A PROCESSING REQUIREMENT AND RESOLUTION CAPABILITY COMPARISON OF SIDE-SCAN AND SYNTHETIC-APERTURE SONARS

Synthetic-aperture sonar (SAS), unlike synthetic-aperture radar (SAR), suffers a constraint of the pulse repetition frequency (PRF) imposed by the relatively slow sound speed in water. This in turn can limit platform velocity, and consequently, area coverage rate in survey and imaging applications. Despite this, SAS is a viable imaging technique that is capable of providing improved resolution and search rate in comparison to comparable side-look sonars (SLS). The physical length of an SAS transducer is a parameter of fundamental importance in determining coverage rate and is inherently related to PRF and platform speed. It is shown that constraints on these parameters can limit the resolution and coverage rate of a single-beam SAS, but certain performance specifications may often be met by employing a multibeam system. Multiple beams are not required unless fine-resolution imagery is specified for large swath collections at high survey speeds. It is demonstrated that SAS systems can be designed to achieve survey coverage rates comparable to SLS systems while providing finer along-track resolution. As an example, proposed SAS designs are compared to the SeaMARC side-scan system in two different configurations.