STUDY OF STABLE OSCILLATOR FOR USE IN NAVIGATION SATELLITE,
JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB
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A study of standards of frequency and time was made. From this study it appears that of the many systems proposed for freqency control work only three have reasonable feasibility. They are 1 Ammonia Maser 2 so-called gas cell with optical pumping with either cesium or sodium 3 atomic cesium resonance absorption beam. From the study it is concluded that all of the systems require considerably more development work before any one of them will be feasible for use in a satellite. The Maser presents unusual engineering problems when considered for satellite use. In addition the long time stability of the Maser is not adequate at present. Thus it appears best adapted for use as a laboratory standard where the highest attainable stability 1 part in 10 to the 12th power for short periods one-half hour is required. The gas cell with optical pumping as proposed promises to provide a frequency standard of good stability 1 part in 10 to the 10th power for a period of one month. However, to achieve greater stability or accuracy for longer time will require solution of some unusual problems. Among them the most intractable appears to be a zero-pressure frequency shift and aging due to the buffer gas. To date the cesium resonance absorption beam device has provided the best long-term stability 1 or 2 parts in 10 to the 10th power for some 4000 hours.
- Test Facilities, Equipment and Methods
- Unmanned Spacecraft