JRC JMR-5410-6XH - False Echoes; Shadow; Side Lobe Effect

7-7 Section 7 True and False Echoes on Display
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付録
7.4 False Echoes
The radar observer may be embarrassed with some echoes that do not exist actually. These false
echoes appear by the following causes that are well known:
7.4.1 Shadow
When the radar antenna is installed near a funnel or mast, the echo of a target that exists in the
direction of the funnel or mast cannot appear on the radar display because the radar beam is reflected
on the funnel or mast. Whether there are some false echoes due to shadows can be checked
monitoring the sea clutter, in which there may be a part of weak or no returns. Such shadows appear
always in the same directions, which the operator should have in mind in radar operation.
7.4.2 Side lobe effect
A broken-line circular arc may appear at the same range as the main lobe of the radar beam on the
radar display. This type of false echo can easily be discriminated when a target echo appears isolated.
HL
False Echoes
When a radar antenna for the solid-state radar is connected, a false echo may occur in the range
direction of the target image. This false echo normally means a range side lobe, which is generated as
a result of pulse compression processing when a large target such as a vessel is at a short distance.
Range Side Lobe
HL
False echo
False
echo