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