Sample Recording - JW Fishers SCAN-650 Operation Manual

SAMPLE RECORDING

The procedure below provides an example on how to record a file and will step you through some
of the recording options. The complete system needs to be cabled up and ready to go with the
SCAN-650 deployed on an ROV or on a pole over the side of a boat (3-4 ft off the bottom).
1. Open the Scan-650 application.
2. Select a scan range under "Range" on the right side toolbar. The choices are 5, 10, 20, 40, and
60 meters. Longer range settings allow a larger area to be scanned, but the resolution of the
scan is lower. Shorter range settings produce higher resolution images and are recommended
when searching for small or "soft" targets. For this exercise select 10 meters.
3. Select a step degree setting under "Step" on the right side toolbar. The choices are .5, 1, 1.5,
and 2. Larger steps allow the sonar beam to scan the area more quickly, however, resolution is
lower. The smaller the step, the higher the resolution of the sonar image. For this exercise
select a step of 0.5. This setting provides the highest resolution.
4. Select a sector to be scanned in the right side toolbar. The sector selected represents the
portion of a circle that will be scanned. The choices for the "Start" (left menu) and "Stop" (right
menu) angle are 0, 30, 45, 60, 90, 120, 150, 180, 210, 240, 270, 300, 315, and 330. The larger
the sector, the longer it takes the sonar beam to sweep the area. If Sector is selected the sonar
beam will rotate right to left, then left to right in a motion similar to a windshield wiper. If "360
Scan" is selected, the sonar beam will continuously rotate 360 degrees, refreshing the sonar
image with each subsequent pass of the beam. For this exercise select 360 Scan.
5. Under "Zoom" on the right side toolbar select 100%. This is the normal operating setting. When
an image of interest is appears on the screen the operator can select one of the other zoom
settings - 150%, or 200% to enlarge the image. The operator can also choose which portion of
the scanned area to display by selecting one of the screen positions in the Mode/Screen Toolbar
on the left side of the screen the repositions the origin point.
6. Select a screen color under "Colors" on the right side toolbar. The color combinations allow the
sonar image to be displayed in various shades of both colors. The best color is a matter of
operator preference although at times a sonar image can appear to be more distinct in one
particular color. For this exercise select red-yellow for the Colors list.
7. Select a gain value under "Gain" on the right side toolbar. The choices are -5, -4, -3, -2, -1, 0,1,
2, 3, 4, and 5. The gain settings are used to lighten or darken the sonar image. The lower the
number the lighter the image. A zero gain setting is recommended when recording files as this
setting will allow the gain to be adjusted up or down when the file is played back. When record-
ing files the gain can be adjusted on the Sonar Processor to produce the desired sonar image.
8. Select "0" under "Threshold" on the right side toolbar. The choices range from 0 - 255. Thresh-
old is similar to gain in that it adjust the lightness and darkness of the sonar image, however,
threshold allows much finer adjustment because of the broader range. A setting of "0" is recom-
mended when recording files. This will allow the threshold to be varied widely when playing back
recorded files. Small details in the sonar image may become visible as the threshold is in-
creased. If a high threshold setting is selected when recording a file, the sonar reflections from
hard targets will be so high on the threshold scale that all detail will be lost. This data can not be
recaptured when playing back the file even if the threshold is lowered to the minimum setting.
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