Observability of HEO Satellite Autonomous Navigation System Using GPS

The high altitudes reached by HEO (highly eccentric orbits) spacecraft present a very unfavorable environment for the reception of GPS signals. This paper analyzed the GPS signal visibility viewed from running HEO spacecraft, and then investigated the observability of the autonomous navigation system with the pseudo-range measurements using a PWCS method , adopted the condition number of the observability matrix as a scalar measure of degree of observability, finally assessed the navigation performance. The results of simulation showed that, with measurements from only one GPS satellite, the observability of the navigation system can be observable; the error of position and velocity could be verified. Therefore, the HEO autonomous navigation using GPS is feasible.