Signal processing strategies for a bathymetric sidescan sonar

A dominant source of errors in swath bathymetry is acoustic interference. In 1989 the author published an analysis of these errors and predicted depth accuracies for a system which reduced their effect by averaging. This present paper shows how a considerable improvement in performance may be obtained by a variety of signal processing strategies that include the use of several widely spaced receivers and the elimination of the most unsatisfactory measurements before averaging. Simulations show how impressive sea bed profiles can be produced with a single ping, even at low signal-to-interference ratios     

Swath bathymetry: principles of operation and an analysis of errors

The principles of swath bathymetry are described, and the main cause of depth error is identified as acoustic interference, particularly from the sea surface. An error analysis is presented which gives the relationship among depth errors, the signal-to-interference ratio, the grazing angle, receiver spacing, and area resolution. It permits a prediction of when its measurement of depth can meet the accuracies required for nautical charting. Ways of reducing multipath interference and of minimizing its effect when it does occur are discussed. Particularly important are area averaging, the use of widely spaced receivers with ambiguities resolved by the vernier technique, and phase tracking for avoiding bias problems