On 05/08/20 11:42, Stephen DeVience via AMSAT-BB wrote:
The ground station complexity for using the linear satellites is a real issue, especially for anyone trying to rove or use a handheld antenna. I've always found the suggestion to use two FT-817s strapped to your neck very awkward (and pricey).
On the downlink (RX), one can use a very cheap SDR dongle such as:
Here's a demo from Drew (KO4MA) at Hamvention 2018:
https://www.youtube.com/watch?v=hBZvWCKxjcM
He's using a FUNcube dongle (not sure if Pro+ or not, but ~$155 for the Pro+), but the same could be done with an RTL-SDR dongle ($35):
https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/
Gqrx, the software "receiver" already runs on a cheap Raspberry Pi 3:
https://gqrx.dk/download/gqrx-sdr-for-the-raspberry-pi
Your choice of transmitter includes an existing multi-band radio, or one of many SDRs with transmit capability (assuming that one appropriately filters the output before amplification).
I'm starting to think of what would be needed for a handheld-size linear satellite transceiver. It would have to do SSB on UHF and VHF, and the Doppler correction could probably be handled by a phone app which would also provide visual tracking.
Well, if it were an _open_ digital voice format (down with AMBE!) with error-correcting codes, one might create such a transceiver quite easily, using highly-integrated modem ICs already on the market.
Someone might already be thinking about this.
--- Zach N0ZGO