5.3.3 Local User Terminals
For each of the satellite constellations that are used by the Cospas-Sarsat System, there is a dedicated set of LUTs. The maps in Figure 5‑4 illustrate the locations and the levels of coverage that are provided by the LEOLUTs and GEOLUTs. At FOC, the MEOSAR system will also have enough MEOLUTs, suitably distributed to provide full global coverage. Each operational LUT is an unmanned system that operates in a fully automatic mode.
A LEOLUT normally includes an antenna that tracks the LEOSAR satellites and receives the downlink signals from them, and a processing system to extract the beacon signals and to generate an independent position for each beacon.
Each MEOLUT includes several (at least four, and preferably six or more) antennas, so that it can track several satellites simultaneously, and a processing system that can extract the beacon signals and compute the location of the beacon.
A GEOLUT requires only a fixed antenna, pointed at the selected GEOSAR satellite. Because of the higher altitude of the GEOSAR satellites, the quality of the received signals is not as good as the LEOSAR or MEOSAR reception.
LEOLUTs collect data over the duration of each satellite pass (which is relatively short) and process the data collected from each beacon after the end of the pass. GEOLUTs and MEOLUTs, with a longer viewing time, continually process the data from satellites and can generate a solution from just one or a few beacon transmissions. After each LUT has completed its beacon message processing, it sends all the solutions that it has generated to its associated MCC for distribution.
The solution data produced by a LUT is automatically forwarded to its associated MCC, which then follows the procedures established by document C/S A.001, “Cospas-Sarsat Data Distribution Plan”, to forward the incident alert to the appropriate destination(s).