Echo counting and echo integration with a sector scanning sonar

An investigation is described of the possible application of sector scanning sonar for measuring the spatial density of marine organisms. The two assessment techniques investigated are called echo counting and echo integration. These techniques have been used extensively with single transducer echo sounding equipment for fisheries assessment. One of the main limitations of single transducer assessment systems is that they cannot provide both high resolution and good volume coverage. However, an acoustic assessment system in which a sector scanning sonar is used can provide both. The problems of implementing the two assessment techniques when using a scanning sonar are discussed. The performance of the techniques is evaluated by calculating the normalized rms error in the estimate of spatial density they provide. It is shown that, under certain conditions, the sector scanning assessment will system provide an estimate with a significaantly smaller error than that obtained with a conventional single transducer system.