Recent applications of bandpass filtering

Bandpass filtering has been applied recently in two widely different seismic applications: S.R. Taylor and A.A. Velasco in their source-path amplitude-correction (SPAC) algorithm and N.K. Yacoub in his maximum spectral energy algorithm for picking teleseismic P-wave arrival times. Though the displacement spectrum is the intermediate product in both cases, the filters and scaling corrections used to estimate it are entirely different. They tested both and found that the scaling used by Taylor and Velasco worked in all cases tested whereas Yacoub's did not. They also found that bandpass filtering as implemented by Taylor and Velasco does not work satisfactorily; however, the Gaussian filter used by Yacoub does work. The bandpass filter of Taylor and Velasco works satisfactorily when the results are centered in the band; however, a comb filter with the same number of poles and zeros as the bandpass used by Taylor and Velasco works better than the bandpass filter