25
20. Choose TUNING and then press the EDIT soft key.
TUNING
▲
{
ON
~
OFF
▼
21. Choose ON and then press the ENTER soft k ey. Then, the radar’s video and tuning are
automatically adjusted.
22. After tuning has been completed, choose TIMING ADJUST and then press the EDIT
soft key.
TIMING ADJUST
▲
{
ON
~
OFF
▼
This adjustment ensures proper radar perf or m ance, 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 t he display based on this time. Thus, at the
instant the transmitter is fired, t he 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 largel y on the length of signal cable. During this
period the display unit should wait befor e s tarting the sweep. When the display unit is
not adjusted correctly , the echoes from a straight local object (for example, a har bor wall
or straight pier) will not appear with straight edges – namely, they will be seen as
“pushed out” or “pulled in” near the picture c enter. The range of objects will also be
incorrectly shown.
(3) Target pushed
outward
(2) Correct
(1) Target
pulled
Examples of improper and correct sweep timing a) Choose ON and then press the ENTER soft key.
b) Transmit on the shortest range and confi rm that gain and A/C SEA are properly adjusted.
c) Visually select a target w hich forms straight line (harbor wall, straight piers).
d)
Rotate the ENTER knob to straighten the target selec ted at step b), and then press the
ENTER knob to finish.