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3. VERTICAL MODE
3.9
Rejecting Interference and Noise
While observing the vertical mode display, 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
Identifying noise source
To eliminate noise effectively, you should first identify the noise source as
follows:
1. Stop transmission from the TEST menu and turn on the power of all on-board
equipment one by one while observing the picture.
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, do 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
conditions. 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] key to open the menu.
2. Select the V-SCAN SETTING menu and press the [MENU] key.
3. Select INT REJECT and press the [MENU] key.
4. Adjust setting from the dialog box as appropriate and press the [MENU] key.
The setting range is 0-3 and the default setting is 0. The higher the setting
the greater the degree of interference rejection.
5. Select QUIT and press the [MENU] key to conclude.
6. Select QUIT at the top of the menu screen and press the [MENU] key to
close all menus.
3.9.3
Noise limiter
Weak, unwanted reflections, colored light-blue or green, appear when the water
is dirty, plankton layers exists, or due to ship's noise. The noise limiter can
reduce the effects of these unwanted reflections. Raising the setting causes
unwanted reflections to become colors of blue to background color. Normally a
setting of 3 or 4 is sufficient.
1. Press the [MENU] key to open the menu.
2. Select the V-SCAN SETTING menu and press the [MENU] key.
3. Select NOISE LIMITER and press the [MENU] key.
3-10
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Troubleshooting
