Furuno NAVNET 1833 - Manual (Page 160)

4. VIDEO SOUNDER OPERATION
4-14
4.8 Erasing Weak Echoes
Sediments in the water or reflections from plankton may be painted on the
display as “spots” on the background. These weak echoes may be erased as
below.
Weak
echoes
Appearance of weak echoes
1. Press the [MENU] key.
2. Press the SOUNDER MENU soft key.
3. Select SIGNAL LEVEL, and press the EDIT soft key to show the signal level
window.
SIGNAL LEVEL
▲
¤ OFF
¡ SL1
¡ SL2
▼
Signal level window
4. Use the trackball to select level of erasure or OFF as appropriate. The higher
the number the stronger the echo that will be erased.
5. Press the RETURN soft key followed by the [MENU] key to close the menu.
Note:
Unlike “clutter,” signal level erases echoes. Therefore, if you do not wish
to erase echoes, use clutter instead.