Simrad ME70
Adjusting the TVG gain (backscatter) on the Active menu
Purpose
This procedure explains how to change the Time Varied
Gain (TVG).
The TVG can be chosen using the
Echogram
dialog
box, or with the
TVG
button on the
Active
menu. This
second method is described in this procedure.
Description
TVG means
Time Varied Gain
.
The whole idea with TVG is that echoes from fish shall have the same echo level (colour)
independent of their depths.
The ME70 has a TVG range down to 15 000 meters, which for all practical purposes is
unlimited. The ME70 does not have a TVG compensated receiver like most other echo
sounders. In the ME70 the TVG is made in software after the echoes from the receiver(s)
have been converted to digital format. In order to make this work the receiver must
have very large dynamic range.
The following TVG settings are available:
1
Pr (No TVG)
: Power.
2
Sv (20 log TVG)
: Volume backscattering strength.
3
Sp (40 log TVG)
: Point backscattering strength.
4
TS (40 log TVG)
: Target strength. Only signals accepted as single targets are
displayed. These values are beam compensated.
5
Sp & TS (40 log TVG)
: Point backscattering strength overlaid with target strength
data.
Note
The
TS (40 log TVG)
and
Sp & TS (40 log TVG)
values can not be selected using the
TVG
button on the
Active
menu. To change to these settings, you must use the
Echogram
dialog.
Related topics
•
Selecting TVG gain (Backscatter) in the Echogram dialog box
on page 56
•
on page 97
Procedure
1
Click the
Active
icon.
This icon is located under the
Main
menu. It is
used to open the
Active
menu.
2
Locate the
TVG
button.
3
Method 1:
a
Click [
+
] or [
-
] to choose TVG setting.
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