COSPAS-SARSAT

'Cospas-Sarsat' is an international satellite-based search and rescue (SAR) alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. Since 1982, the Cospas-Sarsat system has tracked distress signals from the following types of beacons (referred to collectively as EPIRBs):

★ Emergency Position-Indicating Radio Beacons (EPIRBs) onboard ships,

★ Emergency Locator Transmitters onboard aircraft, and

★ Personal Locator Beacons designed for individual use.
The four founding countries led development of the 406 MHz marine EPIRB for detection by the system. The EPIRB was seen as a key advancement in SAR technology in the perilous maritime environment. The aviation community had already been using the 121.5 MHz frequency for distress, so ELTs for general aviation were created using 121.5 MHz, a frequency listened to by the airlines. Military beacons using the 243.0 MHz frequency could also be detected by the system.
The design of EPIRBs as a whole has evolved significantly since 1982; the newest 406 MHz beacons incorporate GPS receivers; such beacons transmit highly accurate positions of distress almost instantly to SAR agencies via the GEOSAR satellites. The advent of such beacons has created the current motto of SAR agencies --- "Taking the 'Search' out of Search and Rescue."
Starting on 1 February 2009, the Cospas-Sarsat System will cease processing signals from the depricated 121.5 MHz and 243 MHz beacons; from then on only signals from 406 MHz beacons will be processed [1]. The switch to 406 is expected to result in a substantial reduction in wasted use of SAR resources on false alerts while simultaneuously increasing the responsiveness of the system for real distress cases.
Cospas-Sarsat is an element of the Global Maritime Distress Safety System (GMDSS). Automatic-activating EPIRBs are now required on International Convention for the Safety of Life at Sea (SOLAS) ships, commercial fishing vessels, and all passenger ships, are designed to transmit to a Rescue Coordination Center a vessel identification and an accurate location of the vessel from anywhere in the world.
'COSPAS' is an acronym for the Russian words "'Co'smicheskaya 'S'istyema 'P'oiska 'A'variynich 'S'udov", which translates to "Space System for the Search of Vessels in Distress". 'SARSAT' is an acronym for 'S'earch 'A'nd 'R'escue 'S'atellite-'A'ided 'T'racking [2].

Contents

Technical Information

Rescue Statistics

External links

Technical Information

The Cospas-Sarsat system consists of 5 geosynchronous satellites called GEOSAR satellites and 7 low-earth polar orbit satellites called LEOSAR satellites. The satellites are monitored by receiving stations equipped with satellite-tracking satellite dishes called LUTs (Local User Terminals). The LEOSAR satellites are monitored by 46 LEOLUTs (Low Earth Orbit Local User Terminals). The GEOSAR satellites are monitored by 18 GEOLUTs (Geostationary Earth Orbit Local User Terminals).
The GEOSAR satellites provide continuous coverage of the entire earth below 70 degrees latitude with a view toward the equatorial sky. Some locations have poor radio reception toward the GEOSAR satellites and polar regions are not well covered. The complementary LEOSAR satellites provide periodic coverage of the entire earth with an emphasis on polar regions. The LEOSAR satellites operate in a store-and-forward mode for 406 MHz signals --- they store distress signals and forward them to the next LEOLUT ground station they overfly. The 4-satellite polar-orbit constellation LEOSAR system provides frequent coverage of the poles with approximately 100 minute orbits.
Up until mid-2007, two of the LEOSAR satellites were Cospas satellites provided by the former Soviet Union and operated by the Russian Federation. However, they were recently taken offline, and now, only the American SARSAT satellites are in service. COSPAS satellites orbit at 1000 km altitude.
The five operational LEOSAR satellites are the Sarsat satellites provided by the United States NOAA. These orbit at an altitude of 850 km.
Typical rescue beacon radios transmit a 5 watt signal for 0.5 seconds once every 50 seconds. Most of these terminals sold since 1997 include a GPS receiver so they can report precise GPS lat-lon location. Aircraft rescue radios are automatically activated by acceleration switches after a crash.
The "406 MHz" channel is 170 kHz wide and centered at 406.05 MHz. The message is either a 112-bit "short" message or a 144-bit "long" message both including 49 bits of identification plus position information.
In addition, the Galileo positioning system will be able to detect and report signals from Cospas-Sarsat search-and-rescue beacons in the 406.0–406.1 MHz band, which makes them a part of the Global Maritime Distress Safety System.

Rescue Statistics

In 2004, the Cospas-Sarsat system provided assistance in rescuing 1,748 people in 466 SAR events.

category	people rescued	SAR events
aviation	68	39
maritime	1,505	321
land	175	106
total	1748	466

External links

★ Official website for the International Cospas-Sarsat Programme

★ Official website for the USA's Sarsat Program

★ Detailed SARSAT and COSPAS satellite information

★ Lay Person Explanation of the Satellite System.