What is AIS?

The Universal Shipborne Automatic Identification System is a system of transponders installed on vessels which transmit over two dedicted digital marine VHF channels. The data is sent from each vessel every few seconds and contains position and movement information such as course, speed, latitude, longitude, and rate of turn. Static information about the vessel is sent every few minutes and includes the name, type of ship, length, beam, draft, etc.

Nearly all commercial ships are mandated to carry AIS transponders. You can receive this data with an AIS receiver which translates the digital radio signals into standard NMEA sentences. These sentences can be routed to a computer, chart plotter, or the AISWatchMate. Some of the advantages to using the AISWatchMate are that it's a low cost dedicated AIS alarm and display operating on ultra low power.