Marine AIS data transmissions

If you live near naviagable waterways, you may want to tune your FM monitor receiver to 161.975 MHz and 162.025 MHz FM. If you hear data bursts, you are able to receive ships sending messages using the Automatic Identification System (AIS). These data transmissions are sent using GMSK modulation, and can be decoded for readout on your Linux computer using programs such as GNU AIS, FreeAIS, and others. Messages include information such as ship position, speed and related data and are sent using the NMEA data standard. To interface your radio receiver with your Linux box would required a connection to your radio’s discriminator output running via patch cable to your computer’s sound card microphone of line-in jack. (Many two-meter amateur radio gear already has the necessary discriminator tap in the form of a packet radio data output connection.)