Furuno FCV-668 Operator's Manual page 12

2.3.2 Display mode description
NORM display
The normal display appears on the full screen. This mode is
useful for general observation of the seabed and fish schools.
M/Z (Marker Zoom) mode
The marker zoom mode expands selected
area of the normal picture to full vertical size
of the screen on the left-half window. You may
specify the portion to expand with the VRM
(Variable Range Marker), which you can shift
with [ ] or [ ]. The area between the VRM
and the zoom range marker is expanded. The
length of the segment is equal to one division
of the depth scale.
2-2
49.6
15
14.7
Fish
school
20
Z o o m e d f i s h
s c h o o l
25
28.2
Marker-zoom
display
0.0
Fish
school
Bottom
0
Normal
display
10
Variable range
marker (green)
20 This section
is zoomed
30
40
Zoom marker
(yellow)
0
20
40
60
80