I'm trying to build an FM receiver (and eventually transmitter) in GnuRadio that will be able to interact with my local repeater. Starting with WBFM (because I can consistently pull in broadcast stations for testing) I created 3 receivers:
- Directly tuning my SDR hardware to the station I want to listen to
- Tuning the hardware to some base frequency, then multiplying by a cosine; heterodyne
- Tuning the hardware to some base frequency, then using the
Frequency Xlating FIR Filter
My question is, which is the better method given I eventually want narrow-band FM with split transmit & receive against a repeater?
I'm guessing having to change the hardware's frequency from receive to transmit, then back again will be "too slow". I'd think that going back-and-forth between cosine sources wouldn't be too bad, but I'm wondering if there is an advantage to the
Frequency Xlating FIR Filter. Thoughts or advice? Thanks!