Furuno GP-1600F - Manual (Page 57)

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3.4 Manual Video Sounder Operation
Manual operation is useful for observing fish schools and the sea-
bed using fixed gain setting.
The gain, range and range shifting functions used together give
you the means to select the depth you can see on the screen. The
basic range can be thought of as providing a "window" into the
water column and the range shifting as moving the "window" to
the desired depth.
Figure 3-10 Basic range and range shifting concept
Manually adjusting the video sounder picture
1) Press the [AUTO] key to display the AUTO MODE menu.
2) Press the [▼] key to select "Manual."
AUTO MODE
▲ Cruise
Fish
▼
Manual
Low High
▲ Gain
Range 15 30 60
120 200 400 800 ft
▼ Shift 60 ft
Figure 3-11 Gain, range and shift adjustment display
3) Press the [▼] key to select Gain.
Normally, set the gain to the point where excessive noise does
not appear on the screen. As a general rule of thumb, use a
higher gain setting for greater depths and a lower setting for
shallower waters. See Figure 3-12 for examples of proper and
improper gain settings.