Furuno FSV-75, Operator'S Manual

Page: 87 / 235

3. VERTICAL SLANT MODE
3-9
3.6.4 Noise suppression
Removing or suppressing noise from weak echoes such as surface reflections, plank-
ton and distant seabeds can help you clear the display. The noise suppression func-
tion adjusts the gain level for weak echoes only, leaving echoes schools of fish
unadjusted.
1. Open the menu.
2. Select [2 Gain Setting], then left-click.
3. Select [9 Noise Suppression], then left-click.
4. Left-click the
S or T button to select the desired setting.
The available setting range is [0.0] to [10.0]. The higher the setting value, the high-
er the reduction. Adjust this setting with caution to avoid smaller schools of fish
being hidden.
5. Select [Quit], then left-click.
6. Close the menu.
3.7 How to Suppress Bottom and Sea Surface Re-
flections in Shallow Waters
In shallow fishing grounds with hard or rocky bottom, bottom reflections often interfere
with wanted fish echoes and they can not be eliminated sufficiently with the aforemen-
tioned TVG and AGC functions, especially when the TILT is set to a larger angle in
order to track schools of fish approaching within 400 m. In such cases try to reduce
the output power by adjusting the Tx output instead of turning down the gain. The pic-
ture becomes clearer when output power is reduced rather than when the GAIN is de-
creased as illustrated below.
How to reduce the TX power
1. Open the menu.
2. Select [1 TX/RX Setting], then left-click.
3. Select [3 Transmission Power], then left-click.
TVG and AGC
adjusted with
TX POWER kept high
Fish echo
Reduce TX POWER
with TVG and AGC
kept constant
INCORRECT METHOD
CORRECT METHOD
Fish echo
Fish echo
weakened