Measurements on the superconducting cavity maser (SCM) oscillator that show frequency stability of parts in 10/sup 5/ for times from 1 s to 10000 s are reported. A phase noise of approximately -80 dB/f/sup 3/ was measured. This short- and midterm performance is believed to be better than that of any known microwave oscillator. In particular, stability at a measuring time of 1 s is ten times better than that of a hydrogen maser, and phase noise is more than 20 dB below that of the best multiplied quartz crystal oscillators.>
The superconducting cavity maser oscillator (SCMO) is tested for environmental sensitivity in the controlled environment of a frequency standards test facility (FSTF). Measured sensitivities to temperature, magnetic field, pressure and humidity are used to predict SCMO performance in various laboratory environments. A comparison to SCMO frequency stability tests in these same environments shows good results, and indicates a need to reduce sensitivities to temperature and magnetic field. Characterization provides continual evaluation of SCMO for the next generation of frequency standards for NASA's deep space network.>