Furuno 1942 MARK-2 - Manual (Page 15)

2-3
Note1: Availability of a particular display item
depends on incoming data.
Note2:
When Range to Waypoint reaches 0.1
nm, the WPT marker jumps to dead ahead
even though a difference may exist between
heading and BRG to WPT.
Note3: When cross track error exceeds 1 nm
on either side, the XTE mark starts blinking.
2.5 Selecting the Range
The range selected automatically determines
the range ring interval, the number of range
rings, pulselength and pulse repetition rate,
for optimal 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 cor-
ner of the display.
To select a range;
Press the [- RANGE +] key . The range and
range ring interval appear at the top left cor-
ner of the display.
Tips for selecting the range
¡ When navigating in or around crowded
harbors, select a short range to watch for
possible 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.
2.6 Adjusting Picture Brilliance
The [BRILL] key adjusts the brilliance of the
radar picture in sixteen levels. The current
level momentarily appears on the screen
whenever the [BRILL] key is pressed.
2.7 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 back-
ground noise is just visible on the screen. If
you set up for too little sensitivity, weak ech-
oes may be missed. On the other hand ex-
cessive sensitivity yields too much
background noise; strong targets may be
missed because of the poor contrast 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.
2.8 Adjusting the A/C SEA
Control
(reducing sea clutter)
Echoes from waves can be troublesome, cov-
ering the central part of the display with ran-
dom signals known as “sea clutter .” The
higher the waves, and the higher the scan-
ner above the water , the further the clutter
will extend. Sea clutter appears on the dis-
play as many small echoes which might af-
fect radar performance. (See the left-hand
figure in Figure 2-3.) 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 amplifi-
cation of echoes at short ranges (where clut-
ter is the greatest) and progressively
increases amplification as the range in-
creases, so amplification will be normal at
those ranges where there is no sea clutter.