estimator bias

An estimation of cross-spectral components for periodically non-stationary random processes

Correlations between harmonic components of random processes is a feature of signal non-stationarity. In the case of periodically non-stationary random processes (PNRP) correlate harmonics distant one from another on frequencies, what multiple to value T, T - period of non-stationarity [1, 2]. Since faults appearance in rotating elements of mechanical systems leads to periodical non-stationarity of vibration signals when searching of correlations between harmonic components can lay in the base for defects detection [1, 3-5].