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Developers Disclose Schematics For 50-1000 MHz Software-Defined Transceiver
Bruce Perens writes Chris Testa KD2BMH and I have been working for years on a software-defined transceiver that would be FCC-legal and could communicate using essentially any mode and protocol up to 1 MHz wide on frequencies between 50 and 1000 MHz. It's been discussed here before, most recently when Chris taught gate-array programming in Python. We are about to submit the third generation of the design for PCB fabrication, and hope that this version will be salable as a "developer board" and later as a packaged walkie-talkie, mobile, and base station. This radio is unique in that it uses your smartphone for the GUI, uses apps to provide communication modes, contains an on-board FLASH-based gate-array and a ucLinux system. We intend to go for FSF "Respects Your Freedom" certification for the device. My slide show contains 20 pages of schematics and is full of ham jargon ("HT" means "handi-talkie", an old Motorola product name and the hams word for "walkie talkie") but many non-hams should be able to parse it with some help from search engines. Bruce Perens K6BP
It would be possible to use it in a short-range transmit mode or as a receiver without a ham license. That said, I spend several years of my life helping to get rid of the Morse Code test for radio hams, so that smart folks like you could just take technical tests to get the license. They aren't that difficult. It might be worth your time.
Bruce Perens.
Most hams (including myself) are interested in HF (and others are interested in SWL and the new below-AM BCB ham frequencies.)
50 MHz means 6 meters and above -- basically, nothing that has any regularly occurring usable propagation modes. Many of these upper bands are almost dead -- I've not heard anyone on 2 meters or 70 cm around here in the last year -- but 10 through 160 meters (28 MHz through 1.8 MHz) are busy as heck, and of course all the SW spectrum in between.
Worse, we're almost certain to be about to slide down the sunspot curve, making the already mostly dead-by-choice bands completely dead-by-nature, propagation-wise.
RFSPACE's upcoming new unit is .009 (9khz) through 50 MHz. That's a lot more attractive to me. Both to use, and to support.
Then there's funcube dongle pro plus... 50 khz through 1.8 GHz, albeit without adequate filtering up front. But it's reasonably cheap, so there's that. (and I already supported it, PITA though it was, so it's not subject to the no-more-USB-devices rule.)
Well, whatever they end up with, I sure hope it's ethernet-connected and uses the standard SDR protocol as do Andrus, AFEDRI and RFSPACE. I've supported my last black sheep USB device (every darned OS has radically different USB interfacing and requirements... building my free cross-platform SDR software is most tricky with regard to USB issues. Ethernet, by comparison, is almost identical on all platforms -- the same SDR protocol / interfacing code works fine across linux, Windows and OS X.)
I've fallen off your lawn, and I can't get up.
The first version is marketed as test equipment. Which gets us around the various type-acceptance issues.
Nobody will be able to use this in the ham bands without a ham license, or in the LMR without the appropriate licenses. At least not as a transmitter. It is a really bad idea to suggest to people that they can use a transceiver without the appropriate license. That's why we have license-free CB -- so many people got the idea they didn't need a license for a radio they bought from K-Mart that the FCC had to give up on requiring licenses.
The second version is focused on end-users rather than developers and will be type-certified for either Amateur or one of the land-mobile bands.
It should be LMR, since amateur typing won't make use on commercial frequencies legal. Since it's open source software, you will have a hard time claiming that the radio is limited to any specific bands or uses.
You talk in your slides about how the "big 3" will sell you something and they don't interoperate in digital mode. Yes, that's a problem. (And I, too, wonder what Yaesu was thinking with their C4FM radios.) Your solution is this system. So, you'll need apps that do all the existing digital modes. As soon as someone modifies one of them and starts passing their nifty new app around, you'll have the same interop problem. Even worse -- instead of three main manufacturers to keep track of, there will be potentially hundreds of amateur tinkerers creating new "not-modes" digital ops. Saying the amateur community should come up with the digital standards is like saying a herd of cats should guard the catnip. Herding cats, herding amateurs ...
You're going to need a master contacts-app that keeps track of who you talk to and what app you need and even then you'll need to know which app they're using at the moment.
Don't get me wrong. It's an interesting piece of hardware. It's just the idea of saying "without a license" that needs to be controlled. Handing a transceiver to someone that can cover 50-1000 MHz (even at just 2W) and suggesting that they don't need a license to use it, well, I dunno. I think that's dangerous for the future of ham radio, not beneficial.
By the way, you say that "the AMBE 1000 IP will be unenforceable after Hamvention" (or something like that. ) What does Hamvention have to do with it?
50 MHz means 6 meters and above -- basically, nothing that has any regularly occurring usable propagation modes.
Moon-bounce and ham-sats occur regularly enough to be useful. Granted, hamsat passes are so short-duration and so sought-after that they aren't useful for much more than bragging rights, and moon-bounce is too technically challenging to be useful for routine communications, but they are there.
RF-based repeater networks on the 2m (~146MHz) and 70cm (~440MHz) bands are common in the United States. They offer communications over hundreds of miles without using anything but the airwaves. Ditto some mountaintop- and very-high-tower-based repeaters. A single repeater that covers a 50-mile-or-more radius is more convenient and therefore frequently more useful in an emergency than an HF-based NVIS net (NVIS is a way of setting up your HF antenna for "short range" communications of about a few hundred miles or less. Unlike typical antenna setups, they do not have any "skip", which is very useful in an emergency).
In situations where the Internet infrastructure is still up (which is almost always except during emergencies, and frequently during emergencies as well), repeaters that link to the Internet can provide worldwide communication on any band.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Michael's a good guy, but HackRF One is not a communications transceiver. He made it for hacking RFID. The receiver isn't that good and the transmitter is not FCC legal when amplified.
Bruce Perens.