BOTTOM REFLECTION COEFFICIENT MEASUREMENT AND GEOACOUSTIC INVERSION AT THE CONTINENTAL MARGIN NEAR VANCOUVER ISLAND WITH THE AID OF SPIKING FILTERS

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Authors
  1. Heard, G.J.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
The paper presents the results of an experiment to measure the reflection coefficient-vs-grazing angle at the continental margin west of Vancouver Island. The measured reflection coefficients are inverted and estimates of the surficial sediment geoacoustic properties obtained. The receiver used in this experiment was a long towed-array with the source in aft-endfire aspect. The acoustic sources for this experiment were explosives that produced direct-path arrivals approximately 0.1 seconds in length. Bottom and sub-bottom arrivals continued for several seconds duration. Explosives were detonated at intervals such that bottom reflected energy received at the array sampled grazing angles in the interval 10-80 degrees. Source-receiver ranges were computed by measuring arrival time differences at each of the array elements, comparing these time differences with those computed using a ray-tracing propagation model, and globally minimizing the accumulated squared time difference residuals. To aid in the measurement of arrival times, spiking filters were employed to produce a deconvolution-like output that separates arrivals overlapped in the original time-series. The reflection coefficient estimates were determined from the linear spiking filter outputs by forming the ratio of the direct-path and bottom-reflected arrival amplitudes. TRUNCATED
Keywords
Shaping filters;Bottom measurement
Date of publication
01 Apr 1997
Number of Pages
15
DSTKIM No
97-00746
CANDIS No
501055
Format(s):
Hardcopy;Document Image stored on Optical Disk

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