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GNU Radio
Max Hyre writes "Apropos (!= man -k :-) RIAA, web radio, and other such data-dispersal disagreements, here's a new way to do it your way: a
fully software-driven radio receiver; just strap some
off-the-shelf DAC hardware into a generic computer, and let the software do the rest. While I can just barely spell `sideband', this looks like it could be
more fun than any set you ever had before, especially after those in the know build up some kewl apps for the great unwashed like me. They're also dreaming of GPS,
cellular phones, &c.. My only gripe is that the web pages proper don't seem to have any cookbook recipes for the hardware; maybe that's in the docs with the source, or
maybe this is strictly for the experienced, for now."
Check out tapr.org and the DSP-10 project. It's a 2 meter ham radio that is defined in software, using the DSP board to handle modulation. I am saving my nickels and dimes to buy a kit, and it seems interesting. Also, since it's all defined in software, it can be connected to a transverter and the output can be SSB, FM, etc and the software for the PC can be programmed to take into account that the transverter is making the 2 meter rig into say a 10 meter or microwave rig.
-RickTheWizKid
Great! you are right on....
so where do you get DSP's that are field programmable in C?
and connect easily to a computer costing less than $200.00 in parts to cover from DC to 10Ghz?
DSP's are good for end products that are to be released to the sheep. This is better than any DSP ever created and will do it better than any DSP ever created for research and expierimentation. doing that with a DSP is near impossible for the amateur and is 100% impossible without breaking the law for poor expierimenters.
DSP's suck for research by the hobbiest..This process is best.
be sure to include the entire costs of development before offering your opinion as to weither an expensive alternative is better. (DSP's are ungodly expensive after you factor in the programming software,devkit, and required hardware all purchased legally... TI's devkit costs over $20KUSD that has all the tools available (the student kit doesnt do 1/2 of the pro devkit.)
Do not look at laser with remaining good eye.
This page has the details. Too pricey for a tinkertoy.
While TAPR has tried a lot of things, unfortunately not many of their projects have gotten off the ground since the TNC II (A packet radio modem (Terminal Node Controller) for amateur radio use.) Whatever their development process is, I think it could use an infusion of bazaar style development. They've worked on a spread spectrum radio since the early '90s. Each time they're "just a few months" from releasing a working model something changes and the project disappears again. I ended my membership after a couple of years as I just didn't see the project progressing. To be fair, it's a volunteer/hobbyist organization. Perhaps some friendly competition from GNU will spur both to release a usable product by the end of the year.
The past few years the major advancements in amateur radio digital technology have come from Europe. i.e. PacTOR, PSK31, and now MFSK. Clover was developed in the States, but being patented and other issues (leading to high prices) kept it from becoming a mainstream technology.
"Insanity is doing the same thing over again expecting a different result."
I do this for a living, and I can tell you this won't help you listen to cellular.
First, all they are doing is taking the 455kHz IF from an existing radio, digitizing it, and using the computer to do the demodulation. Thus, if your radio won't receive the cellular band, your computer won't either. And if your radio can tune into the cell band, you can listen to AMPS without a computer - it's just narrowband FM.
Now, if you are talking about GSM, PCS, CDMA, or anything other than AMPS, then you will need more than just a receiver that can tune those bands. CDMA is spread over 1.5MHz of spectrum - unless your radio has an IF that wide you are out of luck.
GSM and PCS (which is just GSM at a different frequency) is narrowband, but it's still more complicated than FM- you need to be able to receive the complex (in the a + (srqt(-1))w sense of the word) waveform, and pull the bits out of the air. Then, you need to decode the protocol, run the vocoder algorithm, and generate the audio. We use TI C6X DSPs capable of 1.6BOPS, with special opcodes to help the decoding, and Special chips to do the grunt work and it still takes a lot of work to get it to run in real time.
Now, if you are a ham, and you want to do sideband, PSK31, or other modes, this is a great thing. But don't expect to be able to monitor your neighbor's phone with it.
Besides, if you ever HAD monitored cellular, you't realize it's about as interesting as watching grass grow.
www.eFax.com are spammers
My notion of GNU Radio would be simple and inexpensive free FM BROADCASTING. Of course, the FCC has issues with that... if you pay attention to the micropower FM scene, it's actually quite similar to what GNU stands for. It's about empowering people.
The catch is, it's pretty easy to screw up an adjacent station if your signal is screwy and out of spec.
The low-power FM movement is worth your attention- if you're even reading this article you probably 'get' the importance of micro/local broadcasting. It should come as no surprise that corporate radio has been using Congress and the government to try to stamp out even the possibility of people using local FM broadcasting to provide alternatives- it mirrors what other content industries have been doing with more Slashdot attention. In December 2000 Congress passed an appropriations bill with a rider that was snuck in to halve the number of low power FM licenses the FCC could legally issue. Not only was corporate radio behind this- NPR also supported the illegalization of low power FM broadcasting. McCain (R-AZ) has introduced a bill to counter this and support low power FM again. Furthermore, on February 8, 2002, the Court Of Appeals struck down language in this anti-LPFM act which had prohibited the FCC from issuing a license to anyone who had ever previously been involved with pirate radio. The court held that this was unconstitutional. (funny how both in the judiciary and Congress, these guys are forced to deal with all types of injustice and power grabs, not just the sorts that are close to the hearts of Slashdotters ;) )
These people are the other side of the coin: transmitters from microwatt to 500 watts and kits for all kinds of nifty things like subcarrier decoders, shortwave, the aviation band etc. I don't know anything about them but their catalog but it would make any true geek absolutely drool, with all the build-it-yourself devices to do arcane and amusing things, and the flashy computerised rackmountable transmitters. Too cool.
The DSP-10 is a cool project. Some of the things that distinguish GNU Radio from it is our preference for a *much* wider IF bandwidth, and our use of conventional CPUs instead of DSPs. The vast majority of our code is in C++, versus Analog Devices 21xx DSP assembler.