Accession Number : ADA308523

Title :   Depth and Geoacoustic Parameter Measurement in Littoral Regions Using the UQN-4A Sonar Sounding Set.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB STENNIS SPACE CENTER MS FREQUENCY ACOUSTICS SECTION

Personal Author(s) : Fidler, Raymond W. ; Broome, Robert D.

PDF Url : ADA308523

Report Date : 08 APR 1996

Pagination or Media Count : 29

Abstract : The data in this report demonstrates that SIMAS (Sonar In situ Mode Assessment System) can obtain current in situ bathymetric and geoacoustic information from the AN/UQN-4A Sonar Sounding Set (depth sounder) in littoral regions where vessels equipped with SIMAS systems will operate. Acoustic time series and digital depth output data were collected from the depth sounder for recording and transmission to the SIMAS system on-board the USS Curtis Wilbur (DDG-54). It was demonstrated that the digital depth output of the depth sounder could be acquired with little effort at a 30-second time interval instead of the present 5-minute time interval through the present data link. In addition, if the present depth sounder is modified to inhibit the writing to chart paper, then the sonar transmission pulse rate (ping rate) could be increased to provide shorter time intervals between depth samples to less than 3 seconds. This would allow depth soundings at distance intervals of approximately 100 ft at a ship speed of advance of 20 knots. The data clearly demonstrated the presence of geoacoustic information in the depth sounder acoustic return from the stratigraphy below the ship, but the limited bandwidth makes the extraction of this information complicated. Extraction of the geoacoustic information from these limited-bandwidth traces would require successive regression analyses to separate the time horizons and amplitudes of the reflections from each layer in the stratigraphic cross-section below the ship. This is computationally inefficient and can be easily remedied by using spread spectrum techniques.

Descriptors :   *SHALLOW WATER, *SONAR SOUND ANALYZERS, VELOCITY, DATA BASES, SIGNAL PROCESSING, OUTPUT, DIGITAL SYSTEMS, TIME INTERVALS, MEASUREMENT, SHIPS, DATA TRANSMISSION SYSTEMS, PARAMETERS, TIME SERIES ANALYSIS, PROCESSING EQUIPMENT, REFLECTION, DEPTH, REGRESSION ANALYSIS, GEOACOUSTICS, BATHYMETRY, STRATIGRAPHY, PULSE RATE, CROSS SECTIONS, SAMPLING, ACOUSTICS, TRANSDUCERS, CIRCUITS, CHARTS, DATA RATE, DEPTH FINDERS, RANGE(DISTANCE), BANDWIDTH, DATA LINKS, AMPLITUDE, WRITING, LITTORAL ZONES, ONBOARD, SONAR, PAPER, SIGNAL GENERATION, SPREAD SPECTRUM, INTERVALS, SOUNDING, SONAR PULSES.

Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE