AquaPix: A family of software-defined synthetic aperture sonars

The area coverage of current high resolution bathymetric imaging sonars is limited to 4-5 times the water depth W at a typical survey speed of 8 knots, which represents a severe limitation in shallow water. The AquaPix family of wideband interferometric synthetic aperture sonars has been designed to remove this shortfall cost-effectively. Firstly, the range x cross-range resolution of these systems is 1.5 × 2.5 cm, made independent of range or frequency due to the use of synthetic aperture technology; this step change will greatly facilitate the unambiguous detection of small objects, such as mines and improvised explosive devices, while also improving the accuracy and spatial density of bathymetric soundings. Secondly, the achievable area coverage rate scales with the length of the physical array, thereby allowing a family of systems, optimized for different platforms sizes and speeds, to be offered. Results of a comprehensive feasibility study conducted with the NATO sonar performance model ESPRESSO are presented showing that more than 10dB signal to multipath and noise ratio is obtained up the edges of a 15W swath width, up to a maximum swath of 600m, exploiting a unique 200-400 kHz frequency multiplexed dual row array.