User's Manual Part 2

Operator Manual
3−10
3748DOC020102 Edition: 14.JAN.2005
It often appears that the radio wave propagation is abnormal (duct effect), when
the object is a very large mountain. If the signal reception level, however, is
small and the transmitted pulse intervals are slightly changed, then a long
cloudy form echo appears as shown in the figure, and can easily be identified.
If it is difficult to identify, reduce the receiver gain (GAIN) slightly. In rare cases,
the guard ring alarm goes off. In this case, check and observe the video echoes,
and reduce the receiver gain, and in case of medium range scale (3, 6, 12 NM)
switch to LONG PULSE or to 24 NM range scale (see Figure: 3−7).
Second trace false echo
Second trace false echo
Atmosphere
Second trace false echo
Out of RangeRadar Range
Figure: 3−7 Second Trace False Echo, Duct Effect