How To Reject Sonar Interference And Noise; How To Identify The Noise Source; Interference Rejector; Shift Tx Frequency - Furuno FSV-25 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

The interference rejector suppresses randomly appearing noise, sea surface reflec-
tions, and interference from other acoustic sounding equipment. 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.
4. Click [Int Reject] or [Int Reject (ES)].
• [Int Reject]: Use this item to sup-
press sea surface reflections, and
sea surface reflections.
• [Int Reject (ES)]: Use this item to
suppress interference from other
acoustic sounding equipment.
5. Click
• [Int Reject]: The setting range is 0 to 3. The degree of rejection in ascending
strength is 2, 1, 3. "0" disables the interference rejector.
• [Int Reject (ES)]: Use this item to suppress interference from other acoustic
sounding equipment. The degree of rejection in ascending strength is 1, 2, 3.
"0" disables the interference rejector.
6. Click [Quit] on the setting box to close the box.
7. 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.
3-10
or to change the setting.
Picture Setting
H1 P1
H2 P1
Echo Average
Int Reject
Int Reject (ES)
Smooth Echo RNG
Smooth Echo CIR
2nd Echo Rej.
Quit
V P1
: 3
: 2
: 2
: 2
: 0
: 0