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Press Release
Changes Coming To Emergency Beacon Frequencies

Price, UT -- The acronym SARSIS is not a product; rather, it is a philosophy of tying all available search and rescue assets together in order to save lives. SARSIS (Search And Rescue Surveillance Integrated Solution) came about after years of experience manufacturing electronic search and rescue equipment. The life expectancy of an uninjured person involved in a plane crash is measured in days. An injured person needs help immediately. Modern technology is making it possible to find people in distress faster than ever before.


Emergency Locater Transmitters (ELTs) for aircraft, Emergency Position Indication Radio Beacons (EPIRBs) for maritime and Personal Locater Beacons (PLBs) for individuals have transmitted a low power (approximately 100 mW) swept tone alert signal on 121.5 and 243.0 MHz since their inception. In 1998, a new type of emergency beacon that transmits a 400 ms encode pulse at 5 watts in the 406 MHz band became available. The encoded signal contains information about the beacon, letting search crews know who it belongs to. Newer beacons can contain GPS information, letting search crews know the exact position of the beacon.


On July 1, 2003, the Federal Communications Commission (FCC) authorized 406 MHz PLBs to be used nationwide by the general public. Now, anyone in distress can summons help via the COSPAS-SARSAT system.


From field trials and actual emergencies, an emergency beaconís radio signal is much more reliable than the GPS functionality of a beacon equipped with GPS. Not all beacons have GPS and, even if they do, situations can prevent the GPS from obtaining the beacons location.


Polar-orbiting and geostationary GEOS weather (GEOSAR) satellites are constantly listening for emergency beacons. When one is detected, the system will try to locate its location. The accuracy of locating a beacon transmitting on 121.5 and 243 is 25km. Newer 406 MHz devices can be located down to 2 to 5 km. At that point, it is up to the local government authorities to conduct a search.


Today, the 121.5, 243 and 406 MHz distress signals are detected by COSPAS-SARSAT; however, on February 1, 2009, the COSPAS-SARSAT satellites will no longer detect and process 121.5 and 243 MHz distress signals. This change has required search and rescue organizations to change as well. Currently, the primary SAR DF equipment is only capable of 121.5 or 121.5 and 243 MHz signals. Older equipment will soon be mostly obsolete with limited practical value.


Older beacons transmitting continually on 121.5 or 243.0 MHz could be located by pointing a directional antenna in different directions until the strongest signal is identified. New beacons can be detected at a greater range due to the higher 5 watt power they output; however, the signal is transmitted once every 50 seconds or so and it only last for 400 ms making the old method of using directional antennas impractical for bearing a signal.


New SAR radio direction finders are capable of detecting and giving bearing azimuth information for the short burst transmitted by modern beacons. Because of the robustness of a radio beaconís signal, azimuth information pointing to a beacon is the primary concern of a SAR RF direction finder. Although modern emergency beacons may be equipped with GPS receivers, the GPS information is dependent on several factors: Is the beacons GPS antenna in view of satellites? A downed aircraft may be upside down shielding the GPS antenna preventing it from providing location information. Where was the GPS turned on last? Is the almanac updated? If the GPS was manufactured in a part of the world distant from where it is turned on in an emergency, it can take some time to figure out where in the world it is.


Direction finders like the RHOTHETA DF 517 and RT-500M provide: Azimuth information and beacon registration information for a signal as short as 25 ms. The beacons latitude and longitude information is also displayed if the beacon is GPS equipped. When a beacon is at the extreme edge of a direction finders ability to receive, its data is not decodable; however, even a very weak signal can provide azimuth information for a SAR team.


GPS moving maps are now becoming standard features in automobiles. They are also becoming an integrated part of radio direction finding. When coupled to a SAR DF, a target can be triangulated giving SAR teams an approximate location before they ever arrive on the scene. Direction finders for air, land, sea and stationary mounting are now available for bearing all emergency frequencies.


In 2000, the USAF Auxiliary Civil Air Patrol started installing the RHOTHETA DF 517 4 band SAR direction finder in all their new aircraft. The success of the system is such that aircrews have jokingly stated that the new electronic equipment takes the fun out of the search. They are able to fly directly to the beacon even in bad weather conditions. The German Coast Guard uses the RT-500M for their maritime fleet. In Canada, NATO Flight Training Center uses the RT-500M for their ground SAR teams.


The addition of a moving map system greatly increases situational awareness. Any map that can be geo-referenced can be used. In the air, a flight plan can be made to a street address or major landmark. On land, a route can be planned to get to the target. At sea, the approximate location of a beacon can be marked as a backup in case the beacon fails before rescue teams arrive.


SAR is not the only use of beacons direction finders and moving map systems: LoJack theft recovery systems can also be detected with the RHOTHETA DF 517 and RT-500M. Live weather as well as other sensor information can be placed on the map helping SAR teams know what environmental conditions to expect. Range of detecting a 5 watt 406 MHz beacon using the DF 517 is 90 miles at 8,200 feet. The range of beacon detection changes with a number of factors including the altitude of the detection finding equipment, terrain, vegetation, buildings, etc.


Even with an air asset having a direct line of sight to a beacon, Mother Nature sometimes makes things challenging. Aircraft go down, vessels at sea and people on land seem to get into trouble when the rest of us would choose to be home in front of a nice warm fireplace in our living rooms. Numerous downed aircraft have been found in Instrument Meteorological conditions (IMC) as it is known by pilots. SAR Direction finders have a place in the air, land and sea. If an emergency beacon is detected during bad weather a ground based direction finder can be invaluable to ground search teams.


Lon B. Arnold is the President of RHOTHETA USA, Inc. He has been involved with airborne and ground emergency services for the past 30 years. He can be reached at lon.arnold@rhothetaamerica.com or by phone at 435-578-1270.

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