Frequency stability specification and measurement :: high frequency and microwave signals

Frequency is generally defined as the number of cycles which occur in a given interval of time. This interval is usually chosen to be the second. The interdependence of frequency and time interval requires that a standard of one be also a standard of the other. Similarly, it can be said that the measurement of frequency is based upon time measurement. While certain instruments will measure either quantity with equal facility, many methods apply to the measurement of one or the other. Therefore, the sections dealing with actual measuring techniques will present separately frequency measurements and time measurements.

Frequency and Time Measurements

: A study is described of the effects of noise on the r.m.s. frequency deviation of an oscillator. Several models are assumed. In one case the noise and signal are linearly added and the assumption is made that the noise does not enter the feedback loop o the oscillator. It is shown that this predicts an inverse first power variation of the r.m.s. frequency deviation with respect to the integration time inherent in the frequency measurement. In other models, the noise is included in the feedback loop and results in an inverse one-half power variation. Evidence is adduced to indicate that both effects take place in practical oscillators and some estimates of the magnitude of these effects are made. (Author)

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B. Boychuk

Papers

Study of Short Term Stability of Crystal Oscillator