Humminbird 767 manual How Sonar Works, Peak to Peak measures power output at the highest points

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531427-1_C - 767_Man_Eng.qxd 10/25/2005 10:29 AM 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 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 pointsQuadraBeam Sonar DualBeam Plus SonarWideSide Sonar With optional-purchase QuadraBeamTM transducerMulti-Media Card MMC/SD Slot Software UpdatesHow GPS and Cartography Work With 200 KHzF f e r e n t Bait Ball Hard Bottom Rocky BottomTraveled with Distance distanceAverage Speed Average speed readingViews Zoom View Chart View 200/83 kHz Split Sonar ViewSonar View Sonar viewsReal Time Sonar RTS Window Understanding Sonar HistoryFreeze Frame Bottom PresentationSonar Zoom View Sonar Zoom ViewCircular Flasher View 200/83 kHz Split Sonar ViewScreen Snapshot View Big Digits ViewSide Beam View Side Beam ViewBird’s Eye View Bird’s Eye ViewWideSide View View Orientation Chart ViewCombo View Waypoints, Routes and Tracks Viewing CartographyNavigate to a Waypoint or Position Save, Edit, or Delete a WaypointSave or Clear a Current Track Save, Edit or Delete a RouteAdd a Waypoint Target or Trolling Grid Press menuEdit, Delete or Hide Saved Tracks POWER/LIGHT KeyKey Functions View KeyWAY Cursor Control Key Accessory BusMark Key Goto KeyTitle Screen Powering Up the UnitMenu System Simulator Start-Up Options MenuNormal Operation Accessory Test GPS Diagnostic ViewSystem Status Self TestSonar X-PressTMMenu To adjust the SideSide Sonar views 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-PressTMMenuNavigation views only Only with an active cursor on a waypointSave 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 To turn Fish ID+ on or offZoom Width Fish ID SensitivityKHz Sensitivity KHz BalanceTo change the Depth Lines setting To change the 455 kHz Balance settingWideSide Sensitivity Depth LinesMax 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 TabTo change the Chart Detail Level setting To change the Map Borders settingSpot 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 Units Depth User ModeUnits Temp Units DistanceRestore Defaults Triplog ResetSelect Readouts Advanced, Sonar view onlyTemp Offset Depth OffsetSpeed Calibration Advanced, with Temp/Speed onlyTime Format Position FormatDate Format Nmea OutputUsing 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 Magnetic North Contact Humminbird