Furuno CH-37 - Manual (Page 51)

3-7
Function Procedure/Purpose
Trackball
Data
1) Position the trackball marker on the desired location.
2) Read the trackball data displayed at the upper left corner
of the screen.
Trackball data
Trackball marker
Horizontal Range
Depth
3.8 Applying Proper TVG
The TVG function is the same as the one explained in the so-
nar mode. For best results, set both TVG level and time a little
lower than the ones in the sonar mode. The setting is mode on
the BOTTOM/3D menu screen and the usual setting for both
time and level is 3.
MENU : SONAR BOTTOM/3D DUAL E/S
TVG LEVEL : 3.0
TVG TIME : 3.0
BEAM WIDTH : NAR
Figure 3-7 Bottom/3D menu screen
TVG level rejects surface noise, which may mask shallow tar-
gets and TVG time adjusts the effective depth.
Level too low Proper Level too high Time to high
Figure 3-8 Examples of proper and improper TVG