I’m building a UHF amateur repeater and want to use SDRs for the whole thing so that we can experiment easily without changing hardware much. I have a couple of LimeSDRs and an amplifier already that I can use for this. I still need to get a UHF cavity duplexer, but that’s easy enough.
Has anyone written any gnuradio flow graphs or other software that creates a repeater? I’m happy to contribute, I just don’t want to reinvent the wheel if this has already been done and I just can’t find it.
Yes. Mostly for digital experimentation (VoIP linked), but also analog FM. I’ve used a small linear PA in the past then switched to the LimeRFE frontend because it’s more frequency agile and less hassle to change bands. No duplexer though - either crossband or using spatial antenna separation. Software - see http://qradiolink.org/ (it uses gnuradio flowgraphs under the hood). Takes some time to get used to it and iron out issues, and the stability for long time periods is not great, but it works. My current problem with this setup is a segmentation fault in the Opus decoder (used for TCP/IP voice transport) which means I can’t leave it unsupervised for long.