Optimising collection geometry for long-range synthetic aperture sonar interferometry

Abstract

Interferometric synthetic aperture sonar (SAS) is a technique to image and map the seabed in very high resolution. For large area coverage rate systems with hundreds of metres swath width, the achievable performance varies significantly over the swath. The performance is a function of system, collection geometry, and seabed type. A model is suggested to optimise the collection geometry for maximising area coverage rate given certain optimisation criteria, such as observation geometry, signal-to-noise ratio, depth measurement accuracy, and coverage within swath. The model is fitted to measurements (or calibrated) through a simple procedure. Specifically, the effect of vehicle altitude during the interferometric SAS data collection is studied. A novel model on data collected by a HUGIN Superior autonomous underwater vehicle carrying a HISAS 1032 Dual Rx interferometric SAS is demonstrated. The authors show that optimising the collection geometry, and in this case specifically the vehicle altitude, significantly improves the overall performance.