Chapter 5: Sonar Mode Operation
67
The DSM300 provides three pre-defined automatic gain settings:
CRUISING is the lowest automatic gain setting. It is ideal for viewing sonar image
with a minimum of background noise as you are travelling to your fishing spot.
TROLLING is a slightly higher gain setting that displays more detailed echos as
you search for targets.
FISHING is the highest automatic gain setting. It gives the best details of the
targets you have located but also displays the most background noise and surface
clutter.
Note:
The automatic gain modes are named so as to suggest when you might use them.
However, it is not necessary for you to select, for example, Fishing Mode only when you are
fishing. You may want to take advantage of Fishing Mode’s higher gain even when cruis-
ing at high speeds. Your personal preference should determine which automatic gain
mode you use, not necessarily your boat speed.
Color Gain
The COLOR GAIN determines how echoes of different strengths are displayed.
Three shades of gray (monochrome display) or seven colors (color LCD) per
palette are available and the echo strengths are divided into three (monochrome)
or seven (color) bands to correspond with each shade of gray/color.
The color bar on the right hand side of the display, when set to ON in the Sonar Set
Up menu (see Section 3.4), 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
shade/color.
All echoes weaker than this value are divided equally between the remaining
shades/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:
On a color LCD, the sounder also provides a COLOR THRESHOLD control to reduce
the number of colors displayed. Use COLOR THRESHOLD with COLOR GAIN to determine
how echoes are displayed.
The DSM300 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.
CRUISING
AUTO
45%
GAIN
MANUAL
CLR GAIN
50%
