Smitty Working on SOMETHING: SOAR! FM Satellite Radio Part 6: Co-Stream with KF7IJZ
Channel: Mark Smith
Date: 2017-05-28

Part 6: Continuing work on SOAR v1.1, while Jeremy KF7IJZ is swearing at his 3D-Printer Assembly... :-)

Full duplex cross-band HTs are getting harder to come by/more expensive, but are really the best way to operate an FM satellite. Expect to spend between $300 and $400 on one (even used ones), and only ONE (Kenwood D72a) is currently available new.

Enter the DRA818V [1] and DRA818U [2] modules. They're basically 1W FM radio modules. You feed them power and audio, and they put out/receive FM.   They come in both VHF and UHF, and they're about $13 each shipped [3].

We could put together a custom rig with one of each of these modules, LPFs to make them legal (they're rather dirty otherwise), a diplexer to let them share an antenna port, and a microcontroller with display and controls to program the modules.  Add an RTC module, tell it rise and set times, and it can even handle the Doppler shift for you.

BECAUSE, APPARENTLY I NEED ANOTHER PROJECT, I'm going to look into designing some of this tonight.

[1] http://www.dorji.com/docs/data/DRA818V.pdf
[2] http://www.dorji.com/docs/data/DRA818U.pdf
[3] http://www.ebay.com/itm/191210888951 and http://www.ebay.com/itm/191243649892