Distress radio beacons, also known as emergency beacons, are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are radiobeacons that interface with Cospas-Sarsat, the international satellite system for search and rescue (SAR). When activated, such beacons send out a distress signal that, when detected by non-geostationary satellites, can be located by triangulation.
In the case of 406 MHz beacons which transmit digital signals, the beacons can be uniquely identified almost instantly (via GEOSAR), and furthermore, a GPS position can be encoded into the signal (thus providing both instantaneous identification and position). Often using the initial position provided via the satellite system, the distress signals from the beacons can be homed by SAR aircraft and ground search parties who can in turn come to the aid of the concerned boat, aircraft, or people.
PLBs (personal locator beacons) are for personal use and are intended to indicate a person in distress who is away from normal emergency services. They are also used for crewsaving applications in shipping and lifeboats at terrestrial systems.
ASU Baltija offers following models which are most popular ones: