GQRX scanner

Gqrx has a handy “remote control” feature that allows you to connect to it over a TCP socket, and send commands to it.

Aside from changing the frequency, it also allows you to read the current signal strength on the tuned frequency.

This combination of features allows you to write a simple scanner that will scan a range of frequencies, and turn on the squelch when it detects a signal.

Software-defined radio