A Phase Correction Filter for Waveform Recovery of Compressed Direct-Recorded Ocean Bottom Seismometer Data.
Final rept. 1975-1978,
WASHINGTON UNIV SEATTLE DEPT OF OCEANOGRAPHY
Pagination or Media Count:
A phase convolution filter has been developed for the University of Washingtons ocean bottom seismometers OBS to correct severe waveform distortion on playback. Signals are recorded directly on magnetic tape after compression by taking the bipolar square-root of the signal. Prior to digitization, the analog playback head shifts the phases of the low frequency harmonics and thus distorts the recorded waveform. If the distorted signal is squared without correction, the original waveforms and bandwidths are not recovered, leading to errors in the selection of arrival times and an inability to analyse the seismic code for late arrivals. The phase-correcting filter has been constructed by inverting a smoothed version of the spike spectrum that results when a square wave is recorded on the tape. Author
- Physical and Dynamic Oceanography
- Recording and Playback Devices