Software Defined Radio

The RTL2832 USB Software Defined Radio is incredibly cheap (circa £6) and tunes between 50 MHz and just over 2 GHz (approximately). Plugged into a laptop with SDR Sharp software it can be used on its own to probe the use of the spectrum in this frequency range or, with add on software, decode AIS, ACARS and other digital messages. The types of demodulation available allow many transmissions to be intercepted and produced as clear voice.

An MCX to BNC converter connects my RTL2832 dongle to a disk-and-cone antenna.