NorthStar 6000i, Быстрый старт и справочное руководство

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119
Reference section 6 — Echo sounding
The picture menu Reference Manual Revision D
4. Press
Return
to go back to the
SOUNDER
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 desired signal range, Signal Level
completely removes the weaker colors and
their echoes.
To adjust the signal level:
1. On the
SOUNDER
screen, press Picture .
2. Press
Signal level
.
3. Press the cursor pad up or down to
remove the weaker color levels from the
picture, or use the keypad to manually
enter the desired signal level.
The available settings range from
1 (mini-
mum) to 5 (maximum). For example, if
you select a signal level of 3, echo
strengths of
0 through 3 are all displayed
using the same color as the background.
4. Press
Return
to go back to the
SOUNDER
screen.
Suppressing interference (the noise
limiter)
The noise limiter reduces the adverse
effects of interference caused by other
nearby echo sounders or electronic
devices. However, the noise limiter may
cause some very weak echoes to be made
smaller or be entirely eliminated, since it
removes any echoes that aren’t sustained
for at least two pings.
To turn on the noise limiter:
1. At the
SOUNDER
screen, press
Picture
.
2. Press
Noise limiter
.
Clutter window