Furuno TS-331A - Manual (Page 23)

2. SONAR OPERATION
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2.2.2 Adjusting gain
Adjust the gain from the Data Gain combo box. The gain range is 0-100(%).
Data gain is used to increase or decrease the intensity (color levels) of the
vertical sonar and sounder images.
2.2.3 Choosing train angle
Select the scan train angle from 0° to 360° in 10° increments. Train angle is used
to control the relative direction of the mid point of the vertical sonar in the sector
scan mode. Train is inoperative in the polar mode.
2.2.4 Choosing scan sector
Select the scan sector (from 0° to 360° in 10° increments). Sector is used to
control the size of the angle scanned by the vertical sonar. Note that this function
is inoperative in the polar and locked modes.
2.2.5 Choosing scanning speed
Select scan speed of vertical sonar. The options are
0.3 deg.: slow, one shot covers 0.3°
0.6 deg.: medium, one shot covers 0.6°
0.9 deg.: fast, one shot covers 0.9°
1.2 deg.: faster, one shot covers 1.2°
2.4 deg.: fastest, one shot covers 2.4°
2.2.6 Choosing sonar frequency
Choose the vertical sonar operating frequency for high or low.
2.2.7 Freezing the display
Click the HOLD button to freeze the system from interrogating sensors and
freeze the data display. The sonar display shows “HELD” when the image is
frozen. Click the button once again to release the freeze condition and restart
the sonar. This feature is useful for inspecting an image, taking a picture of the
display and printing.
2.2.8 Reversing the scan direction
Click the REV button to reverse the current scan direction of the vertical sonar. If
the sonar is scanning clockwise, clicking the REV button will make the sonar
scan counter clockwise and vice-versa. This is particularly useful when tracking
moving targets.