Tutorial: Cheap AIS Ship Tracking. Large ships and passenger boats are required to broadcast an identification signal containing position, course, speed, destination, and vessel dimension information to help prevent sea collisions.
This system is known as the “Automatic Identification System” or AIS for short. There are dedicated AIS receivers intended to be used on boats, or by hobbyists, but they can be expensive. A radio scanner or the cheap rtl-sdr can be used to receive these signals, and with the help of decoding software, ship positions can be plotted on a map. This tutorial will show you how to set up an AIS receiver with the rtl-sdr. Index of /~schwehr/papers.