8 sweep timing, 9 closing the installation menus, Press the [menu] key and turn off the power – Furuno 841 User Manual
Page 54
43
6) As a final test, move the boat towards a
small buoy and confirm that the buoy
shows up dead ahead on the radar when
it is visually dead ahead.
5.8 Sweep Timing
This adjustment ensures proper radar per-
formance, especially on short ranges. The
radar measures the time required for a trans-
mitted echo to travel to the target and return
to the source. The received echo appears on
the display based on this time. Thus, at the
instant the transmitter is fired, the sweep
should start from the center of the display
(sometimes called sweep origin.)
A trigger pulse generated in the display unit
goes to the antenna unit through the signal
cable to trigger the transmitter (magnetron).
The time taken by the signal to travel up to
the antenna unit varies, depending largely
on the length of signal cable. During this
period the display unit should wait before
starting the sweep. When the display unit is
not adjusted correctly, the echoes from a
straight local object (for example, a harbor
wall or straight pier) will not appear with
straight edges—namely, they will be seen
as “pushed out” or “pulled in” near the pic-
ture center. The range of objects will also
be incorrectly shown.
m
e
t
I
L
E
D
O
M
1
2
8
L
E
D
O
M
1
4
8
s
k
r
a
m
e
R
n
o
r
t
e
n
g
a
M
t
n
e
r
r
u
c
5
#
4
0
8
P
T
V
1
.
2
-
7
.
1
5
#
3
0
8
P
T
V
1
.
1
-
9
.
0
g
n
o
l
,
x
T
e
g
n
a
r
n
o
r
t
e
n
g
a
M
r
e
t
a
e
h
e
g
a
t
l
o
v
6
#
4
0
8
P
T
V
1
.
8
-
9
.
7
4
#
3
0
8
P
T
V
6
.
7
-
4
.
7
y
b
-
d
n
a
t
S
V
H
7
#
4
0
8
P
T
V
9
.
8
-
9
.
7
1
#
3
0
8
P
T
V
0
3
3
-
0
9
2
g
n
o
l
,
x
T
e
g
n
a
r
Table 5-1 Voltage ratings (reference for installer)
(1) Correct
(2) Target pushed
inward
(3) Target pushed
outward
Figure 5-21 Examples of improper and
correct sweep timings
1) Transmit the radar on the shortest range
and adjust the sensitivity and STC.
2) Visually select a straight echo (harbor
wall, straight pier).
3) Display the Installation Setup 2 menu
and select Adjust Sweep Timing.
5) While looking at the target selected at
step 2, press cursor pad at the 9 o’clock
or 3 o’clock position to straighten the tar-
get.
6) Press the [ENT] key.
5.9 Closing the Installation
Menus
Press the [MENU] key and turn off the
power.