Precision oscillators flown on the LES-8/9 spacecraft

This paper describes the characteristics of four quartz crystal oscillators incorporating high stability crystals flown on the LES-8/9 spacecraft. LES-8/9 are a pair of military communication satellites operating at synchronous altitude with multiplied frequencies. Each incorporates redundant master oscillators for time and frequency control. These four master oscillators, built especially for the LES-8/9 program have been measured since launch (March 1976) for absolute frequency drift as well as spectrum quality. To examine long-term drift, a measurement scheme has been employed which to a first order cancels Doppler. The data presented is believed to include aging only since effects caused by radiation have been minimized by shielding.