Furuno Blind Sector and Shadow Sector of Radar Explained: Key Differences and Calculations

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	Direct	Heading
	path	line
	Target
	Indirect
	path
	Obstruction
	Antenna (mast, funnel.
	etc.)		True
Indirect	Target		True
Indirect		Indirect	echo
path	Direct	echo
	path
	Own	Heading
	Own	line
	ship	line
	ship

True echo

Bridge

Indirect

Indirectecho echo

Figure 4-3 Indirect echoes

4.4 Blind and Shadow Sectors

Funnels, stacks, masts, or derricks in the path of antenna may reduce the intensity of the ra- dar beam. If the angle subtended at the antenna is more than a few degrees a blind sector may be produced. Within the blind sector small tar- gets at close range may not be detected while larger targets at much greater ranges may be detected. See Figure 4-4.

Vessel taller

than wharf				Mast, etc. in
				Mast, etc. in
				path of radar
		Wharf		path of radar
				beam
				beam

Wharf

Blind sector

(no echo)

Size of blind

sector

depends on target

size and range.

Figure 4-4 Blind and shadow sectors

21

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Contents Page 00080788713 Important Notices Radio Frequency Radiation Hazard Compliance with R&TTE Directive 1999/5/EC Foreword Table of Contents Model 1832 Specifications Vii SpecificationsViii OptionEquipment List Installation Materials Configuration of Model 1832/1932/1942 Xii Radar Display What is Radar?How Radar Determines Range How Radar Determines BearingHow radar works Control Description Basic Operation125 NM Display Indication and MarkersStand-by Economy modeTurning the Radar On/Off TransmittingSelecting the Range Adjusting Picture BrillianceAdjusting Receiver Sensitivity Adjusting the A/C SEA Control reducing sea clutterAdjusting A/C Rain Adjusting the A/C Rain Control reducing rain clutterAdjusting the A/C SEA control Tip for adjusting the A/C SEABy cursor Erasing the Heading Line, North MarkMeasuring the Range By range ringPredicting collision course Using the Offset EBLMeasuring the Bearing By EBLMeasuring range and bearing between two targets Cancelling shifted pictureShifting off centering the Picture Zoom Cancelling zoomPress the Menu key to close the menu Selecting the Presentation ModeBasic Menu Operation Magnifying Long Range Echoes echo stretch Echo TrailSelect OFF deactivate at Echo Trail on the menu Suppressing Radar InterferenceMentally create the guard zone you want to set Guard AlarmSelecting Pulsewidth Guard WatchmanGo into the Others menu, and set 15. Watchman for off Displaying Navigation DataFollowing summarizes the Other Menu Other Menu DescriptionOutputting Target Position Adjusting Brilliance of MarkersFunction Keys Suppressing NoiseIndirect Echoes Multiple EchoesSide-lobe Echoes Indirect echoes Blind and Shadow SectorsMaintenance & Troubleshooting Troubleshooting Self Test Mounting Model Where the temperature is more than 70 CUnpacking the antenna unit Siting, handling considerationsMounting platform Wiring and final preparationMounting Model 1932 Connections Fasten the cable gland assemblyWaveguide Groove Final preparationMounting Navigation aid, video sounder con- nectionYou will need an Nmea cable Mounting considerationsInput/Output Data List Heading signal can be connected to the HDG connectorHeading Sensor Connection Preparation Tick boxEntering antenna height Adjusting tune/videoWhen adjustment is completed, the mes- sages disappears Adjusting sweep timing Adjustment range0.000~3.239nm Adjusting MBS Adjustment 0.00~0.25Magnetron heater voltage Setting a blanking areaThis page is intentionally left blank Menu Tree ARP-10 Option Targets Limits, Visual alarm against lostTargets violating CPA/TCPA AP-4 Auto acquisition area is predefined between One minute after acquisition Vector still un- reliableAP-6 AP-7 Make sure the follows on Self Test menu ARP-10Not used Page Hatai Page Marine Radar Marine Radar