User's Manual

13
Satellite Distress Beacons explained
Satellite Distress Beacons such as Personal Locator Beacons (PLBs) are used to
alert search and rescue services in the event of an emergency. They do this by
transmitting a coded message on the international 406 MHz distress frequency which
is relayed via satellites and earth stations to the nearest rescue co-ordination centre.
* System graphics courtesy of COSPAS SARSAT.
Cospas Sarsat explained
The Cospas-Sarsat satellite system has global coverage that provides a typical time
to alert notification of between approximately 3 and 45 minutes. The geographical
location of a GPS PLB (with inbuilt GPS receiver) can normally be resolved within 5
minutes and 45 minutes for a non-GPS PLB. The time to alert is dependant on which
satellites are in view in the sky at the time of PLB activation. Non-GPS PLBs rely on
passing orbiting satellites to determine an approximate position, this can take longer
and the resolved position is less accurate than can be achieved compared to a GPS
PLB.
Why GPS PLBs?
GPS PLBs have been designed to enhance further the lifesaving capabilities of
conventional distress beacons. When a GPS PLB is activated in an emergency, GPS
positional information is automatically transmitted as part of the distress message.
The Global Positioning System (GPS) has an array of orbiting satellites and provides
the PLB with positional information and with new positional updates occurring every