The impact of expected satellite availability on global positioning system (GPS) accuracy

Global Positioning System (GPS) navigation accuracy will be determined primarily by the geometry of the available GPS satellite constellation. The GPS constellation will be changing monthly as it is filled at a rate of about six launches per year up to 24 GPS satellites. The expected performance of GPS from the point of view of: the constellation build-up schedule and the GPS satellite failure-replacement process will continue to yield degraded GPS navigation accuracy through 1994 and, perhaps, beyond. Recommendations are: the GPS program should accelerate the GPS launch rate from six to eight per year, and GPS users should continue to plan for daily cycles of degraded GPS accuracy and availability