A Spaceborne GPS Receiver for Electric Propulsion Driven Geosynchronous Satellites

This paper presents the latest GPS receiver developed by JAXA and NEC Space Technologies, Ltd. for satellites in geosynchronous orbit. This is the first attempt by a Japanese GPS receiver to use GPS signals above the GPS constellation of satellites. The expected signal strength is weaker at geosynchronous orbit than that observed at low Earth orbit. A new GPS receiver was developed to receive such signals and determine satellite position, by improving sensitivity and optimized software for GEO. In addition, signals received at GEO transfer phase has various doppler frequency and signal strength. This characteristic increase acquisition time of the receiver, thus the acquisition algorithm was modified to optimize during the transfer phase. This paper introduces the newly developed GPS receiver for geosynchronous satellites and its performance obtained by experiments using GNSS simulator. The results indicated that the GEO GPSR could determine its position within a few meters error at GEO. GEO GPS receiver could not be used whole transfer phase, but it could output its position at least once in every orbit around perigee. This result indicated that the GEO GPS receiver will help raising orbit.