Raymarine L1250D, Owner'S Handbook Manual

Page: 137 / 246

Chapter 6: Sonar Operations 6-7
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Color Gain
The
COLOR GAIN
determines how echoes of different strengths are displayed.
Seven colors per palette are available and the echo strengths are divided into
seven bands to correspond with each shade of color.
The color bar on the right hand side of the display, when set to
ON
in the Sonar
Set Up menu (see Section 4.4 ), shows the colors being used, with strongest
echo color at the top and the weakest echo color at the bottom.
The COLOR GAIN control sets the lower limit for the top color band:
All echoes with a signal strength above this value are displayed in the
strongest color.
All echoes weaker than this value are divided equally between the remaining
colors.
Setting a low value produces wide band for the weakest color, but a small
signal band for the other colors; setting a high value gives a wide band for the
strongest color, but a small signal band for the other colors.
Note: The Fishfinder also provides a COLOR THRESHOLD control to reduce the
number of colors displayed. You can use
COLOR THRESHOLD
with
COLOR
GAIN
to determine how echoes are displayed.
The Fishfinder provides automatic or manual
COLOR GAIN
adjustment.
Automatic adjustment displays colors based on current conditions, with as
many colors as possible, while minimizing noise and clutter. As conditions
change the auto-color gain adjusts. If you select manual adjustment, you will
need to re-adjust the gain as conditions change.
STC
STC
(Sensitivity Time Control) reduces surface clutter by reducing the gain in
the top 100 ft of the display. This function is useful for reducing noise (caused
by air bubbles and floating debris) that often appears in shallow water. A low
STC
value has little effect on gain in shallow water; a high
STC
value decreases
the gain in shallow water so that only the strongest echoes are displayed.
Although you can manually set the STC level, Raymarine recommends letting
the sounder module choose the proper level for you by selecting
AUTO STC
.
Automatic STC mode takes advantage the hardware’s advanced DSP
technology, which typically achieves a sharper image in auto mode than is
possible in manual mode.
STC is not available in Sonar Simulator mode.
MULTI GAIN
MANUAL
CLR GAIN
50%
MULTI GAIN
MANUAL
STC
15%
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