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Open-Hardware Licensed Handheld Software-Defined Radio In the Works

timothy posted about a year and a half ago | from the good-speculation dept.

Communications 50

An anonymous reader writes "Chris Testa recently presented at TAPR Digital Communications Conference and annouced his development work on a hand-held software defined radio. Running uClinux on an ARM Corex-M3 coupled to a Flash-based FPGA, it will be capable of receiving and transmitting from 100MHz to 1GHz. Designed to be low power, Chris has designed the radio primarily with the Amateur 2m and 70cm bands in mind. Currently in early prototyping stage, Chris intends to release the design under the TAPR Open Hardware License."

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Parts (0)

Anonymous Coward | about a year and a half ago | (#42465641)

I hope the parts is easily obtain and solder by home-brew hobbyist

Re: Title (0)

RightSaidFred99 (874576) | about a year and a half ago | (#42465707)

Uhh, lolwut? Poorly defined inscrutably formulated article tile is difficultly read.

Re: Title (0)

Anonymous Coward | about a year and a half ago | (#42466429)

I think it's your reading comprehension skills.

Open-Hardware Licensed
Handheld
Software-Defined Radio
In the Works

Which of these is difficult to read?

Why just 2m and 70cm? (1)

tipo159 (1151047) | about a year and a half ago | (#42465765)

Why is he designing it primarily for 2m and 70cm (better known in amateur radio land as 440)? 2m is kinda crowded around here and 70cm doesn't seem to like the hills and trees around here. Our local ham group (in particular our ARES/RACES subgroup) is thinking about going to 6m.

I'd be more interested in something like this if it went down to 50MHz. But I don't know enough about designing this kind of thing to know if that is feasible.

Re:Why just 2m and 70cm? (3, Interesting)

atrus (73476) | about a year and a half ago | (#42465815)

The only real limits are: RF front end/IF section (if any, could be a direct conversion) FPGA speed The latter really only comes into play for high datarate/frequency work, so its all in the (hopefully replaceable) front end.

Re:Online Income (-1, Troll)

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Re:Why just 2m and 70cm? (4, Informative)

dtmos (447842) | about a year and a half ago | (#42465895)

But I don't know enough about designing this kind of thing to know if that is feasible.

The SDR is feasible, in fact, easier, but the problem is the "handheld" part -- "emphasis on the word, 'handheld.'" The physical size of the antenna starts becoming uncomfortably large as the frequency goes down -- or, said another way, the efficiency of the antenna goes down with frequency if the physical size is held constant. A full-size 50 MHz quarter-wave whip antenna is 1.5 meters (or metres, if you prefer; about 59 inches) long; that's pretty unwieldy for a handheld radio.

Re:Why just 2m and 70cm? (1)

Skuld-Chan (302449) | about a year and a half ago | (#42468663)

Yeah hardly anyone uses quaterwave whip antennas on a hand held radio. In all the radios I've ever used - easily a dozen they've all had loaded coils. Which are not all that efficient sure, but they work well enough - especially with an infrastructure which there is plenty of on 2m and 70cm (and 6m as in your example).

Re:Why just 2m and 70cm? (2)

dtmos (447842) | about a year and a half ago | (#42469113)

Yes. And if one makes a 6m antenna the same physical size as a handheld 2m antenna the 6m loading coil will be larger, its series resistance will be higher, and the 6m antenna will be significantly less efficient than the 2m antenna. It will work "well enough", for suitably generous definitions of "well enough."

The optimum operating frequency for a given service can be determined (in the absence of regulatory restrictions, of course) analytically, taking atmospheric noise, antenna performance, and receiver noise figure into account. See, for example, Kai Siwiak, Radiowave Propagation and Antennas for Personal Communications." Second Edition. Boston: Artech House. 1998. Chapter 4.7.

Re:Why just 2m and 70cm? (2, Interesting)

Anonymous Coward | about a year and a half ago | (#42465947)

The 2 meter and 70cm bands are by far and away the most popular amateur radio bands, and they are the most accessible. All license tiers can use them, and equipment can be had for reasonable prices.

These sorts of considerations are very important if you want to kick off something you want to see widespread use. HF can always be added later, once a project develops traction.

Re:Why just 2m and 70cm? (0)

Anonymous Coward | about a year and a half ago | (#42466071)

Oh, and notice he puts emphasis on "handheld". HF is much harder to squeeze into a handheld than VHF and UHF.

Re:Why just 2m and 70cm? (4, Informative)

maird (699535) | about a year and a half ago | (#42465977)

Then if the future of 2m, 70cm is narrower channel bandwidth than is currently used (how could it not be given the public service channel bandwidth now used) the nice thing here is that you only have to install the ROM image with the new modulation, keeping the old bandwidth as a feature anyway. Leading to more space for local groups in the long term from free software. I'd bet the lack of 6m comes from one of the chips at the RF end being limited to 100MHz. It's quite easy to fill-in the 0-100MHz block for receive with a cheap mixer (see the article in this month's QST, pg 30 I think).

Re:Why just 2m and 70cm? (2)

CC12123 (443428) | about a year and a half ago | (#42478065)

Chris Testa KD2BMH here. marid, your suspicion is correct, the CMX991 transceiver I'm using has a low-end cutoff of 100MHz.

The HF converter w/ a NE-602 mixer in the latest QST looks like an attractive solution to support the missing lower frequencies receive, I'm guessing 2 would allow me to build a full duplex transceiver.

I'm using a 40MHz ADC & DAC, so at least some of the HF bands should be possible using direct conversion.

Either way, HF wasn't part of my initial plan, I'm focusing on exactly what I can fit inside easily, and then more features can be added later. Launch & iterate... the kitchen sink will come in one of those iterations :)

Re:Why just 2m and 70cm? (1)

maird (699535) | about a year and a half ago | (#42479183)

Hi Chris, thanks for the response! It's maird rather than marid BTW but AD7GH or David works too ;-) I have the parts for a pair of 125MHz NE-602 mixers en-route from Mouser as I write and they should be here on Monday. The ultimate goal is to extend a RTL2832 USB receiver that should get here in early February. So hoping for a nice little project for fun and some spare parts in case I blow it. I might just build it before the USB device gets here and test it on one of my other receivers. I watched the show Chris and I'm attracted to the project. I appreciate the explanation why HF isn't in the initial plan and the mixer in QST won't cope with a transmitter on the same antenna lead without more work anyway. Anyway, my main point is that I write software for a daily living at an open source maintainer, perhaps I can contribute...

Re:Why just 2m and 70cm? (0)

Anonymous Coward | about a year and a half ago | (#42466863)

Nevermind 220 getting left in the dust, as usual. I agree though, 6m tends to be the best band in almost all circumstances.

Re:Why just 2m and 70cm? (1)

jfalcon (163956) | about a year and a half ago | (#42468191)

It's likely it can do 1.25m as well as 33cm. It depends on the final amplifier circuit (if present).

Re:Why just 2m and 70cm? (1)

tlhIngan (30335) | about a year and a half ago | (#42466889)

Why is he designing it primarily for 2m and 70cm (better known in amateur radio land as 440)? 2m is kinda crowded around here and 70cm doesn't seem to like the hills and trees around here. Our local ham group (in particular our ARES/RACES subgroup) is thinking about going to 6m.

I'd be more interested in something like this if it went down to 50MHz. But I don't know enough about designing this kind of thing to know if that is feasible.
 

Probably because the RF power amplifiers needed - just because you can theoretically receive and transmit from DC to daylight, doesn't mean it works in practicality. For receive, you need to amplify the incoming signal, and broadband amplifiers that have the desired characteristics are hard. For transmit, you'd need amplifiers for every band you're interested in - in this case, 3 separate power amps - 6m, 2m, 70cm. You don't want to use a wideband one because their general characteristics suck and you REALLY don't want to accidentally transmit off-band (you're still responsible for all emissions, after all) either accidentally (due to bugs) or intentionally.

There are very few HTs from the big guys that actually do 6m, as well. And consider yourself lucky that the bands are so crowded - it means there's lots of action. A dead band is one ripe for reclamation.

Re:Why just 2m and 70cm? (1)

bobthesungeek76036 (2697689) | about a year and a half ago | (#42468709)

Like 6M and 1.25M? They are both pretty dead where I live (DFW). I have a radio that will do 6M but no antenna yet. I have yet to hear anything on it while spinning the dial. I do have a 220MHz receive-only radio but all the repeaters in my area are linked to either 2M or 70cM repeaters and serve no real purpose...

Re:Why just 2m and 70cm? (1)

Muad'Dave (255648) | about a year and a half ago | (#42475875)

Bob,

Keep an eye on www.dxmaps.com [dxmaps.com] and when you see QSOs near you, fire up your 6m rig using your HF antenna. I've worked over 100 grid squares using a 756 PRO, 100W and my multiband HF dipole (that isn't cut for 6m) and is only 15 feet off the ground. If your rig has an antenna tuner, I bet it can find a match for 6m. I think part of why I can load up that antenna is that the coax is so bad it presents enough raw resistance so that the SWR is under 3:1 regardless of the actual antenna impedance!

See you on the air! 73 de k4det

USRP (-1)

Anonymous Coward | about a year and a half ago | (#42465877)

Doesn't the USRP with GNURadio already do this and more? Why not just try to shrink that? This is just from a layperson's perspective though.

Re:USRP (1)

jfalcon (163956) | about a year and a half ago | (#42468163)

It's not designed the same way however it's very similar and presumably will have more powerful transmitters.

Also GNURadio has a steeper learning curve to work with compared to a normal radio interface.

Great for taxidermy (0)

Anonymous Coward | about a year and a half ago | (#42465953)

His brother chuck is going to love this.

Kewl (2)

ickleberry (864871) | about a year and a half ago | (#42465955)

I want! Imagine a mesh network of these, put the evil telco's out of business :)

Re:Kewl (1)

SuricouRaven (1897204) | about a year and a half ago | (#42467537)

In that narrow spectrum? Shannon says no.

Re:Kewl (1)

baker_tony (621742) | about a year and a half ago | (#42470485)

Try using the Internet instead...

Re:Kewl (0)

Anonymous Coward | about a year and a half ago | (#42471075)

You think that's cool, imagine a Beowulf cluster connected with these...

GQRX and RTLSDR (2)

theklap (1804944) | about a year and a half ago | (#42466155)

I just started using Gqrx and a rtl device for $20 to get started in software radio.
Grabbing the APT images from polar orbiting satellites.

http://www.oz9aec.net/index.php/gnu-radio/gnu-radio-blog/477-noaa-apt-reception-with-gqrx-and-rtlsdr [oz9aec.net]

There is also the Funcube USB Dongle you can use but its more $$$$.

Re:GQRX and RTLSDR (0)

Anonymous Coward | about a year and a half ago | (#42468585)

The rtl (and similar chipsets) devices are RX only, unfortunately!
- TX (transmitting), and transmitting ONLY on the right frequencies makes it much more tough but also interesting :ø)

It should be interesting to follow the HW development, as .1 to 1 GHz and digital (highspeed) modulation - especially with a somewhat big bandwith - isn't easy to do, if you want to keep your licence for long.

I hate to be _that_ guy... (1)

KZigurs (638781) | about a year and a half ago | (#42466273)

But perhaps there's a text article somebody could link to instead? Video is an unbearable format when it comes to technical news - just stop doing that (although the fact that reading (and writing) is hard is understandable...).

Re:I hate to be _that_ guy... (2, Informative)

Anonymous Coward | about a year and a half ago | (#42466797)

Found text link in the comments to the video:

http://blog.testa.co/

Text Link (0)

Anonymous Coward | about a year and a half ago | (#42466731)

http://blog.testa.co/

Open what? (2)

westlake (615356) | about a year and a half ago | (#42466773)

Correct me if I am wrong.

But is there any shortage of openly published and easily accessible hardware designs for amateur radio?

Re:Open what? (1)

coldfarnorth (799174) | about a year and a half ago | (#42466937)

Are you saying there are too many? You can always sign off and go get some fresh air.

I happen to be kind of excited about his work, it's compact, it has a nice frequency range, and it can transmit, which is a bit novel. To each their own.

Re:Open what? (1)

westlake (615356) | about a year and a half ago | (#42471323)

I happen to be kind of excited about his work, it's compact, it has a nice frequency range, and it can transmit, which is a bit novel. To each their own.

It's not the project I object to.

It is the ridiculous "open hardware" hype applied to radio enthusiasts who were sharing designs, techniques, etc., long before the invention of the vacuum tube.

Re:Open what? (0)

Anonymous Coward | about a year and a half ago | (#42468893)

Many are analog. This is a digital design at its core. So sure, its cool. Besides, if you dont care, dont read it.

Looks cool (1)

Anonymous Coward | about a year and a half ago | (#42468655)

It would be even better if it covered the HF bands.

I've had this fantasy about designing a very low bitrate (short messages only may take minutes to hours to send one message) massivly multiple access self organizing messaging protocol using GPS ref with ability to operate way way way way below the noise floor leveraging only ISM bands and effective power limits.

The ultimate would be a tablet sized (mostly antennas) device able to communicate short text messages directly to others (P-T-P ONLY no meshing or gateways) within hundreds of miles radius supporting millions of devices. No infustructure, no licensing, no monthly fees and assured equal access opportunity for all participants.

I still have much to learn about signal processing and RF but when my other projects are finished I intend to look seriously into it. No doubt my hopes will be dashed by reality but at least I'll have learned something.

Re:Looks cool (1)

Muad'Dave (255648) | about a year and a half ago | (#42476145)

Look here [princeton.edu] . I've used WSPR to send a small message from Richmond, VA to New Zealand using a 0.1 Watts on 30m (about 10.1 MHz). Dr. Taylor is a weak signal nut, and has done an amazing job of creating modulation schemes that work well for a lot of very weak signal scenarios. Want to bounce signals off of the ion trails left by meteors that are so small you can't even see them? Done - it's called FSK441 [princeton.edu] .

His newest JT9-x schemes [princeton.edu] can detect signals 40 dB _below_ the noise floor - that's 1/10,000th the noise power. Amazing, really, and all it takes is a radio and a PC with a soundcard.

Audience (0)

Anonymous Coward | about a year and a half ago | (#42468793)

Did you notice how much white hair was in that audience? As a younger guy interested in ham radio, I sure hope it isn't on a one-way-trip to the history books.

Re:Audience (1)

Anonymous Coward | about a year and a half ago | (#42472191)

The abundance of white hair is because a couple of generations didn't seem to value anything that had "old people" involved, so it's no surprise that many of us are old, the youngsters had no drive or vision for the future, no interest in science except watching it on TV, and the only interest they have in technology is in consuming it.

But aside from that, welcome to Amateur Radio there are hundreds of paths one can follow and also have a good time meeting some great people, and more than a few "characters", and all the while learning many quite interesting things along the way.

73

Never 73's, bad, bad, bad.

Re:Audience (0)

Anonymous Coward | about a year and a half ago | (#42473587)

I tried to get into amateur radio but all I found were little closed groups that were unintentionally elitist, but that wasn't the problem, I found the culture was just so impenetrable for newbies like me and their internet presence is a bit of a joke, old mailing lists and websites that are from 1995 are difficult to navigate and find introductory information. Not only that, I've found a lot of them use technology which is proprietary so you need to fork out thousands and thousands of dollars to even get started. I've found people like me just focusing on 802.11 technologies instead as they're much more accessible and far cheaper. You can do a lot of with some of the cheap long distance (long for 802.11 anyway) directional stuff and the mesh stuff is interesting too. This is just my experience but I've heard the same things from people my age who tried to go into amateur radio.

Why don't cell phones have software defined radios (0)

Anonymous Coward | about a year and a half ago | (#42471675)

It would make sense for providers to be able to send a command to customer phones to unlock more frequencies for them to use. And their towers, too. Faster 4G and future technology deployment.

Is there some practical limitation here?

Can't wait! (2)

no_such_user (196771) | about a year and a half ago | (#42472865)

12 hours and only 37 comments? The response to a device like this should be far greater on a site like Slashdot. *Sigh*.

Anyway, I've always felt TAPR kits were not entirely within my grasp due to either high prices or high complexity. I hope this will be an affordable kit which doesn't require a ton of SMD soldering. Take the lead from Raspberry Pi - small, simple, affordable hardware.

Good luck! I'll see you guys at Dayton!

hidden transmission? (0)

Anonymous Coward | about a year and a half ago | (#42473799)

OK, I try: can I buy half a dozen of these chips, and program them to simultaneously transmit on a series of wavelengths, with an amplitude/frequency coding that allows me to globally stay below noise level, so that I can extend my home network up to my office in a basically undetectable way?
I don't need a large throughput, I just don't want to be bothered...

Re:hidden transmission? (0)

Anonymous Coward | about a year and a half ago | (#42493351)

1. VPN would be a better idea unless your office is literally next door, the bandwidth overhead, power requirements, skill requirements, and the fact that the FCC frowns upon running encrypted traffic on the public bands. 2. What are you browsing that will get your employer angry that can't be plausibly explained as you doing your job, Goat porn? Careerbuilder? WoW?. Also, wasting your employer's time is a great idea in the current economy, as it is so easy to get a job in spite of termination for being a goldbricking jackass. And if you are salary, all you are doing is making more work for yourself later and wasting time that you could be spending at home with your family and a real gaming PC, not a crappy optiplex the office bought 4 years ago.

Re:Can't wait! (1)

robot_love (1089921) | about a year and a half ago | (#42477631)

I see these articles occasionally, but I don't know the significance. Can you outline *why* I should be excited about this?

Re:Can't wait! (1)

CC12123 (443428) | about a year and a half ago | (#42478329)

Chris Testa KD2BMH here...

This is one of the most interesting and challenging questions to answer. Here's a blurb excerpt from Eric Blossom, an early innovator in software radio as to why this stuff is so valuable:

"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 Perhaps most exciting of all is the potential to build decentralized communication systems. A centralized system limits the rate of innovation. We could take some lessons from the Internet and push the smarts out to the edges. 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." - Eric Blossom, Exploring GNU Radio

What's exciting is now a radio, which has the "brains" to be a major part of Internet infrastructure (think Veriozon's cell towers everywhere) will fit in your pocket. This should enable a change in the landscape of the Internet itself, and I hope it frees our comms from bondage to wire's and large multi-national corporations.

This was my original inspiration, at least.

Re:Can't wait! (1)

robot_love (1089921) | about a year and a half ago | (#42483515)

Thanks, Chris. That was useful, and I'll do some more Googling based on your reply.

Re:Can't wait! (1)

CC12123 (443428) | about a year and a half ago | (#42478335)

Thanks no_such_user... see you at Dayton! I'll hopefully be helping out at the TAPR booth.

73,
Testa KD2BMH

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