EPIRBs are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress.An Emergency Position Indicating Radio Beacon(EPIRB) is used to alert search and rescue services in case of an emergency. EPIRB does it by transmitting a coded message on 406 MHz distress frequency via satellite .
When manually activated, or automatically activated upon immersion or impact, such beacons send out a distress signal. The signals are monitored worldwide and the location of the distress is detected by non-geostationary satellites and in more recent EPIRBs also by GPS.
Emergency beacons operating on 406 MHz transmit a unique character serial number called a Hexa decimal Code. When the beacon is purchased, the Hex Code should be registered with the relevant national (or international) authority.
Registration provides Search and Rescue agencies with crucial information such as:
- Phone numbers to call
- A description of the vessel, aircraft, vehicle, or person (in the case of a PLB)
- The home port of a vessel or aircraft
- Any additional information that may be useful to SAR agencies
How EPIRB transmission takes place?
The transmitter is activated, either automatically in a crash or after sinking, or manually by survivors of an emergency situation.
- At least one satellite picks up the beacon’s transmission.
- The satellites transfer the beacon’s signal to their respective ground control stations.
- The ground stations process the signals and forwards the data, including approximate location, to a national authority.
- The national authority forwards the data to a rescue authority
- The rescue authority uses its own receiving equipment afterwards to locate the beacon and commence its own rescue or recovery operations.
How does EPIRB work/ function?
When the EPIRB is activated it transmits on 406.025 MHz. A digital signal is transmitted on 406.025 MHz. After the EPIRB is activated, the next passing satellite will detect the transmitted signal and relay it to an antenna at a ground station, called a LUT.
Once the signal is received by the LUT, it is processed for location and sent to a Mission Control Centre (MCC). The MCC sorts the alert data according to geographic search and rescue regions and distributes the information to the appropriate Rescue Co-ordination Centre (RCC), or if outside the national search and rescue area, to the appropriate MCC that covers the area where the distress signal was detected.
The RCC in turn takes the necessary action to initiate search and rescue activities. 406 MHz beacons will be detected by the Cospas- Sarsat satellite system. This affects all maritime beacons (EPIRBs), all aviation beacons (ELTs) and all personal beacons (PLBs).