Sonardyne International has expanded its capabilities with the launch of its first sidescan sonar at the Oceanology International exhibition in London (Stand No. H355 ).

The new Solstice sonar has been specifically developed by Sonardyne to provide new levels of performance that meet the needs of operators of Autonomous Underwater Vehicles (AUVs).

Solstice emerges as the result of three years of intensive development work and provides the crucial benefits of low power consumption and class-leading range and imagery including co-registered bathymetry.
With a total power budget of less than 12W, Solstice can provide high area coverage rates and long endurance. All processing is carried out onboard the vehicle, greatly reducing analysis time when the vehicle is recovered, and allowing onboard data interpretation during the survey.

The capabilities of the new Solstice are expected to make it attractive for a wide range of applications besides survey. These can include mine warfare, harbour protection and also search and recovery.

Solstice has several unique technologies designed to provide the user with class-leading imagery. Amongst these are Multipath Suppression Array Technology (MSAT), Pixel Perfect Imaging (P2I) and Real Time Auto Calibration (RTAC).

The loss of contrast due to reverberation and multipath, common to even the best of the previous generation of sidescans – particularly in shallow water – is mitigated by Solstice’s innovative Multipath Suppression Array Technology (MSAT). This technology has been developed to overcome the trade-off between multi-path suppression at longer ranges, and wide elevation coverage at short ranges. MSAT offers a unique combination of the two and provides high shadow contrast right out to the maximum range of the sensor whilst maintaining high quality imagery close to nadir. The ability to recognise shape from acoustic shadows cast by objects on the sea floor is a powerful classification tool and the capabilities of Solstice to deliver high shadow contrast throughout its range is an important benefit for many applications.

Solstice now provides the ultimate in high-fidelity focus by providing unique Pixel Perfect Imaging (P2I)on a 1-inch by 1-inch grid enveloping the entire sea floor within the sensor’s field of view. Solstice uses an entirely new approach known as Classification Optimised Focused Imaging (COFI) that subtly varies the details of the signal processing at every individual pixel in the image to optimise classification performance. The Solstice real-time onboard processor is capable of addressing up to 3.1 Mega pixels every second which means that the image will maintain the best focus and resolution possible at that position in space relative to the sensor. At longer ranges where the spatial sampling rate significantly exceeds the resolution, the interpolated real-time imagery dramatically aids human ability to recognise the target. Uniquely, P2I also guarantees 100% sea-floor coverage due to its ability to track intra-frame motion during image formation. The associated local micro-mosaicing also ensures the sea-floor imagery is geometrically undistorted by the platform dynamics.

Despite being designed to be physically compact, the high operating frequency of Solstice (750 kHz) means that the array is still over 300 wavelengths in extent. To maintain the acoustic linearity of this array necessary for class-leading imagery, Solstice also includes Real Time Auto Calibration (RTAC) which dynamically re-phases each individual hydrophone element seven times a second to compensate for any dynamic strains that might cause array misalignment.