3. Radar Observation
3-3
3.2 False
Echoes
Occasionally echo signals appear on the screen at positions where there is no target or disappear even if there are
targets. They are, however, recognized if you understand the reason why they are displayed. Typical false echoes are
shown below.
Multiple echoes
Multiple echoes occur when a transmitted pulse returns from a
solid object like a large ship, bridge, or breakwater. A second, a
third or more echoes may be observed on the display at double,
triple or other multiples of the actual range of the target as shown
below. Multiple reflection echoes can be reduced and often
removed by decreasing the gain (sensitivity) or properly adjusting
the A/C SEA control.
Sidelobe echoes
Every time the radar pulse is transmitted, some radiation escapes
on each side of the beam, called sidelobes. If a target exists where
it can be detected by the side lobes as well as the main lobe, the
side echoes may be represented on both sides of the true echo at
the same range. Side lobes show usually only on short ranges and
from strong targets. They can be reduced through careful
reduction of the gain or proper adjustment of the A/C SEA
control.
Spurious
target
True echo
Main-lobe
Side-lobe
Antenna
Virtual image
A relatively large target close to your ship may be represented at
two positions on the screen. One of them is the true echo directly
reflected by the target and the other is a false echo which is
caused by the mirror effect of a large object on or close to your
ship as shown in the figure below. If your ship comes close to a
large metal bridge, for example.
Shadow sectors
Funnels, stacks, masts, or derricks in the path of the antenna block
the radar beam. If the angle subtended at the antenna is more than
a few degrees, a non-detecting sector may be produced. Within
this sector targets can not be detected.
Содержание FCR-2107 series
Страница 42: ...1 Operational Overview 1 20 This page intentionally left blank...
Страница 73: ...2 Radar Operation 2 31 ROUGH SEA SHIP HARBOR COAST Picture setup options and default settings con t...
Страница 154: ...5 AIS Operation 5 28 This page intentionally left blank...
Страница 253: ...7 Vector Chart Material 7 81 More information is available in text More information is available as a picture...
Страница 255: ...7 Vector Chart Material 7 83 Recommended track defined by two beacons...
Страница 256: ...7 Vector Chart Material 7 84 Recommended track defined by a building and a beacon...
Страница 257: ...7 Vector Chart Material 7 85 Measurement mile tails tails...
Страница 279: ...8 Manual Updates 8 19 12 10 11 9 13 7 8 Set positions with cursor and push left mouse button Click Accept button...
Страница 298: ...9 Chart Alerts 9 14 This page intentionally left blank...
Страница 322: ...10 Route Planning 10 24 This page intentionally left blank...
Страница 368: ...14 Backup Operations 14 6 This page intentionally left blank...
Страница 404: ...16 Recording Functions 16 16 This page intentionally left blank...
Страница 406: ...17 NAVTEX Messages 17 2 This page intentionally left blank...
Страница 416: ...19 Parameters Setup 19 8 This page intentionally left blank...
Страница 456: ...Appendix 2 IHO ECDIS Chart 1 AP 4 Information about the chart display 1 Information about the chart display 2...
Страница 457: ...Appendix 2 IHO ECDIS Chart 1 AP 5 Nature and Man made features Port features...
Страница 458: ...Appendix 2 IHO ECDIS Chart 1 AP 6 Depths Currents etc Seabed Obstructions Pipelines etc...
Страница 459: ...Appendix 2 IHO ECDIS Chart 1 AP 7 Traffic routes Special areas...
Страница 460: ...Appendix 2 IHO ECDIS Chart 1 AP 8 Aids and Services Buoys and Beacons...
Страница 461: ...Appendix 2 IHO ECDIS Chart 1 AP 9 Topmarks Color test diagram...
Страница 462: ...Appendix 2 IHO ECDIS Chart 1 AP 10 Mariners navigational symbols...
Страница 464: ...Appendix 3 Interpreting S57 Charts AP 12 Plain or symbolized boundaries Limited or full light sectors...
Страница 467: ...Appendix 3 Interpreting S57 Charts AP 15 Land features Water and seabed features Traffic routes...
Страница 468: ...Appendix 3 Interpreting S57 Charts AP 16 Cautionary areas Information areas Buoys and beacons Lights...
Страница 469: ...Appendix 3 Interpreting S57 Charts AP 17 Fog signals Radars Services...
Страница 472: ...Appendix 3 Interpreting S57 Charts AP 20 Low accuracy Services and small craft facilities Special areas...
Страница 474: ...Appendix 3 Interpreting S57 Charts AP 22 Light descriptions Nature of seabed Geographic names etc...
Страница 476: ...Appendix 3 Interpreting S57 Charts AP 24 This page intentionally left blank...
Страница 511: ...Appendix 5 Digital Interface AP 59 NRX NAVTEX received data...
Страница 544: ...Appendix 6 Parts List and Parts Location AP 92 This page intentionally left blank...
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