SCAN-650A Model for Larger ROV’s. 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 or in 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.
JW Fishers SCAN-650 is a high performance scanning sonar system that can be mounted on an ROV or pole-mounted for use from a small boat in shallow water. The scanning sonar serves as an obstacle avoidance system and provides target identification. The sonar beam sweeps in a 360 degree circle (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 played back at anytime. Software is provided to allow post-processing of data including editing and merging of files. Small file sections, including screen shots, can be edited out and copied to a small file for emailing. A sizing tool is included in the software which allows the operator to determine the size of the targets on the screen.
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).
Scanning sonars operate very similar to radar, a signal is sent out from its antenna 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 step (.5, 1, 1.5, or 2 degrees) 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-650A Operator Controls
JW Fishers scanning sonars have a full set of operator controls and indicators which are conveniently located on the front of the sonar processor and on the PC screen. The controls are:
- Size: Displays size of selected target
- Gain: Increases overall gain of picture
- Zoom: Zooms in or expands/enlarges picture
- Colors: Different color scales are selectable
- Invert Color: Inverts the color bar to give a different look to the target being examined
- Record and Playback: A complete set of controls for both recording and playback of files
- Amplifier adjustments: Allow the operator to fine-tune the received signal for the sharpest displayed picture
- Print Delay: Delays start of image on screen which moves targets that are at the outer edge towards the center of the screen
- Speed Control: Allows the operator to optimize the speed of the scanning sonar to match the speed of the computer; the result is faster sweeps
- From and To Sweep angles: The system can perform continuous 360 degree sweeps or "back and fourth" sweeps between any two selected degree angles
- Range Setting: Selection from 5 to 80 meters in five steps allowing both short range scanning for the smallest of targets to long range for locating larger targets. The range settings are 5, 10, 20, 40, and 80 meters
- 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. A total of 256 colors can be displayed
- Step Degree: From .5 deg to 2 deg in four steps: .5, 1, 1.5 and 2 degrees. The smaller the step the higher the resolution and detail of the picture. The larger the step the more coarse the picture, but the faster the sweep
Dimensions / Weight
- Sonar Processor 8"W x 9"D x 2.5" H, air/water x lbs
- 650A Sonar head and housing 3.5" Dia x xx" L, air/water x/x lbs
- 650B Sonar head 3.5" Dia x 4"L, air/water x lbs, Housing 3.5" Dia x 9" L, air/water x lbs
- Frequency - 650kHz
- Two Year Limited Warranty
- Target Sizing
- Display Colors 256
- Cable 2 or 4 conductor
- For Laptop or Desktop PC
- Max depth 300 m (1,000 ft)
- Ranges 5, 10, 20, 40 meters
- .5, 1, 1.5, or 2 Degree Steps
- Fast Scan Even On 1/2 Degree Steps
- High Resolution Picture of Sea Bottom
- Beamwidth - horizontal x vertical 2.4 deg by 40 deg.
- Sonar Head from Sonar Processor or 9-36 from ROV
- 360 Deg. Continuous Sweep, Or Any Portion of 360 deg.
- Input voltage - Sonar Processor 9-36 vdc or 120 vac (xx watt)