Chapter 3
TRUE AND FALSE ECHOES ON DISPLAY
3.4
FALSE ECHOES
3-6
Fig. 3.4-2
Radar
scanner
Funnel
HL
Direct microwave
Secondary reflection
of microwave
Actual target
False echo from funnel
3.4.4
FALSE ECHO BY MULTIPLE REFLECTION
When there is a large structure or ship with a high vertical surface near own ship as
shown in Fig. 3.4-3, multiple refection returns may appear on the radar display. These
echoes appear in the same intervals, of which the nearest echo is the true echo of the
target.
Fig. 3.4-3
HL
3.4.5
SECOND TIME ECHOES
The maximum radar detection range depends upon the height of the scanner and the
height of a target as described in the Section "3.1 RADAR WAVE WITH THE
HORIZON". If a so-called "duct" occurs on the sea surface due to a certain weather
condition, however, the radar beam may propagate to a abnormally long distance, at
which a target may be detected by the radar.
For instance, assuming that the pulse length is MP3 (on the repetition frequency of 1400
Hz), the first pulse is reflected from a target at about 58 NM or more and received during
the next pulse repetition time. In this case, a false echo (second time echo) appears at a
position that is about 58 NM shorter than the actual distance. If the false echo appears at
5 NM on the radar display, the true distance of the target is 5+58=63 NM. On the pulse
Summary of Contents for JMA-3300 Series
Page 2: ......
Page 16: ...WARNING LABEL MOUNTING POINT xiv NCD 2182 Display Unit ...
Page 17: ...WARNING LABEL MOUNTING POINT xv NBA 5111 Power Supply NBD 865 Rectifier unit ...
Page 30: ...GLOSSARY xxviii ...
Page 46: ...Chapter 1 GENERAL AND EQUIPMENT COMPOSITION 1 5 GENERAL SYSTEM DIAGRAMS 1 16 ...
Page 244: ...Chapter 4 MAINTENANCE 4 6 TROUBLE SHOOTING 4 36 ...
Page 266: ...APPENDIX APPENDIX 2 Fig A2 NKE 2043 SCANNER INTERCONNECTION DIAGRAM ...
Page 268: ...APPENDIX APPENDIX 4 Fig A4 NKE 2062HS SCANNER INTERCONNECTION DIAGRAM ...
Page 271: ...APPENDIX APPENDIX 7 APPENDIX INSTRUCTION MANUAL LJ 1 6 6 11 5 17 5 211 7 21 5 0 ...
Page 272: ...APPENDIX APPENDIX 8 Fig A8 NKE 2063AHS SCANNER INTERCONNECTION DIAGRAM ...
Page 274: ...APPENDIX APPENDIX Fig A NCD 2182 DISPLAY UNIT INTERCONNECTION DIAGRAM ...
Page 276: ...APPENDIX APPENDIX 1 Fig A1 JMA 3314 INTERCONNECTION DIAGRAM ...
Page 277: ...APPENDIX APPENDIX 1 APPENDIX INSTRUCTION MANUAL Fig A1 JMA 3334 INTERCONNECTION DIAGRAM ...
Page 278: ...APPENDIX APPENDIX 1 Fig A1 JMA 3316 HS INTERCONNECTION DIAGRAM ...
Page 280: ...APPENDIX APPENDIX 1 Fig A1 JMA 3340 4 4HS 6 6HS INTERCONNECTION DIAGRAM ...
Page 297: ......
