ACR Electronics Satellite3 406 RLB-38 Product Support Manual

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ACR Electronics Satellite3 406 RLB-38 Product Support Manual Manual pdf 28 page image

Y1-03-0250 Rev. B 27APPENDIX B - THE COSPAS-SARSAT SYSTEM1. General overviewEPIRBs transmit to the satellite portion of the Cospas-Sarsat system. Cospas-Sarastsatellites are an international system that utilizes Russian Federation and United States’low altitude, near-polar orbiting satellites (LEOSAR). These satellites assist in detectingand locating activated 406 MHz satellite beacons.Cospas-Sarsat satellites receive distress signalsfrom EPIRBs transmitting on the frequency of406 MHz. The Cospas-Sarsat 406 MHz beaconsignal consists of a transmission of non-modulated carriers followed by a digital messageformat that provides identification data. The 406MHz system uses satellite-borne equipment tomeasure and store the Doppler-shifted frequencyalong with the beacon’s digital data message andtime of measurement. This information istransmitted in real time to an earth station calledthe Local User Terminal (LUT), which may bewithin the view of the satellite, as well as being stored for later transmission to otherLUTs.The LUT processes the Doppler-shifted signal from the LEOSAR and determines thelocation of the beacon, then the LUT relays the position of the distress to a MissionControl Center (MCC) where the distress alert and location information is immediatelyforwarded to an appropriate Rescue Coordination Center (RCC). The RCC dispatchesSearch and Rescue (SAR) forces.The addition of the GEOSAR satellite system greatly improves the reaction time for aSAR event. This satellite system has no Doppler capabilities at 406 MHz, but will relay thedistress alert to any of the LUT stations. When there is GPS data included in the distressmessage, SAR authorities instantly know your location to within 110 yards (100 m). Thisspeeds up the reaction time by not having to wait for one of the LEOSAR satellite to passoverhead. Because most of the search and rescue forces presently are not equipped tohome in on the 406 MHz Satellite beacons signal, homing must be accomplished at 121.5MHz.Once the 406 MHz signal is relayed through the LEOSAR and/or GEOSAR network, SARforces determine who is closest, and then proceed to the beacon using the 121.5 MHzhoming frequency.2. Global Positioning System (GPS)The GPS system is a satellite group that enables a GPS receiver todetermine its exact position to within 30 m (100 ft.) anywhere onearth. With a minimum of 24 GPS satellites orbiting the earth at analtitude of approximately 11,000 miles they provide users withaccurate information on position, velocity, and time anywhere in theworld and in all weather conditions. The GlobalFix™ iPRO storesadds this data to its distress transmission, allowing search andrescue forces to narrow the search to a very small area, thusminimizing the resources required, and dramatically increasingthe effectiveness of the overall operation.

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