(Invited Paper) G. John Dick and Rabi T. Wang
ABSTRACT A cryocooled compensated sapphire oscillator (CSO), developed for the Cassini Ka-band Radio Science experiment, and operating in the 7 K-10 K temperature range, was demonstrated to show ultra-high stability of σy = 2.5 x 10-15 for measuring times 200 seconds ≤ τ ≤ 600 seconds using a hydrogen maser as a reference [1]. CSO-1 and CSO-3 are now both operational with new low noise receivers. We have made initial phase noise and Allan deviation measurements that show more than 10 times stability improvement over the hydrogen maser for measuring times 1 second ≤ τ ≤ 10 seconds, and indicate performance for the individual units of σy ≈ 3 x 10-15 for measuring times from 10 to 1000 seconds. Phase noise is reduced by 20 to 28 dB over the design offset frequency range from 1 Hz to 40 Hz. Receiver design is also discussed.
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