Smart Radio SR161, AIS Receivers
Smart Radio SR161, AIS Receiver is a well respected and cheap option if you are looking for an AIS receiver, but not interested in transponding or broadcasting.
Class B AIS units are available in the US now but they run closer to $800 and may not be worth it. The SR161 costs $189.
Sending an AIS signal lets other vessels know where you are but many believe its better to know the other vessels in your area and not send a signal yourself. Pilots in heavy shipping areas will be filtering out signals to reduce their screen down the commercial vessels only.
Milltech Marine's Description
The Smart Radio SR161 and SR162 AIS Receivers are compact, easy to install, stand alone marine receivers that monitor the channels assigned to the Automatic Identification System or AIS. These radio receivers are specially built for marine environments for the intended use of deciphering Automatic Identification System data. Most commercial vessels are required to have an AIS transponder that transmits information about the vessel and its movements. The system is designed to assist vessels with identifying the traffic around them and to help with marine safety and collision avoidance.
The SR161 is a low cost, single channel scanning receiver designed for recreation vessels and the SR162 is a full time dual channel receiver designed for both recreational and professional use. The SR162 is also the most appropriate device for use in areas where Class B AIS transponders are in use since Class B transponders provide position updates less often than commercial Class A transponders.
The SR162G has all of the features of the SR162 but also includes an integrated GPS and an external GPS antenna.
The SR161, SR162 and SR162G can be used with computer-based navigation solutions using a standard RS232 serial port interface.