D. A. Howe and D. B. Percival (1995), `Wavelet Variance, Allan Variance, and Leakage,' IEEE Trans. on Instrumentation and Measurement, IM-44, no. 2, pp. 94-7.
Wavelets have recently been a subject of great interest in geophysics, mathematics and signal processing. The discrete wavelet transform can be used to decompose a time series with respect to a set of basis functions, each one of which is associated with a particular scale. The properties of a time series at different scales can then be summarized by the wavelet variance, which decomposes the variance of a time series on a scale by scale basis. The wavelet variance corresponding to some of the recently discovered wavelets can provide a more accurate conversion between the time and frequency domains than can be accomplished using the Allan variance. This increase in accuracy is due to the fat that these wavelet variances give better protection against leakage than does the Allan variance.
Analysis of variance; Atomic clocks; Frequency stability; Power-law processes
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