Observations on the Reliability of Rubidium Frequency Standards on Block II/IIA GPS Satellites
DEPARTMENT OF THE AIR FORCE WASHINGTON DC
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Currently, the Block IIIIA Global Positioning System GPS satellites are equipped with two rubidium frequency standards. These frequency standards were originally intended to serve as the back-ups to two cesium frequency standards. As the constellation ages, the Master Control Station is forced to initialize an increasing number of rubidium frequency standards. Unfortunately, the operational use of these frequency standards has not lived up to initial expectations. Although the performance of these rubidium frequency standards has met and even exceeded GPS requirements, their reliability has not. The number of unscheduled outage times and the short operational lifetimes of the rubidium frequency standards compare poorly to the track record of the cesium frequency standards. Only a small number of rubidium frequency standards have actually been made operational. Of these, 4 large percentage have exhibited poor reliability. If this trend continues, it is unlikely that the rubidium frequency standards will help contribute to the navigation payload meeting program specification.
- Test Facilities, Equipment and Methods
- Unmanned Spacecraft