Furuno FMD-1712 - Manual (Page 12)

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1.7 Selecting the Range
The range selected automatically
determines the range ring interval, the
number of range rings and pulse repetition
rate.
Press the [+] or [-] key to select a range.
The range and range ring interval appear at
the top left-hand corner on the screen.
045.0
°
3.35 NM
Range
Range ring
interval
6.0 NM
2.0
Figure 1-4 Location of range and range
ring interval indications
1.8 Receiver Sensitivity
The [GAIN] key adjusts the sensitivity of the
receiver. It works in precisely the same
manner as the volume control of a
broadcast receiver, amplifying the signals
received.
You can adjust the sensitivity manually, or
let the unit do it automatically. In either case
the proper setting is such that the
background noise is just visible on the
screen. For manual adjustment, adjust the
sensitivity on the highest range since the
background noise is clearer on that range.
If you set up for too little sensitivity, weak
echoes may be missed. On the other hand
excessive sensitivity yields too much
background noise; weak targets may be
missed because of the poor contrast
between desired echoes and the
background noise on the display.
Automatic adjustment of sensitivity
1. Press the [GAIN] key once or twice to
display the screen shown in Figure 1-5.
AUTO GAIN MOD
LOW HIGH
1 2 3
Figure 1-5 Dialog box for
automatic adjustment of gain
2. Press or to set level desired: 1,
Low; 2, Normal; 3, High.
Manual adjustment of sensitivity
1. Select the highest range.
2. Press the [GAIN] key once or twice to
display the screen shown in Figure 1-6.
MAN GAIN MOD
LOW
HIGH
32
Figure 1-6 Dialog box for
manual adjustment of gain
3. Press or to set level desired. 61
levels are available.
Note: The dialog boxes for adjustment of
sensitivity are automatically erased
when there is no Omnipad operation
for 10 seconds. To erase them
quicker, press the [GAIN] key after
completing the setting.
1.9 Suppressing Sea Clutter
In rough weather, returns from the sea
surface are received over several miles
around own ship and mask nearby targets.
This situation can be improved by properly
using the [STC] key.
If the STC setting is too low, targets will be
hidden in the clutter, while if it is set too high,
both sea clutter and targets will disappear
from the display. In most cases adjust the
key until clutter has disappeared to leeward,
but a little is still visible windward.