Furuno NAVIONICS GP-1850F - Manual (Page 77)

11-9
4. Select a range, ZOOM RANGE or B/L
RANGE, and press the soft key EDIT.
ZOOM RANGE selects the range to zoom
in the marker and bottom zoom modes.
The setting range is 7 to 5000 feet, and
the default setting is 30 feet. B/L RANGE
sets the expansion width for the bottom-
lock display, 10 or 20 feet. The default
setting is 20 feet.
5. Adjust the range with the cursor pad.
6. Press the soft key RETURN to go back
to the RANGE SETUP menu.
SYSTEM SETUP soft key
The system setup menu provides functions
for selection of fish alarm sensitivity, TX
power selection, TVG adjustment, echo level
offset and seabed echo offset.
1. Press the [MENU] key.
2. Press the soft key SOUNDER SETUP
OPTIONS.
3. Press the soft key SYSTEM SETUP.
DGPS 3D
SYSTEM
SETUP
EDIT
FISH ALM LVL
TX POWER
TVG 200kHz
TVG 50kHz
ECHO OFFSET 200kHz
ECHO OFFSET 50kHz
SEABED LVL 200kHz
SEABED LVL 50kHz NORMAL
ON
5
5
+00
+00
80
80
RETURN
s
Figure 11-16 System setup menu
SYSTEM SETUP menu description
FISH ALM LVL: Sets the fish alarm sensitiv-
ity; namely, which echo strength will trigger
the alarm. HIGH, only the strongest echoes
trigger the alarm; NORMAL, echoes from
strong to medium strength trigger the alarm,
LOW, any echo triggers the alarm. The de-
fault setting is NORMAL.
TX POWER: Turns TX power on/off. The
default setting is ON.
TVG 200kHz, TVG 50kHz: TVG (Time Var-
ied Gain) compensates for propagation at-
tenuation of the ultrasonic waves. It does this
by equalizing echo presentation so that fish
schools of the same size appear in the same
density in both shallow and deep waters. In
addition, it reduces surface noise. Note that
if the TVG level is set too high short range
echoes may not be displayed.
Fish school B
Fish school A
Figure 11-17 TVG concept
ECHO OFFSET 200kHz, ECHO OFFSET
50kHz:
If the on-screen echo level appears to be too
weak or too strong and the level cannot be
adjusted satisfactorily with the gain control,
adjust echo offset to compensate for too weak
or strong echoes. The default setting for both
200 kHz and 50 kHz is zero.
SEABED LVL 200kHz, SEABED LVL
50kHz:
If the depth indication is unstable in automatic
operation or the bottom echo cannot be dis-
played in reddish-brown by adjusting the gain
control in manual operation, you may adjust
the bottom echo level detection circuit, for
both 50 kHz and 200 kHz, to stabilize the in-
dication. Note that if the level is set too low
weak echoes may be missed and if set too
high the depth indication will not be displayed.
The default setting for both 200 kHz and 50
kHz is 80.