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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."
This would be a perfect way to listen to geeks in space!
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
While it might be cool to get your computer to do all sorts of signal processing stuff, a DSP is just going to do it better no matter what. Do we really need 60W CPUs being used for modulating/demodulating signals?
Kill'em! Kill'em all!
I love the way there was a candid admission of the situation.
I spent a good 15 minutes wondering if I'd some screwed up cookie which was preventing me logging in.
All boasting "I've got a brand GNU radio and it runs Linux"
We could have all those bands again that they banned; the 800mhz AMPS area, HDTV, anything just pumped into our boxen.
Does the ADC mix down the frequency prior to A/D conversion?
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."
Since you are a linux zealot, you have already experienced an anus-opening experience, right?
Karma whoring, Anthony Boyd style:
In case of slashdot effect, here's the summary:
Introduction
GNU Radio is a collection of software that when combined with minimal hardware, allows the construction of radios where the actual waveforms transmitted and received are defined by software. What this means is that it turns the digital modulation schemes used in today's high performance wireless devices into software problems.
What is a Software Defined Radio?
Joe Mitoloa says, "A software radio is a radio whose channel modulation waveforms are defined in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband DAC and then possibly upconverted from IF to RF. The receiver, similarly, employs a wideband Analog to Digital Converter (ADC) that captures all of the channels of the software radio node. The receiver then extracts, downconverts and demodulates the channel waveform using software on a general purpose processor." [1]
For our purposes, on the receive side, the idea is to get a wide band ADC as close to the antenna as is convenient, get the samples into something we can program, and then grind on them in software.
appearantly is the PCI-DAS4020/12 - that's what the alpha driver posted is for, specs cached here. Described as "low cost" (from a lab gear point of view) but is GBP 1200 or so.
I've always wondered what generic CPU's could do in the HF (3-30Mhz) radio spectrum since CPU speeds passed 120Mhz long ago.
try { do() || do_not(); } catch (JediException err) { yoda(err); }
don't worry kids, the introduction of digital radio and subsequent shut down of analog will prevent any fair u, Erhm, unauthorised distribution of copyrighted content.
Joe Schmo: but won't that mean I have to fork out
$$$ on a new receiver?
RIAA exec: yes, but the new one has an LCD display
that shows you the song title!
"I think it would be a good idea" Gandhi, on Western Civilisation
The MC DAC supported has a sampling rate of 20MHz. Does that limit the range of possible frequencies to 20MHz ? Are there any ADCs out there that can sample upto, say, 500MHz ?
so why is a software radio getting the geek seal of approval?
"I've configured the main computer to search all open channels for communications, so we gave it a blast at the XXXhz range to see if it would trigger a response"... "Any siugnificantly advanced modern-day technology is just trying to make StarTrek/StarWars a reality" - me
meh
If the software is digitally creating the waveforms before conversion to analog and transmission, then encryption could be applied to the waveform, and decrypted with the appropriate key by the receiver (a radio version of PGP, anyone?). This could prove to be a very cool method of secure communication.
$1300 is very pricy! For hobbiest use, is 20 MHz really needed? Is there any Linux supported sound cards that can sample at 88Khz or above? How about using a "winmodem" as the ADC?
Now I can try out tempest for eliza without need to actually use a radio!
Make even shorter URLs - 8LN.org
It is not pointless, however, but it is very bleeding edge. I can see this being more practical as processor speed improves.
Maybe eventually there will be something like a box with a firewire connection or something.
You know some companies will freak if people start producing software to receive HDTV, Satellite Radio, etc. HDTV is supposed to be the standard nation wide by 2006(??). This ties in with the ability in HDTV to block recording of certain programs, etc. if you have a digital recorder. This will also tie into that bill Sen Hollings introduced.
So this is all part of a somewhat larger picture.
"It is a greater offense to steal men's labor, than their clothes"
Sorry, i'm going to have be a luddite here. If you have GNU Radio envy, here's the antidote: the distinctly analog (and fantastic sounding) Henry Kloss Model Two Desktop Stereo Radio. AM and FM. Lovely smooth-sliding analog dials. And nothing else sounds as good for $159. And if that's too rich, there's the original $99 Mono Henry Kloss Model One. Rest In Peace, Mr. Kloss.
That's why you use a prescaler in front of your ADC.
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.
Some guys in Germany are working on a software decoder for DRM, this is basically a new digital radio service for SW/LW/MW radio, there's a few test transmitters running in Europe. The transmissions consist of a COFDM modulated channel and a 20-30kbps AAC stream within, doesn't sound like much but when you can get flawless delivery from Finland to Portugal and farther afield it's not bad and makes old SW look very poor indeed.
This has some possibilities. One is a radio that listens to the entire FM band and, quickly and automatically, builds an MP3 music library of popular music. Legal, too. (Audio Home Recording Act)
Add-ons to this project could include automatic song identification (there are song-signature databases for this), use of multiple copies to recognize and remove announcer blithering, and intelligent audio cleanup from multiple copies.
Great open-source project for audio people. Nice device for cars, too.
Project seems neat but I wonder how you get the alliasing of computer frequencies filtered out? Computer systems don't just generate frequencies at the main freq. That may be the fundamental freq but there will be hundreds of side bands generated in the local vicinity of you PC. Plus even if just had the fundamental freqency all other switching signals at less than the clock rate would generate a frequency and side bands themselves. It would seem like a great big noisy mess in the 5 to 30 Mhz range near your PC.
On another note it would be interesting to see if any one could build an amateur baseband system for 802.11b. That has a bandwidth that should alias down to below the 30 Mhz range with the right analog receiver. But it would not be real time as it takes ~10 Bops of computing power to decode the signal on just a PC. (802.11a would take ~30 Bops according to the literature!)
So, could I make a scanner out of this? To be able to listen to 1mhz-1000mhz?
I'm a big retard who forgot to log out of Slashdot on Mike's computer! LOOK AT ME.
Whooa - Per fect for a mobile pirate radio setup - something to blot out those Christian radio stations with Grateful Dead and other jambad tunes.
the gnu radio site doesn't say how to build the hardware! anyone know where to find out?
so when is this radio going to have tivo like capabilities? that would be the killer app making it all worth it.
rhy
I hold very few opinions. I hold information based on observation and fact. If you wish to disagree, please use facts.
Anyone too stupid to add:
127.0.0.1 images.slashdot.org
127.0.0.1 m.doubleclick.net
to their hosts file deserves whatever that get.
also, in the interim, anyone know about how to hook up a gps receiver to a laptop a la cryptonomicon?
that is, without having to resort to windows-only software that the gps mfr supplies, but rather have programmatic access to the receiver's info via serial/usb/etc?
even better, a gps receiver that allows all that and is tiny enough that it could actually be used regularly and unobtrusively w/ a laptop.
It would be interesting to add a webpage containing a list of hardware that is compatible with this SDR out-of-the-box or is planned to be supported.
Hi, this is Eric Blossom. I'm the primary maintainer on GNU Radio. With regard to hardware requirements, there are several things that will work. It all depends on what you are trying to do.
Those of us who are currently doing most of the work on GNU Radio are using an off the shelf 20 million sample/second A/D card made by Measurement Computing. It's not cheap, about $1300 US, but its the best value we've found so far.
We're using this card in combination with a tuner module designed for cable modems. This allows us to receive pretty much anything from 50 MHz up to 890 MHz and we get to suck down about 6 MHz worth of usable spectrum centered at a particular frequency. This means that depending on what we're looking at, we can either process many narrow band signals simultaneously or a single wide band signal. Examples of narrow band signals include conventional FM broadcast, cellular, paging, etc. The wide band signals that we have currently been spending most of our time on are ATSC (Advanced Television Systems Committee) digital broadcast TV.
Others have talked about using conventional sound cards, AC97 codecs etc along with a narrow band downconverter of some kind. The software supports I/O using sound cards, but somebody, perhaps from the amateur radio community needs to draw up a simple schematic that's straight forward to build.
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.
Could I just point out, that instead of $1300-worth of digital bits, you could do this in simple analogue stuff, on your kitchen table, with no more tools than even beginning electronics hobbyists have?
Oh, and amateur radio enthusiasts have been homebrewing radio gear for years... all analogue.
What's the advantage in using a DSP? And how do you get rid of all the clock hash?
That depends on whether you've got a `transmit' button or not.
One place I worked at left a scanner running in the main office (the boss was more than a bit weird), and one day we got an entire 20-minute conversation between husband (on mobile) and wife (on land-line) discussing the previous weekend's partner-swapping exercise, ratings and so on, exploring the prospects for a repeat and so on.
Towards the end wife asked if it was wise to discuss this on the 'phone and husband returned copious assurances that since he was on a mobile (but evidently sitting still) the conversation would be chopped up across channels and nobody could make head or tail of it.
And me with no transmit button. Sigh.
Got time? Spend some of it coding or testing
but if you had subscribed, numbnuts, you would have noticed that you wouldn't have been charged for when the service was down. Kind of like how you can't pay tolls on the Big Dig yet...
Hrm, I wonder what interaction these types of things are going to have with 'privacy' laws for cellphones. It used to be that you could get radio recivers that could listen to any freqency out there, but today they are restricted from listening in on cellphone conversations.
Would the advent of software radio bring that to an end, or cause DMCA style restrictions on radio-capable software?
autopr0n is like, down and stuff.
Descrambling CDMA is likely even outside of the abilities of much local law enforcement, and it probably still very difficult even for the Feds.
They'd probably get access to the base switching stations rather than bother with trying to intercept the radio link.
CDMA looks like noise - without having the right information about where the various parts of each bit are - you aren't going to even get your hands on the data.
You need to know the right "chipping" functions and also time synchronize yourself to the network and mobile unit. This is really, REALLY, *REALLY* hard. Probably costs many many thousands of dollars to get equipment that can do it.
CDMA is spread spectrum - which at one time was classified and only used by the military.
Sometimes I think declassifying it wasn't a very good idea from a national security perspective...
Just because it CAN be done, doesn't mean it should!
Instead of SETI RXing the signals and dispersing them to be processed and sent back- With something like this, dispersed "listening" stations could RX signals, process them, and send them on to SETI.
"Is there anybody out there?" Pink Floyd
You're created a winmodem for the radio...
Buy any PCCard based GPS (virtually any) and use the text based information they spit out. NMEA-0183.
What I want is software that pulls timestamps out of the data stream so it can set a PC clock - either Windoze or Linux is fine, given the limited accuracy I need. (Actually, I've found that GPS reception inside buildings, at least for older handheld and wristwatch units, is bad enough that it's probably not going to be useful unless your lab has windows.)
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Please mod Eric's article up if you're a moderator this week - he's the authoritative person to be writing about this stuff...
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Humm mr wowbagger, I know for a fack CB kicks FRS and GMRS in the a** 1000 times plus!, because of its power, features and many other things it can do and you can do to it, so tell me why you dissed it so many times!!?? KITT