GPSPAC space navigation simulation results

An application of the NAVSTAR Global Positioning System (GPS) is GPSPAC, a satellite-to-satellite navigation system. An overview of the NSWC navigation simulator is presented. In the navigation mode GPSPAC uses a Kalman filter to provide real time navigation solutions. To arrive at a good steady state solution, the filter needs pseudorange and delta pseudorange measurements from four sequentially tracked GPS satellites. Because of less desirable geometry and longer propagation intervals in the Phase I environment, the average Phase I navigation solution is not as accurate as one for Phase III. Specific results for the Landsat-D mission are discussed.