J.W. Fisher's Scanning Sonar
Scanning sonar is an ideal tool for underwater search because it produces a picture of the underwater environment regardless of the water visibility. It does this by sending out a sound wave that reflects off objects on the bottom orin the water column. The reflected wave returns to the sonar head where it is received and sent to the surface for display. The reflected sonar image is displayed on a laptop computer.
Fishers SCAN-650 is a high performance scanning sonar system that can be mountedon an ROV, pole-mounted for use from a small boat in swallow water, or mounted on a tripod on the bottom. The scanning sonar serves as an obstacle avoidance system and provides target identification. The sonar beam sweeps in a 360 degreecircle (or any portion of 360) allowing any object in the sonar's field of view to be seen and displayed on the computer monitor.
In a typical application the sonar head or transducer is mounted on top of an ROV. The head scans a circle around the ROV and sees targets in all directions, including those that are well beyond camera range. The sonar images are displayed on the topside computer. The operator, using the sonar for direction bearings, drives the ROV to the various targets for identification and videotaping
Scanned data files are stored on the PC's hard drive along with boat's GPS position, time, date, and other pertinent data. The recorded files can be playedback at anytime. Software is provided to allow post-processing of data includingediting and merging of files. Small file sections, including screenshots, can be edited out and copied to a small file for emailing. A sizing tool is included inthe software which allows the operator to determine the size of the targets on the screen.
Scanning sonar does operate very similar to radar, a signal is sent out from itsantenna and then it listens for return signals. The signal is fan shaped and very narrow in width. The return echoes are displayed on the computer screen as a very narrow line that changes color along its length depending on the intensity of the echoes.
After the line is displayed, the antenna (called a transducer in sonar) rotates (steps) slightly to the right and the sequence is repeated. The smaller the rotating step of the antenna is (1/2, 1, 1 1/2, or 2 degree) the higher the resolution of the picture. The transducer continuously steps, and the display quickly fills with the sonar image. The sequence is repeated, and if nothing moves (targets or sonar), then the identical picture will be overlaid over the previous picture (one line at a time).
SCAN-650 OPERATOR CONTROLS:
Fishers scanning sonar's have a full set of operator controls and indicators which are conveniently located on the front of the sonar processor and on the PCscreen. The controls are:
Record and Playback: Complete set of controls for both recording and playback of files.
Range Setting: Selection from 16.5' to 131' (5 meters to 40 meters) allowing both short range scan for the smallest of targets to long range for locating larger targets. The range settings are 16.5', 33', 66' and 131' (5, 10, 20, and 40 meters).
Step Degree From 1/2 deg to 2 deg in four steps. The smaller the step degree the higher the resolution and detail, the larger the step degrees the more coarse the picture, but the faster the sweep will be.
From and To Sweep Angles: The system can perform continuous 360 degree sweeps or "back and forth" sweeps between any two selected degree angles.
Zoom: Zooms in or expands/enlarges picture.
Print Delay: Delays start of image on screen.
Size: Displays size of selected target.
Amplifier Adjustments: Allow the operator to fine-tune the received signal for the sharpest displayed picture.
Gain: Increases overall gain of picture.
Colors: Different color scales are selectable.
Color Bar: Displays the range of colors selected. A small return signal displays the color on the left end of the bar; a large return displays the color on the right end of the bar.
Invert Color: Inverts the color bar to give a different look to the target.
SCAN-650 DISPLAY: In addition to the scanned sonar signal a variety of information is displayed and recorded including: Time, Date, Boat Lat/Lon, Range, Step degrees, Start and Stop sweep degrees, Zoom, Overall digital gain, and Color bar selected.
LAPTOP REQUIREMENT: USB port, Win 98 or higher, VISTA, Win 7
The system package includes the sonar head with downstairs electronics, cable, surface sonar processor, software, and A/D board for your computer. The A/D board significantly improves data transfer time to the computer which increases the sweep speed (takes less time to complete each sweep). Fishers SCAN-650 is ruggedly built for commercial operations, and is covered by a full 2 year warranty