10
[Tune/Video Auto Adjustment]
Now under correction.
Return to installation setup
menu after the correction.
Figure 22 Tune/video auto
adjustment message
3. When adjustment is completed, the mes-
sage disappears.
5. Aligning heading
You have mounted the scanner unit facing
straight ahead in the direction of the bow.
Therefore, a small but conspicuous target dead
ahead visually should appear on the heading
marker (zero degrees).
In practice, you will probably observe some
small bearing error on the display because of
the difficulty in achieving accurate initial po-
sitioning of the scanner unit. The following
adjustment will compensate for this error.
1. Identify a suitable target (for example, ship
or buoy) at a range between 0.125 to 0.25
nautical miles, preferably near the head-
ing marker. To lessen error, keep echoes
in the outer half of the picture by chang-
ing the range. Also, be sure the zoom and
off center functions are off.
2. Select 9. Heading Alignment on the Instal-
lation Setup menu and press the [ACQ/
ENTER] key. The following message ap-
pears:
[Heading Alignment]
Set EBL1 to center of target
dead ahead and press ENTER.
Correction 0.0
°
<Press MENU for inst setup>
Figure 23 Heading alignment message
3. Operate the trackball to bisect target se-
lected at step 1 with the heading marker.
4. Press the [ACQ/ENTER] key.
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.
6. Adjusting sweep timing
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 scanner unit through the signal
cable to trigger the transmitter (magnetron).
The time taken by the signal to travel up to
the scanner unit varies, depending largely on
the length of the signal cable. During this pe-
riod the display unit should wait before start-
ing 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 – 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 24 Examples of improper and
correct sweep timing
1. Transmit on the shortest range and con-
firm that the [GAIN] and [A/C SEA] con-
trols are properly adjusted.
2. Visually select a target which forms a
straight line (for example, harbor wall,
straight pier).
3. Select 10. Sweep Timing Adjustment on
the Installation Setup menu and press the
[ACQ/ENTER] key. The following mes-
sage appears:
