CALIBRATION OF AN UNDERWATER SOUND SOURCE AT VERY LOW FREQUENCY

Authors
  1. Scrimger, P.
  2. Henderson, D.M.
  3. Chapman, N.R.
Corporate Authors
Defence Research Establishment Pacific, Victoria BC (CAN);JASCO Research Ltd, Sidney BC (CAN)
Abstract
The paper describes an experiment carried out to calibrate a very low frequency sound source in deep water using a method similar to that described by Carey et al (JASA 81(2), Feb. 1987). In the experiment, a cw sound signal was recorded as the uncalibrated source was towed past a vertical line array out to ranges of about 3 km. At these close ranges the sound field is dominated by the Lloyd's mirror interference pattern which arises as a result of the interaction between the direct and surface-reflected sound paths. The calibration procedure is based on a comparison of the measured sound field with numerical calculations of the Lloyd's mirror interference field. The experimental track for the towed source was determined using GPS navigation records, and the source-receiver range was checked using the beamforming capability of the array. The signals recorded on a single hydrophone were processed to determine the received sound level versus range, and these data were corrected for the transmission loss using a full-wave numerical model for the sound field. The corrected sound levels provided a measure of the source level of the uncalibrated source. The procedure was carried out for hydrophones at three different depths. Results are presented for the calibration at frequencies of 7, 10, 15 and 20 Hz.
Keywords
Beamforming
Report Number
DREP-CR-93-34 — Contractor Report
Date of publication
01 Jul 1993
Number of Pages
100
DSTKIM No
93-04269
CANDIS No
134547
Format(s):
Hardcopy;Originator's fiche received by DSIS

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