3) Sweep timing
This adjustment ensures proper radar performance, 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 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 antenna 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 picture center. The range of objects will also be incorrectly shown.
Correct | Target pushed | Target pushed |
| inward | outward |
Figure 24 Examples of improper and
correct sweep timings
1.Transmit the radar on 0.125 or 0.5 nm range and adjust the sensitivity and STC.
2.Visually select a straight echo (harbor wall, straight pier).
3. Press and for 10 seconds to show the installation menu.
4.Select ADJ TMG on the menu.
SEL MENU | TOTAL ON TIME | |
▼ ▲ | 00000 : 00 | |
BY / KEY | TOTAL TX TIME | |
1. ADJ HDG | ||
00000 : 00 |
2.ADJ TMG
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3. | NM | /KM |
IDENTIFY STRAIGHT TA | RGET | ||
SUCH AS BREAKWATER. MAKE | |||
ITS ECHO STRAIGHT ON SCREEN | |||
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USING / | ▲ | KEYS. | |
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Figure 25 Installation menu, ADJ TMG selected
4.While looking at the target selected at step
2, straighten it by pressing | if it is pulled | |
inward, or | if it is pushed outward. | |
4)Unit of range measurement for VRM and cursor
The unit of range measurement for the VRM and the cursor may be selected to nautical mile or kilometers as follows:
1.Select NM/KM on the menu.
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NAUTICAL MILE OR KILOMETER
AS THE UNIT OF RANGE.
Figure 26 Installation menu, NM/KM selected
2.Select unit of range desired.
3.Press the [MENU] key to close the
installation menu.
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