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Oceanic Engineering, IEEE Journal of

Issue 3 • Date July 1992

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Displaying Results 1 - 6 of 6
  • Design constraints and error analysis of the temporal correlation log

    Page(s): 269 - 279
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1078 KB)  

    The basic principles of spatial and of temporal correlation sonar for velocity measurement of both surface vessels and autonomous underwater vehicles are considered, showing the advantages of using a pulsed temporal correlation log. To achieve correlation, the conditions for waveform invariance must be met, and there is a velocity-depth limitation to be observed; these are described in detail. Practical design constraints such as the effects of different transducer sizes/geometry and carrier frequencies are also considered.<> View full abstract»

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  • Differential phase estimation with the SeaMARCII bathymetric sidescan sonar system

    Page(s): 239 - 251
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    A maximum-likelihood estimator is used to extract differential phase measurements from noisy seafloor echoes received at pairs of transducers mounted on either side of the SeaMARC II bathymetric sidescan sonar system. Carrier frequencies for each side are about 1 kHz apart, and echoes from a transmitted pulse 2 ms long are analyzed. For each side, phase difference sequences are derived from the full complex data consisting of base-banded and digitized quadrature components of the received echoes. With less bias and a lower variance, this method is shown to be more efficient than a uniform mean estimator. It also does not exhibit the angular or time ambiguities commonly found in the histogram method used in the SeaMARC II system. A figure for the estimation uncertainty of the phase difference is presented, and results are obtained for both real and simulated data. Based on this error estimate and an empirical verification derived through coherent ping stacking, a single filter length of 100 ms is chosen for data processing applications View full abstract»

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  • A chum scale pattern analyzer and stock identification based on scale patterns by discriminant function and power spectrum analysis

    Page(s): 280 - 287
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    An optoelectronic instrument has been developed to analyze the scales and scale patterns of chum salmon. This device, with specially developed software, has been used to study populations of salmon. Fish from two different rivers approximately 200 km apart from each other were grouped with an accuracy of 82% or more. Machine-measured ages coincided with those derived from visual estimation in approximately 80% of the fish sampled. These results suggest the proposed system could be of practical use for measuring and analyzing the scale patterns that allow one to accurately measure both natural and farmed populations of salmon View full abstract»

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  • The acoustic transient recording buoy (ATRB): system description and initial measurement results

    Page(s): 227 - 238
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    An acoustic transient recording buoy (ATRB) developed to provide improved dynamic range and recording capacity in a reconfigurable manner is described. This digital system can acquire and record up to 16 h of broadband wide dynamic range (≈80 dB) acoustic data from eight hydrophones. A unique feature is the use of two inexpensive video cassette recorders to obtain up to 10 Gb of data storage capacity. The system is self-contained and capable of unattended bottom-moored operation. An experiment designed and conducted using a single ship and this system to obtain simultaneous measurements of sea surface forward scatter, propagation loss, and sea floor interaction is reported. Data obtained demonstrate the utility of this system for ocean acoustic experiments. Explosive charge source levels using direct path measurements agreed with previous measurements. Surface reflected data exhibited a frequency dependence attributed to sea surface swell and roughness View full abstract»

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  • High-speed bubble sizing using the double frequency technique for oceanographic applications

    Page(s): 288 - 291
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    A high-speed bubble sizing technique that should have the capability of accurately determining bubble populations in breaking waves has been developed. The system was able to acquire an average bubble spectrum from 2.5 to 6 kHz in 0.1 s. Through the use of a double frequency technique, there would be very little or no contribution from nonresonant bubbles at each frequency of interest. The results of the system were compared to the data obtained by listening to ambient bubble noise with a transducer and from photographic population counts View full abstract»

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  • Geometric distortions in side-scan sonar images: a procedure for their estimation and correction

    Page(s): 252 - 268
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    A procedure is introduced for the estimation and correction of geometric distortions frequently observed in side-scan sonar images as a result of motion instabilities of the sonar towfish. This procedure estimates geometric distortions from the image itself, without requiring navigational or altitude measurements. Estimates of the local degree of geometric distortion are obtained by cross-correlating segments of adjacent lines of the image. A mathematical model for the distortions is derived from the geometry of the problem and is applied to these estimates to reconstruct the sampling pattern on the seabed, under the assumption of a planar bottom. The estimated sampling pattern is then used for resampling the image to correct the geometric distortions. The model parameters may also be used for calculating approximate estimates of the attitude parameters of the towfish. A simulation is employed to evaluate the effectiveness of this technique and examples of its application to high-resolution side-scan sonar images are provided View full abstract»

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Aims & Scope

The IEEE Journal of Oceanic Engineering (ISSN 0364-9059) is published quarterly by the IEEE Oceanic Engineering Society (IEEE OES). The scope of the Journal is the field of interest of the IEEE OES, which encompasses all aspects of science, engineering, and technology that address research, development, and operations pertaining to all bodies of water. This includes the creation of new capabilities and technologies from concept design through prototypes, testing, and operational systems to sense, explore, understand, develop, use, and responsibly manage natural resources.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
N. Ross Chapman
School of Earth & Ocean Sciences
University of Victoria
3800 Finnerty Road
Victoria, BC V8P 5C2 Canada
chapman@uvic.ca