among cell phone handsets and other handheld devices like personal digital audio and video players.

UWB is used as a part of location systems and real time location systems. The precision capabilities combined with the very low power makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare. Another benefit of UWB is the short broadcast time which enables implementers of the technology to install orders of magnitude more transmitter tags in an environment relative to competitive technologies. USA based Parco Merged Media Corporation was the first systems developer to deploy a commercial version of this system in a Washington, DC hospital.

UWB is also used in "see-through-the-wall" precision radar imaging technology, precision positioning and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. It exhibits excellent efficiency with a spatial capacity of approximately 10,000,000,000,000 bit/s/m².

UWB is a possible technology for use in personal area networks and appears in IEEE 802.15.3a draft PAN standard.

From Wikipedia, the free encyclopedia

Organic light-emitting diode

2007-08-28T14:46:00.000+07:00

An organic light-emitting diode (OLED) is any light-emitting diode (LED) whose emissive electroluminescent layer comprises a film of organic compounds. The layer usually contains a polymer substance that allows suitable organic compounds to be deposited. They are deposited in rows and columns onto a flat carrier by a simple "printing" process. The resulting matrix of pixels can emit light of different colors.

Such systems can be used in television screens, computer displays, portable system screens, advertising, information and indication. OLEDs can also be used in light sources for general space illumination, and large-area light-emitting elements. OLEDs typically emit less light per area than inorganic solid-state based LEDs which are usually designed for use as point-light sources.

A great benefit of OLED displays over traditional liquid crystal displays (LCDs) is that OLEDs do not require a backlight to function. Thus they draw far less power and, when powered from a battery, can operate longer on the same charge. OLED-based display devices also can be more effectively manufactured than LCDs and plasma displays. But degradation of OLED materials has limited the use of these materials. See Drawbacks.

OLED technology was also called Organic Electro-Luminescence (OEL), before the term "OLED" became standard.

History
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Bernanose and co-workers first produced electroluminescence in organic materials by applying a high-voltage alternating current (AC) field to crystalline thin films of acridine orange and quinacrine. In 1960, researchers at Dow Chemical developed AC-driven electroluminescent cells using doped anthracene.

The low electrical conductivity of such materials limited light output until more conductive organic materials became available, especially the polyacetylene, polypyrrole, and polyaniline "Blacks". In a 1963 series of papers, Weiss et al. first reported high conductivity in iodine-"doped" oxidized polypyrrole.They achieved a conductivity of 1 S/cm. Unfortunately, this discovery was "lost", as was a 1974 report of a melanin-based bistable switch with a high conductivity "ON" state. This material emitted a flash of light when it switched.

In a subsequent 1977 paper, Shirakawa et al. reported high conductivity in similarly oxidized and iodine-doped polyacetylene. Heeger, MacDiarmid & Shirakawa received the 2000 Nobel Prize in Chemistry for "The discovery and development of conductive organic polymers". The Nobel citation made no reference to the earlier discoveries.

Modern work with electroluminescence in such polymers culminated with Burroughs et al. 1990 paper in the journal Nature reporting a very-high-efficiency green-light-emitting polymer. The OLED timeline since 1996 is well documented on oled-info.com site.

Related technologies
------------------------------------------
Small molecules
OLED technology was first developed at Eastman Kodak Company by Dr. Ching Tang using Small-molecules. The production of small-molecule displays requires vacuum deposition, which makes the production process more expensive than other processing techniques (see below). Since this is typically carried out on glass substrates, these displays are also not flexible, though this limitation is not inherent to small-molecule organic materials. The term OLED traditionally refers to this type of device, though some are using the term SM-OLED.

Molecules commonly used in OLEDs include organo-metallic chelates (for example Alq3, used in the first organic light-emitting device) and conjugated dendrimers.

Recently a hybrid light-emitting layer has been developed that uses nonconductive polymers doped with light-emitting, conductive molecules. The polymer is used for its production and mechanical advantages without worrying about optical properties. The small molecules then emit the light and have the same longevity that they have in the SM-OLEDs.

PLED
Polymer light-emitting diodes (PLED) involve an electroluminescent conductive polymer that emits light when subjected to an electric current. Developed by Cambridge Display Technology, they are also known as Light-Emitting Polymers (LEP). They are used as a thin film for full-spectrum color displays and require a relatively small amount of power for the light produced. No vacuum is required, and the emissive materials can be applied on the substrate by a technique derived from commercial inkjet printing. The substrate used can be flexible, such as PET. Thus, flexible PLED displays may be produced inexpensively.

Typical polymers used in PLED displays include derivatives of poly(p-phenylene vinylene) and poly(fluorene). Substitution of side chains onto the polymer backbone may determine the color of emitted light or the stability and solubility of the polymer for performance and ease of processing.

TOLED

Transparent organic light-emitting device (TOLED) uses a proprietary transparent contact to create displays that can be made to be top-only emitting, bottom-only emitting, or both top and bottom emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view displays in bright sunlight.

SOLED
Stacked OLED (SOLED) uses a novel pixel architecture that is based on stacking the red, green, and blue subpixels on top of one another instead of next to one another as is commonly done in CRTs and LCDs. This improves display resolution up to threefold and enhances full-color quality. 1439

Working principle
An OLED is composed of an emissive layer, a conductive layer, a substrate, and anode and cathode terminals. The layers are made of special organic polymer molecules that conduct electricity. Their levels of conductivity range from those of insulators to those of conductors, and so they are called organic semiconductors.

A voltage is applied across the OLED such that the anode is positive with respect to the cathode. This causes a current of electrons to flow through the device from cathode to anode. Thus, the cathode gives electrons to the emissive layer and the anode withdraws electrons from the conductive layer; in other words, the anode gives electron holes to the conductive layer.

Soon, the emissive layer becomes negatively charged, while the conductive layer becomes rich in positively charged holes. Electrostatic forces bring the electrons and the holes towards each other and recombine. This happens closer to the emissive layer, because in organic semiconductors holes are more mobile than electrons, (unlike in inorganic semiconductors). The recombination causes a drop in the energy levels of electrons, accompanied by an emission of radiation whose frequency is in the visible region. That is why this layer is called emissive.

The device does not work when the anode is put at a negative potential with respect to the cathode. In this condition, holes move to the anode and electrons to the cathode, so they are moving away from each other and do not recombine.

Indium tin oxide is commonly used as the anode material. It is transparent to visible light and has a high work function which promotes injection of holes into the polymer layer. Metals such as aluminium and calcium are often used for the cathode as they have low work functions which promote injection of electrons into the polymer layer.

Advantages
------------------------------------------
The radically different manufacturing process of OLEDs lends itself to many advantages over flat-panel displays made with LCD technology. Since OLEDs can be printed onto any suitable substrate using inkjet printer or even screen printing technologies, they can theoretically have a significantly lower cost than LCDs or plasma displays. Printing OLEDs onto flexible substrates opens the door to new applications such as roll-up displays and displays embedded in clothing.

OLEDs enable a greater range of colors, brightness, and viewing angle than LCDs, because OLED pixels directly emit light. OLED pixel colors appear correct and unshifted, even as the viewing angle approaches 90 degrees from normal. LCDs use a backlight and cannot show true black, while an "off" OLED element produces no light and consumes no power. Energy is also wasted in LCDs because they require polarizers which filter out about half of the light emitted by the backlight. Additionally, color filters in color LCDs filter out two-thirds of the light.

OLEDs also have a faster response time than standard LCD screens. Whereas a standard LCD currently has around 8 millisecond response time(though can be much lower such as 2 miliseconds), an OLED can have less than 0.01ms response time.

Commercial uses
------------------------------------------
OLED technology is used in commercial applications such as small screens for mobile phones and portable digital audio players (MP3 players), car radios, digital cameras and high-resolution microdisplays for head-mounted displays. Such portable applications favor the high light output of OLEDs for readability in sunlight, and their low power drain. Portable displays are also used intermittently, so the lower lifespan of OLEDs is less important here. Prototypes have been made of flexible and rollable displays which use OLED's unique characteristics. OLEDs have been used in most Motorola and Samsung color cell phones, as well as some Sony Ericsson phones, notably the Z610i, and some models of the Sony Walkman.

eMagin Corporation is the only manufacturer of active matrix OLED-on-silicon displays. These are currently being developed for the US military, the medical field and the future of entertainment where an individual can immerse themselves in a movie or a video game.

VoiceXML

2007-08-27T10:53:00.000+07:00

VoiceXML (VXML) is the W3C's standard XML format for specifying interactive voice dialogues between a human and a computer. It allows voice applications to be developed and deployed in an analogous way to HTML for visual applications. Just as HTML documents are interpreted by a visual web browser, VoiceXML documents are interpreted by a voice browser. A common architecture is to deploy banks of voice browsers attached to the public switched telephone network (PSTN) so that users can use a telephone to interact with voice applications.

Usage
-------------------------------
Many commercial VoiceXML applications have been deployed, processing many millions of telephone calls per day. These applications include: order inquiry, package tracking, driving directions, emergency notification, wake-up, flight tracking, voice access to email, customer relationship management, prescription refilling, audio newsmagazines, voice dialing, real-estate information and national directory assistance applications.

VoiceXML has tags that instruct the voice browser to provide speech synthesis, automatic speech recognition, dialog management, and audio playback. The following is an example of a VoiceXML document:


<?xml version="1.0"?>
<vxml version="2.0" xmlns="http://www.w3.org/2001/vxml">
  <form>
    <block>
      <prompt>
        Hello world!
      </prompt>
    </block>
  </form>
</vxml>

When interpreted by a VoiceXML interpreter this will output "Hello world" with synthesized speech.

Typically, HTTP is used as the transport protocol for fetching VoiceXML pages. Some applications may use static VoiceXML pages, while others rely on dynamic VoiceXML page generation using an application server like Tomcat, Weblogic, IIS, or WebSphere. In a well-architected web application, the voice interface and the visual interface share the same back-end business logic.

Historically, VoiceXML platform vendors have implemented the standard in different ways, and added proprietary features. But the VoiceXML 2.0 standard, adopted as a W3C Recommendation 16 March 2004, clarified most areas of difference. The VoiceXML Forum, an industry group promoting the use of the standard, provides a conformance testing process that certifies vendors implementations as conformant.

Related standards
-------------------------------
The W3C's Speech Interface Framework also defines these other standards closely associated with VoiceXML.

SRGS and SISR
The Speech Recognition Grammar Specification (SRGS) is used to tell the speech recognizer what sentence patterns it should expect to hear: these patterns are called grammars. Once the speech recognizer determines the most likely sentence it heard, it needs to extract the semantic meaning from that sentence and return it to the VoiceXML interpreter. This semantic interpretation is specified via the Semantic Interpretation for Speech Recognition (SISR) standard. SISR is used inside SRGS to specify the semantic results associated with the grammars, i.e., the set of ECMAScript assignments that create the semantic structure returned by the speech recognizer.

SSML
The Speech Synthesis Markup Language (SSML) is used to decorate textual prompts with information on how best to render them in synthetic speech, for example which speech synthesizer voice to use, when to speak louder or softer.

PLS
The Pronunciation Lexicon Specification (PLS) is used to define how words are pronounced. The generated pronunciation information is meant to be used by both speech recognizers and speech synthesizers in voice browsing applications.

CCXML
The Call Control eXtensible Markup Language (CCXML) is a complementary W3C standard. A CCXML interpreter is used on some VoiceXML platforms to handle the initial call setup between the caller and the voice browser, and to provide telephony services like call transfer and disconnect to the voice browser. CCXML can also be used in non-VoiceXML contexts such as teleconferencing.

History
AT&T, IBM, Lucent, and Motorola formed the VoiceXML Forum in March 1999, in order to develop a standard markup language for specifying voice dialogs. By September 1999 the Forum released VoiceXML 0.9 for member comment, and in March 2000 they published VoiceXML 1.0. Soon afterwards, the Forum turned over the control of the standard to the World Wide Web Consortium. The W3C produced several intermediate versions of VoiceXML 2.0, which reached the final "Recommendation" stage in March 2004.

VoiceXML 2.1 added a relatively small set of additional features to VoiceXML 2.0, based on feedback from implementations of the 2.0 standard. It is backward compatible with VoiceXML 2.0 and reached W3C Recommendation status in June 2007.

Future versions of the standard
VoiceXML 3.0 will be the next major release of VoiceXML, with new major features. It will use a new XML statechart description language called SCXML.

LightScribe

2007-08-26T12:35:00.000+07:00

LightScribe is an optical disc recording technology that utilizes specially coated recordable CD and DVD media to produce laser-etched labels.

The purpose of LightScribe is to allow users to create direct-to-disc labels (as opposed to stick-on labels), using their optical disc writer. Special discs and a compatible disc writer are required. After burning data to the read-side of the disc, the user simply turns the medium over and inserts it with the label side down. The drive's laser then etches into the label side in such a way that an image is produced.

History
-------------------------------------------
LightScribe is a registered trademark of the Hewlett-Packard Development Company, L.P. LightScribe was conceived by an HP engineer (Daryl Anderson) in Corvallis, Oregon, and brought to market through the joint design efforts of HP's imaging and optical storage divisions.

Mode of operation
-------------------------------------------
The surface of a LightScribe disc is coated with a reactive dye that changes color when it absorbs 780nm infrared laser light. The etched label will show no noticeable fading under exposure to indoor lighting for at least 2 years. Optical media should always be stored in a protective sleeve or case that keeps the data content in the dark and safe from scratches. If properly stored as such, the label should last the life of the discs in real-world application.

LightScribe labels burn in concentric circles, moving outward from the center of the disc. Images with the largest diameters will take longest to burn.

Initially LightScribe was monochromatic, a grey etch on a gold looking surface. From late 2006, LightScribe discs are also available in colors for categorization. The "burning" is still monochromatic, but the backgrounds can now be produced in various colors, under the v1.2 specification.

Currently it's not possible to rewrite a LightScribe label but it's possible to add more content to a label that is already burned.

The center of every LightScribe disc has a special code that allows the drive to know the precise rotational position of the disc. This in combination with the drive hardware allows it to know the precise position from the center outwards, and the disc can be labeled while spinning at high speed using these references. It also serves a secondary purpose: The same disc can be labeled with the same label again, several times. Each successive labeling will darken the blacks and generally produce a better image, and the successive burns will line up perfectly. However it is recommended to use the Control Panel to modify the printing parameters and have images with higher contrast.

Wibree

2007-08-26T12:26:00.000+07:00

Wibree is a digital radio technology (intended to become an open standard of wireless communications) designed for ultra low power consumption (button cell batteries) within a short range (10 meters / 30 ft) based around low-cost transceiver microchips in each device.

History
---------------------------------
In 2001, Nokia researchers determined that there were various scenarios that contemporary wireless technologies did not address. To address the problem, Nokia Research Center started the development of a wireless technology adapted from the Bluetooth standard which would provide lower power usage and price while minimizing difference between Bluetooth and the new technology. The results were published in 2004 using the name Bluetooth Low End Extension. After further development with partners, e.g., within EU FP6 project MIMOSA, the technology was released to public in October 2006 with brand name Wibree. After negotiations with Bluetooth SIG members, in June 2007, an agreement was reached to include Wibree in future Bluetooth specification as an ultra-low-power Bluetooth technology.

Technical information
---------------------------------
Wibree is designed to work side-by-side with and complement Bluetooth. It operates in 2.4 GHz ISM band with physical layer bit rate of 1 Mbit/s. Main applications include devices such as wrist watches, wireless keyboards, toys and sports sensors where low power consumption is a key design requirement. The technology was announced on 3 October 2006 by Nokia . Partners that currently license the technology and cooperate in defining the specification are Nordic Semiconductor, Broadcom Corporation, CSR and Epson. Other contributors are Suunto and Taiyo Yuden.

Wibree is not designed to replace Bluetooth, but rather to complement the technology in supported devices. Wibree-enabled devices will be smaller and more energy-efficient than their Bluetooth counterparts. This is especially important in devices such as wristwatches, where Bluetooth models may be too large and heavy to be comfortable. Replacing Bluetooth with Wibree will make the devices closer in dimensions and weight to current standard wristwatches.

Bob Iannucci, head of Nokia's Research Centre, claims the technology is up to ten times more efficient than Bluetooth. Reportedly, it will have an output power around -6 dBm. Nordic Semiconductor is aiming to sample Wibree chips during the second half of 2007.

From Wikipedia, the free encyclopedia

Radio-frequency identification

2007-08-25T05:40:00.000+07:00

Radio-frequency identification (RFID) is an automatic identification method, relying on storing and remotely retrieving data using devices called RFID tags or transponders.

An RFID tag is an object that can be stuck on or incorporated into a product, animal, or person for the purpose of identification using radiowaves. Some tags can be read from several meters away and beyond the line of sight of the reader.

Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a (RF) signal and perhaps other specialized functions. The second is an antenna for receiving and transmitting the signal. A technology called chipless RFID allows for discrete identification of tags without an integrated circuit, thereby allowing tags to be printed directly onto assets at lower cost than traditional tags.

Today, a significant thrust in RFID use is in enterprise supply chain management, improving the efficiency of inventory tracking and management. However, a threat is looming that the current growth and adoption in enterprise supply chain market will not be sustainable. A fair cost-sharing mechanism, rational motives and justified returns from RFID technology investments are the key ingredients to achieve long-term and sustainable RFID technology adoption.

History of RFID tags
-------------------------------------------------
In 1946 Léon Theremin invented an espionage tool for the Soviet Union which retransmitted incident radio waves with audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, which modulated the reflected radio frequency. Even though this device was a passive covert listening device, not an identification tag, it has been attributed as the first known device and a predecessor to RFID technology. The technology used in RFID has been around since the early 1920s according to one source (although the same source states that RFID systems have been around just since the late 1960s).

A more similar technology such as the IFF transponder was invented by the British in 1939 was routinely used by the allies in World War II to identify airplanes as friend or foe. Transponders are still used by military and commercial aircraft to this day.

Another early work exploring RFID is the landmark 1948 paper by Harry Stockman, titled "Communication by Means of Reflected Power" (Proceedings of the IRE, pp 1196–1204, October 1948). Stockman predicted that "…considerable research and development work has to be done before the remaining basic problems in reflected-power communication are solved, and before the field of useful applications is explored."

Mario Cardullo's U.S. Patent 3,713,148 in 1973 was the first true ancestor of modern RFID; a passive radio transponder with memory. The initial device was passive, powered by the interrogating signal, and was demonstrated in 1971 to the New York Port Authority and other potential users and consisted of a transponder with 16 bit memory for use as a toll device. The basic Cardullo patent covers the use of RF, sound and light as transmission medium. The original business plan presented to investors in 1969 showed uses in transportation (automotive vehicle identification, automatic toll system, electronic license plate, electronic manifest, vehicle routing, vehicle performance monitoring), banking (electronic check book, electronic credit card), security (personnel identification, automatic gates, surveillance) and medical (identification, patient history).

A very early demonstration of reflected power (modulated backscatter) RFID tags, both passive and active, was done by Steven Depp, Alfred Koelle and Robert Freyman at the Los Alamos Scientific Laboratory in 1973. The portable system operated at 915 MHz and used 12 bit tags. This technique is used by the majority of today's UHF and microwave RFID tags.

The first patent to be associated with the abbreviation RFID was granted to Charles Walton in 1983 (U.S. Patent 4,384,288).

RFID tags
-------------------------------------------------
RFID tags come in three general varieties:passive, active", or semi-passive (also known as battery-assisted). Passive tags require no internal power source, whereas semi-passive and active tags require a power source, usually a small battery.

Passive
Passive RFID tags have no internal power supply. The minute electrical current induced in the antenna by the incoming radio frequency signal provides just enough power for the CMOS integrated circuit in the tag to power up and transmit a response. Most passive tags signal by backscattering the carrier wave from the reader. This means that the antenna has to be designed to both collect power from the incoming signal and also to transmit the outbound backscatter signal. The response of a passive RFID tag is not necessarily just an ID number; the tag chip can contain non-volatile EEPROM for storing data.

Passive tags have practical read distances ranging from about 10 cm (4 in.) (ISO 14443) up to a few meters (Electronic Product Code (EPC) and ISO 18000-6), depending on the chosen radio frequency and antenna design/size. Due to their simplicity in design they are also suitable for manufacture with a printing process for the antennas. The lack of an onboard power supply means that the device can be quite small: commercially available products exist that can be embedded in a sticker, or under the skin in the case of low frequency RFID tags.

In 2006, Hitachi, Ltd. developed a passive device called the µ-Chip measuring 0.15×0.15 mm (not including the antenna), and thinner than a sheet of paper (7.5 micrometers). Silicon-on-Insulator (SOI) technology is used to achieve this level of integration. The Hitachi µ-Chip can wirelessly transmit a 128-bit unique ID number which is hard coded into the chip as part of the manufacturing process. The unique ID in the chip cannot be altered, providing a high level of authenticity to the chip and ultimately to the items the chip may be permanently attached or embedded into. The Hitachi µ-Chip has a typical maximum read range of 30 cm (1 foot). In February 2007 Hitachi unveiled an even smaller RFID device measuring 0.05×0.05 mm, and thin enough to be embedded in a sheet of paper. The new chips can store as much data as the older µ-chips, and the data contained on them can be extracted from as far away as a few hundred metres. The ongoing problem with all RFIDs is that they need an external antenna which is 80 times bigger than the chip in the best version thus far developed.

Alien Technology's Fluidic Self Assembly, SmartCode's Flexible Area Synchronized Transfer (FAST)and Symbol Technologies' PICA process are alleged to potentially further reduce tag costs by massively parallel production. Alien Technology and SmartCode are currently using the processes to manufacture tags while Symbol Technologies' PICA process is still in the development phase. Alternative methods of production such as FAST, FSA and PICA could potentially reduce tag costs dramatically, and due to volume capacities achievable, in turn be able to also drive the economies of scale models for various Silicon fabricators as well. Some passive RFID vendors believe that Industry benchmarks for tag costs can be achieved eventually as new low cost volume production systems are implemented more broadly.

Non-silicon tags made from polymer semiconductors are currently being developed by several companies globally. Simple laboratory printed polymer tags operating at 13.56 MHz were demonstrated in 2005 by both PolyIC (Germany) and Philips (The Netherlands). If successfully commercialized, polymer tags will be roll-printable, like a magazine, and much less expensive than silicon-based tags. The end game for most item-level tagging over the next few decades may be that RFID tags will be wholly printed – the same way a barcode is today – and be virtually free, like a barcode. However, substantial technical and economic hurdles must be surmounted to accomplish such an end: hundreds of billions of dollars have been invested over the last three decades in silicon processing, resulting in a per-feature cost which is actually less than that of conventional printing.

Active
Unlike passive RFID tags, active RFID tags have their own internal power source, which is used to power the integrated circuits and broadcast the signal to the reader. Active tags are typically much more reliable (e.g. fewer errors) than passive tags due to the ability for active tags to conduct a "session" with a reader. Active tags, due to their onboard power supply, also transmit at higher power levels than passive tags, allowing them to be more effective in "RF challenged" environments like water (including humans/cattle, which are mostly water), metal (shipping containers, vehicles), or at longer distances. Many active tags today have practical ranges of hundreds of meters, and a battery life of up to 10 years. Some active RFID tags include sensors such as temperature logging which have been used to monitor the temperature of perishable goods like fresh produce or certain pharmaceutical products. Other sensors that have been married with active RFID include humidity, shock/vibration, light, radiation, temperature, and atmospherics like ethylene. Active tags typically have much longer range (approximately 500 m/1500 feet) and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. The United States Department of Defense has successfully used active tags to reduce logistics costs and improve supply chain visibility for more than 15 years.

Semi-passive
Semi-passive tags are similar to active tags as they have their own power source, but the battery is used just to power the microchip and not broadcast a signal. The RF energy is reflected back to the reader like a passive tag.

Antenna types
The antenna used for an RFID tag is affected by the intended application and the frequency of operation. Low-frequency (LF) passive tags are normally inductively coupled, and because the voltage induced is proportional to frequency, many coil turns are needed to produce enough voltage to operate an integrated circuit. Compact LF tags, like glass-encapsulated tags used in animal and human identification, use a multilayer coil (3 layers of 100–150 turns each) wrapped around a ferrite core.

At 13.56 MHz (High frequency or HF), a planar spiral with 5–7 turns over a credit-card-sized form factor can be used to provide ranges of tens of centimeters. These coils are less costly to produce than LF coils, since they can be made using lithographic techniques rather than by wire winding, but two metal layers and an insulator layer are needed to allow for the crossover connection from the outermost layer to the inside of the spiral where the integrated circuit and resonance capacitor are located.

Ultra-high frequency (UHF) and microwave passive tags are usually radiatively-coupled to the reader antenna and can employ conventional dipole-like antennas. Only one metal layer is required, reducing cost of manufacturing. Dipole antennas, however, are a poor match to the high and slightly capacitive input impedance of a typical integrated circuit. Folded dipoles, or short loops acting as inductive matching structures, are often employed to improve power delivery to the IC. Half-wave dipoles (16 cm at 900 mHz) are too big for many applications; for example, tags embedded in labels must be less than 100 mm (4 inches) in extent. To reduce the length of the antenna, antennas can be bent or meandered, and capacitive tip-loading or bowtie-like broadband structures are also used. Compact antennas usually have gain less than that of a dipole — that is, less than 2 dBi — and can be regarded as isotropic in the plane perpendicular to their axis.

Dipoles couple to radiation polarized along their axes, so the visibility of a tag with a simple dipole-like antenna is orientation-dependent. Tags with two orthogonal or nearly-orthogonal antennas, often known as dual-dipole tags, are much less dependent on orientation and polarization of the reader antenna, but are larger and more expensive than single-dipole tags.

Patch antennas are used to provide service in close proximity to metal surfaces, but a structure with good bandwidth is 3–6 mm thick, and the need to provide a ground layer and ground connection increases cost relative to simpler single-layer structures.

HF and UHF tag antennas are usually fabricated from copper or aluminum. Conductive inks have seen some use in tag antennas but have encountered problems with IC adhesion and environmental stability.

Tag Attachment
Basically, there are three different kinds of RFID tags based on their attachment with identified objects, i.e. attachable, implantable and insertion tags. In addition to these conventional RFID tags, Eastman Kodak Company has filed two patent applications for monitoring ingestion of medicine comprises forming a digestible RFID tag.

Tagging Positions
RFID tagging positions can influence the performance of air interface UHF RFID passive tags and related to the position where RFID tags are embedded, attached, injected or digested.

In many cases, optimum power from RFID reader is not required to operate passive tags. However, in cases where the Effective Radiated Power (ERP) level and distance between reader and tags are fixed, such as in manufacturing setting, it is important to know the location in a tagged object where a passive tag can operate optimally.

R-Spot or Resonance Spot, L-Spot or Live Spot and D-Spot or Dead Spot are defined to specify the location of RFID tags in a tagged object, where the tags can still receive power from a reader within specified ERP level and distance.

From Wikipedia, the free encyclopedia

Grid Computing

2007-08-23T01:45:00.000+07:00

From Wikipedia, the free encyclopedia

Grid computing is a phrase in distributed computing which can have several meanings:

-A local computer cluster which is like a "grid" because it is composed of multiple nodes.
-Offering online computation or storage as a metered commercial service, known as utility computing, computing on demand, or cloud computing.
-The creation of a "virtual supercomputer" by using spare computing resources within an organization.
-The creation of a "virtual supercomputer" by using a network of geographically dispersed computers. Volunteer computing, which generally focuses on scientific, mathematical, and academic problems, is the most common application of this technology.
These varying definitions cover the spectrum of "distributed computing", and sometimes the two terms are used as synonyms. This article focuses on distributed computing technologies which are not in the traditional dedicated clusters; otherwise, see computer cluster.

Functionally, one can also speak of several types of grids:
-Computational grids (including CPU Scavenging grids) which focuses primarily on computationally-intensive operations.
-Data grids or the controlled sharing and management of large amounts of distributed data.
-Equipment grids which have a primary piece of equipment e.g. a telescope, and where the surrounding Grid is used to control the equipment remotely and to analyze the data produced.

Grids versus conventional supercomputers
----------------------------------------------------------------
"Distributed" or "grid computing" in general is a special type of parallel computing which relies on complete computers (with onboard CPU, storage, power supply, network interface, etc.) connected to a network (private, public or the Internet) by a conventional network interface, such as Ethernet. This is in contrast to the traditional notion of a supercomputer, which has many CPUs connected by a local high-speed computer bus.

The primary advantage of distributed computing is that each node can be purchased as commodity hardware, which when combined can produce similar computing resources to a many-CPU supercomputer, but at lower cost. This is due to the economies of scale of producing commodity hardware, compared to the lower efficiency of designing and constructing a small number of custom supercomputers. The primary performance disadvantage is that the various CPUs and local storage areas do not have high-speed connections. This arrangement is thus well-suited to applications where multiple parallel computations can take place independently, without the need to communicate intermediate results between CPUs.

The high-end scalability of geographically dispersed grids is generally favorable, due to the low need for connectivity between nodes relative to the capacity of the public Internet. Conventional supercomputers also create physical challenges in supplying sufficient electricity and cooling capacity in a single location. Both supercomputers and grids can be used to run multiple parallel computations at the same time, which might be different simulations for the same project, or computations for completely different applications. The infrastructure and programming considerations needed to do this on each type of platform are different, however.

There are also differences in programming and deployment. It can be costly and difficult to write programs so that they can be run in the environment of a supercomputer, which may have a custom operating system, or require the program to address concurrency issues. If a problem can be adequately parallelized, a "thin" layer of "grid" infrastructure can cause conventional, standalone programs to run on multiple machines (but each given a different part of the same problem). This makes it possible to write and debug programs on a single conventional machine, and eliminates complications due to multiple instances of the same program running in the same shared memory and storage space at the same time.

Design considerations and variations
----------------------------------------------------------------
One feature of distributed grids is that they can be formed from computing resources belonging to multiple individuals or organizations (known as multiple administrative domains). This can facilitate commercial transactions, as in utility computing, or make it easier to assemble volunteer computing networks.

One disadvantage of this feature is that the computers which are actually performing the calculations might not be entirely trustworthy. The designers of the system must thus introduce measures to prevent malfunctions or malicious participants from producing false, misleading, or erroneous results, and from using the system as an attack vector. This often involves assigning work randomly to different nodes (presumably with different owners) and checking that at least two different nodes report the same answer for a given work unit. Discrepancies would identify malfunctioning and malicious nodes.

Due to the lack of central control over the hardware, there is no way to guarantee that nodes will not drop out of the network at random times. Some nodes (like laptops or dialup Internet customers) may also be available for computation but not network communications for unpredictable periods. These variations can be accommodated by assigning large work units (thus reducing the need for continuous network connectivity) and reassigning work units when a given node fails to report its results as expected.

The impacts of trust and availability on performance and development difficulty can influence the choice of whether to deploy onto a dedicated computer cluster, to idle machines internal to the developing organization, or to an open external network of volunteers or contractors.

In many cases, the participating nodes must trust the central system not to abuse the access that is being granted, by interfering with the operation of other programs, mangling stored information, transmitting private data, or creating new security holes. Other systems employ measures to reduce the amount of trust "client" nodes must place in the central system such as placing applications in virtual machines.

Public systems or those crossing administrative domains (including different departments in the same organization) often result in the need to run on heterogeneous systems, using different operating systems and hardware architectures. With many languages, there is a tradeoff between investment in software development and the number of platforms that can be supported (and thus the size of the resulting network). Cross-platform languages can reduce the need to make this tradeoff, though potentially at the expense of high performance on any given node (due to run-time interpretation or lack of optimization for the particular platform).

Various middleware projects have created generic infrastructure, to allow various scientific and commercial projects to harness a particular associated grid, or for the purpose of setting up new grids. BOINC is a common one for academic projects seeking public volunteers; more are listed at the end of the article.

CPU scavenging
----------------------------------------------------------------
CPU-scavenging, cycle-scavenging, cycle stealing, or shared computing creates a "grid" from the unused resources in a network of participants (whether worldwide or internal to an organization). Usually this technique is used to make use of instruction cycles on desktop computers that would otherwise be wasted at night, during lunch, or even in the scattered seconds throughout the day when the computer is waiting for user input or slow devices.

Volunteer computing projects use the CPU scavenging model almost exclusively.

In practice, participating computers also donate some supporting amount of disk storage space, RAM, and network bandwidth, in addition to raw CPU power. Nodes in this model are also more vulnerable to going "offline" in one way or another from time to time, as their owners use their resources for their primary purpose.

Current projects and applications
----------------------------------------------------------------
Grids offer a way to solve Grand Challenge problems like protein folding, financial modeling, earthquake simulation, and climate/weather modeling. Grids offer a way of using the information technology resources optimally inside an organization. They also provide a means for offering information technology as a utility for commercial and non-commercial clients, with those clients paying only for what they use, as with electricity or water.

Grid computing is presently being applied successfully by the National Science Foundation's National Technology Grid, NASA's Information Power Grid, Pratt & Whitney, Bristol-Myers Squibb, Co., and American Express.

One of the most famous cycle-scavenging networks is SETI@home, which was using more than 3 million computers to achieve 23.37 sustained teraflops (979 lifetime teraflops) as of September 2001.

As of May 2005, Folding@home had achieved peaks of 186 teraflops on over 160,000 machines.

Another well-known project is distributed.net, which was started in 1997 and has run a number of successful projects in its history.

The NASA Advanced Supercomputing facility (NAS) has run genetic algorithms using the Condor cycle scavenger running on about 350 Sun and SGI workstations.

United Devices operates the United Devices Cancer Research Project based on its Grid MP product, which cycle scavenges on volunteer PCs connected to the Internet. As of June 2005, the Grid MP ran on about 3,100,000 machines.

The Enabling Grids for E-sciencE project, which is based in the European Union and includes sites in Asia and the United States, is a follow up project to the European DataGrid (EDG) and is arguably the largest computing grid on the planet. This, along with the LHC Computing Grid (LCG) have been developed to support the experiments using the CERN Large Hadron Collider. The LCG project is driven by CERN's need to handle huge amounts of data, where storage rates of several gigabytes per second (10 petabytes per year) are required. A list of active sites participating within LCG can be found online as can real time monitoring of the EGEE infrastructure. The relevant software and documentation is also publicly accessible .

DVB-H

2007-08-18T03:44:00.000+07:00

From Wikipedia, the free encyclopedia

DVB-H (Digital Video Broadcasting - Handheld) is a technical specification for bringing broadcast services to handheld receivers. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification (EN 302 304) can be downloaded from the official DVB-H website. DVB-H is officially endorsed by the European Union.The major competitor of this technology is Digital Multimedia Broadcasting (DMB).

Technical explanation
---------------------------------------------------------------
It is the latest development within the set of DVB transmission standards. DVB-H technology is a superset of the very successful DVB-T (Digital Video Broadcasting - Terrestrial) system for digital terrestrial television, with additional features to meet the specific requirements of handheld, battery-powered receivers.

DVB-H can offer a downstream channel at high data rates which can be used as standalone or as an enhancement of mobile telecommunication networks which many typical handheld terminals are able to access anyway.

Time slicing technology is employed to reduce power consumption for small handheld terminals. IP datagrams are transmitted as data bursts in small time slots. Each burst may contain up to 2 Mbits of data (including parity bits). There are 64 parity bits for each 191 data bits, protected by Reed-Solomon codes. The front end of the receiver switches on only for the time interval when the data burst of a selected service is on air. Within this short period of time a high data rate is received which can be stored in a buffer. This buffer can either store the downloaded applications or playout live streams.

The achievable power saving depends on the relation of the on/off-time. If there are approximately ten or more bursted services in a DVB-H stream, the rate of the power saving for the front end could be up to 90%. DVB-H is a technical system which was carefully tested by the DVB-H Validation Task Force in the course of 2004 (see ETSI Technical Report TR 102 401).

Frequencies
---------------------------------------------------------------
DVB-H is designed to work in the following bands:

-VHF-III (170-230 MHz, or a portion of it)
-UHF-IV/V (470-862 MHz, or a portion of it)
-L (1.452-1.492 GHz)
DVB-H can coexist with DVB-T in the same multiplex.

DVB-IPDC
---------------------------------------------------------------
The set of DVB specifications for IP Datacasting (DVB-IPDC) can most simply be described as the essential components required to deploy a commercial mobile TV service based on Internet Protocol. DVB-IPDC is a set of systems layer specifications originally designed for use with the DVB-H physical layer, but that will ultimately be used as a higher layer for all DVB mobile TV systems, including DVB-SH, and indeed as a higher layer for any other IP capable system.

In short, with regard to mobile TV, these specifications define what is delivered, how it is delivered, how it is described, and how it is protected. They cover system architecture, use cases, DVB PSI/SI signalling, electronic service guide (ESG), content delivery protocols (CDP), and service purchase and protection (SPP). Almost all of these have now been published as formal ETSI standards. The full set of DVB-IPDC specifications is available from dvb-h.org.

DVB-SH
---------------------------------------------------------------
DVB-SH (satellite services to handheld devices) is a hybrid (satellite/terrestrial) standard derived from DVB-H and ETSI SDR. A similar architecture is already being used in S-DMB, XM Satellite Radio, Sirius Satellite Radio, MobaHo! but DVB-SH promises to be more powerful. The envisaged system incorporates a high power geostationary satellite for outdoor and light indoor coverage integrated with a terrestrial repeater (low power gap-filler) network for indoor coverage in urban areas.

Alcatel-Lucent expects to deliver DVB-SH terrestrial repeaters in 2007. Eutelsat and SES ASTRA plan to launch an S-band satellite covering Europe in 2009. DVB-SH satellite services will become operational in 2009 but maybe DVB-SH operations will start earlier with terrestrial networks in certain regions of the world. Chip maker DiBcom is designing a chipset that will be compatible with the DVB-H standard working in the S-Band, Sagem is developing DVB-H phones that support both UHF and S-Band. It's an official DVB Project standard. The DVB Technical Module launched a Study Mission on SSP (Satellite Services to Portable Devices) and in June 2006 TM-SSP started to develop standards. The DVB Project approved the definitive standard in February 2007.

French Agence de l'innovation industrielle is now financing this effort through TVMSL, a project led by Alcatel-Lucent that plans to develop a DVB-SH standard suitable for hybrid satellite and terrestrial transmission. Other partners involved in TVMSL are Sagem, Alenia, RFS, Philips, DiBcom, TeamCast, UDcast, CNRS, INRIA, CEA-LETI.

DVB-H2
---------------------------------------------------------------
A study mission on a possible DVB-H2 system is due to commence in 2007 which could produce a finalized specification in 2008. It is not unthinkable that DVB-H2 and DVB-T2 specifications will be interrelated systems.

Service launches
---------------------------------------------------------------
In Albania, DigitALB launched nationwide Service on 20 December 2006 with the product commercially available from 21 April 2007.

In Finland, the license to operate a DVB-H network was awarded to Digita in March 2006. In May 2006 they announced that they had signed a contract with Nokia to use its DVB-H platform for the service. The network was supposed to be launched on the 1st December 2006, but disagreements regarding copyrights of the broadcasted material have stalled the launch. Among the services available will be Voice TV and Kiss digital radio.Initially the network should cover 25% of the population with coverage area Helsinki, Oulu and Turku. Mobiili-TV started commercial services on May 10 2007.

In India, Indian public broadcaster Prasar Bharti (also known as DD for Doordarshan) has teamed with Nokia to start a DVB-H. And trial is going in various metropolitan areas to test the reception quality of the broadcast coverage. Moreover, DD is currently broadcasting 8 channels in the New Delhi.

In Italy, 3 Italia launched nationwide services in May 2006, both Telecom Italia Mobile (TIM) and Mediaset in June 2006, Vodafone in December 2006.

In Singapore, TVMobile uses DVB technology to broadcast live news, entertainment and music content directly to over 1500 Singapore Bus Service buses islandwide, along with various other indoor and outdoor locations.

In the United States, a nationwide service will be rolled out by Modeo a company owned by Crown Castle. The service will begin in 2006 in New York City and will roll out to the top thirty markets in the USA during 2007. Modeo owns 5 MHz of spectrum nationwide at 1600 MHz. At the NAB trade show in April 2006, a second service launch was announced by SES Americom and Aloha Partners. Titled Hiwire Mobile Television, the service is set to begin trials in Las Vegas in Q4 2006. Hiwire owns two 6 MHz channels of spectrum at 700 MHz covering most of the country.

In Vietnam, VTC launched nationwide service on 21 December 2006.

O2 Ireland commenced a trial in March 2007 with a single high site 1.2 kW transmitter at Three Rock covering the greater Dublin area.

In France, Spain and South Africa nationwide service launch is planned for 2007, in Austria, Germany and Switzerland for 2008.

In China two companies have been issued licenses by the government, Shanghai Media Group and China Central Television. Trials are currently underway, with service launch expected before the 2008 Beijing Olympics.

iMac

2007-08-14T00:13:00.000+07:00

From Wikipedia, the free encyclopedia

The iMac is a desktop computer designed and built by Apple, Inc. It has been a large part of Apple's consumer desktop offerings since its introduction in 1998 and has evolved through three distinct forms. In its original form, the G3, the iMac was egg-shaped with a CRT monitor and was mainly enclosed by colored, translucent plastic. The second major revision, the G4, moved to a design of a hemispherical base containing all the main components and an LCD monitor on a freely-moving arm attached to the top of the base. The iMac G5 and the Intel iMac placed all the components immediately behind the monitor, creating a slim design which tilts only up and down on a simple metal base. The current iMac shares the same form as the previous models but is now thinner and uses aluminum and glass for its case.

The machine enjoys a relatively high profile in popular culture due to its distinctive aesthetics and Apple's successful marketing. The iMac and other Macintosh computers can also be seen in various movies, commercials, and TV shows (both live action and animated) due to their wide use in video editing/film production.

The iMac has also received considerable critical acclaim, including praise from technology columnist Walt Mossberg as the “Gold Standard of desktop computing;” Forbes Magazine described the original candy-colored line of iMac computers as being an “industry-altering success”. The original 24" Core 2 Duo iMac received CNET's “Must-have desktop” in their 2006 Top 10 Holiday Gift Picks.

Popular culture
-----------------------------------------------
The announcement of the iMac initially caused considerable buzz among commentators, Mac fans, and detractors in the press and on websites. Opinions were polarized over Apple’s drastic changes to the Macintosh hardware. At the time, Apple was revamping its retail strategy to improve the Mac purchasing experience. Apple famously declared that “the back of our computer looks better than the front of anyone else’s.” The distinctive aesthetics were easily spotted in public. The iMac was recognizable on television, in films and in print. This increased Apple’s brand awareness, and embedded the iMac into popular culture. When released, the iMac was one of the best selling computers in the U.S. and Japan for months, and Apple was unable to meet demand.

Apple declared the ‘i’ in iMac to stand for ‘Internet’. Attention was given to the out-of-box experience: the user needed to go through only two steps to set up and connect to the Internet. “There's no step 3!” was the catch-phrase in a popular iMac commercial narrated by actor Jeff Goldblum. Another commercial, dubbed ”Simplicity Shootout”, pitted seven-year-old Johann Thomas and his border collie Brodie, with an iMac, against Adam Taggart, a Stanford University MBA student, with a Hewlett-Packard Pavilion 8250, in a race to set up their computers. Johann and Brodie finished in 8 minutes and 15 seconds, whereas Adam was still working on it by the end of the commercial. Apple later adopted the ‘i’ prefix across its consumer hardware and software lines, such as the iPod, iBook, iPhone, iLife, iPhoto, iMovie, iDVD, iTunes, iWeb, iWork, iSight, iChat, iCal, and iSync. The prefix has caught on for non-Apple products as well. This caused a problem when the long rumored Apple phone was dubbed in the media as the iPhone, a name already taken by a Cisco product. In the end, Apple came to an agreement with Cisco, although details of the deal were not disclosed.

Apple’s use of translucent candy-colored plastics inspired similar designs in other consumer electronics. For example, grilling machines, portable electronics, pencil sharpeners, video game consoles and peripherals (including the Nintendo 64, which was released in special edition ‘Funtastic’ colors) featured the translucent plastic. Apple’s introduction of the iPod, iBook, and iMac G4, all featuring snowy white plastic, inspired similar designs in consumer electronic products. The color rollout also featured two distinctive ads: ‘Life Savers’ color scheme was based upon the Rolling Stones song She's a Rainbow and the white advert had Cream’s White Room, specifically its introduction, as its backing track.

USB
-----------------------------------------------
The original iMac was the first Macintosh computer to include a USB port. In fact, USB was the only peripheral interface built into the original iMac; Apple dropped legacy ports such as the Apple Desktop Bus and SCSI in favor of the newer interface. Although USB was invented by Intel and was also available on PCs at the time, the iMac’s popularity and sole dependence on USB helped popularize the interface among third party peripheral makers, as evidenced by the many early USB peripherals that were made of translucent colored plastic to match the color schemes of the original iMac. Via the USB port, hardware makers could make products compatible with both PCs and Macs. This has allowed Macintosh users to use a large selection of inexpensive devices, such as hubs, scanners, storage devices and mice. After the iMac, Apple continued to remove legacy peripheral interfaces and floppy drives from the rest of its product line.

The successful iMac allowed Apple to continue targeting the Power Macintosh line at the high-end of the market. This foreshadowed a similar strategy in the notebook market, when the iBook was released in 1999. Since then, the company has continued this strategy of differentiating the consumer versus professional product lines. Apple's focus on design has allowed each of its subsequent products to create a distinctive identity. Apple derided the beige colors pervading the PC industry. The company would later use anodized aluminium, and white, black and clear polycarbonate plastics.

Legal action
-----------------------------------------------
Apple protected the iMac design with aggressive legal action against computer makers who made imitations, such as eMachines’ eOne. Some manufacturers added translucent plastics to existing designs. In 1999, Apple obtained the domain name www.appleimac.com from Abdul Traya, after legal intervention.

Timeline of iMac models
-----------------------------------------------

UltraSPARC T2

2007-08-13T23:53:00.000+07:00

From Wikipedia, the free encyclopedia

Sun Microsystems' UltraSPARC T2 microprocessor, is a multithreading, multi-core CPU. It is the successor to the UltraSPARC T1. The chip is sometimes referred to by the codename Niagara II. Sun plans to start selling servers with the T2 processor in Q3 2007.

New Features
----------------------------------------------------
The T2 is a commodity derivative of the UltraSPARC series of microprocessors, targeting internet workloads in computers, storage and networking devices. The processor, manufactured in 65 nm, is available with eight CPU cores, and each core is able to handle eight threads concurrently. Thus the processor is capable of processing up to 64 concurrent threads. Other new features include:

-Speed bump for each thread, increased to 1.4 GHz from 1.2 GHz
-one PCI Express port (x8 1.0)
-two 10 Gigabit Ethernet ports with packet classification and filtering
-the L2 cache size increased to 4 MB (8-banks, 16-way associative)
-improved thread scheduling and instruction prefetching to achieve higher single-threaded performance
-two integer ALUs per core instead of one, each one being shared by a group of four threads
-one floating point unit per core, up from just one FPU per CPU
-eight encryption engines (instead of just one in T1), with each supporting DES, 3DES, AES, RC4, SHA1, SHA256, MD5, RSA-2048, ECC, CRC32
-four dual-channel FBDIMM memory controllers
The UltraSPARC T2 is the first major processor whose blueprints are available under a free software license, namely the GPL.

Virtualization
-----------------------------------------------------
Like the T1, the T2 also supports the Hyper-Privileged execution mode. The SPARC Hypervisor runs in this mode, and it can partition a T2 system into 64 Logical Domains, each of which can run an operating system instance.

Tape-Out
-----------------------------------------------------
On April 12, 2006, Sun announced the tape-out completion of the T2. It also disclosed that under the same power envelope, the T2 will deliver twice the performance of the T1 when running transactional workload.

Announcement webcast Sun announced the UltraSPARC T2 on 7 August 2007. It is now being billed "The world's fastest microprocessor."

Performance Improvement: T2 vs. T1
-----------------------------------------------------
-Integer throughput and throughput/watt (>2x improvement)
-Integer single-thread performance (>1.4x improvement)
-Better floating-point throughput (>10x improvement)
-Better floating-point single-thread performance (>5x improvement)

Power consumption
-----------------------------------------------------
Peak power consumption can go as high as 123 watts, but the T2 typically consumes 95 watts during nominal system operation. This is up from 72 watts from the T1, but Sun explains that this is due to a higher degree of system integration onto the chip.

iPhone

2007-08-12T02:16:00.000+07:00

From Wikipedia, the free encyclopedia

The iPhone is a multimedia and Internet-enabled quad-band GSM EDGE-supported mobile phone designed and sold by Apple Inc. The iPhone's functions include those of a camera phone and a multimedia player, in addition to text messaging and visual voicemail. It also offers Internet services including e-mail, web browsing, and local Wi-Fi connectivity. User input is accomplished via a multi-touch screen with virtual keyboard and buttons.

The iPhone has been available since June 29, 2007 in the United States from Apple Retail Stores, the Apple Online Store, and from AT&T Mobility, formerly Cingular Wireless, for a contracted price of US$499 for the 4 GB model and US$599 for the 8 GB model.

Features
---------------------------------
Apple has released a video explaining many of iPhone's features through a series of demonstrations.

Touch screen
The 3.5 in liquid crystal display (320×480 px at 160 ppi) HVGA touch screen topped with optical-quality glass is specifically created for use with a finger, or multiple fingers for multi-touch sensing. Because the screen is a capacitive touch screen, no stylus is needed, nor can one be used. The requirement for bare skin to be used has caused concerns for users in areas with winter climates; gloves worn would then have to be removed to use the touchpad.

For text input, the device implements a virtual keyboard on the touchscreen. It has automatic spell checking, predictive word capabilities, and a dynamic dictionary that learns new words. The predictive word capabilities have been integrated with the dynamic virtual keyboard so that users will not have to be extremely accurate when typing—i.e. touching the edges of the desired letter or nearby letters on the keyboard will be predictively corrected when possible. The keys are somewhat larger and spaced further apart when in landscape mode (currently, only using Safari). Reviewers, writers and analysts have pointed out several areas in which the iPhone falls short. The virtual keyboard has been considered its chief weakness and a risk for Apple. David Pogue of The New York Times and Walt Mossberg of The Wall Street Journal both tested the iPhone for two weeks and found learning to use it initially difficult, although eventually usable. Pogue stated use was "frustrating" and "text entry is not the iPhone’s strong suit" but Mossberg considered the keyboard a "nonissue." Both found that the typo-correcting feature of the iPhone was the key to using the virtual keyboard successfully.

The iPhone varies from common desktop interfaces by using a direct manipulation model of scrolling. Where a typical desktop GUI achieves scrolling by using a scroll-arrow to push a view-window down and thus the content itself up (or the reverse, clicking up to move content down), the iPhone interface enables the user to move the content itself up or down by a touch-drag-lift motion of the finger, much as one would slide a playing card across a table. Additionally, the speed desired for scrolling is computed based on the speed and acceleration with which the drag motion is performed.

Scrolling through a long list works as if the list is pasted on the surface of a wheel: the wheel can be "spun" by sliding a finger over the display. After the finger is lifted from the display the wheel continues to "spin" for a short moment before coasting down. In this way, the iPhone seems to simulate the physics of a real object, which, it is thought, should give a natural feel to the whole process.

The user interface also features other visual effects, such as horizontally sliding sub-selections and co-selections from right and left, vertically sliding system menus from the bottom (e.g. favorites, keyboard), and menus and widgets that turn around to allow settings to be configured on their back sides.

The photo album and web page magnifications are examples of multi-touch sensing. It is possible to zoom in and out of objects such as web pages and photos by respectively "unpinching" and "pinching" them, that is, placing two fingers (usually thumb and forefinger) on the screen and moving them farther apart or closer together as if stretching or squeezing the image. This scaling is done uniformly and proportionally based on the image in question so there is no distortion of the image itself, as would be the case if the image were actually stretched or squeezed.

One disadvantage of multi-touch with regards to AJAX web sites is that there is no mechanism for 'hovering' over a UI element. That is, there is no separate paradigm for indicating interest or focus on a portion of a web control other than clicking on it.

The iPhone's touch interface has been compared by some media to the HTC Touch, which also features a touchscreen designed for fingers, although it can also be used with a stylus and lacks multi-touch.

Other inputs
The display responds to three sensors: a proximity sensor that shuts off the display and touchscreen when the iPhone is brought near the face to save battery power and to prevent spurious inputs from the user's face and ears, an ambient light sensor that adjusts the display brightness which in turn saves battery power, and a 3-axis accelerometer, which senses the orientation of the phone and changes the screen accordingly. Web browsing and music playing support three orientations, while videos play in only one widescreen orientation.

A single "home" hardware button below the display brings up the main menu. Subselections are made via the touchscreen. The iPhone utilizes a full-paged display, with context-specific submenus at the top and/or bottom of each page, sometimes depending on screen orientation. Detail pages display the equivalent of a "Back" button to go up one menu.

The iPhone has three physical switches on its sides: sleep / wake, volume up / down, ringer on / off. All other multimedia and phone operations are done via the touch screen.

Phone
The iPhone allows conferencing, call holding, call merging, caller ID, and integration with other cellular network features and iPhone functions. For example, a playing song fades out when the user receives a call. Once the call is ended the music fades back in.

The iPhone includes a Visual Voicemail feature in conjunction with AT&T which allows users to view a list of current voicemail messages on-screen, without having to call into their voicemail. Unlike most other systems, messages can be listened to in a non-chronological order, by choosing messages from an on-screen list. AT&T modified their voicemail infrastructure to accommodate this new feature designed by Apple.

SMS messages are presented chronologically in a mailbox format similar to Mail, which places all text from recipients together with replies. Text messages are displayed in speech bubbles (similar to iChat) under each recipient's name.

Camera
The iPhone features a built in 2.0 megapixel camera located on the back for still digital photos, but not video recording. It also includes software that allows the user to upload, view, and e-mail photos. The user zooms in and out of photos by "unpinching" and "pinching" them through the multi-touch interface. The software interacts with iPhoto on the Mac.

Multimedia
The layout of the music library differs from previous iPods, with the sections divided more clearly alphabetically, and with a larger font. Similar to previous iPods, the iPhone can sort its media library by songs, artists, albums, videos, playlists, genres, composers, podcasts, audiobooks, and compilations. The Cover Flow, like that on iTunes, shows the different album covers in a scroll-through photo library. Scrolling is achieved by swiping a finger across the screen.

Like the fifth generation iPods introduced in 2005, the iPhone can play video, allowing users to watch TV shows and films. Unlike other image-related content, video on the iPhone plays only in the landscape orientation, when the phone is turned sideways. A two-fingered tap is used to switch between the video's true wide-screen aspect ratio (with black bars on the top and bottom of the screen) and a zoomed mode (to fill the iPhone's screen).

Web connectivity
The iPhone has built-in Wi-Fi, with which it is able to access the World Wide Web (through a wireless network) via a modified version of the Safari web browser. The iPhone is also able to connect to the web through AT&T's EDGE network, but is not able to utilize AT&T's 3G/HSDPA network; Steve Jobs mentioned at the Keynote presentation that 3G support would be a future feature of a new version. The use of the EDGE network instead of 3G has been criticized by analysts. When the user is not in a Wi-Fi hot spot, the iPhone's network connection will use the older EDGE network, which, before the launch, reviewers found that the EDGE network was "excruciatingly slow," with the iPhone taking as long as 100 seconds to download the Yahoo! home page for the first time. Immediately before the launch the observed speed of the network increased to almost 200 kbit/s. This is probably due to the new "Fine EDGE" upgrades AT&T has been making to their network prior to the launch. There has also been some criticism stemming from the iPhone's inability to download iTunes content wirelessly.

The web browser displays full web pages as opposed to simplified pages as on most non-smartphones. The iPhone does not support Flash or Java technology. Web pages may be viewed in portrait or landscape mode and support automatic zooming by "pinching" or double-tapping images or text. The iPhone also has Bluetooth 2.x+EDR built in. It works with wireless earpieces that use Bluetooth technology.

An agreement between Apple and Google provides for access to a specially modified version of Google Maps—in map, local list, or satellite form, optimized for the iPhone, which also provides optional real-time traffic information. During the product's announcement, Jobs demonstrated this feature by searching for nearby Starbucks locations and then placing a prank call to one with a single tap. Google's ownership of YouTube means that viewing videos on the website can be achieved on the iPhone through a specialised application built into the system.

E-mail
The iPhone also features an HTML e-mail program, which enables the user to embed photos in an e-mail message. PDF, Microsoft Word, and Microsoft Excel attachments to mail messages can be viewed on the phone. Yahoo! is currently the only e-mail provider offering a free Push-IMAP e-mail service similar to that on a BlackBerry for the iPhone; IMAP and POP3 mail standards are also supported, including Microsoft Exchange. The iPhone will sync e-mail account settings over from Apple's own Mail application, Microsoft Outlook and Microsoft Entourage, or can be manually configured using the device's Settings tool. With the correct settings, the e-mail program can check many IMAP or POP3-enabled web based accounts such as Gmail, .Mac mail, and AOL.

OS X
Apple has confirmed that an optimized version of the Mac OS X operating system (without unnecessary components) runs on the iPhone, although differences between the operating system (OS X) running on Macs and the iPhone have not been officially explained. As iPhone's CPU is an ARM processor, the version of OS X that runs on iPhone differs from the desktop version in that code written in high-level programming languages is compiled to, and code written in assembly language is written in, instructions from the ARM instruction set architecture (ISA) instead of the x86 and PowerPC ISAs that the Mac version of OS X uses.

The operating system takes up about 700 MB of the device's total 4 or 8 GB storage. It will be capable of supporting bundled and future applications from Apple.

Apple intends to offer a smooth method for updating the iPhone's operating system, in a similar fashion to the way that Mac OS X and iPods are updated, and touts this as an advantage compared to other cell phones.

Widgets, similar to the ones available in Mac OS X v10.4's Dashboard, are included on the iPhone. They include Stocks and Weather widgets.

The iPhone's version of OS X includes the software component "Core Animation" which is responsible for the smooth animations used in its user interface. Core Animation has not yet been released for Macs, but will be part of Mac OS X v10.5.

The build of OS X on at least one iPhone is "OS X 1.0 (1A543a)", as seen in a crash log for the MobileMail application. The application apparently runs as the superuser.

Applications
There are several applications located on the "Home" screen. The YouTube application streams videos over Wi-Fi and/or EDGE after encoding them using QuickTime's H.264 codec, to which YouTube has converted about 10,000 videos. They are expected to convert the entire catalog by Fall 2007. As a result, the YouTube application on iPhone can currently only view a certain selection of videos from the site. Also, because YouTube displays videos using Flash, the iPhone can only view videos through the YouTube application as opposed to accessing the website using Safari.

At WWDC 2007 on June 11, 2007 Apple Inc. announced that the iPhone will support third party "applications" via the Safari web browser that share the look and feel of the iPhone interface. The applications must be created in Ajax or JavaScript to maintain device security. The iPhone cannot officially install full programs from anyone but Apple, although Steve Jobs has hinted that future third party applications are in development. Enthusiasts have demonstrated the possibility of unauthorized native code with a simple "Hello, World" program, as well as a fully functional terminal emulator.

Analysts also claim that iPhone lacks any type of firewall, which some experts claim is posing a data security risk. It is not confirmed by Apple or by independent analysts that used the actual device for tests that it doesn't have a firewall. Daniel Eran writes: "Dulaney doesn't know if the iPhone has a firewall, has no reason to suggest that its installation of OS X wouldn't offer a firewall, and offers no reasons why a mobile device would need a firewall anyway."

Platform support
The iPhone is compatible with Mac OS X version 10.4.10 or later, and 32-bit Windows XP or Vista. For each, the user must download the latest version of iTunes Version 7.3. The iPhone is not compatible with any 64-bit version of Windows such as Windows XP x64 or any 64-bit edition of Windows Vista.

Software updates
Apple has confirmed that software updates can be distributed to the iPhone device via iTunes. Security patches as well as new and improved features, such as a mobile chat client, Flash support, and voice recording, may be released in this fashion. The first iPhone software update was released on July 31, 2007.

Microformat

2007-08-11T16:40:00.000+07:00

From Wikipedia, the free encyclopedia

In web development, a microformat (sometimes abbreviated μF or uF) is a way of adding simple semantic meaning to human-readable content which is otherwise, from a machine's point of view, just plain text. They allow data items such as events, contact details or locations, on HTML (or XHTML) web pages, to be meaningfully detected and the information in them to be extracted by software, and indexed, searched for, saved or cross-referenced, so that it can be reused or combined.

More technically, they are items of semantic mark up, using just standard (X)HTML with a set of common class-names. They are open and available, freely, for anyone to use.

Current microformats allow the encoding and extraction of events, contact information, social relationships, and so on. More are being developed. Version 3 of the Firefox browser, as well as version 8 of Internet Explorer are expected to include native support for microformats.

Principles

(X)HTML standards allow for semantics to be embedded and encoded within them. This is done using specific HTML attributes:

class
rel
rev
For example, 52.48,-1.89 is a pair of numbers which may be understood, from their context, to be a set of geographic coordinates. By wrapping them in spans (or other HTML elements) with specific class names (in this case part of the geo microformat specification):

52.48, -1.89

machines can be told exactly what each value represents, and can then index it, look it up on a map, export it to a GPS device, etc.

Uses of microformats
-------------------------------------
Using microformats within HTML code provides additional formatting and semantic data that can be used by applications. These could be applications that collect data about on-line resources, such as web crawlers, or desktop applications such as e-mail clients or scheduling software.

Several browser extensions, such as Operator, provide the ability to detect microformats within an HTML document and export them into formats compatible with contact management and calendar utilities, such as Microsoft Outlook.

Microsoft expressed a desire to incorporate Microformats into upcoming projects; as have other software companies.

In Wikipedia - and more generally in MediaWiki - microformats are used as part of templates like {{coord}} for example.

Creation of microformats
----------------------------------------
Most of the existing microformats were created at the microformat wiki and associated mailing list, by a process of gathering examples of web publishing behaviour, then codifying it. Some other microformats (such as rel=nofollow and unAPI have been proposed, or developed, elsewhere.