If satellite systems were goals in a competitive hockey game, the Communications Research Centre Canada (CRC) could claim an impressive “hat trick” as a key player in the three phases of development of Cospas-Sarsat.

Cospas-Sarsat is a renowned collection of satellite systems that work as one. Search And Rescue Satellite-Aided Tracking (SARSAT) is operated by Canada, France and the United States, while Cospas performs the equivalent function in Russia. Now approaching a quarter-century of service, this international satellite system provides alert and location information to search-and-rescue services throughout the world. To date, Cospas-Sarsat has helped save over 20,000 lives, of which more than 1,000 have been in Canada. Each month, about 100 people are rescued from distress situations, ranging from plane crashes and boating accidents to hiking mishaps.

The future of Cospas-Sarsat will be realized through the third phase of development, based on a Medium-Earth Orbit Search-and-Rescue (MEOSAR) system. The CRC is an active participant in this current project, along with the Canadian Space Agency, EMS Satcom and NASA. The MEOSAR system, now at the prototype stage, will offer improved beacon detection and will overcome the time and coverage limitations of its two predecessors, the Low-Earth Orbit Search-and-Rescue (LEOSAR) system and the Geostationary-Earth Orbit Search-and-Rescue (GEOSAR) system.

While the MEOSAR system consists of both a satellite and a ground station, CRC’s role is focused on the research and development of the ground-receiving equipment. A prototype Medium-Earth Orbit Local User Terminal (MEOLUT) station, installed in 2006 at CRC, is making use of experimental equipment on satellites in orbit to evaluate the new MEOSAR system. CRC’s MEOLUT station is one of only two such facilities in the world, with U.S.-based NASA being the second. There is some technical exchange of data between CRC and NASA during testing exercises, and both ground stations are already demonstrating the great potential of the MEOSAR system.

Comprised of many satellites in MEO at about 20,000 km, the prototype system can relay 406 MHz beacon signals to the MEOLUT station. By operating at a higher orbit than LEO, MEOSAR is able to “see” a greater area of earth, resulting in faster detection of a distress beacon. It also moves more slowly over the earth’s surface, giving a greater chance of detecting a beacon. Researchers at CRC and Canadian industry are using this experimental system to develop more effective transmission parameters, made possible by the latest developments in computing power and speed. This system will quickly compute beacon locations by ranging or triangulating signals received via multiple satellites, using techniques similar to satellite navigation (i.e. GPS), but in reverse since the user activates a transmitter rather than a receiver.

In spring 2007, CRC began MEOSAR testing with its MEOLUT in Ottawa, Canada, capturing test signals transmitted from Centre National d’Etudes Spatiales (CNES) in Toulouse, France via MEO satellites as they pass over the Atlantic Ocean. Currently, plans are being made to have 406 MHz SAR payloads on future global navigation satellite systems (GNSS), such as USA’s GPS, Russia’s GLONASS and Europe’s new Galileo system in the next few years.

Adding the MEOSAR enhancement will be like moving from a slow, dial-up Internet connection to a high-speed, always-on connection. In addition to continuous global coverage, the system will provide more reliable reception of beacon signals by multiple signal paths. MEOSAR also enables near-instantaneous detection and location of beacons, plus the ability to track moving beacons on a life raft or on an aircraft even before it crashes.

The technology behind Cospas-Sarsat has been linked to CRC since the beginning. Back in the 70s, Canada conducted experiments with the space agencies of USA and France that led to the creation of a satellite-aided search-and-rescue system. In 1976, the proof-of-concept demonstration was carried out at CRC, using a modified distress beacon operating through an amateur radio satellite. Today, close to 40 countries are members of the Cospas-Sarsat program, which recently moved its headquarters from London, England to Montréal, Canada.

CRC’s ongoing work with the Cospas-Sarsat MEOSAR system will ensure that both search and rescue forces and 406 MHz beacon users worldwide will have the optimum distress alerting and locating service for many years to come.

(Adapted with text from “MEOSAR to the Rescue” by Jim King, published in EMS SATCOM Quarterly, January 31, 2007.)