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Articles

1974: Vol. LI, No. 1

Side Scanning Sonar - A Theoretical Study

Soumise
août 11, 2015
Publié-e
2015-07-06

Résumé

The principle of operation in side scanning sonars is here studied. After briefly describing the various existing equipments, the influence of different design factors on the range is first examined, and then the resolution in both the horizontal and the vertical plane. Next distortions are analysed. Firstly there are those inherent in the principle adopted for tïîèuistruinent : these distortions are due either to the obliquity of the acoustic waves, or to the ratio between recording scales, or again to the slope of the sea bottom. Secondly, accidental distortions are discussed : these result from the pitch, roll or yawing of the fish carrying the transducer, from the crabwise motions of the vessel due to cross winds or currents, and from variations in the velocity of sound in water. Finally acoustic interferences are discussed : those attributable to the recording paper, to several instruments being operated simultaneously, or to shoals o f fish, the Deep Scattering Layer, or to airbubbles in the water. Some indications as to how to achieve satisfactory results with a side scanning sonar for specified purposes are given in a brief conclusion. For illustrated examples the reader is referred to various earlier issues of the International Hydrographic Review.