Shift Tx Frequency; How To Reject Sonar Interference And Noise; How To Identify The Noise Source; Interference Rejector - Furuno FSV-25S Operator's Manual

3. VERTICAL MODE
3.9

How to Reject Sonar Interference and Noise

While observing the sonar picture, you may encounter occasional or intermittent noise
and interference. These are mostly caused by on-board electronic equipment, engine
or propeller noise, or electrical noise from other sonars being operated nearby.
3.9.1

How to identify the noise source

To eliminate noise effectively, you should first identify the noise source as follows:
1. On the [Test] menu, turn off [TX] to stop transmitting. Turn on all on-board elec-
tronic equipment one by one while observing the picture. If noise appears on the
sonar display, that equipment is emitting noise. Check the offending equipment's
ground and installation.
2. Run the boat at various speeds to check if the noise is speed dependent.
If neither of the above two steps has effect on the picture, adjust one of the following:
3.9.2

Interference rejector

This control is similar to the interference rejector on echo sounders and radars. It is
effective for rejecting random noise and sea surface reflections in rough sea condi-
tions. Set it so that noise is just eliminated. Do not use an unnecessarily high setting
since it may also reject small wanted echoes.
1. Press the MENU/ESC key to show the
main menu.
2. Click [Picture Setting].
3. Press the H/V/S key to select the [V]
tab, then click [Int Reject].
4. Click
setting range is 0 to 3. The degree of
rejection in ascending strength is 2, 1,
3. "0" disables the interference rejector.
5. Click [Quit] on the setting box to close the box.
6. Long-push the MENU/ESC key to close all menus.
3.9.3

Shift TX frequency

If the interference can not be suppressed by the interference rejector or change in TX
interval, shift the Tx frequency with the [Freq Shift] menu.
1. Press the MENU/ESC key to show the main menu.
2. Click [TX/RX Setting].
3. Press the H/V/S key to select the [V] tab, then click [Freq Shift].
4. Click
5. Click [Quit] on the setting box to close the box.
6. Long-push the MENU/ESC key to close all menus.
3-10
or to change the setting The
or to change the setting, among [Low], [Mid], [High].
Picture Setting
H1 P1
H2 P1
Echo Average
Int Reject
Smooth Echo RNG
Smooth Echo CIR
Quit
V P1
: 3
: 2
: 2
: 0