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:0.000~3.239nm)
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 | (3) Target pushed |
| inward | 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.
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