Open-Hardware Licensed Handheld Software-Defined Radio In the Works 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."
Why just 2m and 70cm? (Score:1)
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? (Score:4, Interesting)
Re:Why just 2m and 70cm? (Score:5, Informative)
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.
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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).
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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 receive
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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? (Score:5, Informative)
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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
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It's likely it can do 1.25m as well as 33cm. It depends on the final amplifier circuit (if present).
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Probably because the RF power amplifiers needed - just because you
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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...
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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 t
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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.
Kewl (Score:3)
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In that narrow spectrum? Shannon says no.
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Try using the Internet instead...
GQRX and RTLSDR (Score:2)
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 $$$$.
I hate to be _that_ guy... (Score:2)
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...).
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Found text link in the comments to the video:
http://blog.testa.co/
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Here's the paper published in the TAPR DCC conference proceedings: http://www.tapr.org/pdf/DCC2012-Handheld-Software-Radio_KD2BMH.pdf [tapr.org]
Also, follow me on twitter http://twitter.com/testa [twitter.com] or my blog http://blog.testa.co/ [testa.co]
Open what? (Score:3)
But is there any shortage of openly published and easily accessible hardware designs for amateur radio?
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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.
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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.
Looks cool (Score:1)
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
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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 powe
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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 "character
Can't wait! (Score:3)
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!
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I see these articles occasionally, but I don't know the significance. Can you outline *why* I should be excited about this?
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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
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Thanks, Chris. That was useful, and I'll do some more Googling based on your reply.
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Thanks no_such_user... see you at Dayton! I'll hopefully be helping out at the TAPR booth.
73,
Testa KD2BMH