Suppressing Bottom Tail - Furuno FSV-30 Operator's Manual

2. HORIZONTAL MODE
When a fish school is located on a long range setting (about 800 meters)
and is approaching own ship do as follows:
Adjust the tilt to keep the fish school in the center of the sonar beam, namely,
fish school is displayed in strongest colors possible. Confirm that the fish
echo is displayed in the same color as it approaches. If the color suddenly
changes to weaker colors as the fish enters MEDIUM and NEAR areas, the
TVG is improperly set. Adjust the TVG. If this again produces sea surface
reflections and noise try to remove them with the AGC and noise limiter.
Note: If the above procedure does not produce satisfactory results, the
2.7

Suppressing Bottom Tail

2.7.1 AGC
The AGC functions to automatically reduce the receiver gain only against strong
echoes such as the bottom or a large fish school. Since weak echoes remain
unaffected, a small fish school becomes easier to detect. Adjust it so that the
AGC works only on bottom reflections. Do not set it too high; weak echoes may
be missed.
1. Press the [MENU] key to open the menu.
2. Select H-SCAN SETTING menu and press the [MENU] key.
3. Select AGC and press the [MENU] key.
4. Adjust setting from the dialog box as appropriate and press the [MENU] key.
The setting range is 0-9. The higher the setting the greater the degree of
suppression.
5. Select QUIT and press the [MENU] key to conclude.
6. Select QUIT at the top of the menu screen and press the [MENU] key to
close all menus.
2-14
TVG curve can be changed on the OTHERS sub menu in the H-SCAN
SETTING menu. Also, adjust the setting of NEAR AGC, referring to
next section.