Furuno FR-8111 - Manual (Page 39)

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A
B
Guard zone
to set
D
C
Set cursor
on point A
(or B) and
press GUARD
ALARM.
(1) (2)
Set cursor
on point C
(or D).
(3) (4)
Guard zone
A
Press
GUARD
ALARM.
GUARD1
SET
GUARD1
SET
GUARD1
IN
(or GUARD2)
(or GUARD2) (or GUARD2)
(or OUT)
Figure 1-25 How to set the guard alarm
Note: When the radar range is less than one half
of the guard zone range, the guard zone disap-
pears and the indication of active guard zone
(GUARD1 or GUARD2) appears in highlighted
video. If this happens, raise the range to re-display
the guard zone.
Silencing the aural alarm
When a target violates the guard zone, the target
flashes and the aural alarm sounds. You can si-
lence the aural alarm by pressing the GUARD
ALARM
key. When this is done, ACK replaces
IN (or OUT). This means the aural alarm is tem-
porarily deactivated; but, the target still flashes.
Press the key again to reactivate the alarm.
Canceling the guard zone and guard
alarm
Press and hold down the GUARD ALARM key
about two seconds until the guard zone disap-
pears.
1.29 Watch Alarm
The watch alarm works like an alarm clock,
sounding an aural alarm and blinking a visual
indication "T ALM" at the predetermined time
interval. When the alarm sounds, you can silence
it by pressing the AUDIO OFF key.
You can select time interval (3 min, 6 min, 12
min, 15 min, or 20 min) on the TIME ALM menu.
1) Press the MENU key.
2) Select the TIME ALM menu.
3) Press the ENTER/SELECT key.
4) Select TIME ALM and press the ENTER/SE-
LECT key.
5) Select time interval (or OFF).
6) Press the ENTER/SELECT key.
7) Press the MENU key.
1.30 Echo Average
The echo average feature effectively suppresses
sea clutter and other random noise. Echoes re-
ceived from stable targets such as ships (if not
moving at high speeds) appear on the screen at
almost the same position every rotation of the
antenna. On the other hand, unstable echoes such
as sea clutter appear at random positions.
To distinguish real target echoes from sea clutter,
this radar performs scan-to-scan correlation. Cor-
relation is made by storing and averaging echo
signals over successive picture frames. If an echo
is solid and stable, it is shown in its normal in-
tensity. Sea clutter is averaged over successive
scans and reduced in brightness. This makes it
easier to discriminate real targets from sea clut-
ter.
To properly use the echo average feature, first
properly suppress sea clutter with the A/C SEA
control and then select echo average function as
follows;
How to turn on echo averaging
1) Press the MENU key.
2) Select the ECHO SIG menu.