Furuno FSS-3BB, Руководство оператора

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1. OPERATION
1-33
1
1.26 How to Adjust TVG (Time Varied Gain)
A school of fish at a deep depth is displayed in weak colors even if it is equal in
strength to one in shallow waters. This is due to propagation attenuation of the ultra-
sonic wave. To compensate for this difference, use TVG. TVG automatically adjusts
the gain with depth so that echoes of the same strength and different depths are
shown in the same colors regardless of their depths. The gain is increased with depth
to display echoes of equal strengths in the same colors. In the figure below, for exam-
ple, the TVG is set for 100 m and the TVG level is adjusted. Then, unwanted echoes
at a distance less than 100 m are deleted and echoes at depths greater than 100 m
are not affected.
1. Click the [Advanced Settings] icon ( ) from the InstantAccess bar™, then click
the [Advanced Settings] icon ( ) to show the [Advanced Settings] window.
2. Click the [Sounder] menu, then click [HF] or [LF] as appropriate. The example il-
lustration below shows the HF menu (the contents of the LF menu are the same).
3. Use the buttons ( ) for [TVG Level] to adjust the TVG level. (You can also ad-
just the level by using the software keyboard.) A higher setting reduces the gain
for nearby echoes.
4. Use the buttons ( ) for [TVG Distance] to set the TVG distance. (You can also
adjust the distance by using the software keyboard.)
5. Click [OK] to save the current changes and close the menu window.
Click [Cancel] to abort all changes and close the menu window.
TVG OFF:
Schools of fish of equal strengths
shown in different sizes and colors.
TVG adjusted:
Schools of fish of equal strengths
shown in same sizes and colors.
Unwanted echoes appear. Unwanted echoes suppressed.
0 m
100 m
0 m
100 m
FSS-3BB [ 025470-xx.xx]