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本文中提出短期频率稳定度的两个定义:(1)时域,离标称频率的相对频率起伏的方差的数学期望〈σ_y~z(N,T,τ)〉,其中 N 是采样数目,T 是采样时间加上采样之间的间隔时间,τ是采样时间;(2)频域:离标称频率的相对频率起伏的功率频谱密度S_y(f)。讨论了频域到时域的变换和时域量度之间的变换等课题。所有的测量都是利用周期计数技术在时域进行的。利用一块专门制造的比另一振荡源频率低10千赫的单片石英晶体作一个在频率上有所偏离的振荡器,这个振荡器是用来取得周期计数方法所需的拍频。
In this paper, two definitions of short-term frequency stability are proposed: (1) The mathematical expectation of the variance of relative frequency fluctuation in time domain and nominal frequency, where N is the number of samples, T is the sampling time plus the sampling interval, τ is the sampling time; and (2) the frequency domain: the relative frequency fluctuations from the nominal frequency of the power spectral density S_y (f). The topics such as the transformation from frequency domain to time domain and the transformation between time domain metrics are discussed. All measurements are performed in the time domain using period counting techniques. A frequency-deviated oscillator was fabricated using a specially fabricated monolithic quartz crystal 10 kHz lower than the frequency of another oscillator source. The oscillator was used to obtain the beat frequency required for the cycle counting method.