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COSPAS-SARSAT

If you were lost in the wilderness there<br>
is a free service which will allow you to<br>
call for help using a radio beacon valued at<br>
less than C$1,000.<br><br>
If you were lost in the wilderness there

is a free service which will allow you to

call for help using a radio beacon valued at

less than C$1,000.

COSPAS-SARSAT

14,000 Lives Saved and Counting

If you were lost in the wilderness, on foot, in a downed aircraft, or stranded at sea, you would want to know that someone was looking for you. You would also want to know that they would be able to find you in hours rather than days.

Fortunately, there is a free service which will allow you to call for help using a radio beacon valued at less than C$1,000. Once turned on, the beacon will transmit your distress signal to a monitoring station via satellite. The service known as Cospas-Sarsat has been credited with saving more than 14,000 people since its creation 20 years ago.

Jim King , Director, Major Satellite Communications Programs at CRC took a few minutes to explain what the system is and the role that CRC played and still plays in its development.

"Cospas-Sarsat is an international, humanitarian search and rescue system. It consists of three main components: satellites to detect and locate emergency beacons carried by ships, aircraft, or individuals; the emergency beacons themselves; and a network of ground stations that detect the emergency signals.

When an emergency beacon is activated, the signal is relayed via a satellite to the nearest available ground station where it triggers a search and rescue action on the part of the responsible agency. Cospas-Sarsat is now a well established international service with many participating countries.

Today all Canadian Cospas-Sarsat ground stations and the Canadian mission control centre are operated by CRC. However, like so many communication technology innovations, CRC has played a role in both its conception and its ongoing development.

Some of the earliest experiments were done at Shirleys Bay in the mid 1970s. CRC first carried out a proof of concept experiment. They modified an existing distress beacon to work at a frequency that allowed it to transmit through an amateur radio satellite. By doing a series of calculations CRC showed that a dedicated search and rescue satellite system could operate effectively using the beacons that were then in use for the existing aircraft based search-and-rescue service.

The original SARSAT program started as an experiment between Canada, USA and France, and soon Russia joined and developed and launched its own COSPAS satellites, which were compatible with ours, so it became a four-country program. Today, some 35 countries share in the operation of the system and the administrative costs, and many provide their own ground stations.

The initial Cospas-Sarsat system, used what is called LEOSAR or Low Earth Orbit SAR. These satellites monitor a continent wide swath during each polar orbit they make around the earth. One satellite provides coverage for the entire earth in 12 hours. By using the constellation of four or more satellites that we have today, there is usually no more than a two-hour window without at least some coverage.

By the mid 1980s the international team began launching what we call GEOSAR satellites. "GEO" standing for GEOstationary. This has given us constant coverage in the areas that the system reaches. Since GEOSAR doesn't cover the polar regions and it can miss beacons hidden behind a mountain, or behind the superstructure of a ship, we still need LEOSAR as part of the complete solution.

Today CRC and the international Cospas-Sarsat team are looking at new areas of development including:
  • MEOSAR, or Medium Earth Orbit SAR is a system where repeater payloads would be placed on board GPS and other multipurpose satellites, with 25 to 30 satellites in a constellation there would be almost constant coverage AND the satellites would not suffer from shadow effects to the extent that GEOSAR does since they would be in constant motion; and CRC is also looking at
  • Improved detection and verification using signal processing techniques to distinguish and filter out interfering signals that are not originated by distress beacons."






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