Furuno FSV-84 manual Rejecting Sonar Interference and Noise, Identifying noise source

2. HORIZONTAL MODE

2.9Rejecting 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.

2.9.1Identifying noise source

To eliminate noise effectively, you should first identify the noise source as follows:

1.Stop transmission on the TEST menu, by turning ON “TX” in the TEST menu, and turn on the power of all on-board 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:

2.9.2Interference 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 H-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. The higher the setting the greater the degree of interference rejection.

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.

2-21