Suppressing Noise And Interference - Furuno CH-250 Operator's Manual

4. Press or to adjust TVG distance, considering sea conditions. The larger the figure the
greater the distance at which the TVG works.
TVG
Distance 0
Setting
Meters 3
Feet 10
Passi/braza 2
Hiro 2
5. Press or to close the dialog box and return to the VERT menu.
6. To suppress reflections by the sea surface or plankton, select TVG LEVEL and press
7. Press or to adjust TVG LEVEL, considering sea conditions. The larger the figure the
less the gain over distance.
8. Press the [MENU] key to register your selection and close the menu.
Wrong

3.11.2 Suppressing noise and interference

You may encounter occasional or intermittent noise and interference as shown below. This is
mostly caused by electrical equipment, engine, propeller noise from own ship, or noise from
other sonars being operated nearby. If interference appears, turn on the interference rejector in
the COMN menu to suppress it.
0.5 1.0 1.5
8 20 40
30 70 130
5 10 20
5 10 20
Correct
Figure 3-14 Examples of proper and improper TVG
Interference rejector ON
Figure 3-15 Appearance of interference
2.0 2.5 3.0 3.5
60 100 130 160
210 330 410 520
40 60 80 100
40 60 80 100
Level too high
Interference
(In this display,
interference shows
itself every 6˚.)
4.0 4.5 5.0 . . . .
200 250 320 . . . .
660 820 1040
120 150 180
. . . .
130 170 210
Distance too high
10.0
1000
3280
600
660
.
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