Erasing Weak Echoes - Furuno CH-250 Operator's Manual

6. Press or to close the TVG distance dialog box and return to the HORZ menu.
7. To suppress reflections by the sea surface or plankton, select TVG LEVEL and press
8. 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.
9. Press the [MENU] key to register your selection and close the menu.
10. Watch a distant fish echo which is approaching own ship. Adjust 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 interference 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 COMN.
4. Press or to select SIG LEVEL.
5. Press to open the dialog box.
6. Press or to select echo color to erase. Pressing
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.
SIG LEVEL OFF
OFF 1 14
(OFF, 1-14)
8-color display: OFF, 1-6
16-color display: OFF, 1-14
erases echoes from weak to strong
.
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