Selecting The Range; Adjusting Picture Brilliance; Adjusting Receiver Sensitivity; Adjusting The A/C Sea Control (Reducing Sea Clutter) - Furuno Marine Radar Operator's Manual

Note 1: Availability of a particular display item
depends on incoming data.
Note 2: When Range to Waypoint reaches 0.1
nm, the WPT mark jumps to dead
ahead even though a difference may
exist between heading and BRG to
WPT.
Note 3: When cross track error exceeds 1 nm
on either side, the XTE mark starts
blinking.

2.6 Selecting the Range

The range selected automatically determines the
range ring interval, the number of range rings,
pulselength and pulse repetition rate, for opti-
mal detection capability in short to long ranges.
You can select which ranges and pulselength
(for 1.5 and 3 mile ranges) to use through the
menu. The range, range ring interval and
pulselength appear at the top left-hand corner
of the display.
To select a range;
Press the [- RANGE +] key. The range and range
ring interval appear at the top left corner on the
display.
Tips for selecting the range
¡ When navigating in or around crowded har-
bors, select a short range to watch for pos-
sible collision situations.
¡ If you select a lower range while on open
water, increase the range occasionally to
watch for vessels that may be heading your
way.

2.7 Adjusting Picture Brilliance

The [BRILL] key adjusts the brilliance of the
radar picture in sixteen levels.
Press the [BRILL] key to set the brilliance level.
The current level momentarily appears on the
screen.
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2.8 Adjusting Receiver Sensitivity

The [GAIN] control 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.
The proper setting is such that the background
noise is just visible on the screen. If you set up
for too little sensitivity, weak echoes may be
missed. On the other hand excessive sensitivity
yields too much background noise; strong tar-
gets may be missed because of the poor con-
trast between desired echoes and the
background noise on the display.
To adjust receiver sensitivity, transmit on long
range, and adjust the [GAIN] control so back-
ground noise is just visible on the screen.
2.9 Adjusting the A/C SEA
Control (reducing sea
clutter)
Echoes from waves can be troublesome, cover-
ing the central part of the display with random
signals known as "sea clutter." The higher the
waves, and the higher the scanner above the
water, the further the clutter will extend. Sea
clutter appears on the display as many small
echoes which might affect radar performance.
(See the left-hand figure in Figure 2-4.) When
sea clutter masks the picture, adjust the A/C SEA
control to reduce the clutter.
How the A/C SEA control works
The [A/C SEA] control reduces the amplifica-
tion of echoes at short ranges (where clutter is
the greatest) and progressively increases am-
plification as the range increases, so amplifica-
tion will be normal at those ranges where there
is no sea clutter.