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Operation
Q)
What would you consider a good place to start with the gain Controls?
A)
I start with the Near Gain 5, the Far Gain 7, and the Overall Gain 7. If the image produced
with the TVG controls at these settings is much too light, increase the Cable Compensation switch
setting by 1. The Cable Compensation switch is located on the SCAN-650 Sonar Processor box.
This switch is used to adjust the gain to compensate for various lengths of cable. Switch position 1
is used for shorter cables (such as a 150ft cable); switch position 5 is used for long cables (such
as a 2000ft cable). Fine tune the Near Gain so objects close to the scanning head look good.
Next, adjust the Far Gain so objects farthest from the scanning head look good. Finally, use the
Overall Gain to adjust the overall darkness or lightness of the image.
Q)
How do I adjust to compensate for a bottom that slopes away or towards the scanner
head?
A)
The SCAN-650 produces a fan shaped beam that is 40 degrees in the vertical plane. This
allows the SCAN-650 to scan gently sloped bottoms without altering the orientation of the scan-
ning head. For bottoms that slope gently away from the scanning head, you can compensate by
raising the far gain. For bottoms that slope gently up towards the scanning head, you can compen-
sate by lowering the far gain. Steeper slopes would require you to adjust the head to be perpen-
dicular to the slope. This would ensure complete coverage of the surface of the slope.
Q)
Some of the images are clearly vehicles, while others only show a large, undefined shape.
A)
This is normal. When performing a search, it is important to remember that objects will not
always be displayed as you would expect. The orientation of the target in relation to the scanning
head can make a big difference in the how the sonar “sees” the target. Changing the orientation
of the scanning head in relation to the target will change how it appears on the display.
Q)
Why is a lot of detail lost farther out in the scan?
A)
The sonar beam produced by the SCAN-650 is a fan shaped beam.
The farther the beam travels away from the transducer, the more the spread out the beam be-
comes. Since the beam spreads as it travels, the images produced at long ranges are not as
detailed as images of close objects. (Echoes from all portions of this fan shaped beam are com-
bined to draw the image on the screen)
Q)
Will I still be able to see small objects on the larger scans?
A)
The 40 meter plus ranges are best when searching for large objects such as vehicles.
Small objects are often overlooked due to their small size when drawn on the screen. On a 21",
monitor, with the screen positioned so the a 270-90 degrees sweep is shown at maximum size, a
3ft length measures only ¼”, which is very easy to overlook. To thoroughly search an area for a
FAQs
(Continued)
Summary of Contents for SCAN-650
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