I am having a problem with using multiple frequencies with rtl_fm. Single frequencies work just fine. For example: rtl_fm -f 462.5625M -f 462.5725M -N -s 12k -r 12k -g 48 -l 50 | play -r 12k -e signed-integer -b 16 -t raw -c 1 -V1 - Will get to: Sampling at 1008000 Hz. Output at 12000 Hz. Exact sample rate is: 1008000.009613 Hz Tuner gain set to 48.00 dB. Then freeze. If I set the squelch low enough, it will continuously monitor the first channel. If I have a transmitter on before starting the command, it will monitor that. But when the transmitter turns off, rtl_fm hangs. I looked at the code but couldn't fix it. Maybe it's some reset command that's not being done between frequencies. If I force "data_ready" to unlock, it scans, but there's no data. Although, rtl_tcp works just fine when connecting with SDR# and changing frequencies. This is on a Raspberry Pi btw, latest rtl-sdr source code. Sorry if this has already been discussed somewhere, I could not find it. - Ben