6.4 FALSE ECHOES
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6.4
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:
[I] Shadow
When the radar scanner 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
returns, 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.
[II] 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. (See
Figure 6.3)
Figure 6.3
[III] False Echo by Secondary Reflection
When a target exists near own ship, two echoes from the single target may appear on the radar display.
One of those echoes is the direct echo return from the target and the other is the secondary reflection return
from a mast or funnel that stands in the same direction as shown in Figure 6.4.
Direct microwave
Actual target
Radar scanner
False echo from funnel
Secondary reflection
of microwave
Funnel
Figure 6.4
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Summary of Contents for JMA-5206
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Page 31: ... xxv Environ mental Protection ENVIRONMENTAL PROTECTION ...
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Page 39: ...1 6 1 4 EXTERIOR DRAWINGS y 1 Fig 1 1 Exterior Drawing of Scanner Unit Type NKE 2062 HS ...
Page 40: ...1 7 Fig 1 2 Exterior Drawing of Scanner Unit Type NKE 2102 4 ...
Page 41: ...1 8 1 4 EXTERIOR DRAWINGS y 1 Fig 1 3 Exterior Drawing of Scanner Unit Type NKE 2102 6 ...
Page 42: ...1 9 Fig 1 4 Exterior Drawing of Scanner Unit Type NKE 2252 7 ...
Page 43: ...1 10 1 4 EXTERIOR DRAWINGS y 1 Fig 1 5 Exterior Drawing of Scanner Unit Type NKE 2252 9 ...
Page 44: ...1 11 Fig 1 6 Exterior Drawing of Monitor Unit Type NWZ 164 ...
Page 45: ...1 12 1 4 EXTERIOR DRAWINGS y 1 Fig 1 7 Exterior Drawing of Processor Unit Type NDC 1340 ...
Page 46: ...1 13 Fig 1 8 Exterior Drawing of Keyboard Unit Type NCE 7699 ...
Page 47: ...1 14 1 4 EXTERIOR DRAWINGS y 1 Fig 1 9 Exterior Drawing of NSK Unit Type NCT 4106 ...
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Page 345: ...8 44 8 5 Adjustments yyyy yyyy 8 Exit 1 Press RADAR MENU key The Main Menu will reappear ...
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Page 403: ...SECTION 9 AFTER SALES SERVICE ...
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Page 438: ...Figure 7 Key board unit NCE 7699 Inter connection Diagram ...
Page 439: ...APPENDIX Figure 8 JMA 5200 On screen controls ...
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