Furuno FSV-84 manual Suppressing Bottom Tail

3. VERTICAL MODE

3.8Suppressing Bottom Tail

3.8.1Adjust 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 main menu.

2.Select V-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.

6.Select QUIT at the top of the menu screen and press the [MENU] key to close all menus.

3.8.2Decrease pulse length

The pulse length determines the length of the transmission pulse emitted into the water. While a longer pulse is advantageous for long-range sounding, it has the disadvantage of being poor in discrimination of targets, that is, 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. For search of surface and midwater fish in which bottom reflections are not so strong, use the longest pulse length “9”.

1.Press the [MENU] key to open the main menu.

2.Select the V-SCAN SETTING menu and press the [MENU] key.

3.Select TX PULSELENGTH 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 longer the pulse length.

5.Select QUIT and press the [MENU] key.

6.Select QUIT at the top of the menu screen and press the [MENU] key to close all menus.

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