Remote control protocol.



Supported command:
 f - Get frequency [Hz]
 F - Set frequency [Hz]
 m - Get demodulator mode
 M - Set demodulator mode (OFF, RAW, AM, FM, WFM, WFM_ST, WFM_ST_OIRT, LSB, USB, CW, CWL, CWU)
 l - Get signal strength [dBFS]
 c - Close connection
 AOS - Acquisition of signal (AOS) event, start audio recording
 LOS - Loss of signal (LOS) event, stop audio recording



Reply:
 RPRT 0 - Command successful
 RPRT 1 - Command failed
