Furuno FR-8051 manual Suppressing Rain Clutter, Heading and North Markers, Measuring the Range

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A common mistake is too over-adjust the A/C SEA control so that the surface clutter is com- pletely removed. By rotating the control fully clockwise, you will see how dangerous this can be; a dark zone will be created near the center of the screen, causing a loss of close-in targets. This dark zone is even more dangerous if the gain has not been properly adjusted. Always leave a little surface clutter visible on the screen. If no clutter is observed (on very calm waters), set the control at the fully counterclockwise position.

1.12 Suppressing Rain Clutter

In adverse weather conditions, clouds, rain or snow produce a lot of spray-like spurious echoes and impairs target detection over a long distance. This situation can be improved by using a Func- tion key that is so programmed. If the Function key fails to effectively suppress rain clutter, use the A/C RAIN control.

The A/C RAIN control adjusts the receiver sen- sitivity 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.

Appearance of rain

A/C RAIN control adjusted;

clutter on the display

rain clutter suppressed

Figure 1-10 Effect of A/C RAIN control

1.13The Heading and North Markers

The heading marker indicates the ship's heading in all presentation modes. It appears at zero de- grees on the bearing scale in the Head-up mode, in any direction depending on the ship orienta- tion in North-up and True Motion modes. The north marker appears as a short dashed line. In the Head-up mode, the north marker moves around the bearing scale in accordance with the compass signal.

To temporarily extinguish the heading marker to look at targets existing dead ahead of own ship, press the HM OFF (PUSH) control. The heading marker reappears when the key is released.

1.14 Measuring the Range

There are three ways to measure the range to a target: by the range rings, by the cursor and by the VRM (Variable Range Marker).

Measuring range by the range rings

Use the range rings to obtain a rough estimate of the range to a target. They are concentric circles around own ship, or the sweep origin. The num- ber of rings is automatically determined by the selected range scale and their interval is displayed at the upper-left position of the screen. Press the RINGS (PUSH) control to show the range rings if they are not displayed. Successive presses of the RINGS (PUSH) control gradually increase the brightness of the rings in four steps and a fifth press erases the rings.

Measuring range by the cursor

Rotate the trackball to place the cursor on the in- side edge of the target. The range to the cursor appears at the bottom of the display.

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Contents Marine Radar First Edition NOV Safety Information Do not diassemble or modify the equipment Iii Radio Frequency Radation HazardUse the correct fuse Table of Contents Maintenance Features Word to FR-8051/8111/8251 Owners ForewordVii Configuration of FR-8051/8111/8251 Specifications Antenna UnitTransceiver Module Others Power Supply and Power ConsumptionDisplay Unit Environmental ConditionsName Type Qty Remarks Equipment ListsStandard Set XiiName Type Code No Remarks Optional EquipmentSpare Parts XiiiCategorization by Specification XivFunction Type Control Description Operation25 NM Display IndicationsDisplay indications lower part Turning the Radar On/Off Selecting RangeTransmitting, Stand-by Presentation Mode Selecting presentation modePresentation mode Description Representative display Description Presentation modeMenu Overview Basic menu operationChanging pages on the Initial menu MK Erase erase all fixed marks Menu treeInitial Tune SET AUTO, Manu SPD Mode MAN, LOG, NAV Selecting tuning mode Tuning the ReceiverAdjusting Sensitivity Adjusting Picture BrillianceAutomatic anti-clutter control Adjusting Brilliance of Control Panel and MarkersAdjusting Range Ring Brilliance Suppressing Sea ClutterMeasuring range by the range rings Suppressing Rain ClutterHeading and North Markers Measuring the RangeMeasuring Bearing Collision Assessment by Measuring Range Offset EBL Canceling the cursor offsetOff-centering the Picture Index LinesZoom Inscribing Marks on the DisplayFunction key Own Ship Speed Turning on a functionAutomatic speed input Manual speed input Ship’s GraphicInterference Rejector Echo TrailsTrail reference Canceling echo trailStarting echo trail Trail timeElectronic Plotting E-plot Trail brilliancePlotting a target Vector time Canceling target plottingTarget data True or relative vectorActivating the guard zones Setting a Guard Alarm ZoneSetting a guard zone Selecting guard zone typeHow to turn on echo averaging Watch AlarmSilencing the aural alarm Canceling the guard zone and guard alarm26 Echo average Suppressing Second-Trace EchoesSelecting Pulselength Presetting pulselengthEcho Stretch Noise RejectionWaypoint Display Outputting Cursor Position TLL dataSelecting pulselength set to use Alarm Output Signal On/Off Selecting Unit of Range Measurement, Bearing ReferenceSector Blanking Range Resolution Radar ObservationRadar Picture, Target Properties and Radar Pulse Multiple echoes Bearing ResolutionFalse Echoes Indirect echoesBlind and shadow sectors Minimum and Maximum RangesSide-lobe echoes Minimum rangeLocating a Ship or Survival Craft in Distress by Sart Gain When Working on the Antenna Unit MaintenancePart Type Life expectancy Remarks Interval Check point Check and measures RemarksTroubleshooting Simple TroubleshootingProblem Remedy Advanced-level Troubleshooting Serviceman qualificationProblem Check point and probable Remedy Cause Problem Check point and probable Remedy Cause Problem Check point and probable Remedy Cause Diagnostic test, test pattern Diagnostic TestAntenna Unit Location of PartsModulator Trigger RF Transceiver UnitRF transceiver unit FR-8051/8111 Display unit, top view Display Unit common to all modelsDisplay unit, right side view Display Meaning Transmitter normal Receiver normal Performance MonitorOperating a performance monitor Transmitter Receiver PerformanceAuto Plotter ARP-15 Video Plotter RP-15Fluxgate Heading Sensor C-2000 Page