The project I’m working on (an SDR for a spacecraft
communication groundstation) needs to transmit VHF at
around 145 MHz. There seems to be a distinct “gap”
in the transmit capabilities of the USRP daughterboards
between 32 MHz and 400 MHz.
I’m looking for suggestions as to how to best accomplish
this. My initial thought was to output at 10 MHz using
an LFTX board, and upconvert to 145 MHz with an external
mixer, LO, and filter. This seems straightforward, but
would be a custom implementation, and my project wants
to stay with commercial-off-the-shelf if possible.
Another suggestion was to skip the modulation (GMSK) and
output the baseband signal with an LFTX. This could then
be fed into a commercial off-the-shelf VHF FM transmitter.
I was also wondering if it would be possible to modify
an RFX-400 daughterboard to go down that low (Matt?).
Anyway, I was hoping to hear what people thought of these
suggestions, and any others they might have.