Kraken Sonar Systems Inc. announced the development of AquaPix MINSAS - a next generation Miniature Interferometric Synthetic Aperture Sonar designed for operation to depths of 3,000 meters. The system integrates the latest electronics, transducer arrays and signal processing software and is optimized for the demanding size, weight, power and cost constraints of Autonomous Underwater Vehicles (AUV), Unmanned Surface Vehicles (USV) and high speed towfish platforms.
MINSAS uses a subset of Kraken’s award-winning AquaPix INSAS transducer array, but has the addition of an innovative SAS gap filler transmitter that produces high resolution data in the nadir region. A lower frequency transmit element, unique to MINSAS, provides a SAS resolution gap fill directly under the platform. The transmitter and receiver elements are integrated into single monolithic arrays which are mounted close to the electronics module. The system also uses two rows of identical receiver elements to deliver precision bathymetry data.
The system will be provided in two configurations. MINSAS 60 uses a transducer array assembly that measures 60cm in length and is designed for AUVs with body diameters as small as 6 inches. MINSAS 120 uses a transducer array assembly that measures 120cm in length and is designed for larger AUVs as well as for high speed towfish operations. Both systems produce ultra-high resolution, real-time image quality with unparalleled sharpness. Advanced 3D motion compensation and beamforming technologies nullify blurring caused by platform motion.
Karl Kenny, President and CEO of Kraken said, “AquaPix MINSAS is based upon a robust and proven design and is ideal for a variety of military and commercial imaging missions. It’s the latest embodiment of Kraken’s sonar imaging expertise in miniature - a sophisticated system that can generate and process seabed sonar images and maps at blindingly fast speeds with uncompromised precision and ultra-high resolution.”
Conventional side scan systems are limited in that they only provide high resolution imagery at short ranges. MINSAS produces ultra high resolution seabed imagery (3cm along-track x 1.5cm across-track) with constant resolution to full range and high signal to noise ratio.
The additional information provided by the MINSAS delivers detection and identification capabilities that cannot be achieved with conventional sidescan sonar and achieves an area coverage rate that is significantly higher than that of sidescan sonar in a like for like comparison.
MINSAS also generates highly accurate bathymetry data (12.5cm along-track x 12.5cm across-track x 5cm height) that’s co-registered and geo-referenced to the same pixel grid co-ordinates as the imagery. Operators can produce crisp seabed imagery and detailed 3D digital terrain maps of seafloor topography that exceed IHO SP-44 survey standards.
The capability of generating centimeter-scale resolution in all three spatial domains also provides significant performance improvements in the detection, classification and identification of small objects on the seabed. Many of today’s precision mine classification algorithms demand long range, high quality imagery with pixel resolution of 5cm or less. In addition to shallow water hydrographic surveys, MINSAS is ideal for littoral mine countermeasures.
Many conventional imaging sonars are designed for deep water operation and suffer from severe multi-path reverberation in shallow water operations. This multipath significantly impairs image contrast. MINSAS uses an innovative transducer array design that produces high contrast imagery even in very shallow water. Near shore and shallow water hydrographic surveys can be completed much more efficiently due to both the multipath suppression and wide swath coverage.
Imagery from both conventional side scan and other synthetic aperture sonars is often distorted due to platform motion, resulting in coverage gaps due to platform roll, pitch, yaw and crabbing. MINSAS uses a series of advanced motion compensation techniques to eliminate the effects of platform motion, producing undistorted imagery with 100% ground coverage. Compared to other sonars that can only tolerate a 5° crab angle, MINSAS tolerates crab angles to 20°.
The sonar electronics and arrays can be easily integrated into small diameter AUVs or configured for towed system and USV operations. Sonar data is transferred from the transceiver to the processing unit via a Gigabit Ethernet network interface. The sonar operation is controlled from a graphical user interface (GUI) on a notebook computer. The operator sets the sonar parameters in the sonar control window, while depth, imagery and other sensor data are captured and displayed by Kraken’s INSIGHT application software.
Other features and capabilities of the AquaPix MINSAS include:
-Ultra-high resolution - 3cm across entire swath
-Swath widths of up to 500m
-Superior area coverage rate
-Nadir gap filler with SAS resolution
-Innovative multipath suppression
-Real time SAS image processor
-SAS – 3D motion compensation
-Low to high speed operation
-Shallow water to full ocean depth
-Co-registered imagery and 3D bathymetry
-Advanced sonar array design mitigates multipath
-Very tolerant of UUV yaw / crabbing action
-Modular design integrates to AUV, ROV, ROTV and towfish
-Superior image resolution and area coverage rate over SSS
-Compliant to IHO SP44 hydrographic survey standard
-Interfaces to industry-standard visualization software
MINSAS 60 and MINSAS 120 are expected to be commercially available in February, 2014 and will be priced at $149,995 and $225,000 respectively.