Furuno FR-1710 manual Suppressing Precipitation Clutter, Interference Rejector

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1.16Suppressing Precipitation Clutter

The vertical beamwidth of the scanner is de- signed to see surface targets even when the ship is rolling. However, by this design the unit will also detect rain clutter (rain, snow, or hail) in the same manner as normal tar- gets. Figure 1-12 shows the appearance of rain clutter on the display.

The A/C RAIN control adjusts the receiver sensitivity as the A/C SEA control does but rather in a longer time period (longer range). Clockwise rotation of this control increases the anti-clutter effect.

A/C RAIN control

A/C RAIN control

OFF

adjusted

Figure 1-12 Effect of A/C RAIN control

1.17 Interference Rejector

Mutual radar interference may occur in the vicinity of another shipborne radar operating in the same frequency band (9 GHz). It is seen on the screen as a number of bright spikes either in irregular patterns or in the form of usually curved spoke-like dotted lines extending from the center to the edge of the picture. This type of interference can be re- duced by activating the interference rejector circuit.

The interference rejector is a kind of signal correlation circuit. It compares the received signals over successive transmissions and suppresses randomly occurring signals.

There are three levels of interference rejec- tion depending on the number of transmis- sions that are correlated. These are indicated by the legends IR1, IR2 and IR3 at the lower- left position of the screen.

Figure 1-13 Interference

To activate the interference rejector;

1.Press the [MENU] key.

2.Press the [5] key twice to select ECHO SIG.

 

ECHO SIG

 

 

 

 

 

 

 

 

 

 

 

1.

TGT COLOR

YEL

GRN

COLOR

 

 

 

 

 

 

 

2.

ECHO AVG

OFF

0.5

1

2 3

 

 

 

 

 

 

 

 

3.

INT REJ

OFF

1

2

3

 

 

 

 

 

 

4.

N REJ

OFF

ON

 

 

 

 

 

 

 

 

 

5.

ENHANCE

OFF

ON

 

 

 

 

 

 

 

6.

2ND ECHO

OFF

ON

 

7.

CONTRAST

1

2

3

 

 

 

 

 

 

 

 

8.

CLTR SWEEP

OFF

 

ON(LINK) ON(FIX)

9.

SWEEP LVL

1

2

3

 

 

 

 

 

 

0. CNTR ENHANCE

OFF

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1-14 ECHO SIG menu

3.Press the [3] key to select interference rejection level (OFF, 1, 2, or 3) from the INT REJ field.

4.Press the [ENTER/SELECT] key.

5.Press the [MENU] key.

1-13

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Contents Marine Radar First Edition NOV Keep heater away from equipment Do not operate the equipment with wet handsDo not open the equipment Do not disassemble or modify the equipmentUse the proper fuse Table of Contents Declaration of Conformity FR-1760DS SP-1Features IntroductionWord to the Owner of This Furuno Radar FR-1760DS System ConfigurationAntenna Unit Display Unit FR-1710/1725Viii Menu TreePlot Menu Mark Disp OFF Erase VEC REF REL True VEC Time Curs RNG INT REJ OFF Stretch Enhance Contrast Auto Xii Turning on the Power Operational OverviewTransmitter on Control description Control DescriptionTuning the Receiver CRT BrillianceControl Panel Backlighting Initializing the Compass Readout Degaussing the ScreenOn-screen legends and markers On-screen Legends and MarkersPresentation Modes Selecting presentation modeCourse-up Mode Screen shows Selecting the Range ScaleEntering Own Ship’s Speed Automatic speed inputManual speed input 10 Echo stretch Pulselength, Echo StretchS1P Suppressing Sea Clutter Adjusting the SensitivityManual adjustment by the A/C SEA control Automatic adjustment by the A/C Auto controlInterference Rejector Suppressing Precipitation ClutterMeasuring range by the variable range marker VRM Measuring the RangeMeasuring Bearing Measuring range by the fixed range ringsMeasuring Range and Bearing Between Two Targets Collision Assessment by the Offset EBL18 Measuring range and bearing Between two targets Setting a Target Alarm ZoneOff-centering shift Acknowledging alarmDeactivating target alarm zone Inward and outward alarms23 Echo SIG menu Echo AveragingPlotting a target Electronic Plotting Aid EPAReading the target data True or relative vector, vector timeTarget data Terminating target plottingCPA/TCPA Alarm Setting CPA/TCPA alarm rangesSilencing CPA/TCPA audible alarm Lost target alarmTarget Trails Echo Trails Past plot pointsTrue or relative trails Displaying, erasing target trails Trail gradationSelecting trail time Restoring trailsTrail afterglow Resetting target trailsTrail brilliance Thin trailsOrigin Mark Parallel Index LinesMarkers ZoomFunction Keys Presetting the user keysPresetting the function keys User Keys F1, F2, F342 FUNC1 menu Func key objectivesSuppressing Second-trace Echoes Adjusting Brilliance of Screen DataTime Alarm Noise RejectorEnhanced Video Navigation Data Degaussing IntervalVideo Contrast Clutter SweepOutputting Target Position Available color combinations Background ColorSelecting Range Scales Selecting Bearing Scale Format46 A/D Converter Curve Setting A/D curve settingsEnlarging Close-in Targets Alarms AlarmsPeformance Monitor Alarms con’tMinimum and maximum ranges Radar resolutionRadar Observation GeneralMultiple echoes False EchoesBearing accuracy Range measurementSart Search and Rescue Transponder Virtual imageShadow sectors Radar bandwidth Sart range errorsShowing Sart marks on the radar display General remarks on receiving SartSEA control Racon Radar BeaconRadar side lobes GainOn next MAINTENANCE, TroubleshootingPeriodic Maintenance Schedule Maintenance scheduleMaintenance schedule con’t Life Expectancy of Major PartsLife expectancy of major parts Easy troubleshooting Fuse Replacement Simple TroubleshootingReplacement of Batteries Battery replacement informationAdvanced-level Troubleshooting Serviceman qualificationService call Problem Check point Remedy Probable cause Advanced-level troubleshootingAdvanced-level troubleshooting con’t Sequence for diagnostic test Diagnostic TestTest results screen Display circuit test Left side view Parts LocationDisplay unit, top view Scanner unit, left side view FR-1760DS Scanner UnitScanner unit, right side view, RF section removed FR-1760DS Scanner Unit con’tFR-1760DS Power supply unit FR-1760DS Power Supply UnitRF module Upper part FR-1710/1725 Scanner UnitModule Lower part Specifications of Marine Radar Radar Display Dimension and Mass Coating Color Racon IndexIndex-2