Increasing the envelope
Solstice increases the operational envelope of a vehicle significantly by providing wide swath coverage at high resolution whilst consuming typically only 18 Watts of power. The low power and wide swath results in long vehicle endurance and high area coverage rates.
Solstice’s onboard processing produces geo-coded side-scan imagery which is available for onboard automatic target recognition and post-mission analysis. The imagery produced by Solstice is designed to be of the highest quality possible from a conventional (non-SAS) sonar. It is designed to produce wide swath coverage (±100m), with image quality suitable for simultaneous search and classification. To achieve this, the system uses a number of innovative techniques.
High quality imagery
Solstice provides a high fidelity image by using a back-projection beam-forming technique to focus at every single pixel in the image, unlike most conventional side scan sonars which have a fixed focus. Imagery from conventional side scans is distorted due to non-linear platform motion, and may have gaps in coverage due to platform roll, pitch and yaw. Solstice uses knowledge of the platform motion to eliminate its effects, producing undistorted imagery with 100% ground coverage.
Accurate imaging demands highly linear element alignment, which cannot easily be achieved mechanically. Real-time array calibration is therefore used to dynamically re-calibrate each individual hydrophone element several times a second to compensate for any dynamical strains causing array non-linearity. Solstice has been designed to produce high-contrast imagery even in very shallow water, eliminating noise from multi-path reverberation, enhancing the contrast of the imagery. It employs a unique array technology which allows wide swath coverage normally associated with wide vertical beamwidth, whilst providing the shadow contrast associated with very narrow vertical beams.
Solstice produces high quality bathymetry data from a vertical hydrophone array on each flank. The bathy data is co-registered onto the same pixel grid as the side scan imagery, and therefore can produce stunning digital terrain maps, with the side scan imagery accurately draped over the bottom topography.