Humminbird 141c manual How Sonar Works, Single Beam Sonar

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531442-1_A_141c_Eng.qxd 11/15/2005 8:39 PM Page 6

How Sonar Works

Sonar technology is based on sound waves. The 100 Series™ Fishing System uses sonar to locate and define structure, bottom contour and composition, as well as depth directly below the transducer.

Your 100 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.

Single Beam Sonar

Your 100 Series™ Fishing System uses a 200 kHz Single Beam sonar system with a 20° area of coverage. The 20° beam is focused on the bottom, to show you structure, weeds and cover.

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Contents 141c Operations Manual Table of Contents Thank YouTable of Contents How Sonar Works Peak to Peak measures power output at the highest pointsSingle Beam Sonar What’s On the Display High Sonar Intensity Return Bait BallViews Sonar ViewSonar View Zoom View Big Digits View Circular Flasher View Sonar ViewReal Time Sonar RTS Window Understanding Sonar HistoryBottom Presentation Sonar Zoom View Sonar Zoom ViewPOWER/LIGHT Key Big Digits ViewKey Functions Circular Flasher ViewMenu Key WAY Cursor Control KeyExit Key Owering Up the UnitMenu System Sonar Tab, Normal Mode Sonar Tab, Advanced ModePress TM Menu Normal Operation Start-Up Options MenuSimulator Accessory Test System Status Sonar X-Press TM MenuConduct a unit self-test StatusTo adjust the Sensitivity To adjust the Upper RangeSensitivity Upper RangeLower Range Chart SpeedZoom Level To adjust the Bottom Range Bottom LockBottom Range Sonar Menu TabTo change the Fish ID Sensitivity setting To change the RTS Window settingFish ID+TM Fish ID SensitivityZoom Width Bottom ViewDepth Lines Noise Filter Surface ClutterMax Depth Alarms Menu Tab To change the Water Type settingAlarms Menu Water TypeDepth Alarm Fish ID AlarmLow Battery Alarm Temp AlarmAlarm Tone Setup Menu TabTo change the Alarm Tone setting Highlight Alarm Tone on the Alarms main menuUser Mode Units DepthUnits Temp Units DistanceRestore Defaults Triplog ResetSelect Views Depth Offset Select ReadoutsTemp Offset Troubleshooting To change the Speed Calibration settingSpeed Calibration Advanced, with Temp/Speed onlyDisplay Problems Problem Possible CauseControl head loses power at high speeds Finding the Cause of NoiseGlossary SpecificationsSonar Terms 531442-1A141cEng.qxd 11/15/2005 840 PM Receiver See Transmitter 531442-1A141cEng.qxd 11/15/2005 840 PM 531442-1A141cEng.qxd 11/15/2005 840 PM Contact Humminbird