Furuno CSH-23F/24F manual Sea Surface Reflections, Wake

Page 89

Sea Surface Reflections

To reduce sea surface reflections, set the tilt angle to 5° or higher, so the upper edge of the sonar beam does not hit the sea surface, or adjust TVG. When a narrow tilt angle is used, sea surface reflections cover a large area as illustrated below.

Sea surface	Tilt angle
	Tilt angle
	indication
15°
	Sea surface
Sea surface	reflections
15°

Figure 12-3 Sea surface reflections

Wake

A wake produced by own ship or another ship can be a strong reflecting object when a narrow tilt angle is used. As the wake appears as a thick continuous line, it can be easily distinguished from a fish school. A wake contains many air bubbles which attenuate ultrasonic energy, making it difficult to sound beyond the wake.

Other ship

Own ship

Own ship's screw noise

	Wake produced
	by other ship	Own ship's wake
	Own ship's	Own ship's wake
	Own ship's	(produced when
	screw noise	own ship turned)

Figure 12-4 Wake appearance on the display

12-3

Image 89

Contents Color Scanning Sonar 00080818600 Safety Instructions Do not use the equipment for other than its intended purpose Table of Contents Vertical Scanning Display Self Tests This page is intentionally left blank Word to CSH-23F/24F Owners FeaturesForeword Standard Option System ConfigurationControl Description Control Layout on Display Unit and Remote Control BoxMain panel control description Main PanelRECALL, Memo NORM, E/S, HistRange GainControl Function Sub PanelSub Panel 2 data setting window AGC SignalProcess 2AGCSonar AlarmUP/TM Sonrbeam+ + Remote Control BoxAdjusting Screen Brilliance, Control Panel Backlighting Turning the Power On/OffOperational Overview Lowering the TransducerDescription Selecting a Display ModeMode Seabed echo and tilt angle Setting the Tilt AngleSelecting a Display Range Points to consider How to discriminate fish echoes from the seabedTilt angle and sea surface reflections Tilt angle for surface fishTilt angle and beam coverage Suitable tilt angleMeasuring Range and Bearing to a Target Adjusting the GainPage Eliminating Unwanted Feeble Echoes Fine Tuning the PictureHow to adjust TVG Page Pulselength data setting window TVGTX, PL AGC data setting window SIGNAL, Signal2AGC data setting window SIGNAL, Signal Process Suppressing Seabed TailIdentifying noise source Data setting window TVGTX, OutputRejecting Sonar Interference and Noise Cycle Changing Tx cycle data setting window TvgtxSetting F-shift data setting window Sonrbeam Adjusting BeamwidthNoise limiter data setting window SIGNAL, Signal Menu ApplicationMarks and Data Marks, Data and Display ModeNormal display mode Echo sounder combination display Normal display mode w/textMark/Data Description Permanently Displayed Marks and DataHistory display Erasable Marks and Data Bearing marker Mark Description Range R Auto Tilt Auto Scan Gain Brill TVG TVG DIM This page is intentionally left blank User Menu Operation Menu How to openMenu Overview User Menu Hist DSP/GRPH Menu screen location and display modeMenu Menu Item Description User Menu DescriptionSave Picture Current VECTM DSP System Menu DescriptionFAR TVG Mark Size BRG ReadoutData Display ES/NET REC DefaultsHist Display InterlockColor Curve Data SET Menu DescriptionChange Color Plan NET ShootNET Sonde NET Plot CorrInit SET/TEST Menu Description Echo Test Menu DescriptionProgramming the Function Keys Function KeysReplaying a Function Key Function Key Fine TuningReplaying Function Key Settings from a Memory Card Saving Function Key Settings to a Memory CardThis page is intentionally left blank Finding Fish School Center Advanced Level OperationTracking a fish school Tracking a Fish School target lockErasing target lock mark Choosing target lock modeTarget lock mark appearance Target lock and tilt angle Tracking target lock markSystem Menu Target Lock Setting target lock conditionsDescription of target lock items Detecting Fish Schools Aurally How to set the fish alarm zone Fish AlarmRelocating Fish School for Easy Observation How to relocate fish schoolsEstimate marks and their data Comparing of Fish School ConcentrationMeasuring Fish School Speed How to measure fish speed10 Event marks Event MarkErasing an event mark Entering an event mark12 True motion display True Motion Display13 Net location mark Plotting Net Location Mark14 Net behavior Observing Net BehaviorNo. Display Information Applications Target Slice DisplayThis page is intentionally left blank Vertical Scanning Display Using Vertical Scanning DisplaySearching Application to Bonito and Tuna FishingDisplay Indications Approaching TrackingCatching CatchingPort/Starboard display PORT/STARBOARD, Horizontal Slice DisplaysHorizontal slice display Horizontal slice displayInitializing Memory Cards Memory Card OperationsData to Save Saving Method Saving to Saving the PictureTransferring Echo Data from Internal Memory to Memory Card Saving Net Shooting Data Net shooting data contentsHow net shooting data is saved Transferring net shooting data to memory cardReplaying Saved Data Deleting Memory Card ContentsTurning marks on/off through the user menu Turning marks on/off through the data setting windowTurning MARKS, Data ON/OFF This page is intentionally left blank Seabed Echoes Interpreting the DisplayMidwater, bottom fish Tilt angle 30 or more Fish SchoolsWake Sea Surface ReflectionsNoise and Interference False Echo by SidelobeUnretracted Transducer Warning Overvoltage WarningHow to manually raise the transducer Opening the Self Test Menu Self TestsContinuous test Self Test DescriptionSingle test Color test Panel testSIO test Gray testInterface unit CS-120A, cover opened Interface Unit CS-120A Self TestThis page is intentionally left blank Selection of Data at Interface Unit CS-120A Input Data SelectionHow to set net sonde transmitter distances Setting Distances Between Net Sonde TransmittersDisplay Unit Maintenance MaintenanceZinc block near the transducer must be replaced yearly Hull Unit MaintenanceUser Menu Menu TreeData SET Menu Init SET/TEST Menu System Menu Previous This page is intentionally left blank SP-1 SpecificationsSP-2 DisplaySP-3 Hull UnitThis page is intentionally left blank 12-2 IndexIN-2