Furuno CH-250 - Manual (Page 33)

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5. Press the [MENU] key to register your selection and close the menu.
6. To suppress reflections by the sea surface or plankton, select TVG LEVEL and press .
7. Press or to adjust TVG LEVEL, considering sea conditions. A setting between 2.0 and
5.0 should provide satisfactory results. The higher the figure the less the gain over distance.
8. Press the [MENU] key to register your selection and close the menu.
9. Watch a distant fish echo which is approaching own ship. Adjusting the tilt angle so the fish
echo is within the sounding beam. Observe color of fish echo. If the color and size of the
echo stay the same as the echo approaches own ship, the TVG setting is proper. If the echo
suddenly becomes smaller, the TVG level may be too high.
2.11.4 Erasing weak echoes
Weak echoes such as interfere can be erased from the screen. This is useful when you want to
observe a fish school echo.
1. Press the [MENU] key to open the menu.
2. Press to select MENU.
3. Press to select COM2.
4. Press or to select SIG LEVEL.
5. Press to open the dialog box.
SIG LEVEL
OFF 1 14
(OFF, 1-14)
OFF
8-color display: OFF, 1-6
16-color display: OFF, 1-14
6. Press or to select echo color to erase. Pressing erases echoes from weak to
strong in ascending order of strength. You can also see which echo color is erased by
watching the color bar.
7. Press the [MENU] key to register your selection and close the menu.