There are three main types of beacons, EPIRBs (for use in the maritime environment), ELTs (aviation) and PLBs (personal locator beacons). These can further be subdivided into those that provide a GPS position (location protocol) and those that do not have this capability.
2. Satellite detects the beacon
Your 406 MHz beacon signal will be received by two types of Cospas-Sarsat satellites. A GEO satellite will detect your beacon nearly immediately. Some wait time, dependent on latitude, may be associated with detection by a LEO satellite.
3. Beacon signal is transferred from satellite to LUT
Your beacon signal will be received by two types of Local User Terminals (LUTs).
One or more GEOLUTs will nearly immediately receive your beacon’s signal but can only locate your beacon if a GNSS (GPS-type) position is encoded in the beacon’s message. Beacon registration information is critical to efficient search and rescue operations if no position is provided in the beacon coding.
LEOLUTs use Doppler information to calculate the beacon’s position. Processing the SARP channel 2400 bps data is relatively straightforward since the Doppler frequency is measured and time-tagged onboard the spacecraft. All 406 MHz beacon data received from the satellite memory on each pass can be processed within a few minutes of pass completion.
LUTs are also able to provide unique identification information associated with the beacon (Hexadecimal identifier, or Hex ID), which allows the distress alert to be linked to owner specific information in a beacon registration database.
4. LUT transfers the beacon message and location data to its associated MCC
MCCs have been established in most countries operating at least one LUT. Their main functions are to:
- collect, store and sort the data from LUTs and other MCCs;
- provide data exchange within the Cospas-Sarsat System; and
- distribute alert and location date to associated Rescue Coordination Centres (RCCs) or Search and Rescue Points of Contact (SPOCs)
5. The MCC transfers the Cospas-Sarsat alert message to two places:
- the MCC associated with the beacon owner’s country (encoded in the beacon message); and
- the MCC associated with the geographic region where the beacon was detected.
6. These MCC transfer the distress alert to the SPOCs, who:
- look up the beacon’s registration information in the appropriate database and obtain emergency contact and other important information; and
- coordinate search and rescue activities, if required.