Stability and phase noise tests of two cryo-cooled sapphire oscillators

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2000-09, Vol.47 (5), p.1098-1101
• Main Authors: Dick, G.J., Wang, N.T.
• Format: Article
• Language: English
• Subjects: Applied sciences; Astronomical and space-research instrumentation; Astronomy; Auxiliary and recording instruments; clocks and frequency standards; Cassini mission; Circuit properties; Cryogenics, refrigerators; low-temperature techniques; Earth, ocean, space; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Hydrogen; Hydrogen masers; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Low noise; Masers; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Noise; Noise measurement; Oscillators; Oscillators, pulse generators, and function generators; Oscillators, resonators, synthetizers; Phase measurement; Phase noise; Physics; Receivers; Sapphire; Stability; Temperature distribution; Testing; Thermal instruments, apparatus and techniques; Time and frequency
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/58.869038

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 /spl sigma//sub y/=2.5/spl times/10/sup -15/ for measuring times 200 seconds /spl les//spl tau//spl les/600 seconds using a hydrogen maser as a reference. 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 /spl les//spl tau//spl les/ 10 seconds, and indicate performance for the individual units of /spl sigma//sub y//spl ap/3/spl times/10/sup -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.