Furuno FSV85MK2, Manual

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3. VERTICAL MODE
3-10
3.8.3 2nd AGC
While it is ideal to suppress bottom echoes with the AGC alone there are some fishing
grounds where this is not possible. (The high power sonar has the advantage of long-
range detection but this can also be a disadvantage, since weaker echoes may be hid-
den in strong, unwanted echoes such as the bottom.) If you cannot suppress bottom
echoes or sea surface reflections by the AGC function alone, use the 2ND AGC fea-
ture. Normally a setting of 1 or 2 is suitable. For especially strong echoes, use a setting
of 3 or 4.
1. Press the MENU/ESC key to show the main menu.
2. Select [Gain Setting] then push the left-click button.
3. Press the
H/V/S key to select the [V] tab.
4. Select [2nd AGC] then left-click to show the
setting box.
5. Select [2nd AGC] again then push the left-
click button.
6. Select  or  then push the left-click but-
ton to change the setting.
The setting range is 0 to 20. The higher the
setting, the stronger the suppression on
long range.
7. Select [Quit] on the setting box then push
the left-click button to close the box.
8. Long-press the MENU/ESC key to close all menus.
Other AGC-related items on the [2ND AGC] menu
Distance : Set the start range for the 2nd AGC. The setting range is 0 - 2000 m, in 20
m increments. 2nd AGC is inoperative if the display range is lower than the 2nd AGC
start range.
Type : Select the TVG type for 2nd AGC. Select [Normal] for everyday use.
3.8.4 How to shorten pulse length
The pulse length determines the length of the transmission pulse emitted into the wa-
ter. While a longer pulse is advantageous for long-range sounding, it has the disad-
vantage of being poor in discrimination of targets, that is, the ability to separate several
closely located targets. When searching bottom fish, therefore, it is useful to shorten
the pulse length in order to separate fish echoes from bottom reflections. Decrease
the pulse length setting to shorten the pulse length.
Note: When searching for surface or midwater fish in which bottom reflections are not
so strong, use the longest pulse length 9.
1. Press the MENU/ESC key to show the main menu.