Uplink interference identification for low earth orbiting (LEO) search and rescue satellites

NOAA (National Oceanic and Atmospheric Administration) - LEO environmental satellites provide continuous coverage of Earth, supplying high-resolution global meteorological, oceanic and space observation data. In addition, these satellites are part of the international COSPAS - SARSAT program, which aides search and rescue teams worldwide. The USA segment is referred to as SARSAT (Search and Rescue Satellite Aided Tracking) system, designed to provide distress alert and location data in order to assist on search and rescue operation. SARSAT uplink detects and locates distress beacons (406 MHz) activated at distress location. System calculates the location of distress event using Doppler processing techniques. Processed data is repeatedly retransmitted through SARSAT downlink to Local User Terminals (LUT) when satellites are in view and also stored in on-board memory. The uplink interference on 406 MHz beacon frequency can result in masked bursts or no solutions received at LUT, consequently no data provided about distress location. The method applied on uplink interference detection and impact on system operation is presented in this paper.