NorthStar Navigation NorthStar 8000i - Manual (Page 115)

Northstar 8000i Operation Manual 115
18 Change the sounder range and gain
You can change the gain setting and gain threshold on your Sounder screen.
You can also turn the Auto Range On or Off, and change the range shift.
18.1 What is gain?
You can use the gain setting to control the amount of detail and color that you
want to show on your Sounder screen. The gain setting controls the width of the
color bands at the top of the advanced A-scope screen. Each color is associated
with a sonar amplitude.
20 is the maximum gain (sensitivity) setting and therefore shows the color bands
associated with each sonar amplitude at their maximum widths.
You can adjust the gain if you need to compensate for any adverse effects
produced by water depth and turbidity.
If you set the gain:
•
too high, the strong echoes will dominate the screen and confusing
background noise will be shown.
•
too low, most echoes will be eliminated so most of the useful data will be lost.
Ideally, you should set the gain so that the strongest echoes are close to, or just
touching the thin red vertical line shown on the advanced A-scope screen, which
marks the maximum sonar amplitude.
If you're in fishing mode or cruising mode the sounder adjusts the gain
automatically.
18.2 Change the gain setting
The gain is a fixed line shown on the advanced A-scope screen as a thin red
vertical line. You may find it useful to view this screen while you adjust the gain
setting.
You can adjust the gain settings for the 50 kHz and 200 kHz frequencies
independently of each other.
To change the gain setting:
1. Display the Sounder screen and the control panel. If you can't see the
Gain and Filters button, select Return.
2. Select
Gain and Filters, then select either:
ƒ
200 kHz Gain if you want to adjust the gain setting for the
200 kHz frequency or for a Mixed frequency. The default is 13.
ƒ
50 kHz Gain if you want to adjust the gain setting for the
200 kHz frequency. The default is 17.
3. A slider box appears. The current setting is shown as a line within a
solid box of color and as a number.
4. Drag the line, or use the rotary knob, to change the gain setting.