The Estimation of Atomic Clock's Frequency Stability by Wavelet Variance
Song Li-jie · Yuhang jice jishu · 2009
The discrete wavelet transform can be used to decompose a time series at different scales,the properties of which can then be summarized by the wavelet variance.First starts with the definition of wavelet variance,then presents the the estimation formula of wavelet variance based on the MODWT,and the practical computing methods of EDF.By using a numercial example,the estimated values and equivalent degree of freedom of overlapping Allan variance and overlapping Hadamard variance are compared with those of wavelet variance in the end.From that can get some useful conclusions.Wavelet variance put a curb on the influence of atomic clock signal's nonlinear and non-stationary process.By choosing wavelet basis function rationally,D4 and D6 wavelet variance just as Hadamard variance can decrease both the leakage of FM flicker noise and random walk noise,and is suitable to present the frequency stability of atomic clock.