AIS (Automatic Identification System) is system that continuously transmits a ship’s identification and position to other nearby vessels. All such vessels also receive data from other AIS equipped ships and display their positions and other relevant information on a display on the bridge. In other words, AIS is a navigation aid.

AIS is a global system. It is mandatory on passenger ships and all larger boats from 1st of July 2003. During the years to follow, successively smaller and smaller ships will be required to carry an AIS transponder.

AIS uses two channels (VHF 161.975 and 162.025 MHz) that have been reserved worldwide for this purpose. The modulation type is GMSK (Gaussian Minimum Shift Keying) and the data speed is 9600 bps. It is not easy to distinguish the AIS transmissions from the background noise — they sound the same and the data bursts last only 30 ms. Perhaps the simplest way to tell if you receive anything is to look at your S-meter needle, or adjust the squelch so you can hear it go on and off.

In order to decode the data you will need a scanner tuned into either frequency and a copy of shipplotter.

	Shipplotter on an icom 1000
	shipplotter on an icom 1500
	Dublin Harbour

In order to plot the ships to google earth do the following:
- Run shipplotter.
- Open Google Earth.
- File/Open , select google_ships.kml

For further information visit the great tutorial by Ais Greece.