A comparison of ultrastable oscillators - The relative importance of temporal and frequency measurements

Characterization of ultrastable oscillators for such applications as position and navigation systems is discussed. Methods for evaluating temporal domain variances, reviewed by Rutman (1977), are described. Temporal domain variance histograms and calculations of the time of coherence are also mentioned. Phase spectrum, frequency spectrum and radiofrequency spectrum analyses are treated, and relationships between temporal variances and frequency spectra are considered. In addition, the limits of validity imposed on oscillator characterization by the assumption that the signal is stationary are examined. Use of the Woodward 'ambiguity function' to assess the suitability of an oscillator for a particular application is mentioned.