Adjusting The Picture - Furuno CH-250 Operator's Manual

3.11 Adjusting the Picture

3.11.1 Displaying weak echoes clearly
Echoes from targets (such as the bottom or a fish) return to the transducer in order of the
distance to them, and when their intensities are compared at the transducer face, those from
nearer targets are generally stronger when their reflecting properties are nearly equal. The
sonar operator will be quite inconvenienced if these echoes are directly displayed on the screen,
since he won't be able to judge the actual size of the target from the size of echoes displayed on
the screen. To overcome this inconvenience, use the TVG function. It compensates for
propagation loss of sound in water: amplification of echoes on short range is suppressed and
gradually increased as range increases, so that similar targets are displayed in similar
intensities irrespective of the ranges to them.
The TVG also functions to suppress unwanted echoes and noise which appears in a certain
range area on the screen.
To adjust TVG:
1. Press the [MENU] key to open the menu.
2. Press to select MENU and then press
MENU
TVG LEVEL
TVG DISTANCE
GAIN ADJUST
RES. COLOR
CLUTTER
HORZ RANGE
: SELECT
3. Press or to select TVG DISTANCE and press
3-10
or
COM1 COM2 HORZ
4.0
4.0
0
LOG
0
x1
: CHANGE MENU: END
Figure 3-13 VERT menu
TVG DISTANCE
GAIN
Hi
Lo 200m
to select the VERT menu.
VERT ES PRESET
to show the following dialog box.
4.0
SYS