Humminbird 531438-1_A How Sonar Works, Peak to Peak measures power output at the highest points

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531438-1_A - 737_EnglishOnly.qxd 9/25/2005 7:51 PM Page 8

How Sonar Works

Sonar technology is based on sound waves. The 700 Series™ Fishing System uses sonar to locate and define structure, bottom contour and composition, as well as depth directly below the transducer.

Your 700 Series™ Fishing System sends a sound wave signal and determines distance by measuring the time between the transmission of the sound wave and when the sound wave is reflected off of an object; it then uses the reflected signal to interpret location, size, and composition of an object.

Sonar is very fast. A sound wave can travel from the surface to a depth of 240 ft (70 m) and back again in less than 1/4 of a second. It is unlikely that your boat can "outrun" this sonar signal.

SONAR is an acronym for SOund and NAvigation Ranging. Sonar utilizes precision sound pulses or "pings" which are emitted into the water in a teardrop-shaped beam.

The sound pulses "echo" back from objects in the water such as the bottom, fish and other submerged objects. The returned echoes are displayed on the LCD screen. Each time a new echo is received, the old echoes are moved across the LCD, creating a scrolling effect.

When all the echoes are viewed side by side, an easy to interpret "graph" of the bottom, fish and structure appears.

The sound pulses are transmitted at various frequencies depending on the application. Very high frequencies (455kHz) are used for greatest definition but the operating depth is limited. High frequencies (200kHz) are commonly used on consumer sonar and provide a good balance between depth performance and resolution. Low frequencies (83kHz) are typically used to achieve greater depth capability.

The power output is the amount of energy generated by the sonar transmitter. It is commonly measured using two methods:

•Root Mean Square (RMS) measures power output over the entire transmit cycle.

•Peak to Peak measures power output at the highest points.

The benefits of increased power output are the ability to detect smaller targets at greater distances, ability to overcome noise, better high speed performance and enhanced depth capability.

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Contents 737 GPS Chartplotter Operations Manual Thank You Table of ContentsKey Functions Views Menu Tab Accessories Menu Tab How Sonar Works Peak to Peak measures power output at the highest pointsDualBeam Plus Sonar QuadraBeam SonarWideSide Sonar With optional-purchase WideSide transducerHow GPS and Cartography Work Software UpdatesMulti-Media Card MMC/SD Slot With optional-purchase GPS ReceiverSoft Bottom RTS Real Time Sonar Window 83 kHz, Wide Beam Hollow Fish SymbolWhat’s On the Display Sonar views ViewsSonar View Real Time Sonar RTS Window Understanding Sonar HistoryBottom Presentation Freeze FrameSonar Zoom View Sonar Zoom ViewBig Digits View 200/83 kHz Split Sonar ViewCircular Flasher View 200/83 kHz Split Sonar ViewSide Beam View Screen Snapshot ViewMaking a Screen Snapshot Screen Capture ViewBird’s Eye View WideSide ViewDepth Chart View without Active CursorChart View with Active Cursor Waypoints, Routes and Tracks Viewing CartographySave, Edit, or Delete a Waypoint Add a Waypoint Target or Trolling Grid Chart View with GridKey Functions POWER/LIGHT KeyView Key Info KeyWAY Cursor Control Key Accessory BusMark Key Goto KeyPresence or absence of a transducer Powering Up the UnitMenu System Normal Operation Start-Up Options MenuSystem Status SimulatorGPS Diagnostic View Accessory TestExit PC Connect mode by powering the Fishing System off Sonar X-PressTMMenu To adjust the SideSide WideSide transducer WideSide view onlyTo adjust the Upper Range To adjust the SensitivitySensitivity Upper RangeSide Beam Range Chart SpeedLower Range Bottom View Cancel NavigationBottom Range Bottom LockWaypoint Name Navigation X-PressTM MenuOnly with an active cursor on a waypoint To view the Waypoint Name SubmenuSave Current Track Cursor to WaypointClear Current Track Save Current RouteSonar Window Remove TargetRemove Grid Sonar Menu Tab Screen Snapshot X-PressTMMenuDelete Image Delete All ImagesFish ID+TM Beam SelectTo use Beam Select Highlight Beam Select on the Sonar main menuZoom Width Fish ID SensitivityKHz Sensitivity AdvancedWideSide Sensitivity KHz BalanceDepth Lines Advanced with WideSide transducerMax Depth Surface ClutterNoise Filter Water Type To change the Water Type settingTransducer Select Navigation Menu TabWaypoints Current TrackSaved Tracks Routes Chart OrientationNorth Reference Grid RotationMap Datum Track Min DistanceCourse Projection Line Export All Nav DataChart Detail Level Chart Menu TabMap Borders With optional-purchase GPS Receiver onlySpot Soundings Lat/Lon GridSet Simulation Position Set Map OffsetDepth Alarm Alarms Menu TabFish ID Alarm To change the Depth Alarm settingTemp Alarm Low Battery AlarmOff Course Alarm Arrival AlarmAlarm Tone Drift AlarmSetup Menu Tab To change the Drift Alarm settingUnits Depth User ModeUnits Temp Units DistanceRestore Defaults Triplog ResetSelect Readouts Advanced, Sonar view onlyTemp Offset Depth OffsetSpeed Calibration Position FormatDate Format Time FormatNmea Output SonarUsing Screen Snapshot Accessories Menu TabViews Menu Tab To Change the View Status of Any ViewTo view screen snapshots TroubleshootingTo make a screen snapshot Screen Snapshot must be enabled Finding the Cause of Noise Display ProblemsSpecifications Series Fishing System AccessoriesSonar Terms Glossary100 Receiver See Transmitter 104 GPS & Navigation Terms 108 Contact Humminbird