How it works
A brief introduction to the Cospas-Sarsat systemCospas-Sarsat is an international cooperative venture between the governments of Canada, France, Russia and USA. Its service is free to the citizens of all nations.
When the beacon is activated, it transmits a radio signal on 406 MHz, coded with an identification number which can be linked (via an international database) to the owner.
If it has an integrated GPS receiver, it is also able to transmit its latitude and longitude.
All models also transmit a low powered signal on 121.5 MHz which is used by emergency services to home in during the final phase of a rescue.
Signals are received by two types of satellite:
Low altitude polar orbiting (LEO), and extremely high altitude geo-synchronous (GEO) satellites.
Both forward the beacon data to the nearest Rescue Coordination Centre, who will first try to contact the owner to ensure that it is an intentional activation.
The elimination of false alerts is the most important feature of the 406 MHz system.
Each satellite type has its advantages and disadvantages:
LEOs determine the beacon's position by doppler shift of the transmission frequency, so may take several passes to get it precisely. They also cover polar regions where GEOs can't reach. However, there may be a delay of an hour or more before the beacon comes within the satellite's coverage.
GEOs give an instant alert of the activation, but can't determine the beacon's position unless the beacon has an integrated GPS receiver.
The network uses data from both satellite types, so you are very well covered, anywhere in the world.
If you require clarification, please contact us, or for further information visit
www.cospas-sarsat.org
