The US FCC has recently approved transmissions by AIS SART devices. These devices were originally designed for SOLAS class ships as an alternative to radar SARTs for carriage on life boats, but the efficiency of design has encouraged applications down to man-over-board devices. I started to question how this new large population of AIS devices could best be tracked.
If I were ever involved in an incident, I would certainly want my life jacket to contain an AIS device that is continually transmitting my position, but those of us who work to define standards for these devices must be careful to consider these large populations and ensure that they can be tracked easily and efficiently.
The ITU has recently set aside two channels for satellite detection of Class A AIS devices. These channels can be used by much larger populations of AIS devices, such as AIS man-over-board devices, provided that the new devices do not interfere with detection of Class A devices. However, these AIS units are typically much lower power devices so they will need adjustments for consistent detection from space. These adjustments could be anything from modulation to protocol changes and in fact, exactEarth is studying alternatives that might be applied in the future.
Whatever changes are required, it should be recognized that detection from space for AIS search and rescue devices is not just a "nice to have", it is a "must have".