Validating GPS software and implications for the future

An overview of the GPS (global positioning system) is provided. Details are presented on the navigation message that is utilized by GPS user equipment (UE) to provide the user his position, time, and velocity. In order to reduce the adverse impact on GPS users of hosting a new software (S/W) release (OR 5.10) on the operational computer at the Master Control Station System, a multiphased test plan was developed to thoroughly test the S/W end-to-end prior to space vehicle uploads. Test objectives and results are provided for Phase-I test. The Phase-I report has been completed with test results, recommendations, and conclusions. One of the recommendations centered on improving the test configuration such that correlation of upload and UE data could be performed in near real time. A series of options for such a system testbed (STB) were evaluated. For each option, the pros, cons, and rough order of magnitude costs were identified. A potential STB configuration was recommended. It is concluded that no evidence exists to suggest that OR 5.10 will adversely affect the GPS user community with uploads as old as 11 d.<>