Quick Answer
406 MHz distress signals are received by satellites in orbit around the Earth and relayed to emergency responders on the ground, covering most areas of the globe.
Satellite Coverage
406 MHz signals are received by three main satellite constellations: COSPAS-SARSAT, which includes the Russian, US, and European satellites, such as the Russian LEO (Low Earth Orbit) constellation, the US LEO constellation, and the European LEO constellation. These satellites cover approximately 90% of the Earth’s surface, with coverage extending to 55° north latitude and 55° south latitude. The COSPAS-SARSAT system also includes a geostationary component, which provides coverage over the equatorial regions, extending coverage to within 800 km of the equator.
Signal Detection and Processing
When a 406 MHz distress signal is received by a satellite, it is immediately relayed to a ground station, which processes the signal and attempts to establish communication with the distress beacons transmitter. This is done by sending a response signal back to the beacon, which can then provide the beacon’s GPS location and other relevant information. The ground station then forwards this information to emergency responders, who can then dispatch assistance. The entire process takes approximately 45 seconds to 1 minute, depending on the location and availability of ground stations.
Emergency Response Activation
When a 406 MHz distress signal is received, emergency responders are activated and notified of the distress beacon’s location. Responders can then dispatch aircraft, ships, or other rescue assets to the location of the distress beacon. Emergency responders can also contact the beacon’s registered owner to determine the purpose of the distress beacon and its location, if the beacon is registered. This information can help responders to better understand the situation and dispatch the correct resources.
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