3.12 Adjusting The Picture; Displaying Weak Echoes Clearly - Furuno CH-300 Operator's Manual

3. VERTICAL SCAN MODE

3.12 Adjusting the Picture

3.12.1

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 choose MENU and then press ◄ or ► to choose the VERT menu.
MENU
TVG LEVEL
TVG DISTANCE
RES. COLOR
CLUTTER
HORZ SCAN RATE
VERT SCAN RATE
HORZ RANGE
: SELECT
3. Press ▲ or ▼ to choose TVG DISTANCE and then press ► to show the following dialog
box.
TVG DISTANCE
Hi
Lo
200
3-10
COM1 COM2 HORZ
4.0
4.0
LOG
0
1
1
x1
: CHANGE MENU: END
VERT menu
4.0
VERT ES PRESET SYS