RTL-SDR is a very cheap ~$25 USB dongle that can be used as a computer based radio scanner for receiving live radio signals in your area (no internet required). 4 days ago · What is RTL-SDR. The lowest frequency an RTL-SDR can comfortably tune to is about 24 MHz. Software-defined radio (SDR) is a radio communication system where components that have. The RTL-SDR dipole kit I'm using was also recommended by representatives of the European. Much software is available for the RTL2832.