For Linux/RaspberryPi, Software Defined Radio (SDR) software was generally limited to GQRX, which works great, but now we also have SDR++. This new cross-platform SDR waterfall works perfectly with your favorite SDR dongle, allowing you to see large portions of a band and pounce on unsuspecting transmitters. As a bonus, I'm including a PL-tone command-line filter that works on Pi/Linux, letting you listen to repeaters without the annoying PL-tone. SDR++ Let's listen!
To get rid repeater PL-tones, fire up SDR++ and set the audio sink to "network", or fire up GQRX and press the [UDP] button.
then run:
nc -l -u 7355 | play --buffer 100 -t raw -b 16 -e signed -r 48k - -r 16k sinc 0.3k -n 3000
Good bye PL Tone!
apt install sox, if you haven't already