This paper presents an efficient distress signal detection and geolocation scheme for the beacon transmission signal in Medium-Earth Orbit Local User Terminal (MEOLUT) through MEOSAR (Medium-Earth Orbit for search and rescue) satellites of COSPAS-SARSAT system. The transmitted beacon signal is separately arrived by satellites with different FOA (Frequency of Arrival) and TOA (Time of Arrival). It is directly transferred to MEOLUT. In MEOLUT, a LUT track at least 3 or 4 satellites simultaneously and estimate location of beacon using time difference of arrival (TDOA) and frequency difference arrival (FDOA). Because the distress beacons transmit signal in arbitrary time, the transmitted distress signals may be overlapped each other. So we use cross ambiguity function (CAF) Map algorithm in order to geolocate simultaneously overlapped signals. The performance is analyzed for COSAPS-SARSAT MEOSAR service.

Keywords: COSPAS-SARSAT, MEOSAR, cross ambiguity function, geolocation