JW Fishers SCAN-650, Руководство по эксплуатации

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9. The SCAN-650 is now ready to begin displaying and recording sonar data. To record a new file
click the red button at the top of the left side toolbar or click ”Actions” on the top toolbar and
select “Record”. Before the recording begins, you will be asked to name the file and select a
location for the storage. The sonar data will be displayed on the PC monitor and recorded to the
hard drive.
10. Set the Gain Controls on the Sonar Processor. The Sonar Processor amplifies and conditions
the signal from the scanning head. The amplifier in the Sonar Processor is called a Time
Variable Gain (TVG) amplifier. Adjusting the TVG:
a) Start with all three gain controls at their mid-point.
b) Set the CABLE LENGTH COMPENSATION switch. Select the switch position that gives the
best picture with the three GAIN controls set at their mid-point. This is a one time adjustment,
once the best switch setting is found, it is not necessary to change it unless a different cable
is used. 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).
c) Adjust the Far Gain up or down for an even background color.
d) If an even color cannot be obtained by adjusting the Far Gain, adjust the Near Gain up or
down then readjust the Far Gain. The Near Gain usually requires little or no adjustment.
e) Adjust the Overall Gain so that only the very strongest returns (from “hard” objects) cause the
highest color on the color chart to be displayed.
f) If, once the desired picture is displayed, you find that the GAIN controls are set near their
minimum settings, lower the setting of the CABLE LENGTH COMPENSATION switch by
one position and readjust the GAIN controls. Conversely, if you find that the GAIN controls
are set near their maximum settings, increase the setting of the CABLE LENGTH COM-
PENSATION switch by one position and readjust the GAIN controls.
Note: When recording, it is important to have the Gains properly adjusted. If a file is recorded
with the Gains set too high, causing the signal to “saturate” the amplifier, detail lost in the satu-
rated portion of the image cannot be recovered in playback. It would be preferable to have the
Overall Gains set slightly too low; the Gains can be increased by the on-screen Gain Control
during playback, with most of the detail retained.
While the sonar data is being recorded the settings can be changed at any time. Select a new
Range setting, Sector scan angle, Step, color scheme, etc. and note the change in the sonar image.
In most cases the change will not take place until after completion of the present sweep. Once the file
has been recorded, play it back to view the results. Experiment with the file by changing the settings
and noting the results on the displayed image.