Marport Announces Next Generation Synthetic Aperture Sonar

On April 25, Marport Deep Sea Technologies Inc. of St. John’s announced AquaPix®, a new interferometric Synthetic Aperture Sonar (SAS) developed for mine countermeasures, hydrography, seabed survey and other underwater imaging markets. AquaPix® is based on Marport’s Software Defined Sonar®, an underwater acoustics technology platform that enables advanced underwater sensing, communications and imaging products. The software-centric architecture enables digital signal processing to be executed in multiple FPGA cores allowing dynamic reconfiguration and massively parallel processing performance.

The sonar is frequency agile from 200 – 400 kHz and offers range-independent resolution of 2.5cm by 2.5cm with co-registered 3D bathymetry. Effective swath widths are up to 12 times water depth in shallow water, to a maximum width of 600m. According to Marport, this swath width more than doubles that achieved by currently available high-resolution bathymetric sonars. The new sonar is suited to applications where seabed image quality is critical.

SAS is a type of sonar in which sophisticated signal processing of successive acoustic pings is utilized to form an image with significantly higher resolution than conventional sonars. The image formation can require aligning the echoes to less than 0.1 millimetres. This is made possible through recent advances in broadband sonar technology combined with adaptive focusing techniques similar to those used in optics, but performed in software rather than in hardware.

When integrated onboard an AUV, the AquaPix® uses sonar sensor data with multi-aspect diversity to reconstruct images . "Underwater imaging markets present very demanding requirements not only for sonar performance but also overall image quality," said Karl Kenny, President & CEO of Marport. "With AquaPix®, we are again leveraging our latest Software Defined Sonar® technologies to bring critical improvements in quality and performance. AquaPix® provides the underwater imaging markets with a price competitive solution to replace and overcome the performance shortfalls of conventional systems."

Its sonar design exploits a dual row frequency multiplexed transducer array which allows selection of the vertical beamwidth of both the transmitter and the receiver on the fly in order to optimally suppress multipath. Two beams with different beam-widths are transmitted at the same time, at different frequencies, and the best beam is dynamically selected by frequency filtering, a technique based on Orthogonal Frequency Division Multiplexing (OFDM) used in radio communications for the same purpose. The multiplex also provides the high level of spatial overlap required to robustly implement adaptive focusing techniques.