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5. 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.
Adjusting sweep timing
(Adjustment range:0.000~4.266nm)
This adjustment ensures proper radar perfor-
mance, especially on short ranges. The radar
measures the time required for a transmitted
echo to travel to the target and return to the
source. The received echo appears on the dis-
play 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 ad-
justed 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 picture center. The
range of objects will also be incorrectly
shown.
(1) Correct
(2) Target pushed
inward
(3) Target pushed
outward
Figure 6-24 Examples of improper and
correct sweep timing
1. Transmit on the shortest range and confirm
that the [GAIN] and [A/C SEA] controls
are properly adjusted.
2. Visually select a target which forms straight
line (harbor wall, straight pier).
3. Select “10. Sweep Timing Adjustment” on
the installation setup menu and press the
[ACQ/ENTER] key. The message appears.
[ Sweep Timing Adjustment ]
Use omnipad to straighten
target and press ENTER key.
Correction 0.000 nm
<Press MENU for inst setup>
Figure 6-25 Sweep timing adjustment
message
4. Operate the omnipad to straighten the tar-
get selected at step 2, and then press the
[ACQ/ENTER] key.
Adjusting MBS
(Adjustment: 0.00~0.25)
Main bang (black hole), which appears at the
display center on short ranges, can be sup-
pressed as follows.
1. Transmit on long range about 10 minutes.
2. Adjust the gain to show a small amount of
noise on the display.
3. Change to the 0.125 nautical mile range
and adjust the [A/C SEA] control.
4. Select “11. MBS adjustment” on the instal-
lation setup menu.
5. Press the [ACQ/ENTER] key. The follow-
ing message appears.
[ MBS Adjustment ]
Set value by omnipad
and press ENTER key.
Correction 000
<Press MENU for inst setup>
Figure 6-26 MBS Adjustment message
6. Operate the omnipad to suppress main
bang. (left: low, right: high, between 0 and
25)
7. Press the [ACQ/ENTER] key.