Sensors for a forward-looking high resolution AUV sonar

An autonomous underwater vehicle (AUV) needs to be fitted with a forward looking sonar designed to work in the difficult acoustic conditions encountered in shallow water environments. Detection and classification of objects in shallow water requires the sonar to provide significantly more acoustic resolution than is available with current in-service small vehicle sonars. Consequently, design of a shallow water sonar will involve marked departures from prior systems in terms of operating frequency, array geometry and signal processing requirements. A notable consequence is that the acoustic array of a high resolution imaging sonar will contain hundreds of sensors. The feasibility of implementing hundreds of sensors in an AUV sonar will depend on finding a sensor that meets requisite technical requirements and is affordable. This paper describes and discusses two candidate acoustic sensor technologies, one of which has already been incorporated into a high resolution array and one that has been tested in a prototype array and is currently being fabricated into a full size array.