NorthStar Navigation NorthStar 8000i - Manual (Page 110)

110 Northstar 8000i Operation Manual
This option is available only on the split zoom, the split bottom lock, and the split
50/200 screens. The 8000i must be displaying one of these Sounder screens.
If you want to change the ratio of an A-Scope screen (see "Change the ratio of the
A-Scope" page 111), .
To change the ratio of the split screens:
1. Display the Sounder screen and the control panel. If you can't see the
Range, Zoom and Split button, select Return.
2. Select
Range, Zoom and Split.
3. The
Split Ratio button shows the current setting. Select the button
if you want to change the current setting.
4. Select
Increase or Decrease to change the ratio of the split
screens.
5. The new setting is applied immediately and stays until you change it
again.
6. Select
OK to confirm the new setting.
7. When you are finished, select Return.
16.18 What is the A-Scope?
You can use the A-Scope to analyze the sonar echoes in detail, so that you can
optimize the gain (see "What is gain?" page 115)and the gain threshold levels (see
"What is the gain threshold?" page 116) for the current sonar frequency.
The A-Scope appears in the right side of your Sounder screen as a vertical column
of multi-colored, horizontal lines that are constantly moving. It shows a real-time
image of each sonar pulse.
The length of each horizontal line shows the strength of the echo at that particular
depth.
You can show or hide A-Scope. If you show the A-Scope, you can select a standard
or an advanced A-Scope.
The standard A-Scope shows the:
•
strong echoes as long horizontal lines
•
weak echoes as short horizontal lines
The advanced A-Scope also shows:
•
a static thin red vertical line showing the maximum sonar amplitude. You can't
change this. Any echoes that exceed this maximum are always shown in red
•
a white (or black) thin vertical line showing the selected minimum amplitude,
which controls the range of colors displayed. You can change this with the
gain threshold. Any echoes that don't reach this minimum are shown in the
background color of the current palette
•
a color bar at the top of the A-scope, showing the colors associated with each
sonar amplitude. You can change the width of the colors with the gain setting.