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An extraordinary experience begin here!

2008-07-05T16:10:00.004+07:00

From Wireless waffle,

How to listen UFOs

An interesting title which provocate us to read. A blog posting with unique topic
make our eyes catch to read 'em. Here are the post:

Since the late 1990's rumours have abounded that it was possible to hack into American military satellites and use them for wide area communication. The satellites, originally the 'FleetSatCom' newtork (often abbreviated to FLTSATCOM) use basic FM modulation and have uplinks in the area of 300 MHz and downlinks in the area of 260 MHz. Stories went that tuning in to the downlinks it was possible to hear illegal pirates, from Brazil in particular, who were usurping these US military satellites to use for wide-area communications. It was also said that 'Smile 93.9 FM' (rumoured to be from Manila) was using one of the channels as a studio to transmitter link and could often be heard on the downlink frequency of 269.950 MHz.

This seemed a little far fetched and unbelievable: How could one of the world's most super-sophisticated armed forces allow their multi-million dollar military hardware be taken control of by such an unsophisticated enemy armed with nothing more than a simple UHF FM transmitter? Using a simple VHF/UHF receiver and a bog standard roof mounted VHF/UHF antenna, I set out to try and debunk the myth.

Within seconds I was listening to a conversation between two likely sounding chaps on a frequency of 255.550 MHz. Next I stumbled across more voice traffic (definitely in Portuguese, the language spoken in Brazil) on 258.650 MHz. And before long I found more voice traffic on 253.850 MHz. Intrigued that this long reported phenomena was still in evidence I did a bit of digging on the internet to find out more.

The original FleetSatCom satellites which were launched in the late 1970's and early 1980's are no longer operational. They were initially replaced by satellites known as Leased Satellites (Leasat) which have also since been replaced by the UHF Follow-On series of satellites, ironically acronymised as UFO. The UFO satellites continue to provide the same communications capabilities as the earlier ones but with somewhat higher transmitter powers, making reception of them fairly straightforward.

A bit more digging uncovered military standard MIL-STD-188-181A which describes the interface specification for the satellites (i.e. the technical requirements for equipment used to access them) and in it we find a list of the uplink and downlink frequencies used. All the frequencies I could hear are in group 'Charlie', now known as group 'Quebec' (Q) on the UFO satellites. Group Q comprises the following 25 kHz wide downlink frequencies (uplink frequencies are 41 MHz higher):

images ufo fltsatcom jpgQ1 250.650 MHz (Fleet Broadcast)
Q2 252.150 MHz (Navy Channels)
Q3 253.850 MHz
Q4 255.550 MHz
Q5 257.150 MHz
Q6 258.650 MHz
Q7 265.550 MHz
Q8 267.050 MHz
Q9 269.450 MHz
Q10 269.950 MHz
Q11 260.625 MHz (DoD Channels)
Q12 260.725 MHz
Q13 262.125 MHz
Q14 262.225 MHz
Q15 262.325 MHz
Q16 262.425 MHz
Q17 263.825 MHz
Q18 263.925 MHz

So far, I have heard sporadic voice traffic on channels Q2, Q3, Q4, Q5 and Q6 and something, albeit rather weak on Q7. It seems as if the satellite I am hearing is UFO-7 which is situated over the Atlantic. But is this traffic really pirates using the satellites on purpose, or is it something else? Surely there is no longer the need, in Brazil or other countries, to use US military satellites for communications, especially now that mobile phones and mobile coverage are virtually ubiquitous?

A quick look at the Brazilian frequency allocation table, the Plano de Destinação de Faixas de Freqüência, shows us that the frequency range 270 - 326.8 MHz is assigned to the fixed and mobile service, and in particular to public correspondence. So the frequencies are quite legally in use for various communication services; that they are being relayed by the satellite is incidental and a result of the fact that the uplink frequencies are used differently in different parts of the world. So no Brazilian pirate radio mafia trying to jam US military satellites after all then? What a shame, it seemed like such a good story.

Originally posted by admin of Wireless Waffle on Friday 31 August, 2007, 10:48 - Pirate/Clandestine

Blogging on Socialspark about latest tech

2008-07-02T20:06:00.005+07:00

Another interesting site to blog our hobby on technology review! and that is Socialspark. A social community site for blog marketing, advertising and social media marketing founded by Izea. We can review many new techies on internet or blogger who write the same hobby with us about newest and latest tehnology.
Socialspark give us an opportunity to write and blog more to post the latest trend on whatever we like including some review about gadget, electronics, hardware or news about anything. We can also blog anything about ourself as the technology user or anything.

When we have something to blog any topics we interested on just go to Socialspark, or we can review others before we posting a blog or you can just surfing around without being an active blogger (But i won't suggest that as a blogger). One important thing is we can get more traffic by join Socialpark, that's what i experience from my own blog and earn money by support their sponsors. I got trafficflood from any visitor all over the world. That what makes me could share more and more about my own blog. And what i love to review is many sponsored post connected to my interests and hobbies such as gadget review or some products offer.
It said that Socialspark is right around the corner for everybody or blogger who wants to socialize themself or their blog about technology. They accept everyone from anywhere on the world as long as they connected to internet. What a big big connection out there. So blog happily and comfortly by clicking this link on Socialspark .

Watch H.264 over GNU Radio and USRP video

2008-07-02T16:47:00.006+07:00

GNU radio has a good prospect on Software Radio development to realize a 4G content application, one of the most powerful software that can be embedded on a single FPGA with USRP technology. You can watch the demo of Cross-layer wireless video testbed and full description here :

Zhifeng Chen and Jun Xu with Advisor: Prof. Dapeng Oliver Wu from University of Florida are deploying some research works on QoS of wireless video by cross-layer design and results will come very soon. All of their research works will be verified in the real world wireless environment but not just by simply making some assumptions. That will be the major difference to distinguish our research works from others.

In this project, they transmit H.264 video over wireless connection by USRP (and decode H.264 and display in real time). In Windows PC, run H264_display.exe (set your UDP server port number, default value is 50007).

3G, 4G, WiMAX, 802.20, ABI - do we need them all ?

2008-07-02T00:19:00.002+07:00

Last week, AT&T Wireless debuted UMTS services in Detroit, Phoenix, San Francisco and Seattle. Based on technologies shared with Japan's NTT DoCoMo, these are, says the company, the first commercially available 3G UMTS services available in the United States.

That's good news, but is it the whole story? The wireless industry is basing its market strategy on the assumption of an evolution to 4G services, possibly based on orthogonal frequency-division multiplexing (OFDM). NTT DoCoMo expects to roll out its first 4G services in Japan within three years.

Smooth high-speed video and other forms of high-speed data are among the central benefits 4G proponents are touting, and are important reasons for its development. Yet, there are 3G networks delivering them already. WiMAX promises to do the same. So is the need for 4G inevitable?

According to ABI Research's vice president of research, Edward Rerisi, it's all about subscriber numbers and demand. Compared to present-day 3G, fourth generation technologies, he says, will be able to provide many more customers with these rich-media experiences at the same time.

It's all a question of the level of demand for data-based services, and there will be a wide variety to choose from. Some users may want video; some may transfer multi-megapixel images and still others might find location-based services, enterprise applications, or any of the other sophisticated data-based offerings more compelling.

"In any case," adds Rerisi, "when when consumer demand accelerates, the true value of '4G' will be revealed."

ABI Research's report, "Broadband Wireless - Last Mile Solutions" examines the technical features of these technologies and the complex dynamics of this market.

Founded in 1990 and headquartered in New York, ABI Research maintains global operations that support annual research programs, quarterly intelligence services and market reports in wireless, automotive, semiconductors, broadband, and energy.

Originally posted on 2nd August ,2004

Managing Java Application Performance with Microprocessors

2008-07-01T02:37:00.005+07:00

Java is typically a driving force behind innovation within a
business. Yet, the majority of organizations often find themselves
consumed in mundane tasks associated with managing Java and achieving
improved response times. Explore the role microprocessors play in
achieving improved performance from existing Java platforms.

====================================================================
TITLE: The Role of the Microprocessor in the Evolution of Java
Technology Part 1
WHEN: AVAILABLE NOW ON DEMAND
SPEAKER: Dr. Leendert vanDoorn, Senior Fellow, AMD
SPONSOR: AMD

ATTEND THIS VENDOR VIDEOCAST TODAY!

====================================================================
====================================================================
ABOUT THIS VENDOR VIDEOCAST
====================================================================
This Videocast, part one of a three part series, explores the role of
microprocessors in Java technology. Learn how Java has become one of
the strongest and most flexible platforms for computing. Explore how
Java has become the dominant platform for both businesses and
consumers. Discover how microprocessors allow Java developers to
spend more time innovating features for software initiatives as well
as the future of Java technology.

VIEW VIDEOCAST:
1.part-1
2.part-2
3.part-3

====================================================================
ABOUT THE SPEAKER
====================================================================
Dr. Leendert vanDoorn, Senior Fellow, AMD

Dr. Leendert vanDoorn manages the Software Technology Office and
Systems Manageability teams within AMD's software organization. Focus
areas include: managed code, accelerated computing, manageability,
virtualization, security and driving advanced silicon features into
AMD's future processors and platforms. Van Doorn has a Ph.D. from
Vrije Universiteit, Amsterdam and prior to AMD was a senior manager
at IBM's T.J. Watson Research Center.

Originally posted on theserverside.com/

To all visitors and friends

2008-07-01T02:34:00.000+07:00

MyNiceSpace.com

GNU Radio Opens an Unseen World

2008-06-27T13:02:00.004+07:00

Matt Ettus has the sly smile of someone who sees the invisible. His hands fly over the boards of his Universal Software Radio Peripheral, or USRP, snapping them together with an antenna like Lego bricks. Then he plugs in the naked boards to a USB 2 cable snaking to his Linux laptop.

After few minutes of normal Linux messing around ("Takes forever to boot.... Haven't got the sound driver working yet....") he turns the laptop around to reveal a set of vibrating lines in humps and dips across the screen, like a wildly shaking wireframe mountain range. "Here," he explains, "I'm grabbing FM."

"All of it?" I ask.

"All of it," he says. I'm suddenly glad the soundcard isn't working.

Radio is that bit of the electromagnetic spectrum that sits between brain waves and daylight. It's made of the same stuff that composes light, color, electrical hums, gamma radiation from atom bombs, the microwaves that reheat your pizza.

From our perspective, radio devices behave very differently -- a global positioning system gadget doesn't look like a TV doesn't look like a CB set, even if they are all radios. They are single-purpose machines that use small bits of radio spectrum to do very specific tasks -- about as far from the general-purpose personal computer as you can get. But there's no reason they have to be.

Most of the required components of a radio are the same and can be generalized. And with Moore's law making processors fast enough, much of a radio's function can be done with software.

Building a general radio that can receive and transmit, and attaching it to a software system that can fill in the gaps of what we normally think of as radio, is kind of like the Enterprise's deflector dish: Give engineering 20 minutes and it can do anything the captain needs to move the plot along. One of Ettus' USRPs, with the right daughterboards and radio software, can capture FM, read GPS, decode HDTV, transmit over emergency bands and open garage doors.

The GNU radio project was the brainchild of Eric Blossom, who wanted to create a software HDTV receiver in advance of broadcast flag legislation limiting what hardware was allowed to receive the high-def signal. "We'd just go build one of those things (in software) and moot (broadcasters') control over the hardware," says Blossom.

He teamed up with Ettus, but they lacked a radio platform that was cheap enough to get into many people's hands. They could do a lot with the computer, but there were limits. "How do I get from the antenna into the computer?" explains Blossom. "The computer wants digital samples to work on."

Ettus secured National Science Foundation funding through the University of Utah to design what would become the USRP. "Basically we proposed the 85 percent solution for 10 percent of the price. Given that part of the NSF's charter is about education ... you can get 10 more things in your students' hands for your dollars," says Blossom.

Ettus was drawn more to the technical challenge than the political project.

He wanted to build the HDTV receiver "because it was the Mount Everest ... it was the biggest receive-only mountain." Decoding HDTV was a political act of radio, but, mostly, Ettus wanted to see if he could do it.

Four years later, Ettus hasn't just decoded HDTV, but has gone on to write software that does far more. He's quit his day job to build and sell the USRP hardware full time -- you can buy it from his website starting at $550 for the motherboard.

Ettus and Blossom's software-defined radio on the cheap is popping up in unexpected places, describing a very different radio world from the centralized model that has dominated radio history.

"Decentralized controls enable innovation at the edge -- it's closer to the computer model," says Blossom. "I think what we'll find is that people will come up with things we never really thought about."

Ettus is more concrete about the project's possibilities. Citing Wi-Fi as an example, he envisions "a world in which bandwidth is not an issue. People will create applications that will use that bandwidth, like complete telepresence."

Ettus paints a picture of radio bringing about a many-to-many revolution, like blogging, but for a wider segment of the world. "It enables everybody to be a broadcaster," he says.

Toby Oliver's business is a great example of the street finding its own use for stray radio waves. His company, PathIntelligence, uses the USRP and GNU Radio to track foot traffic in U.K. shopping centers.

Listening for the control-channel signals of mobile phones allows the PathIntelligence setup to pinpoint the location of a phone using triangulation by measuring the difference in time it takes for the signal from a phone to get to multiple antennas.

This works like a very local version of GPS, allowing shopping-center owners to see what shop windows are most popular, and where people tend to congregate or avoid, without actually intercepting any personal data. It's something that processing speed made possible, and the GNU Radio/USRP project made cost-effective.

"Only recently, in the last 12 months, has computing power enabled me to do what I need to in general-purpose software without the expensive development of dedicated DSPs (digital signal processors)," says Oliver. "It means that a whole world of opportunities for tinkerers like me is being opened up."

A person without a phone is invisible to his system, but with the market penetration of mobile phones in Britain, the occasional outlier doesn't damage the data set much. Shopping centers are showing a lot of interest in the information.

But despite his new job, Oliver's background isn't in radio. "In some ways, (software-defined radio) enables the arcane world of RF (radio frequency) to be available to software developers. So you will start to be able to do more and more 'mashups' to RF," he says.

The USRP is being put through its paces in research labs and amateurs' basements all over the world. Ettus sells to companies and governments. Some radio sets out there do more, but Ettus claims that generally the USRP costs a tenth of other software-defined radio-ready equipment. He continues to work on the USRP, developing better signal intelligence and more diverse daughterboards to tune to different bits of radio spectrum.

Blossom is working on a passive radar system that will require a more sensitive hardware setup than the current USRP. His passive radar reads in the ambient radio waves from existing sources, like FM stations and cell towers, and uses them to build a map of the area. At the end of his research, he plans to have "this little gadget that you can plug into a laptop and see what's flying around. We're hoping to see stuff on the order of 50 to 70 kilometers away."

Neither Blossom nor Ettus can predict how their next projects will be used. But that's the point.

Originally posted by Quinn Norton on 06.05.06 at www.wired.com

One of the most I've been waiting for

2008-06-27T00:19:00.006+07:00

This article on silicon.com remember me what i've been present on my post-graduate class a few years ago. I got my interesting assignment to present a future technology f telecommunications. Here are the article :

Holograms on handsets by 2010

Forget 3G, mobiles go 3D

Holographic mobile handsets capable of projecting, capturing and sending 3D images have been developed by an Indian tech company.

By 2010 the devices will routinely beam 3D films, games and virtual goods into our laps according to Indian technology giant Infosys, which has patented the handset.
The portable machines will capture and send 3D snapshots of the surrounding world, helping accident investigators, teachers and doctors work remotely by instantly relaying realistic depictions of car damage, injuries, medical scans or educational aids.

The powerful onboard processor on the Infosys machine would build a series of 2D shots taken, for example, from a digital camera, into 3D holograms using algorithms called 'Fourier' transformations to calculate the extra third dimension.

The patent, granted by the US Patent and Trademark Office, says this allows complex 3D holographic images to be squeezed through the narrow pipes of existing communications networks, by sending only the unprocessed data to be translated into the 3D hologram at the other end.

Infosys' device will be able to both send and receive these 3D images, displaying them using a projector with a laser source and micro holographic optical elements lenses.

The global 3D screen market is forecast by industry to grow to 8.1 million units by 2010.

A spokeswoman for Infosys said: "Holographic handsets have the capability of enriching the user experience, with an actual 3D experience and higher quality images. This gives users a more realistic experience in areas like gaming, medicine, movies etc."

She said the technology would enable 3D images to be displayed without losing resolution, something that is not possible using current 3D technology, such as stereoscopic displays.

Originally posted By Nick Heath

Published: 19 June 2008 11:17 BST

This remarkable technology as I remember firstable introduced by NTT DoCoMo Japan through their film of Vision 2010, and it said that they plan to deploy it on 2012. We can see their newest video of Vision 201X now.It was an interesting promo movie that explore my knowledge much better. The requirement of 500MBps bandwidth to held the communication become a challenging part. Who would be the first?

A new world called VHDL

2008-06-25T00:00:00.005+07:00

A few years ago, actually about 1.5 years ago when I have to choose my theses topic, I start to collect much resources about that. And it end when I choose on Broadband Powerline Communication topic. I decided to make a simple modulator demodulator for that kind communication. Maybe it's not a new topic. But i myself have my dreams on that. A prestigious dreams that i hope it can change much of my way of life.
When I decided it, i again collected much resource on how to do it. And i got a new world called VHDL. A Hardware Description Language use to design a digital hardware. This programming language is one of the unpleasant choice for designing such hardware like what I choose one. To make a modem we have to know many theoretical things first.
I hope somebody can directly guide me on my program.
Till now , i haven't finish my program yet. I still hard to find it's detail solution.
And this blog is one of my effort to share and solve my problems. I hope many hardware designer will help me much to finish my graduation. Soon I'll post my program to share others. Before I do that, i'd like to thanks all visitors that have come to my blog.

To All visitor please leave your track here!

2008-06-23T00:21:00.002+07:00

Between DAB and DVB from Wiki, Try World Radio and TV tuner below!

2008-06-22T14:40:00.008+07:00

Digital Audio Broadcasting (DAB), also known as Eureka 147, is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format^[1].

The DAB standard was designed in the 1980s, and receivers have been available in many countries for several years. Proponents claim the standard offers several benefits over existing analogue FM radio, such as higher-fidelity audio, more stations in the same broadcast spectrum, and increased resistance to noise, multipath, fading, and co-channel interference. However, listening tests carried out by experts in the field of audio have shown that the audio quality on DAB is lower than on FM in the UK, which is the country that accounts for the vast majority of global DAB sales-to-date, due to 98% of stereo stations using a bit rate of 128 kbit/s with the MP2 audio codec, which is unable to match the audio quality provided by FM.^[2]^[3]^[4]

An upgraded version of the system was released in February 2007, which is called DAB+. DAB+ is not backward-compatible with DAB, which means that only receivers that support the new standard will be able to receive DAB+ broadcasts. DAB+ is 2 - 3 times more efficient than DAB due to the adoption of the AAC+ audio codec^[5], which means that DAB+ can provide higher audio quality and more radio stations than DAB allows. Reception quality will also be more robust on DAB+ than on DAB due to the addition of Reed-Solomon error correction coding.

Italy has started transmitting DAB+ stations, Malta and Switzerland are due to launch DAB+ stations in 2008, and Australia and Germany planning on launching DAB+ in 2009. The radio industry in the UK is expecting DAB+ stations to launch between 2010 - 2013^[6], and podcast services using the DAB+ format will be launched in the UK in 2009^[7].

Digital Video Broadcasting (DVB) is a suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project, an industry consortium with more than 270 members, and they are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU). The interaction of the DVB sub-standards is described in the DVB Cookbook (DVB-Cook).

DVB systems distribute data using a variety of approaches, including by satellite (DVB-S, DVB-S2 and DVB-SH; also DVB-SMATV for distribution via SMATV); cable (DVB-C); terrestrial television (DVB-T, DVB-T2) and digital terrestrial television for handhelds (DVB-H); and via microwave using DTT (DVB-MT), the MMDS (DVB-MC), and/or MVDS standards (DVB-MS)

These standards define the physical layer and data link layer of the distribution system. Devices interact with the physical layer via a synchronous parallel interface (SPI), synchronous serial interface (SSI), or asynchronous serial interface (ASI). All data is transmitted in MPEG-2 transport streams with some additional constraints (DVB-MPEG). A standard for temporally-compressed distribution to mobile devices (DVB-H) was published in November 2004.

These distribution systems differ mainly in the modulation schemes used and error correcting codes used, due to the different technical constraints. DVB-S (SHF) uses QPSK, 8PSK or 16-QAM. DVB-S2 uses QPSK, 8PSK, 16APSK or 32APSK, at the broadcasters decision. QPSK and 8PSK are the only versions regularly used. DVB-C (VHF/UHF) uses QAM: 16-QAM, 32-QAM, 64-QAM, 128-QAM or 256-QAM. Lastly, DVB-T (VHF/UHF) uses 16-QAM or 64-QAM (or QPSK) in combination with COFDM and can support hierarchical modulation.

The DVB-T2 standard will be published after march 2008 and is expected to be approved and submitted to ETSI during 2008.

The DVB-T2 standard will give more-robust TV reception and increase the possible bit-rate by over 30% for single transmitters (as in the UK) and is expected to increase the max bit-rate by over 50% in large SFN (as in Germany, Sweden...).

Besides audio and video transmission, DVB also defines data connections (DVB-DATA - EN 301 192) with return channels (DVB-RC) for several media (DECT, GSM, PSTN/ISDN, satellite etc.) and protocols (DVB-IPTV: Internet Protocol; DVB-NPI: network protocol independent).

Older technologies such as teletext (DVB-TXT) and vertical blanking interval data (DVB-VBI) are also supported by the standards to ease conversion. However for many applications more advanced alternatives like DVB-SUB for sub-titling are available.

You all may try this technology by installing this World Radio and TV Tuner software for free trials. Or you just wanna rip your favourite music from different Internet radio stations over the world.

Japanese robot companies join forces to compete with South Korea

2008-06-19T13:29:00.005+07:00

South Korea has already made its ambitious robot plans quite well known, and it now looks like a group of Japanese robot companies are doing their best to stay in the race, with them forming a consortium of sorts that they say will let them cooperate in the research, development and marketing of robots. Currently, that group includes Tokyo's ZMP, Nagoya's Business Design Laboratory, Vstone (makers of the Black Ox pictured above), and Tmsuk, each of which will apparently initially focus on "simple service robots" designed to keep watch on the elderly, pets, and children. They're not getting much more specific than that just yet, unfortunately, with one of the company's CEOs only going so far as to say that, "in ten years, robots may be able to help out around the house," but that he doesn't "necessarily know that robots should do everything."
Originally posted by Donald Melanson, on Jun e, 18th 2008 at 2:33PM

Looks like a robot revolution will begin soon. Hope everyone can take a good benefit from them. And I hope it won't make such a big destruction as on Transformer movies.

Wireless and Cellular Communication by William C.Y. Lee

2008-06-16T23:44:00.006+07:00

Publisher: McGraw-Hill Professional
Number Of Pages: 821
Publication Date: 2005-10-22
Sales Rank: 178562
ISBN / ASIN: 0071436863
EAN: 9780071436861
pass: gigapedia.org
Binding: Hardcover
Manufacturer: McGraw-Hill Professional
Studio: McGraw-Hill Professional
Average Rating: 4

The #1 book on wireless communications has been completely updated

World recognized wireless authority William Lee delivers all new in-depth engineering coverage for data sevices, Wi-Fi, 3G, and much more, just in time for the rebounding wireless industry.

Includes specifications for all major wireless systems, including cdmaOne

link for free download: mihd.net

Good book for newbie at Mobile and Cellular Telecommunication. It'sRecommended.

Undergoing MyBlogLog Verification

Public Broadcast Cart

2008-06-15T21:22:00.001+07:00

Public Broadcast Cart

is a shopping cart outfitted with a dynamic microphone, a mixer, an amplifier, six speakers, a miniFM transmitter and a laptop with a wireless card. The audio captured by the microphone on the cart is fed through the mixer to three different broadcast sources. The mixer simultaneiously feeds the audio:

* to the amplifier that powers the six speakers mounted on the cart

* to an FM transmitter transmitting to an FM frequency

* to the laptop that sends the audio to an online server that will stream the live broadcast, such as the thing.net's server - http://radio.thing.net

The Public Broadcast Cart is designed to enable any pedestrian to become an active producer of a radio broadcast. The cart reverses the usual role of the public from audience to producer of a radio broadcast and online content. View original proposal

As the government and the FCC seek to hand over our media resources to the wealthiest corporate media entities looking to monopolize the media from print to radio to television, it is upto the independent producers to subvert big money domination of our culture.

The Broadcast Cart was funded by the Franklin Furnace's Future of the Present Fund and technical assistance was given by Jan McLaughlin, Greg Gong, Dana Speigel and Darrel O'Pry. The broadcast has been supported by thing.net, Ars Electronica, Exit Art, Tesla Radio. I would like to give special thanks to Martha Wilson and Wolfgang Staehle for their work as artists, independent producers and supporters of artists, and thanks to Brooke Singer, Yuri Gitman, and Dana Spiegel the producers of the public net art event Wireless Park Lab Days, September 19th and 20th, 2003, when the Public Broadcast Cart was first presented.

Build Your Own Radio Cart

Use a simple dynamic microphone plugged into a simple audio mixer that allows multiple output for the audio. The Public Broadcast Cart uses an old, incredibly sturdy and handy SHURE mixer donated by Jan McLaughlin. The closest version available on the SHURE site is the FP23 Microphone Preamplifer

Ramsey Electronics offers a great selection of affordable small transmitters from a $35 AM Radio Transmitter Kit to $300 Factory Assembled and Tested Digital FM Stereo Transmitter. The Public Broadcast Cart uses Ramsey's Professional Synthesized FM Stereo Transmitter Kit, it's an excellent learning experience to assemble your own transmitter.

If you have a wifi equiped laptop and an open wifi node available all you need is Internet radio broadcasting software. Rogue Amoeba's Nicecast allows you to turn your own computer into the broadcasting server. A better idea is to use Nicecast to stream the audio to a server designed to handle online broadcasting.

For immediate area audio amplification, just about anything that can recieve audio from the mixer and output it through speakers could be used, even a boom box. The Public Broadcast Cart uses the Samson SERVO 120A 120-Watt Power Amplifier that powers car speakers that have been mounted onto goose neck microphone extensions

The Public Broadcast Cart has used a few different power sources from as poor as car batteries to as a stable power supply as the Galaxy Far Outlet Model 300S, which Gotham Sound rents for a very low price.

Tetsuo Kogawa's 1 Watt Transmitter Schematic:

DAB, DAB+ and DMB for Indonesia

2008-06-13T23:48:00.006+07:00

The regulator and MNC (PT Media Nusantara Citra) launched DMB trials in Jakarta in 2006. In the third quarter of 2007 the PST Indonesian electronics company, PT Agis, IPTV systems integrator, Broadband Network Systems, and Toshiba have joined together to build a nationwide DMB service in Indonesia. The intention is to launch the service in 2008 and this group are currently talking to mobile operators and content provides to fully explore the opportunities available. The group will build the network and then join with video providers for content and mobile operators for distribution. The benefit of using DMB in Indonesia is that a single frequency could be used to cover the whole of the country.

Indonesia has shown great interest in using DMB for Mobile TV and has been progressed faster than any other country in the South East Asian region. Telco operators are expecting that Mobile TV will allow them to differentiate their overall mobile service positioning and help generate new revenue streams. Similarly, content providers and TV broadcasters are planning to use Mobile TV to open up new channel distribution platforms, with targeted content and new advertising schemes. Both PT Media Nusantara Citra (MNC) and DMB-N were granted frequencies and licenses for Mobile TV in Jakarta.

MNC is the largest and only integrated media company in Indonesia. They have been running DMB trials in Jakarta since 2006, with 1 DAB audio and 1 DMB video service using Band-III frequencies. MNC, at the same time, is also the operator of DVB-H. Mobile TV using DVB-H will be marketed as an expensive service, as a result of the increased investment in the network. DVB-H offerings will include around 15 Pay TV channels. However, DMB Mobile TV will be marketed as an affordable product which will be targeted at the mass market. Services will be on a subscription basis but will cost much less than the DVB-H services.

DMBN is a joint company of the local broadcasters and ETRI, a Korean research institute, to implement mobile TV services in Indonesia. DMBN is now running trials in Jakarta and plan for further testing in Bandung, Medan and Surabaya for mobile TV, and DAB services in the near future. It is planned to lunch in may 2008 with one multiplexer.

Both operators plan to launch Mobile TV services in Jakarta in the first quarter of 2008. It is expected that there will be a wide selection of mobile phones and other devices from South Korea.

Originally posted at http://www.worlddab.org/country_information/indonesia

ACORDE - Broadband Railway Internet Access on High Speed Trains Via Satellite Links

2008-06-12T15:07:00.004+07:00

BROADBAND INTERNET ACCESS ON HIGH SPEED TRAINS

ACORDE's railway Internet access communications system (ACVSAT-Train-Ku) combines a bidirectional satellite link with a distribution system on the train. The distribution system (wireless LAN and optical fibre) is also bidirectional within the train itself, linking the satellite terminal and the train users.

The ACVSAT-Train-Ku establishes a connection with a stationary GEO satellite, assuring data rates of at least 4Mbit/s in the downlink and at least 2Mbit/s in the uplink. These data rates are functions of both HUB and satellite transponders, and can be improved by increasing transmit power. These data rates have been successfully tested with the train running at 350km/h.

The satellite link should be provided by a satellite operator which will rent the required bandwidth (for example: 7Mhz for 2+4Mbit/s) to the railway operator. Should the data-rate required by the services provided to each train be lower than 2+4Mbit/s, the 7MHz bandwidth rented from the satellite operator could be shared by several trains without additional HW nor SW modification.

The Internet connection should be provided by an ISP (Internet Service Provider); the railway operator should become the ISP to keep control of the system and increase the business revenue.

SYSTEM DESCRIPTION

The ACVSAT-Train-Ku is composed of a communications subsystem, a pointing subsystem and a distribution subsystem.

COMMUNICATION SUBSYSTEM

The communications subsystem possesses:

Antenna
Transmitter
Modem
Router IP connectivity

POINTING SUBSYSTEM

This subsystem performs the satellite acquisition and tracking. Three axes can be moved in order to maximise the received or transmitted signal, i.e., azimuth, elevation and feeder polarisation. Several elements are required in the pointing subsystem:

IMU (Inertial Measurement Unit)
AGC (Automatic Gain Control)
Control unit

DISTRIBUTION SUBSYSTEM

An optical fibre connection is established between the central server and each train car where the conversion from optical to radio domain, and vice versa, takes place. The signal is eventually distributed to the passengers by means of WiFi IEEE802.11g / WiMax IEEE 802.16 access points.

Based on ACORDE's solution, both passengers and rail operators can benefit from the following services:

WIRELESS ACCESS TO BROADBAND INTERNET FOR THE DURATION OF THE TRIP

Via the Internet:

Web surfing
MSN
Voice over IP connectivity (Skype)
Email

Via railway operator's Intranet:

On line games
Trip maps and facts
Ticket reservations and sales
Video streaming
Electronic newspapers

Passengers willing to use the Internet access service should purchase a prepaid card on the train. Together with the prepaid card users will be provided with a username and password to log on to the system.

IP-BASED VIDEO SURVEILLANCE SYSTEM (CCTV)

The recorded picture on our high speed train CCTV system can be centralised and monitored from a control room. Staff can receive silent alarm messages or even pictures with regard to passenger incidents.

Other specifically anti-terrorism technologies, such as chemical sniffers and radiation detectors, can also be combined into the system.

RAILWAY MEASUREMENT SYSTEM

ACORDE's communications system allows railway operators to implement real-time telemetry services for the railway system by means of a 'laboratory car' carrying the measurement equipment for rail wheels, overhead power cable checks, acceleration on train axles, vibrations, etc.

DaimlerChrysler tests WLAN car-to-car Communication System

2008-06-09T15:29:00.006+07:00

Car-to-car communication has nothing to do with gesturing after a close call on the highway. Futurists foresee a time when cars will use systems of GPS and WiFi tech to let them communicate with each other, relaying information about road conditions and traffic anomalies to prevent smash-ups. DaimlerChrysler is testing such a system — dubbed Willwarn (Wireless Local Danger Warning), with which vehicles are able to "warn" of critical situations picked up by on-board sensors, such as fog, black ice or obstacles such as broken-down car. Such distant early warnings, theoretically, would allow a driver time to take evasive action. As DaimlerChrysler notes in a press release, the system could be enhanced by adding radio beacons at the roadside to give traffic control centers ground reports, as well as transmit information on traffic, construction and other route-related issues. No word on when such a system will be in place, but he who comes out first often sets the standard, a benefit DCX and its suppliers are likely gunning for. – Mike Spinelli

Press Release:

DaimlerChrysler first in the world to effectuate the new technology

In future, motorists will be able to detect danger even if the danger spot lies around the next bend or over the horizon. This has now been successfully verified by DaimlerChrysler experts and their partners in a field test conducted at the conclusion of the "WILLWARN" (Wireless Local Danger Warning) European research project. During the course of this test, five vehicles equipped with WLAN-based radio technology used the "Car-2-X Communication" system to radio details of critical situations detected by their on-board sensors - fog, black ice or obstacles on the road such as broken-down vehicles - to following cars. These early warnings enabled the drivers of the cars behind to prepare for the danger and adapt their speed in plenty of time.

DaimlerChrysler had already tested this technology some six years ago - a world first at the time - by sending the first ever inter-communicating vehicle fleet out onto the road as part of the "FleetNet" research project. This field test demonstrated that WLAN (Wireless Local Area Network) technology, which had already proven a success when used for wireless Internet access, also allowed vehicles to communicate with each other. One of the key benefits is that expensive, fixed-installation transmitting and receiving devices are not required, since the cars themselves act as both transmitters and receivers. The cars establish an ad-hoc radio network and send any necessary warnings to all other vehicles within a radius of around 500 metres. For vehicles outside of this radio range, the cars act as relays and pass on any warnings in much the same way as a relay runner would hand over a baton. No additional sensors are required to detect critical situations, since the necessary information is provided by the anti-lock braking system (ABS), the Electronic Stability Program (ESP ), the steering-angle sensors, the outside thermometer or the navigation system.

The DaimlerChrysler engineers incorporated the key groundwork laid during the course of the "FleetNet" project into the subsequent "NOW" (Network On Wheels) programme (a German cooperation project) and the current "WILLWARN" project. Their aim was to use the experience gained to work together with partners from the automotive components and electronics industries in order to further develop and standardise this promising technology whilst also securing the rights to use the required frequencies. The DaimlerChrysler specialists also supplied information to partners who only joined the project at a later stage, quickly realising that the only way to establish a fully-functioning WLAN radio network that would benefit all road users was to cooperate with other car manufacturers and the relevant authorities. After all, for an ad hoc radio network to be of any use, enough vehicles have to be equipped with the necessary technology.

Radio beacons at the side of the road are required in order to ensure that the first vehicles to be equipped with such a system benefit immediately. These stationary radio nodes could also be used to provide traffic control centres with additional and better information. However, direct contact with the Internet and its numerous fields of application is also possible. In addition to warning motorists of critical situations in advance, the new radio network could therefore also be used to improve the flow of traffic: communicating cars could guide their occupants away from traffic congestion or even prevent tailbacks from occurring at all.

DaimlerChrysler was also one of the instigators behind the European "Car2Car Communication Consortium" and is involved in the American Vehicle-Infrastructure Integration Initiative. These projects lay the political foundations for vehicle communication in Europe and America and have the aim of accelerating the process of standardisation.

originally posted by Mike Spinelli at 11:15 AM on Wed Dec 6 2006

Exploring GNU Radio - Applications

2008-05-29T06:37:00.002+07:00

In addition to the examples discussed above, GNU Radio comes with a complete HDTV transmitter and receiver, a spectrum analyzer, an oscilloscope, concurrent multichannel receiver and an ever-growing collection of modulators and demodulators.
Projects under investigation or in progress include:
A TiVo equivalent for radio, capable of recording multiple stations simultaneously.
Time Division Multiple Access (TDMA) waveforms.
A passive radar system that takes advantage of broadcast TV for its signal source. For those of you with old TVs hooked to antennas, think about the flutter you see when airplanes fly over.
Radio astronomy.
TETRA transceiver.
Digital Radio Mundial (DRM).
Software GPS.
Distributed sensor networks.
Distributed measurement of spectrum utilization.
Amateur radio transceivers.
Ad hoc mesh networks.
RFID detector/reader.
Multiple input multiple output (MIMO) processing.

Exploring GNU Radio by Eric Blossom - What Goes in the FPGA?

2008-05-29T06:32:00.005+07:00

An FPGA is like a small, massively parallel computer that you design to do exactly what you want. Programming the FPGA takes a bit of skill, and mistakes can fry the board permanently. That said, we provide a standard configuration that is useful for a wide variety of applications.
Using a good USB host controller, the USRP can sustain 32 MB/sec across the USB. The USB is half-duplex. Based on your needs, you partition the 32 MB/sec between the transmit and the receive directions. In the receive direction, the standard configuration allows you to select the part or parts of the digitized spectrum you're interested in, translate them to baseband and decimate as required. This is exactly equivalent to what's happening in the RF front end, only now we're doing it on digitized samples. The block of code that performs this function is called a digital down converter (Figure 3, “Digital Down Converter Block Diagram”). One advantage of performing this function in the digital domain is we can change the center frequency instantaneously, which is handy for frequency hopping spread spectrum systems.

Figure 3. Digital Down Converter Block Diagram

In the transmit direction, the exact inverse is performed. The FPGA contains multiple instances of the digital up and down converters. These instances can be connected to the same or different ADCs, depending on your needs. We don't have room here to cover all the theory behind them; see the GNU Radio Wiki for more information.

Exploring GNU Radio by Eric Blossom - GUI, Hardware requirements and USR Peripheral

2008-05-29T06:26:00.005+07:00

Graphical interfaces for GNU Radio applications are built in Python. Interfaces may be built using any toolkit you can access from Python; we recommend wxPython to maximize cross-platform portability. GNU Radio provides blocks that use interprocess communication to transfer chunks of data from the real-time C++ flow graph to Python-land.

GNU Radio is reasonably hardware-independent. Today's commodity multi-gigahertz, super-scalar CPUs with single-cycle floating-point units mean that serious digital signal processing is possible on the desktop. A 3 GHz Pentium or Athlon can evaluate 3 billion floating-point FIR taps/s. We now can build, virtually all in software, communication systems unthinkable only a few years ago.
Your computational requirements depend on what you're trying to do, but generally speaking, a 1 or 2 GHz machine with at least 256 MB of RAM should suffice. You also need some way to connect the analog world to your computer. Low-cost options include built-in sound cards and audiophile quality 96 kHz, 24-bit, add-in cards. With either of these options, you are limited to processing relatively narrow band signals and need to use some kind of narrow-band RF front end.
Another possible solution is an off-the-shelf, high-speed PCI analog-to-digital board. These are available in the 20M sample/sec range, but they are expensive, about the cost of a complete PC. For these high-speed boards, cable modem tuners make reasonable RF front ends.
Finding none of these alternatives completely satisfactory, we designed the Universal Software Radio Peripheral, or USRP for short.

Our preferred hardware solution is the Universal Software Radio Peripheral (USRP). Figure 2, “Universal Software Radio Peripheral” shows the block diagram of the USRP. The brainchild of Matt Ettus, the USRP is an extremely flexible USB device that connects your PC to the RF world. The USRP consists of a small motherboard containing up to four 12-bit 64M sample/sec ADCs, four 14-bit, 128M sample/sec DACs, a million gate-field programmable gate array (FPGA) and a programmable USB 2.0 controller. Each fully populated USRP motherboard supports four daughterboards, two for receive and two for transmit. RF front ends are implemented on the daughterboards. A variety of daughterboards is available to handle different frequency bands. For amateur radio use, low-power daughterboards are available that receive and transmit in the 440 MHz band and the 1.24 GHz band. A receive-only daughterboard based on a cable modem tuner is available that covers the range from 50 MHz to 800 MHz. Daughterboards are designed to be easy to prototype by hand in order to facilitate experimentation.

Figure 2. Universal Software Radio Peripheral

The flexibility of the USRP comes from the two programmable components on the board and their interaction with the host-side library. To get a feel for the USRP, let's look at its boot sequence. The USRP itself contains no ROM-based firmware, merely a few bytes that specify the vendor ID (VID), product ID (PID) and revision. When the USRP is plugged in to the USB for the first time, the host-side library sees an unconfigured USRP. It can tell it's unconfigured by reading the VID, PID and revision. The first thing the library code does is download the 8051 code that defines the behavior of the USB peripheral controller. When this code boots, the USRP simulates a USB disconnect and reconnect. When it reconnects, the host sees a different device: the VID, PID and revision are different. The firmware now running defines the USB endpoints, interfaces and command handlers. One of the commands the USB controller now understands is load the FPGA. The library code, after seeing the USRP reconnect as the new device, goes to the next stage of the boot process and downloads the FPGA configuration bitstream.
FPGAs are generic hardware chips whose behavior is determined by the configuration bitstream that's loaded into them. You can think of the bitstream as object code. The bitstream is the output of compiling a high-level description of the design. In our case, the design is coded in the Verilog hardware description language. This is source code and, like the rest of the code in GNU Radio, is licensed under the GNU General Public License.

Exploring GNU Radio by Eric Blossom - A Complete FM Receiver

2008-05-29T06:24:00.001+07:00

Example 2 shows a somewhat simplified but complete broadcast FM receiver. It includes control of the RF front end and all required signal processing. This example uses an RF front end built from a cable modem tuner and a 20M sample/sec analog-to-digital converter.

Example 2. Broadcast FM Receiver#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
from gnuradio import mc4020
import sys
def high_speed_adc (fg, input_rate):
# return gr.file_source (gr.sizeof_short, "dummy.dat", False)
return mc4020.source (input_rate, mc4020.MCC_CH3_EN mc4020.MCC_ALL_1V)
#
# return a gr.flow_graph
#
def build_graph (freq1, freq2):
input_rate = 20e6
cfir_decimation = 125
audio_decimation = 5
quad_rate = input_rate / cfir_decimation
audio_rate = quad_rate / audio_decimation
fg = gr.flow_graph ()

# use high speed ADC as input source
src = high_speed_adc (fg, input_rate)

# compute FIR filter taps for channel selection
channel_coeffs = \
gr.firdes.low_pass (1.0, # gain
input_rate, # sampling rate
250e3, # low pass cutoff freq
8*100e3, # width of trans. band
gr.firdes.WIN_HAMMING)
# input: short; output: complex
chan_filter1 = \
gr.freq_xlating_fir_filter_scf (cfir_decimation,
channel_coeffs,
freq1, # 1st station freq
input_rate)

(head1, tail1) = build_pipeline (fg, quad_rate, audio_decimation)

# sound card as final sink
audio_sink = audio.sink (int (audio_rate))
# now wire it all together
fg.connect (src, chan_filter1)
fg.connect (chan_filter1, head1)
fg.connect (tail1, (audio_sink, 0))
return fg
def build_pipeline (fg, quad_rate, audio_decimation):
'''Given a flow_graph, fg, construct a pipeline
for demodulating a broadcast FM signal. The
input is the downconverted complex baseband
signal. The output is the demodulated audio.
build_pipeline returns a two element tuple
containing the input and output endpoints.
'''
fm_demod_gain = 2200.0/32768.0
audio_rate = quad_rate / audio_decimation
volume = 1.0
# input: complex; output: float
fm_demod = gr.quadrature_demod_cf (volume*fm_demod_gain)
# compute FIR filter taps for audio filter
width_of_transition_band = audio_rate / 32
audio_coeffs = gr.firdes.low_pass (1.0, # gain
quad_rate, # sampling rate
audio_rate/2 - width_of_transition_band,
width_of_transition_band,
gr.firdes.WIN_HAMMING)
# input: float; output: float
audio_filter = gr.fir_filter_fff (audio_decimation, audio_coeffs)
fg.connect (fm_demod, audio_filter)
return ((fm_demod, 0), (audio_filter, 0))

def main (args):
nargs = len (args)
if nargs == 1:
# get station frequency from command line
freq1 = float (args[0]) * 1e6
else:
sys.stderr.write ('usage: fm_demod freq\n')
sys.exit (1)
# connect to RF front end
rf_front_end = gr.microtune_4937_eval_board ()
if not rf_front_end.board_present_p ():
raise IOError, 'RF front end not found'
# set front end gain
rf_front_end.set_AGC (300)
# determine the front end's "Intermediate Frequency"
IF_freq = rf_front_end.get_output_freq () # 5.75e6
# Tell the front end to tune to freq1.
# I.e., freq1 is translated down to the IF frequency
rf_front_end.set_RF_freq (freq1)
# build the flow graph
fg = build_graph (IF_freq, None)

fg.start () # fork thread(s) and return
raw_input ('Press Enter to quit: ')
fg.stop ()
if __name__ == '__main__':
main (sys.argv[1:])
Like the Hello World example, we build a graph, connect the blocks together and start it. In this case, our source, mc4020.source, is an interface to the Measurement Computing PCI-DAS 4020/12 high-speed ADC. We follow it with gr.freq_xlating_fir_filter_scf, a finite impulse response (FIR) filter that selects the FM station we're looking for and translates it to baseband (0Hz, DC). With the 20M sample/sec converter and cable modem tuner, we're really grabbing something in the neighborhood of a 6 MHz chunk of the spectrum. This single chunk may contain ten or more FM stations, and gr.freq_xlating_fir_filter_scf allows us to select the one we want.
In this case, we select the one at the exact center of the IF of the RF front end (5.75 MHz). The output of gr.freq_xlating_fir_filter_scf is a stream of complex samples at 160,000 samples/second. We feed the complex baseband signal into gr.quadrature_demod_cf, the block that does the actual FM demodulation.
gr.quadrature_demod_cf works by subtracting the angle of each adjacent complex sample, effectively differentiating the frequency. The output of gr.quadrature_demod_cf contains the left-plus-right FM mono audio signal, the stereo pilot tone at 19kHz, the left-minus-right stereo information centered at 38kHz and any other sub-carriers above that. For this simplified receiver, we finish off by low pass filtering and decimating the stream, keeping only the left-plus-right audio information, and send that to the sound card at 32,000 samples/sec.
For a more indepth look at how the FM receiver works, please see "Listening to FM, Step by Step."

Exploring GNU Radio by Eric Blossom - Block Diagram

2008-05-29T06:17:00.004+07:00

Figure 1, “Typical software radio block diagram” shows a typical block diagram for a software radio. To understand the software part of the radio, we first need to understand a bit about the associated hardware. Examining the receive path in the figure, we see an antenna, a mysterious RF front end, an analog-to-digital converter (ADC) and a bunch of code. The analog-to-digital converter is the bridge between the physical world of continuous analog signals and the world of discrete digital samples manipulated by software.

Figure 1. Typical software radio block diagram

ADCs have two primary characteristics, sampling rate and dynamic range. Sampling rate is the number of times per second that the ADC measures the analog signal. Dynamic range refers to the difference between the smallest and largest signal that can be distinguished; it's a function of the number of bits in the ADC's digital output and the design of the converter. For example, an 8-bit converter at most can represent 256 (28) signal levels, while a 16-bit converter represents up to 65,536 levels. Generally speaking, device physics and cost impose trade-offs between the sample rate and dynamic range.
Before we dive into the software, we need to talk about a bit of theory. In 1927, a Swedish-born physicist and electrical engineer named Harry Nyquist determined that to avoid aliasing when converting from analog to digital, the ADC sampling frequency must be at least twice the bandwidth of the signal of interest. Aliasing is what makes the wagon wheels look like they're going backward in the old westerns: the sampling rate of the movie camera is not fast enough to represent the position of the spokes unambiguously.
Assuming we're dealing with low pass signals - signals where the bandwidth of interest goes from 0 to fMAX, the Nyquist criterion states that our sampling frequency needs to be at least 2 * fMAX. But if our ADC runs at 20 MHz, how can we listen to broadcast FM radio at 92.1 MHz? The answer is the RF front end. The receive RF front end translates a range of frequencies appearing at its input to a lower range at its output. For example, we could imagine an RF front end that translated the signals occurring in the 90 - 100 MHz range down to the 0 - 10 MHz range.
Mostly, we can treat the RF front end as a black box with a single control, the center of the input range that's to be translated. As a concrete example, a cable modem tuner module that we've employed successfully has the following characteristics. It translates a 6 MHz chunk of the spectrum centered between about 50 MHz and 800 MHz down to an output range centered at 5.75 MHz. The center frequency of the output range is called the intermediate frequency, or IF.
In the simplest-thing-that-possibly-could-work category, the RF front end may be eliminated altogether. One GNU Radio experimenter has listened to AM and shortwave broadcasts by connecting a 100-foot piece of wire directly to his 20M sample/sec ADC.
On to the Software
GNU Radio provides a library of signal processing blocks and the glue to tie it all together. The programmer builds a radio by creating a graph (as in graph theory) where the vertices are signal processing blocks and the edges represent the data flow between them. The signal processing blocks are implemented in C++. Conceptually, blocks process infinite streams of data flowing from their input ports to their output ports. Blocks' attributes include the number of input and output ports they have as well as the type of data that flows through each. The most frequently used types are short, float and complex.
Some blocks have only output ports or input ports. These serve as data sources and sinks in the graph. There are sources that read from a file or ADC, and sinks that write to a file, digital-to-analog converter (DAC) or graphical display. About 100 blocks come with GNU Radio. Writing new blocks is not difficult.
Graphs are constructed and run in Python. Example 1 is the "Hello World" of GNU Radio. It generates two sine waves and outputs them to the sound card, one on the left channel, one on the right.

Example 1. Dial Tone Output#!/usr/bin/env python
from gnuradio import gr
from gnuradio import audio
def build_graph ():
sampling_freq = 48000
ampl = 0.1
fg = gr.flow_graph ()
src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl)
src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl)
dst = audio.sink (sampling_freq)
fg.connect ((src0, 0), (dst, 0))
fg.connect ((src1, 0), (dst, 1))
return fg
if __name__ == '__main__':
fg = build_graph ()
fg.start ()
raw_input ('Press Enter to quit: ')
fg.stop ()
We start by creating a flow graph to hold the blocks and connections between them. The two sine waves are generated by the gr.sig_source_f calls. The f suffix indicates that the source produces floats. One sine wave is at 350 Hz, and the other is at 440 Hz. Together, they sound like the US dial tone.
audio.sink is a sink that writes its input to the sound card. It takes one or more streams of floats in the range -1 to +1 as its input. We connect the three blocks together using the connect method of the flow graph.
connect takes two parameters, the source endpoint and the destination endpoint, and creates a connection from the source to the destination. An endpoint has two components: a signal processing block and a port number. The port number specifies which input or output port of the specified block is to be connected. In the most general form, an endpoint is represented as a python tuple like this: (block, port_number). When port_number is zero, the block may be used alone.
These two expressions are equivalent:fg.connect ((src1, 0), (dst, 1))
fg.connect (src1, (dst, 1))
Once the graph is built, we start it. Calling start forks one or more threads to run the computation described by the graph and returns control immediately to the caller. In this case, we simply wait for any keystroke.

Exploring GNU Radio by Eric Blossom

2008-05-29T06:13:00.002+07:00

Introduction

Software radio is the technique of getting code as close to the antenna as possible. It turns radio hardware problems into software problems. The fundamental characteristic of software radio is that software defines the transmitted waveforms, and software demodulates the received waveforms. This is in contrast to most radios in which the processing is done with either analog circuitry or analog circuitry combined with digital chips. GNU Radio is a free software toolkit for building software radios.
Software radio is a revolution in radio design due to its ability to create radios that change on the fly, creating new choices for users. At the baseline, software radios can do pretty much anything a traditional radio can do. The exciting part is the flexibility that software provides you. Instead of a bunch of fixed function gadgets, in the next few years we'll see a move to universal communication devices. Imagine a device that can morph into a cell phone and get you connectivity using GPRS, 802.11 Wi-Fi, 802.16 WiMax, a satellite hookup or the emerging standard of the day. You could determine your location using GPS, GLONASS or both.
Perhaps most exciting of all is the potential to build decentralized communication systems. If you look at today's systems, the vast majority are infrastructure-based. Broadcast radio and TV provide a one-way channel, are tightly regulated and the content is controlled by a handful of organizations. Cell phones are a great convenience, but the features your phone supports are determined by the operator's interests, not yours.
A centralized system limits the rate of innovation. We could take some lessons from the Internet and push the smarts out to the edges. Instead of cell phones being second-class citizens, usable only if infrastructure is in place and limited to the capabilities determined worthwhile by the operator, we could build smarter devices. These user-owned devices would generate the network. They'd create a mesh among themselves, negotiate for backhaul and be free to evolve new solutions, features and applications.

What is a portable app?

2008-05-27T17:05:00.002+07:00

portable - carried or moved with ease
app - a computer program like a web browser or word processor

A portable app is a computer program that you can carry around with you on a portable device and use on any Windows computer. When your USB flash drive, portable hard drive, iPod or other portable device is plugged in, you have access to your software and personal data just as you would on your own PC. And when you unplug the device, none of your personal data is left behind.

No Special Hardware - Use any USB flash drive, portable hard drive, iPod/MP3 player, etc
No Additional Software - Just download the portable app, run the portable installer and go
No Kidding - It's that easy

Consider the Possibilities...
Carry your web browser with all your favorite bookmarks
Carry your calendar with all your appointments
Carry your email client with all your contacts and settings
Carry your instant messenger and your buddy list
Carry your whole office suite along with your documents and presentations
Carry your antivirus program and other computer utilities
Carry all your important passwords and account information securely
Consider the Convenience...
Have your favorite websites handy to recommend to a friend or colleague
Have your presentation AND the required software ready to go for that big meeting
Have your password with you if you want to bank online while traveling
Have utilities handy when visiting family or friends that are having PC problems

is Wimax safe?

2008-05-25T03:44:00.005+07:00

Research based Information

WiMAX enabled devices emit radio frequency electromagnetic waves when in use. These waves have been part of our everyday life for decades now, in the use of devices such as radio, television and mobile phones. In fact a good part of the technology being employed in the IEEE 802.16 standard is already being deployed. The body of evidence so far supports the safety of these technologies.
Many independent scientific organizations, safety standard testing and certification panels and health organizations all over the world have conducted research into the safety of radio waves in the past 50 years. The general findings point out that there are no proven adverse health effects from exposure to radio waves at the current ranges prescribed for wireless communication systems.

Are there Safety Limits?

Exposure to radio waves is safe within a certain prescribed range. WiMAX enabled devices and WiMAX towers have to comply with the same safety standards as other radio products like mobile phones. These standards have been developed by the World Health Organization (WHO) and adopted by governments and health agencies around the world. These standards prescribe exposure limits and margins for protecting consumers and the general public.
Do WiMAX Devices Comply with these Norms?
Yes. All WiMAX enabled devices have to be evaluated to check that they conform to globally accepted radio frequency emission safety standards. These evaluations are done against a set of parameters recommended by regulatory bodies around the world.
On an average it takes 40 watts to deliver broadband and wireless signals from tower relay site, although the actual power depends on the frequency. Apart from standard precautions that need to be taken when onsite at communication towers, the configurations are well defined and safe. Customer receptor equipments are tested for safety too.

Is WiMAX Safe forChildren?

Devices used in WiMAX comply with standards endorsed by WHO and other health agencies, making WiMAX safe for everyone including children.
For further information, you may visit the following websites.
www.who.int/peh-emf
www.icnirp.de
or you can download brief information from mobile forums brochure :
www.nokiasiemensnetworks.com/NR/rdonlyres/77D250FC-88B0-449E-B08B-79EBCFF0D315/0/MMF_WiMAX_and_Health.pdf