NorthStar Navigation Echo Sounder NorthStar 491 - Manual (Page 34)

Page 30 491 Echo Sounder Operations Manual
displayed. If you select 5, for example, all weak and moderate
echoes will be displayed using the background color (just as if
they weren’t there). You might choose this setting to eliminate
high levels of background noise and echoes from turbulence
or plankton. A setting of 0 allows all echoes to be displayed.
To adjust the clutter:
1. At the ECHO screen, press PICTURE.
2. At the PICTURE screen, press CLUTTER.
3. Press the CURSOR PAD left or right to adjust the clutter,
or use the KEYPAD to manually enter the desired clutter
value. The available settings range from zero (minimum)
to nine (maximum).
Clutter window
4. Press RETURN to go back to the ECHO screen.
When you adjust the clutter, the color of the AUTO and
PICTURE key tabs changes from green to yellow, since
the echo sounder is no longer in fully automatic mode.
Adjusting the signal level (weak echoes)
As with the CLUTTER key, the SIGNAL LEVEL key controls
the appearance of low level noise in the picture. Whereas
clutter compresses or expands the available colors to fit the