SONAR

METRATEK, Inc......................We innovate for you!

dolphin

The Forward Looking Sonar System (FLOSS) consists of an unmanned remotely-piloted Dolphin submarine, a high resolution multi-beam SONAR, and a Control Module in a portable equipment shelter that can be placed on any ship. FLOSS detects tethered mines at SONAR ranges of up to 400 yards while the submarine is operating at up to 12 knots at distances of up to 5 miles from the Control Module.

FLOSS was developed by METRATEK for DARPA and successfully passed a full Navy OPEVAL during Operation DESERT STORM, although it did not see action in the Gulf war.

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The Control Module is completely self-contained and requires no ship services. The Dolphin control console is on the right. The pilot can maneuver two Dolphins simultaneously and is provided with feedback via Global Positioning System (GPS) receivers on the ship and on the Dolphin. An adjustable grid shows the Dolphin track and position of detected mines. The DOLPHIN submarine (shown above on the surface before the FLOSS SONAR dome was fitted) is built by ISE of Vancouver,BC. It is 39 ft long and can operate at 12 knots for 24 hours without refueling. It is capable of operating in up to Sea State 5 and holds the FLOSS SONAR dome at a constant depth of 8 feet.

FLOSS coherently transmits 12 simultaneous, ten-degree beams covering a 120-degree sector ahead of the submarine. Each transducer has its own receive channel and processor. High probability of detection is achieved by employing a high resolution (15-centimeters) waveform and adaptive threshold processing that recognizes returns that are apt to be due to mines and rejects returns that do not have mine-like signatures. All processing functions are implemented in software, using two fast microcomputers

The FLOSS sonar display of real mines detected during OPEVAL is shown at the left. Up to 200 target reports from each pulse are transmitted to the Control Module via a packet radio link and displayed on the top right-hand frame of the display. Mines appear as diagonal lines showing range vs time. The PC-based processor uses a 20-state signal and motion correlator that separates tethered mines from fish, wakes, ships, reverberation, and surface returns, producing a negligible false alarm rate. Detected mines are shown as red dots on the sector-PPI at the bottom of the display. All input data from the data link, all detections, all confirmed mine reports, and Dolphin position data are recorded on disk so that the data can be rerun and further confirmed after the mission. A real-time display of confirmed mine detections is provided to the ship's bridge and navigation station.

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