P
Paul Keinanen
Is there any commercially available tiny (to be carried in model airplane)
radio modems capable of communicating (full-dublex) at rate of 19200 baud
(or faster) in a radius of up to 5km?
For full duplex operation, you need two separate frequencies, one for
uplink and the other for downlink. If you intend to put these
frequencies on the same frequency band, you need very good filters to
keep away the transmitter power from receiver. For sufficient
selectivity, some form of cavity resonators would have to be used,
which would be far too heavy for model airplane.
I would suggest using the aircraft control frequency (typically around
40 MHz depending on country) for uplink and perhaps 27 MHz or 2450 MHz
for downlink, if it is allowed to operate airborne transmitters at
these frequencies in your country.
Paul