wireless networking

Wifi Finder

noreply@blogger.com (Unknown) — Sun, 24 May 2009 18:27:00 +0000

Sometimes went we need wifi wireless hotspot in public area we must open the laptop or pda phone to cek the signal of the hotspot, it's nice when we find a good signal but when it low it make frustrated. With WIFI FINDER we not necesary open our laptop to cek signal we just need WIFI FINDER. It's small it cheep and very flexible for hand carry.

ZyXEL AG225H 802.11a/b/g/n Wifi Finder, 802.11g USB 2.0 Adapter, and Soft Access Point
The ZyXEL AG-225H is the ultimate high-tech tool for the road warrior.

The AG-225H combines 802.11a/b/g USB 2.0 adapter technology with a fully functional wireless hotspot detector all housed in a sleek device small enough to fit into any pocket. Detect any flavor of wireless network from 802.11a all the way to the newly Drafted 802.11n. The dual-band tri-mode USB adapter is equipped with a high contrast backlit LCD screen and built-in LiON battery, allowing you to scan the environment for hotspots without turning on your computer. With WPA and WPA2 support, the AG-225H can provide a secure wireless connection when used as a 54Mbps high-speed USB wireless adapter. Mac OS support brings the AG-225H to another level of functionality and compatibility never before thought possible!

Apple Airport Express

noreply@blogger.com (Unknown) — Fri, 15 May 2009 07:27:00 +0000

Faster Is Better
Now with blazing 802.11n, the affordable AirPort Express is powerful enough to run a home Wi-Fi network, yet small enough to take on the road. Here's some of the ways you can integrate it into your home.
Compatibility
Part Wi-Fi access point. Part wireless router. AirPort Express just works, seamlessly and wirelessly, with all your Wi-Fi devices. In fact, it’s the easiest way for everyone in your family to share a single broadband Internet connection and USB printer without messy cables.

AirPort Utility
If you think setting up a wireless network is difficult, think again. AirPort Utility for Mac and Windows guides you through the process, and you’ll have your network up and running in minutes. AirPort Utility does most of the work for you by stepping you through the setup process quickly and easily. For the most basic setup, all you have to do is plug your AirPort Express into an electrical outlet and connect your DSL or cable modem. Then open the AirPort Utility software and just follow the onscreen instructions.
AirPort Express works effortlessly with any computer that uses Wi-Fi standards, whether it’s a Mac or a Dell, HP, IBM, or any other Windows-based PC. That’s because the AirPort Express is compatible with computers using the 802.11a, 802.11b, and 802.11g specifications, and it also works with computers that are 802.11n draft 2.0 compliant.
Product Description
Now with blazing 802.11n, the affordable AirPort Express is powerful enough to run a home Wi-Fi network, yet small enough to take on the road. Share your wireless network with up to 10 users, print documents, photos, and more from any room in the house to one central printer, play iTunes music through your stereo or powered speakers using AirTunes, and more.

Wireless Sun/Moon Weather Station

noreply@blogger.com (Unknown) — Fri, 15 May 2009 07:22:00 +0000

Gardeners, hikers, beach combers, farmers, sailors, skiers, daily commuters and anyone who needs to keep an eye on the weather and temperatures indoors and out will love this wireless weather station from La Crosse Technology. With 15 forecast icons, the station makes it easy to plan for that outdoor barbecue, beach outing, or ski day, helping you decide what to wear and when to schedule.
With plenty of versatile features, the unit displays sunrise/sunset and moon phases for 99 U.S. and Canadian cities. A remote sensor helps you monitor outdoor temperatures and the main console displays temperatures and humidity levels inside. The remote sensor works from up to 330 feet away for monitoring temperatures and humidity levels in the greenhouse, shop, and garage. It works great indoors too, helping monitor temperatures in the baby's room, music room, and near plumbing you don't want to freeze up. The main console receives data from up to 3 remote locations with the purchase of additional sensors. A great way to help kids dress for the weather, the weather station's Oscar Outlook icon is always dressed appropriately for weather ahead, with outfits ranging from swimming trunks to a coat, hat and scarf, and other weather-themed accessories in tote, such as a beach chair, an umbrella, or a snow man.
The station's precision clock receives signals from the U.S. Atomic Clock, automatically setting itself to exact time accurate to the second. A manual override setting lets you set date and time yourself for areas where Daylight Savings Time doesn't apply (otherwise the handy unit sets itself for DST, too). A large button lets you toggle between an array of time and weather displays. A flip out table stand sets up quickly on counter, windowsill, or desk, or the unit hangs easily from any wall in the home or office. This weather station is compatible with La Crosse Technology TX29U-IT 915 MHz Wireless Temperature Sensor.

Linksys WRT54G2 Wireless-G Broadband Router

noreply@blogger.com (Unknown) — Fri, 01 May 2009 07:22:00 +0000

The Linksys Wireless-G Broadband Router is really three devices in one box. First, there's the Wireless Access Point, which lets you connect both screaming fast Wireless-G (802.11g at 54Mbps) and Wireless-B (802.11b at 11Mbps) devices to the network. There's also a built-in 4-port full-duplex 10/100 switch to connect your wired-Ethernet devices together. Connect four PCs directly, or attach more hubs and switches to create as big a network as you need. Finally, the router function ties it all together and lets your whole network share a high-speed cable or DSL Internet connection.
Once your computers are connected to the router and the Internet, they can communicate with each other too, sharing resources and files. All your computers can print on a shared printer connected anywhere in the house. And your computers can share all kinds of files--music, digital pictures, and documents. Keep all your digital music on one computer, and listen to it anywhere in the house. Organize all of your family's digital pictures in one place, to simplify finding the ones you want, and easing backup to CD-R. Utilize extra free space on one computer when another's hard drive starts to fill up.

The new Wi-Fi Protected Setup feature makes it easy to configure your wireless devices. Just push the button on the router and on your other Wi-Fi Protected Setup-enabled wireless device to automatically create a WPA2 connection that protects your data and privacy with up to 256-bit industrial-strength encryption. The router can serve as a DHCP Server, has a powerful SPI firewall to protect your PCs against intruders and most known Internet attacks, supports VPN pass-through, and can be configured to filter internal users' access to the Internet. Advanced configuration is a snap with the web browser-based interface.

With the Linksys Wireless-G Broadband Router at the center of your home or office network, you can share a high-speed Internet connection, files, printers, and multi-player games with flexibility, speed, security and simplicity.

Linksys WRT54G Ultimate Hacking

noreply@blogger.com (Unknown) — Fri, 01 May 2009 07:16:00 +0000

This book will teach the reader how to make the most of their WRT54G series hardware. These handy little inexpensive devices can be configured for a near endless amount of networking tasks. The reader will learn about the WRT54G's hardware components, the different third-party firmware available and the differences between them, choosing the firmware that is right for you, and how to install different third-party firmware distributions. Never before has this hardware been documented in this amount of detail, which includes a wide-array of photographs and complete listing of all WRT54G models currently available, including the WRTSL54GS.

Once this foundation is laid, the reader will learn how to implement functionality on the WRT54G for fun projects, penetration testing, various network tasks, wireless spectrum analysis, and more! This title features never before seen hacks using the WRT54G. For those who want to make the most out of their WRT54G you can learn how to port code and develop your own software for the OpenWRT operating system.*Never before seen and documented hacks, including wireless spectrum analysis*Most comprehensive source for documentation on how to take advantage of advanced features on the inexpensive wrt54g platform*Full coverage on embedded device development using the WRT54G and OpenWRT

video mikrotik world wireless record

noreply@blogger.com (Unknown) — Thu, 09 Apr 2009 04:08:00 +0000

here's the movie i'am sorry i can't embeded the link
http://www.tiktube.com/?video=34
download link : http://www.tiktube.com/torrent/304km_Wifi_record_with_MikroTik.torrent
http://www.tiktube.com/video/db16ecc148c56c3e0d9f571dc46413e4.flv

Mikrotik Wireless long distance

noreply@blogger.com (Unknown) — Thu, 09 Apr 2009 03:58:00 +0000

304km Wifi record with MikroTik
i found this news from mikrotik forum, here the news.
On 16-06-2007, we (CISAR, a radioHAM italian association) have realized a 304km link (about 100km ground and 200km sea surface), between Amiata mount (1734asl) and Limbara mount (1300 ca asl).
We utilized a pair of wrap board (but they will be replaced by a new RB532 soon), a pair of Ubiquiti XR5, and a pair of handmade antenna (120cm satellite dish for the surface, and a bronze ball-bearing extracted from a bus).
The signal received on both end was from -58dBm to -62dBm, bitrate between 12 and 48Mbps, CCQ between 70 and 100.

On the moment i'm writing, this seems to be a distance world record (the precedent was from "Politecnico di Torino" on Italy, 295km).
The people which partecipate on this WR:
Amiata Mount
- Giuseppe IW5CGM (CISAR president);
- Antonello IK0TCL
- Mirco IZ3HAD (me)
Limbara Mount
- Natale IW0UIF
- Paolo IK0PCJ (antenna's constructor)
- Mauro IK0YUK
ref[forum.mikrotik.com, wikki.mikrotik.com, tiktube.com]

New Product From RouterBoard.com

noreply@blogger.com (Unknown) — Sat, 20 Sep 2008 04:28:00 +0000

RouterBOARD 433AH
The RB433AH is a more powerful version of the
standard RB433. The 128MB DDR will be capable
of supporting new RouterOS features coming. The
microSD slot supports an additional memory card that
can be used for a Dude database and other features
to be announced in during Spring ‘08.
The 680MHz Atheros MIPs 24K CPU, that can
be overclocked to 800MHz, with a 64KB/32KB
instruction/data cache is probably the fastest CPU
used in low cost wireless access points.
The three Ethernets and mpci slots give you ample
data interfaces to put the big CPU power to work.
The RB433 and RB433AH replace the RB133 and
RB333 positions of our product line.

CPU Atheros AR7161 680MHz network processor (Tested at 800MHz)
Memory 128MB DDR SDRAM onboard memory
Boot loader RouterBOOT
Data storage 64MB onboard NAND memory chip and microSD
Ethernet Three 10/100 Mbit/s Ethernet ports with Auto-MDI/X
miniPCI Three MiniPCI Type IIIA/IIIB slots
Extras Reset switch, Beeper
Serial port One DB9 RS232C asynchronous serial port
LEDs Power, NAND activity, 5 user LEDs
Power options Power over Ethernet: 10..28V DC (except power over
datalines). Power jack: 10..28V DC. Voltage monitor.
Dimensions 10.5 cm x 15 cm, 137 grams
Power consumption ~3W without extension cards, maximum – 25 W, 16W output to cards
Operating System MikroTik RouterOS v3, Level5 license

ref[routerboard.com]

Nano 2,4Ghz Technology From UBNT

noreply@blogger.com (Unknown) — Sat, 20 Sep 2008 04:17:00 +0000

NanoStation2
The Ultimate 2.4GHz CPE for the Global WISP Community
Featuring Adaptive Antenna Polarity (AAP) Technology
The device designed to advance the Global Wireless ISP industry to the next level. Featuring a compact indoor/outdoor design and an interface so intuitive even the most technically challenged can instantly become experts. But, don't be fooled; it is as powerful as it is simple.

Nanostation packs some phenomenal performance with a revolutionary design combining a hi-gain 4 antenna system, advanced radio architecture, and highly researched and developed firmware technology allowing throughput, stability, and capacity performance rivaling even the highest-end WiMax networks. All at a MSRP of $79.

* Atheros AR2315 SOC, MIPS 4KC, 180MHz
* 16MB SDRAM, 4MB Flash
* 1 X 10/100 BASE-TX (Cat. 5, RJ-45) Ethernet Interface
* FCC Part 15.247, IC RS210
* Yes
* 26dBm, +/-2dB
* -97dBm +/-2dB
* Integrated 10dBi Dual Pol + External RP-SMA
* over 15km
* 25Mbps+
* 5 Watts
* 12V, 1A (12 Watts). Supply and injector included
* Passive Power over Ethernet (pairs 4,5+; 7,8 return)
* -20C to +70C (System PCB optimized for hi-temp)
* 5 to 95% Condensing
* ETSI300-019-1.4
* 0.4 kg

wirelless discovery tool's

noreply@blogger.com (Unknown) — Tue, 22 Apr 2008 07:36:00 +0000

Long time not update this blog, try to open the history in my browse software.
yeah in bookmark i find some good link, may i can share this in my blog.
This is about wirelss 802.11b/g discovery tool's, ever here hotspot? yes it's internet service free or open in public place or private place.
in windows xp we find in side bar beside the clock's menu a wifi detector, from that we can know the wifi in our coverage.
i'd like to share a lot link for wifi discovery tool's

Wi-Fi Discovery Tools

Airfart

KisMAC

T-Mobile Connection Manager

The most popular maybe a stumbler, but stumbler only work in windows. that software can't use for wireless site survey or anything else about site coverange test.

Mobile Wireless Communications Today (cont.)

noreply@blogger.com (Unknown) — Fri, 04 Apr 2008 08:02:00 +0000

by Puneet Gupta
Code Division Multiple Access (CDMA) Technology (IS-95) (cdmaOne)

The CDMA technology used in North America is based on the IS-95 protocol standard first developed by QUALCOMM. CDMA differs from the other two technologies by its use of spread spectrum techniques for transmitting voice or data over the air. Rather than dividing RF spectrum into separate user channels by frequency slices or time slots, spread spectrum technology separates users by assigning them digital codes within the same broad spectrum. Advantages of CDMA technology include high user capacity and immunity from interference by other signals. Like TDMA IS-136, CDMA operates in the 1900-MHz band as well as the 800 band.

Work on developing the CDMA standard is conducted mainly by the CDMA Development Group (CDG), a consortium of the main CDMA manufacturers and operators formed to standardize and promote CDMA technology. Whilst work to develop CDMA as a third-generation technology has attracted a great deal of attention over recent months, the CDG has also been working to improve the current performance of CDMA as a second-generation technology. The CDMA Development Group (CDG) has formally adopted the cdmaOne name and logo as a technology designator for all IS-95-based CDMA systems. The term represents the end-to-end wireless system and the necessary specifications that govern its operation. cdmaOne incorporates the IS-95 CDMA air interface, the ANSI-41 network standard for switch interconnection and many other standards that make up a complete wireless system.

The CDMA technology, used in the Interim Standard IS-95, maximizes spectrum efficiency and enables more calls to be carried over a single 1.25 MHz channel. In a CDMA system each digitized voice is assigned a binary sequence that directs the proper response signal to the corresponding user. The receiver demodulates the signal using the appropriate code. The resulting audio signal will contain only the intended conversation, eliminating any background noise. This allows more calls to occupy the same space in the communication channel, thereby increasing capacity. As a simple, example let us assume a user is talking into a mobile phone on a CDMA network. The transmitted portion of a voice signal has frequency components from approximately 300~3400 Hz. This analog signal is digitally encoded, using QPSK (Quadrature Phase Shift Keying), at 9600 bps. The signal is then spread to approximately 1.23 Mbps using special codes that add redundancy. Some of these codes include a device ID that is unique to the phone (like a serial number). Next the signal is broadcast over the channel. When broadcast, the signal is added to the signals of the other users in the channel. On the receiving end, the same code is used to decode the incoming signal. The 9600 bps signal is obtained and the original analog signal is reconstructed. When the same code is used on another user's signal, the redundancy is not removed and the signal remains at 1.23 Mbps.

The problems are the quality of reception and voice squeakiness. To address this major PCS carriers are using 13 kbps vocoders instead of 10 kbps. This improves quality but at the cost of capacity. The technology has been widely adopted by major cellular and PCS carriers in the United States and also internationally. CDMA networks provide operators with reliable digital systems that offer higher capacity, large coverage area and improved voice quality and above all a good 3G upgrade path, CDMA 2000 (I'll discuss this later). It also offers simplified system planning -- through the use of the same frequency in every sector of every cell.

Factors contributing to CDMA's capacity gains are:

* Frequency reuse
* Soft handoffs
* Power control,
* Variable rate vocoders

Some of the benefits of using cdmaOne are:

* Capacity gains of eight to ten times that of AMPS analog systems
* Improved call quality, with better and more consistent sound as compared to AMPS systems
* Simplified system planning through the use of the same frequency in every sector of every cell
* Enhanced privacy through the spreading of voice signals
* Improved coverage characteristics, allowing for fewer cell sites
* Increased talk-time for portables

cdmaOne technology improves quality of service through the use of soft handoffs, which greatly reduce the number of dropped calls and ensure a smooth transition between cells. In soft handoff, a connection is made to the new cell while maintaining the connection with the original cell. This transition between cells is one that is almost undetectable to the subscriber. cdmaOne technology also takes advantage of multipath fading to enhance communications and voice quality. Using a rake receiver and other improved signal-processing techniques, each mobile station selects the three strongest multipath signals and coherently combines them to produce an enhanced signal.

The cdmaOne data capabilities are based on IS-95A, which can provide data speeds of 14.4kbit/s. IS-95B and IS-95C are designed to enhance CDMA's data capability. IS-95B can provide data speeds of up to 64kbit/s by aggregating existing channels. IS 95-B can provide these enhanced data rates through software upgrades only. IS-95C aims to offer a minimum of 24.4kbit/s per channel and aggregated data speeds of more than 115kbit/s. It is expected that IS-95C will define CDMA's capability as a third-generation system. CDMA already supports asynchronous data and faxing (IS-99) and has standardized packet data (IS-657).

The major development initiatives being taken by the CDG for 2G CDMA systems enhancements include Enhanced roaming enables transparent roaming across cellular and PCS networks, with selection of networks and location services. Enhanced roaming will provide roaming between CDMA systems similar to that on GSM: registration, authentication and credit-checking are automatically carried out between the networks without users having to do anything more than switch on their mobiles. Roaming agreements will still be needed between operators.
ref :wirelessdevnet

RF atenuator

noreply@blogger.com (Unknown) — Tue, 18 Mar 2008 13:51:00 +0000

Your wireless to much Noise? it may be cause to high signal. Here's the solution.
Attenuators are used in a wide variety of applications and can satisfy almost any requirement where a reduction in power is needed. Attenuators are used to extend the dynamic range of devices such as power meters and amplifiers, reduce signal levels to detectors, match circuits and are used daily in lab applications to aid in product design. Attenuators are also used to balance out transmission lines that otherwise would have unequal signal levels.

For best results when selecting an RF attenuator for a given connector style, make sure to consider the amount of power being absorbed and the acceptable level of reflection (VSWR) that can be tolerated over the operating frequency range.
reference:
e-meca
wikipedia

up more wifi power on your laptop

noreply@blogger.com (Unknown) — Mon, 10 Mar 2008 02:32:00 +0000

Every one must have same problem with me, if our signal to low for join some acces point of wifi.
there is have to factor, first is the acces point it's self and second is our wifi card on laptop run so low power.

Did you know that our laptop (the new series) have on board wifi card called mini pci card (it's show on pic).
of the two factor upthere let we think the acces point have no problem, so what we do now? here my solution.
don't be affraid for this experiment it's work, and give you more power on your wifi board card.
here the step a hope your laptop have same or little same with my laptop:
1. turn off you laptop, open the back case only in wifi slot. (for this open your manua l laptop or find on website)
2. after open case you will see a small card 5cmx7cm it's call mini pci card. in head of card you will see 2 knop and one of knop join the the cable (it's call pigtail).
3. release the card and the pigtail from the mini pci.
4. now you must change the card with new one, with same card 802.11 a/b/g or 802.11 b/g, but must have more power (dbm).
the regular card have little power (<19dm) href="http://atheros.com">atheros or you can find on wifi store on your local site.

5. if you now have a new card with new dbm, place the card on your laptop for change the old one, dont forget put the pigtail in main knop.
6. turn on your laptop, install your new driver for linux or windows it's for the new card.
usualy windows will detect the new one. or if your system you can find in web for the driver.

finaly it's finish and now try the different of your wifi laptop coverage and power..it's very awasome the signal so strenght.

Getting started in Radio Mobile

noreply@blogger.com (Unknown) — Thu, 06 Mar 2008 09:21:00 +0000

Related my link Radio Mobile for easy site survey now we try how to start the radio mobile.
Radio Mobile is a fantastic program for predicting links and radio coverage. However, it does take some time to get to know and the user documentation is not the best! So here is the G8GTZ how to get started guide.
Downloading the program
The program is located at http://www.cplus.org/rmw/english1.html.
Go to download page and you need to download and install the following:
1) Visual Basic Runtime service pack.
2) Zip file containing Radio Mobile executables,
3) Zip file containing Radio Mobile supplement File
4) File jpeglib.zip to be able to produce JPEGs as well as bit maps.
Run the Visual Basic Runtime service pack and unzip the program and other zips in to the same directory. You can't use it yet as you need the map data!

Get the mapping data
Go to the "Where to get elevation data" page on the Radio Mobile site and use the link to the NIMA website, to get the DTEDs mapping data file. http://geoengine.nima.mil/
This site is a bit unfriendly and slow to use but in the bottom frame enter "London" and "UK" (or your capital city and country if not in the UK) and press "go". This will get you roughly in the right area for your first download - you are bound to come back for more!
When the site has located the area, click on the download tab select "windows" and "DTED" and follow the instructions. You will end up with a DTED Zip file being downloaded.
Copy the DTED zip file in to a new directory under the main program directory called something like c:radiomobile\data. Double click on it to unzip it and extract the unzipped files in to the same directory. It will create 2 directories called dted and text and a file called dmed.
If you download additional DTEDs, extract them in to the same directory - it doesn't seem to matter about overwriting the files that are common - it just adds some new data.
You are now ready to run Radio Mobile!
reference :
cplus.org

Radio Mobile for easy site survey

noreply@blogger.com (Unknown) — Mon, 03 Mar 2008 13:45:00 +0000

Radio Mobile For Windows (RMW), i think this software very use full for us, most wireless enginering use this software.
RMW, is free software (open source). But even is free, this software still have used for most wireless eng.

i'am use this software beside d'other software like mapsource, global mapper, track point, and so on.
in this post i like share about usefull of RMW, sort story of RMW, create by Roger Coudé, VE2DBE.
This is a Radio Propagation simulation program which operates over the frequency range of 20MHz to 20GHz. It is based on the ITS (Longley-Rice) propagation model. The program enables maps to be drawn of specified areas using downloaded SRTM data from the Space Shuttle Radar Terrain Mapping Mission, elevation contours and roads to be added, then Units (stations) can be placed where required. Individual Unit performances can be specified for power, sensitivity, antenna parameters etc. and all Radio Links examined for path profile and signal parameters. Signal coverage patterns can be produced for each separate unit if required. The 'Best Sites' to provide radio coverage to a number of specified unit locations can also be found. The performance of a radio unit which is traversing a defined route on the map can also be generated by the new 'Route Radio Coverage' feature. It is also possible to find the 'Best Unit' from a selection to give the maximum signal level at a defined location.
Radio Mobile is a free and powerful tool for plotting RF patterns and predicting the performance of radio systems. Using freely available terrain elevation data it can produce grey scale, x-ray and rainbow colored virtual maps. One can also produce 3-D and stereoscopic views as well as flyby animations. Background images can be merged with scanned maps, satellite photos and Mapquest maps to produce accurate prediction plots. You can obtain your copy of Radio Mobile from the official website.

When I first began using Radio Mobile I had to spend a great deal of time with the documentation trying to figure out how everything worked. Once I became familiar with the software I thought that others might benefit from my experience and so this tutorial was born. This tutorial will walk you through obtaining and installing the software, obtaining elevation data and finally plotting simple RF plots. Once you become familiar with the software it becomes very easy to use and is a very powerful tool. I used Radio Mobile to plot coverage and design radio links for customers when I owned a wireless ISP. Radio Mobile was able to create plots that were as accurate as the plots from expensive commercial packages used by my hardware vendors.

Radio Mobile is under constant development so if it is missing a feature you want you may have to wait only a short time before it is added to the software. Please realize that I am only a user of the software, not a developer. Please direct any inquiries regarding the software to the author Roger Coudé.
As stated before I am not in any way affiliated with the author of this software. While I may be able to answer some of your questions I simply do not have the time to provide technical support for Radio Mobile. You may find it beneficial to subscribe to the Yahoo! Discussion Group for Radio Mobile. If you find this documentation useful please provide feedback so that it can be improved.

References

1. Official Radio Mobile Web Site
2. Radio Mobile Deluxe Yahoo! Discussion Group
3. pizon.org radio mobile tutorial

keep update my web, i will write how to use dan instalation till implementation.

IBM wireless chipset for video transfers 100x faster

noreply@blogger.com (Unknown) — Tue, 26 Feb 2008 07:59:00 +0000

IBM is looking to change the way you watch video. The company today is announcing
microprocessor chipsets that can wirelessly transmit high-definition video between computers, televisions and handheld devices in the time it takes to push the Play button.

IBM will do this by teaming with MediaTek to launch a joint initiative to develop these ultra fast chipsets that will let users rid their homes and offices of the cumbersome wires needed to connect their HD-TVs to set top boxes and or other devices. The companies will be developing millimeter wave (mmWave) radio technology -- the highest frequency portion of the radio spectrum -- 60 gigahertz rather than 2.4 gigahertz -- and digital chipsets that enable at least 100 times higher data rates than current Wi-Fi standards, IBM said in a release. For example, users could upload a 10 gigabyte file in five seconds with the new technology versus 10 minutes using current Wi-Fi technology. mmWave wireless technology can be widely used at home and office for applications such as multimedia content downloads or uncompressed HDTV streaming from your DVD player. Users could wirelessly download and synchronize iPod-like devices with music and videos in seconds.

The companies will integrate IBM's new mmWave radio chips, antenna, and package technology with MediaTek's digital baseband and video processing chips.

IBM joins an increasingly crowded market aiming to speed networked video. Advanced Micro Devices, Intel, Texas Instruments also have plans for wireless chip packages targeting video applications.

What is GSM

noreply@blogger.com (Unknown) — Fri, 15 Feb 2008 04:51:00 +0000

EveryOne maybe know GSM dan maybe use'it, everyday we use the GSM for communicate voice or data. But did you know what is GSM?, the new tech such us wimax, CDMA, HSDPA or other but we can forget the usefull of GSM. I try to dig from google, wiki dan find some use full artikel.

Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its promoter, the GSM Association, estimates that 82% of the global mobile market uses the standard. GSM is used by over 2 billion people across more than 212 countries and territories. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signalling and speech channels are digital call quality, and thus is considered a second generation (2G) mobile phone system. This has also meant that data communication were built into the system using the 3rd Generation Partnership Project (3GPP).
i found good articel from wirelessdevnet
this articel write by mr. Puneet Gupta.
Global System for Mobile Communication (GSM)
GSM's air interface is based on narrowband TDMA technology, where available frequency bands are divided into time slots, with each user having access to one time slot at regular intervals. Narrow band TDMA allows eight simultaneous communications on a single 200Khz carrier and is designed to support 16 half-rate channels. The fundamental unit of time in this TDMA scheme is called a burst period and it lasts 15/26 ms (or approx. 0.577 ms). Eight burst periods are grouped into a TDMA frame (120/26 ms, or approx. 4.615 ms), which forms the basic unit for the definition of logical channels. One physical channel is one burst period per TDMA frame. A GSM mobile can seamlessly roam nationally and internationally, which requires that registration, authentication, call routing and location updating functions exist and be standardized in GSM networks.

GSM offers a variety of data services. GSM users can send and receive data, at rates up to 9600 bps, to users on POTS (Plain Old Telephone Service), ISDN, Packet Switched Public Data Networks, and Circuit Switched Public Data Networks using a variety of access methods and protocols, such as X.25 or X.32. Other data services include Group 3 facsimile, as described in ITU-T recommendation T.30, which is supported by use of an appropriate fax adapter. A unique feature of GSM, not found in older analog systems, is the Short Message Service (SMS). SMS is a bi-directional service for short alphanumeric (up to 160 bytes) messages. Messages are transported in a store-and-forward fashion. For point-to-point SMS, a message can be sent to another subscriber to the service, and an acknowledgment of receipt is provided to the sender. SMS can also be used in a cell-broadcast mode, for sending messages such as traffic updates or news updates. Messages can also be stored in the SIM card for later retrieval.

The European version of GSM operates at the 900 MHz frequency (and now at the newer 1800 MHz frequency). Since the North American version of GSM operates at the 1900 MHz frequency, the phones are not interoperable, but the SIMs are. Dual-band 900 -1800 and 900 -1900 phones are already released and in production. Tri-band 900 -1800 -1900 GSM phone are expected to be manufactured in the next few years, which will allow interoperability between Europe and North America

A GSM network consists of mobile stations talking to the base transceiver station, on the Um interface. Many BTS are connected to a BSC via the Abis interface and the BSC connect to the MSC (The core switching network) via the A interface.

HLR and VLR provide customized subscriber services and allow seamless movement from one cell to another. The Authentication register and the equipment register provide security and authentication. An OMC and a cell broadcast center allow configuration of the network and provide the cell broadcast service in the GSM network (not shown in the diagram).The voice transmitted on the air interface can be encrypted. The speech is coded at 13kbps over the air interface. Using EFR (Enhanced Fullrate Coding) the voice quality approaches the land line quality. Recent developments like AMR (adaptive multi-rate coding) allow speech coding and channel coding to be dynamically adjusted giving acceptable performance even in case of bad radio conditions. The GSM network supports automatic handovers. Since the mobiles are not transmitting or receiving at all times battery consumption can be conserved. Further using DTX and DRX (Discontinuous transmission and reception, mobile transmits or receives only when there is a voice activity detection) batter power can be conserved even more - a highly desirable characteristic of any mobile system. Also since the mobile is not transmitting or receiving at all times, this allows the mobile to listen to control channels and to provide useful information about other channels back to the cell.

Recent developments and initiatives include:

* GSM Association together with the Universal Wireless Communications Consortium (UWCC), which represents the interests of the TDMA community, are working towards inter-standard roaming between GSM and TDMA (ANSI-136) networks.
* The majority of European GSM operators plan to implement general packet radio system (GPRS) technology as their network evolution path to third-generation
* MExE will allow operators to provide customized, user-friendly interfaces to a host of services from GSM, through GPRS and eventually UMTS. The first implementations of MExE are expected to support the wireless application protocol (WAP) and Java applications. MExE can extend the capabilities that currently exist within WAP by enabling a more flexible user- interface, more powerful features and security.
* GSM cordless telephony system to provide a small home base station to work with a standard GSM mobile phone in similar mode to a cordless phone. The base station would be connected to the PSTN.
* Number portability will allow customers to retain their mobile numbers when they change operators or service providers
* Location services to standardize the methods for determining a GSM subscriber's physical location
* Tandem free operation where the compressed speech is passed unchanged over the 64 kbps links between the transcoders, hence improving the voice quality.
from the articel now we know the very usefull that we can forget.

Google may get its open-access wishes after all; will bid in 700MHz auction

noreply@blogger.com (Unknown) — Mon, 11 Feb 2008 16:20:00 +0000

Very good articel, it's look google more and more powerfull..
Google may get its open-access wishes after all; will bid in 700MHz auction
By Nate Anderson | Published: November 16, 2007 - 10:35AM CT
The search giant has just announced its plans to enter the 700MHz spectrum auction in January, potentially paving the way for a transformation of the US wireless space.

In a statement, a Google spokesperson told Ars, "Our goal is to make sure that American consumers have more choices in an open and competitive wireless world. FCC rules require us to reveal our plans by December 3, and we fully intend to do so. In the meantime, we are making all the necessary preparations to become an applicant to bid in the auction."

Coupled with the company's recent launch of Android and formation of the Open Handset Alliance, the announcement is certain to ignite a new round of frenzied speculation about just what, exactly, the Big G would do with a nationwide swath of 700MHz spectrum.

Conventional wisdom has had it that Google has no interest in actually becoming a network provider, what with all the hassles from those grubby customers who can't make feature X work on Y handset. And then there's billing and engineering and marketing and local storefronts and all the rest of it that makes up a modern wireless carrier's operations.

But if Google is truly serious about the four open access provisions it pushed at the FCC earlier this year, that may not be the company's plan at all. One of those provisions would have forced any winning bidder on the spectrum to lease network access at wholesale rates to others, thus paving the way for a host of innovative wireless providers who could not afford to build a national infrastructure themselves. The FCC rejected that provision, but there's nothing keeping Google from supporting the idea itself.

The company may well may be planning to drop $10 billion on the physical infrastructure and network engineering, but leave customer-facing services and applications up to others who lease bandwidth from the network. This could pave the way for a wireless broadband boom (which would be good for Google), but it could also ensure that the company has a network not at the mercy of the wireless carriers. With that sort of competition, the traditional wireless companies may be forced to (partially) release the stranglehold they have on other applications and devices on their own networks.

In the Open Handset Alliance, Google already has the support of numerous handset makers, all of whom have pledged to produce phones running some version of Android. Imagine the developer's playground this ecosystem could turn out to be: open-source phone OS, support from handset vendors whose feature sets can no longer be dictated by wireless operators, and an open network that will allow any application from any device. Can you say, "Disruptive?"

Whether this will be the route Google goes remains unclear. Certainly, the company wants to get its search tools and apps available on as many cell phones as possible, and to do that in the short term, it will certainly need the help of existing carriers. Throwing up direct competition to those carriers is probably not a great way to accomplish that goal, though Apple has shown that when tech behemoths say "jump!," telcos can be made to ask "how high?"

Google launches US wireless crusade

noreply@blogger.com (Unknown) — Thu, 07 Feb 2008 13:34:00 +0000

By Cade Metz in San Francisco
Google is flirting with yet another effort to offer unfettered internet access over American airwaves, and as usual, it's facing endless back-and-forth with the FCC.

Last Thursday, the world's largest search engine sent a note to the good ol' Federal Communications Commission, expressing its interest in a wireless internet proposal from a new outfit called M2Z Networks. A day later, the FCC rejected the proposal, but Google seems to have high hopes for the "2.1GHz" wireless band targeted by M2Z, as it continues to fight for net access outside the grip of big-name telcos like Verizon and AT&T.

Hoping to offer "fast, free and family-friendly broadband to 95 per cent of the US population within ten years," M2Z Networks is intent on leasing the unused slice of US wireless spectrum between 2155 to 2175MHz. With an FCC application filed in May of 2006, the company suggested that the commission hand over a license to the band in exchange for a cut of the revenues from its planned broadband service.

How can the company generate revenue from a free service? In the usual way. M2Z plans to offer "premium subscription services" as well.

The FCC was slow to answer, and M2Z soon filed a petition insisting that the commision provide a response wihin a year of its original filing. The FCC still waited 15 months, and on Friday, both filings were rejected, along with very similar filings from a copycat firm called NetfreeUS. "We find that the public interest is best served by first seeking public comment on how the band should be used and licensed," the FCC said. "We therefore dismiss all pending applications and related pleadings, without prejudice."

According to its electronic filing, Google was, shall we say, less than enthusiastic with the proposals from M2Z and NetfreeUS. "Google has not participated publicly in any aspect of these proceedings to date, and does not here take a substantive position on the relative merits of M2Z's proposals," the filing said. But the Mountain View, Calif. outfit likes the idea of using the 2.1GHz band to serve up open internet access to American consumers.

If the FCC were to reject M2Z's proposal, Google argued, the commission should explore "the desirability of service rules that foster new entrant competition through 'open platforms' and other license conditions similar to those sought by Google and others in the recent 700 MHz proceeding".

Google spent the summer fighting for unfettered net access over the 700-MHz band, a prized portion of the US spectrum recently vacated by TV stations making the switch to digital transmission.

Clearly, the company wants to give Americans more options when it comes to broadband. It's also latched on to a Microsoft-led effort to provide net access via US "white spaces", portions of television spectrum that go unused by local TV channels.

The 700-MHz band comes up for auction in January, and although Google says it may bid on the band, the FCC failed to match all its demands for open access. The 2.1GHz band may provide new hope for a broadband market served by many ISPs - rather than just a greedy few.

Nokia Siemens Networks Awards Siemens IT Solutions and Services Major Global IT Contract

noreply@blogger.com (Unknown) — Thu, 07 Feb 2008 13:20:00 +0000

WirelessDevNet.com Press Release:
Nokia Siemens Networks and Siemens IT Solutions and Services signed a global service agreement set to run for four years plus an option for another two years. With this contract Siemens IT Solutions and Services becomes the leading vendor for IT infrastructure services for Nokia Siemens Networks.

Siemens IT Solutions and Services will be responsible for operating a major part of the IT Infrastructure for Nokia Siemens Networks. This includes user care, non SAP data centers, PC-client back office functions and local area networks globally. The transition and transformation of the IT will be accomplished within the next 15 months.

“This agreement is a major step in the integration of the IT infrastructure and related processes of Nokia Siemens Networks,” said Manfred Immitzer, Chief Information Officer at Nokia Siemens Networks. “Siemens IT Solutions and Services will provide the IT infrastructure backbone that is essential to the implementation of the company’s new mode of operations.”

“The deal adds a large amount of new business to us as it includes all of Nokia Siemens Networks, not just most parts of the former Siemens infrastructure”, stated Christoph Kollatz, CEO of Siemens IT Solutions and Services. “With this agreement, Nokia Siemens Networks will become one of our largest customers worldwide.”

Siemens IT Solutions and Services is an internationally leading provider of IT solutions and services. It covers the entire IT service chain from a single source, from consulting to system integration, right through to the management of IT infrastructures. In addition, Siemens IT Solutions and Services extends the range of offerings of the other Siemens Groups to include software developments and IT solutions. With its comprehensive know-how and industry-specific knowledge, Siemens IT Solutions and Services provides measurable added value for its customers. Founded in January 2007, the new Siemens Group employs around 43,000 people and posts annual sales of about 5.4 billion euros, of which some 70 percent are generated outside of the Siemens group. www.siemens.com/it-solutions

About Nokia Siemens Networks
Nokia Siemens Networks is a leading global enabler of communications services. The company provides a complete, well-balanced product portfolio of mobile and fixed network infrastructure solutions and addresses the growing demand for services with 20,000 service professionals worldwide. Nokia Siemens Networks is one of the largest telecommunications infrastructure companies with operations in 150 countries. The company is headquartered in Espoo, Finland.

Wi-Fi distance record

noreply@blogger.com (Unknown) — Sat, 26 Jan 2008 17:54:00 +0000

New Wi-Fi distance record: 382 kilometers
Posted by Michael Kanellos

Researcher Ermanno Pietrosemoli has set what appears to be a new record for the longest communication link with Wi-Fi.

Pietrosemoli, president of the Escuela Latinoamerica de Redes (which means networking school of Latin America) established a Wi-Fi link between two computers located in El Aguila and Platillon Mountain, Venezuela. That's a distance of 382 kilometers, or 238 miles. He used technology from Intel, which is concocting its own long-range Wi-Fi equipment, and some off-the-shelf parts. Pietrosemoli gets about 3 megabits per second in each direction on his long-range connections.

Most Wi-Fi signals only go only a few meters before petering out. Conventional Wi-Fi transmitters, however, send signals in all directions. By directing the signal to a specific point, range can be increased.

Honing the signal, however, means that the receiver and transmitter have to be aligned. Trees, buildings and other objects that get between them can sever the link. The curvature of Earth, misalignment between the transmitter and receiver, as well as shaking and any sort of movement at the transmitting or receiving end can also impair the signal. (To ameliorate some of these factors, Intel has created a way to electrically steer the signal, which in turn increases bandwidth.)

Geography was on Pietrosemoli's side. El Aguila and Platillon Mountain sit in the Andes, which form fairly jagged peaks in this part of the range.
The old record was 310 kilometers. Swedish scientists made a link between a balloon and an Earth-bound station. We say "apparently" on Pietrosemoli's record, in case someone out there has set a better record about which we are unaware.

More details can be found in an article at the Web site for The Association for Progressive Communcations. (Inveneo, which is trying to bring PCs to emerging markets, told us about Pietrosemoli's achievement.)

Intel, along with organizations like Inveneo, are testing the feasibility of long-range Wi-Fi as a communication link in Uganda and other emerging nations. Long-range Wi-Fi isn't as robust at WiMax, but the towers cost a lot less. Some hobbyists have accomplished a long-range Wi-Fi connection with low bandwidth.

Similar experiments are being carried out in the United States as well. A long-range Wi-Fi link connects Intel Research's Berkeley Lab and a Sun Microsystems lab on the San Francisco Peninsula, more than 20 miles away.

Hot spot problem

noreply@blogger.com (Unknown) — Sat, 26 Jan 2008 03:46:00 +0000

Do you have problem with your wireless connection on your home, i have it. i have same problem if you same with me, the cover of the radio wifi on my home can't cover all room in my home. it's make me stress if i always do work in working room, i can take my laptop in garden or behind room where the spot on. But solve when i read this "New wireless technology kills 'dead spots' at home" write by Edward C.Baig. I read on usatoday.com. Mr. Baig write about dead spot wifi conection, couse i have problem i read step by step then i try to implement that. This his article :
New wireless technology kills 'dead spots' at home
I wouldn't ordinarily mention wireless networking and baseball in the same breath. But I couldn't resist. The so-called Mimo technology I've been testing is kind of like, um, Wi-Fi on steroids.

There's nothing objectionable about this impressive new wireless technology except maybe its name. Mimo (pronounced My-moh) stands for multiple input, multiple output.Just as performance-enhancing drugs apparently led to more home runs, Mimo in its own (perfectly legitimate) way extends the range of Wi-Fi network base stations to, relatively speaking, McGwire-like proportions. That's while maintaining a speedy connection. Indeed, you can enjoy fast Wi-Fi coverage throughout your home or office, without the "dead spots" you may encounter with your current gear.

To experience Mimo in my house, I tested a wireless base station from the Linksys division of Cisco Systems. Linksys claims its router — the 2.4-GHz Wireless-G broadband router with SRX (speed and range expansion), model WRT54GX — is up to eight times faster and offers up to three times the range of otherwise comparable products without Mimo.

With differing approaches, Linksys competitors Belkin, D-Link and Netgear have unveiled their own Mimo devices.

Mimo is expected to be at the forefront of the speedy next iteration of Wi-Fi, known in geek-speak as "802.11n." The engineers won't finalize the precise standard until next year, which means there's no guarantee today's Mimo devices will get along with whatever the industry eventually cooks up. But Mimo's improvements are dramatic, and the technology already makes nice with the most popular current flavors of Wi-Fi, 802.11b and 802.11g. Thus, you can buy a Mimo router and still exploit the built-in Wi-Fi capabilities of your notebook. f you want the full effect, you can add a Mimo-ready PC card that slips into a slot on your laptop. In a modest-size home, that may be overkill.

Like most new technologies, Mimo devices aren't cheap. Linksys charges $199 for the router and $129 for each laptop card, vs. $79 and $69, respectively, for comparable non-Mimo equipment.

Here's a simplified version of how Mimo works: For about a century, scientists have wanted to mitigate a natural phenomenon known as "multipath." That's when transmitted radio signals bounce off barriers and take multiple paths to get to a receiver, resulting in interference. In the mid-1990s, Stanford researchers determined that not only was multipath not the enemy, but that they could actually take advantage of it. So instead of sending out a single stream of data like most base stations, Mimo sends out multiple data streams simultaneously and uses multiple antennas to sort out the signals.

The Linksys router, for example, has three folding antennas. Inside the router are chips from a company called Airgo Networks, whose executives include those smart Stanford guys. Airgo also works with Belkin.

Wi-Fi chipmaker Atheros employs an alternative method to get at Mimo. Its chips are in the D-Link devices. A third player, Video54, is lending its expertise to Netgear.

Putting together any wireless network can be a chore, especially for novices. But Linksys does a decent job, through its software, of walking users through the set-up process. If you run into snags, the company provides toll-free tech support 24 hours a day, seven days a week.

I connected the router to the cable modem in my basement office. The box has flashing indicator lights and extra ports for hooking up Ethernet devices.

With my previous Microsoft router, I had experienced spotty Wi-Fi coverage in one upstairs bedroom and a dead spot in another. Subbing the Linksys router, I got a sturdy signal throughout the house, even when using the integrated Wi-Fi radio inside my IBM ThinkPad rather than the Linksys laptop card. I didn't notice a terrific increase in speed when I inserted the card.

I also got better range in the bedrooms using the wireless capabilities of my Apple PowerBook. The Mac doesn't have a slot for the type of Mimo card Linksys supplies.

With the Linksys card inside the ThinkPad, I headed to my backyard and a detached garage where I could not previously get a signal. Mimo delivered. I maintained a strong connection across the street and down the block. I walked past four houses before the signal weakened, roughly half a football field from my home.

I didn't get as far when I removed the Linksys card and walked down the street. I was still able to surf more than 100 feet from my front door. Your own mileage will vary, depending on conditions in and around your house.

My testing also took me to LaGuardia and Newark, N.J., airports. In the terminals, I got strong signals when I used just the internal Wi-Fi radio in the ThinkPad, as well as when I relied on the Linksys card. The power of that card and Mimo became evident only at Newark when I sat near a parking garage entrance. The signal strength using the Linksys laptop card was "very good" compared with "low" when I used the ThinkPad's internal Wi-Fi.

To protect privacy, you can set up the network with robust encryption. Alas, I ran into a baffling hitch.

After temporarily losing my Internet connection, the "secure" wireless home network I'd created also disappeared; the router failed to save the security settings and I was back to square one with an unprotected network. I created another secure network, but again the router failed to hold onto the settings after I intentionally pulled the plug. Linksys claims this is an isolated malfunction, likely having to do with the router's flash memory.

I'm willing to give Linksys the benefit of the doubt because of the rewards that Mimo provides. So if your current wireless router has all the pop of a Punch and Judy hitter, I'd recommend switching to a Mimo base station with the muscle to reach the fences. Steroid-free.

from that,know my problem solve, i change the wifi radio, and pick the new wifi with more power and cover. in realy-realy dead spot i use more wifi split by hub device. Yes we can use wds mode to conect with the other wifi so i don't need cable to bring data to wifi in realy dead spot. And now today, can bring my laptop to my garden room behind wall, do work with barebeque, joke with my neigborg.

Site survey software

noreply@blogger.com (Unknown) — Tue, 22 Jan 2008 18:37:00 +0000

According my post about site survey in older post in this blog, i'd like continue write about software which use in wireless site survey. May be if we try to find in search engine we can find alot this about this.
First we can use GPS
with that hardware witch use for mark point site we survey, with gps we have coordinat, elevasi. Guys we can find screen shot about software that use for importing data from our GPS that call mapsource.

Map source or Mapsource Trip and Waypoint Manager is a Mapsource brand product. It is an economic tool for transferring data between a Garmin GPS and a computer. It has similar detail to Worldmap (without navigation aids), but does not load maps to the GPS.
if we buy the original garmin stuff like GPS actualy we have cd contain mapsource, nroute. in that cd we can find the manual to use GPS and related software.
Why mapsource very usefull for wireless site survey? couse if we ex make conection with 2 site we must know distence betwen site.
after we have data we can input to related software that can calculate wireless link in another post i will continue about link budget knowlage..
we can download manualy for garmin.com to know more about mapsource.

Different Types of Wireless Technologies

noreply@blogger.com (Unknown) — Sun, 20 Jan 2008 16:59:00 +0000

Different Types of Wireless Technologies
------------------------------------------------------
Broadband Narrowband
---------------- -----------
WAN WAN and WLAN
Licensed Unlicensed
Digital Analog
Line-of-site Non-line-of-site
Simplex Half-/full-Duplex
Point-to-point Multipoint
------------------------------------------------------

Global Positioning System for Wireless site survey

noreply@blogger.com (Unknown) — Sun, 20 Jan 2008 06:26:00 +0000

Related on my post about RF Site Survey Steps that i took from wifi-planet Jim Geier May 10, 2002.
i like to continue about site survey in wireless network.
usualy most wireless enginer user GPS (Global Positioning System) for site survey) this story about GPS that i took from wiki.

The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 Medium Earth Orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed, direction, and time. Other similar systems are the Russian GLONASS (incomplete as of 2007), the upcoming European Galileo positioning system, the proposed COMPASS navigation system of China, and IRNSS of India.

Developed by the United States Department of Defense, GPS is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program).The satellite constellation is managed by the United States Air Force 50th Space Wing. The cost of maintaining the system is approximately US$750 million per year,[ including the replacement of ageing satellites, and research and development.

Following the shootdown of Korean Air Lines Flight 007 in 1983, President Ronald Reagan issued a directive making the system available for free for civilian use as a common good.[3] Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.
Simplified method of operation

A typical GPS receiver calculates its position using the signals from four or more GPS satellites. Four satellites are needed since the process needs a very accurate local time, more accurate than any normal clock can provide, so the receiver internally solves for time as well as position. In other words, the receiver uses four measurements to solve for 4 variables - x, y, z, and t. These values are then turned into more user-friendly forms, such as latitude/longitude or location on a map, then displayed to the user.

Each GPS satellite has an atomic clock, and continually transmits messages containing the current time at the start of the message, parameters to calculate the location of the satellite (the ephemeris), and the general system health (the almanac). The signals travel at a known speed - the speed of light through outer space, and slightly slower through the atmosphere. The receiver uses the arrival time to compute the distance to each satellite, from which it determines the position of the receiver using geometry and trigonometry

Although four satellites are required for normal operation, fewer may be needed in some special cases. For example, if one variable is already known (for example, a sea-going ship knows its altitude is 0), a receiver can determine its position using only three satellites. Also, in practice, receivers use additional clues (doppler shift of satellite signals, last known position, dead reckoning, inertial navigation, and so on) to give degraded answers when fewer than four satellites are visible.
ok reader i will contiinue next post, still about wireless lan and site survey