Global positioning system (GPS) time dissemination for real-time applications

This paper presents an overview of the Global Positioning System (GPS) for the potential precise time and time interval user with special reference to real-time systems. An overview of GPS operation is presented, and GPS error sources are described as they relate to the timing user. A review of receiver types and receiver tasks provides the basis for understanding GPS time transfer techniques. The accuracies provided by different techniques are reviewed and the special requirements for GPS time and frequency receivers as well as modern timing receiver enhancements are described. The precise time standard provided by GPS is traced through its path from global standards to the user application. GPS time dissemination failure modes that result from control problems, space craft failures, and receiver failures are outlined.