NorthStar 6000i, Быстрый старт и справочное руководство

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Reference section 6 — Echo sounding
The picture menu
Northstar 6000i
1. Press
Picture
.
2. Press
Gain
.
3. Press the cursor pad left or right to adjust
the gain, or use the keypad to manually
enter the desired gain value. The available
settings range from zero (minimum) to 75
(maximum).
The window shows the effect of adjusting
the gain. The fi sh symbols near the bottom
of the window represent various echo
strengths, and the expanding and contract-
ing color bar above shows the colors that
will be used to display echoes of these
strengths. As you adjust the gain to obtain
the best looking picture, also watch the real
echoes on the right side of the screen.
4. Press
Return
to go back to the
SOUNDER
screen.
When you adjust the gain, the color of the
Auto
and
Picture
key tabs changes
from green to yellow, since the echo
sounder is no longer in automatic mode.
Also, a yellow tab appears under the
Depth
key, indicating that the range set-
ting is no longer automatically controlled
and that the 490 may not always identify
the bottom reliably.
Adjusting the clutter (weak echoes)
The clutter setting selects the echo strength
that will be displayed using the bottom
colors of the color bar (the weaker echoes).
Any echoes weaker than this selection are
displayed. If you select a clutter value of
5
,
for example, all weak and moderate echoes
are suppressed. You might choose this
setting to eliminate high levels of back-
ground noise and echoes from turbulence
or plankton. A setting of
0
allows all echoes
to be displayed.
To adjust the clutter:
1. At the
SOUNDER
screen, press
Picture
.
2. 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 avail-
able settings range from zero (shows all
echoes) to nine (suppresses many ech-
oes).
Gain window