High fidelity GPS satellite simulation results

Abstract

Lockheed Martin Mission Systems is developing a high fidelity simulator for the Air Force's Global Positioning System (GPS) satellite command and control operations. To accomplish this goal, each spacecraft subsystem was broken down into a series of algorithms that describes the subsystem dynamic behavior. The measurable effects produced by these algorithms were compared to actual GPS satellite data for algorithm validation. Several subsystems that posed particular difficulty include orbit determination, thermal control, and reaction control. The primary algorithms used to simulate these subsystems are included herein as well as a discussion pertaining to issues surrounding the development of these algorithms. Finally, some of the required anomalies are discussed along with their relation to the derived algorithms.