Raymarine DSM250 Owner's Handbook Manual page 94

6-6
GAIN
ADJUST
200 50
➤
MULTI GAIN
GAIN
ADJUST
200 50
GAIN
MANUAL
80%
GAIN
You adjust gain for each transducer frequency independently.
Press the GAIN ADJUST soft key to highlight the frequency for
which you are making adjustments. You may change settings for
one frequency while displaying the other.
To adjust a parameter:
1. Press the GAIN key or rotate the GAIN knob on radar CRT units.
The gain sliders are displayed. The slider last used is highlighted
(displayed in inverse video) to show that it is selected.
2. If necessary, press the GAIN ADJUST soft key to select the desired
frequency for adjustment.
3. If necessary, press the desired soft key to highlight (select) the
desired slider.
Press it again, if necessary, to toggle between AUTO and MANUAL
modes.
4. In manual mode, use the trackpad to move the selected slider up or
down. You can press and hold the trackpad to move the slider
quickly rather than in single steps.
As you move the slider, the value displayed in the slider is
updated. The new setting takes immediate effect.
Note: Because the changes to the settings take effect immediately,
you cannot revert to the previous settings by pressing CLEAR.
5. When you have set all the controls to the levels you desire, press
ENTER or CLEAR to return to the default display.
Gain
The GAIN, or sensitivity, of the display adjusts background noise
by varying echo strength for display. The value of the gain control
determines the strength above which echoes are displayed. If the
gain is low only the strongest echoes are displayed. As the gain is
increased, weaker echoes (from air bubbles, for example) are also
displayed.
Pressing the GAIN soft key cycles the sounder from manual
through three levels of automatic gain adjustment.
Manual gain should be set high enough to see fish and bottom
detail but without too much background noise. Generally, a high
gain is used in deep and/or clear water; a low gain in shallow and/
or murky water.
DSM250 Digital Sounder Module