Furuno 851 MARK-2 - Manual (Page 15)

2-6
Adjusting FTC
To suppress rain clutter from heavy storms
or scattered rain clutter, adjust the FTC
among 0, 1 and 2 (0 is off). The FTC circuit
splits up these unwanted echoes into a
speckled pattern, making recognition of
solid targets easier. FTC and selected level
appear at the top right-hand corner of the
display when the circuit is turned on.
Note: In addition to reducing clutter, the
FTC can be used in fine weather to
clarify the picture when navigating in
confined waters. However, with the
circuit activated the receiver is less
sensitive. Therefore, turn off the
circuit when its function is not
required.
2.9 Tuning the Receiver
The receiver can be tuned automatically or
manually. For automatic tuning the receiver
is tuned each time you switch from stand-
by to transmit. For manual tuning, the
receiver is properly tuned when the longest
tuning indicator appears. (However, the
length of the indicator changes with the
number of radar echoes, range and other
factors.)
1.5
NM
0.5
AUTO
Tuning
indicator
Figure 2-7 Tuning indicator
Note:When you switch from manual to
automatic, wait 4 seconds before
closing the MENU. Otherwise
automatic tuning may not work
properly.
Manual tuning
The default tuning method is automatic. To
switch to manual tuning;
1. Press the [MENU] key to open the
menu.
2. Press the omnipad at 6 o’clock to
select Tuning.
3. Press the omnipad at 3 o’clock to
select MANUAL.
4. Press the [ENT] key followed by the
[MENU] key.
How to tune manually
While pressing and holding down the [HM
OFF] key, press the 9 o'clock or 3 o'clock
position on the omnipad to tune. Tune to
show the longest tuning indicator.
2.10 Measuring the Range
You can measure the range to a target
three ways: by the range rings, by the
cursor, and by the VRM (Variable Range
Marker).
By range rings
Press the [RINGS] key to display the range
rings. Count the number of rings between
the center of the display and the target.
Check the range ring interval (at the top left
corner) and judge the distance of the echo
from the inner edge of the nearest ring.
By cursor
Operate the omnipad to place the cursor
intersection on the inside edge of the target
echo. The range to the target, as well as
the bearing, appears at the bottom of the
display.