Miniature Space GPS Receiver by means of Automobile-Navigation Technology

Miniature space GPS receivers have been developed by means of automobile-navigation technology. The weight and power consumption of the GPS receiver are 35 g and 1 W, respectively. We expanded the frequency sweep range in order to cover large Doppler shift in orbit. We tested the performance in low earth orbits by means of a GPS simulator. The GPS receiver succeeded in cold start acquisition in less than 60 minutes. The GPS receiver for automobilenavigation generates position data with time tag which is not accurate enough to space application. The GPS receiver was modified to output pseudorange data with accurate time tag. The range error caused by the receiver is measured to be 1 meter. The position accuracy is estimated to be less than 20 meters in the low earth orbits. The GPS receiver can be operated with 20 krad (Co60) radiation and is SEL-free for 200MeV proton radiation. SEU may occur in low earth orbits once a several days. This GPS receiver will be on-boarded on INDEX satellite, which will be launched in 2005.