SOME SPECTRAL COMPUTATION EXPERIMENTS.
ALBERTA UNIV EDMONTON
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The relative accuracy of computed power spectra was studied by examining spectral ratios from related signals. Attempts were made to improve the ratios by removing linear trends and by prewhitening the input signals. Two different spectral windows, Hanning and Daniell were compared. The effect of small relative time shifts between signals was also examined. The relation of these same factors to computed coherency was also studied. It was found that prewhitening always smoothed the ratios, extended the frequency range over which they were useful, and enhanced coherency. Trend removal sometimes leads to a deterioration in these factors. Spectral ratio and coherency were found to be very sensitive to small relative time shifts between signals, leading to the conclusion that simultaneous conversion is desirable if cross-spectral analysis is to be carried out. Author