Furuno FR-8122 - Manual (Page 33)

3. SETTING UP THE EQUIPMENT
3-5
Manual Timing Adjust
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 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 picture center. The range of objects will also be incorrectly shown.
(1) Target pulled (2) Correct (3) Target pushed outward
Examples of improper and correct sweep timing
1. Transmit on the shortest range and confirm that gain and A/C SEA are properly
adjusted.
2. Visually select a target which forms a straight line (harbor wall, straight piers).
3. Open the Installation menu and choose Manual Timing Adjust.
4. Press the
ENTER key to show the setting window.
5. Rotate the trackball to straighten the target selected at step 2, and then press the
ENTER key to finish.