NorthStar Navigation NorthStar 491 manual Glossary

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Glossary

A-scope A horizontally magnified view of each echo, where the strength is shown by the width as well as the color of the line.

COG Course-Over-Ground. The actual path of your vessel relative to the surface of the earth.

clutter Distracting echoes caused by turbulence, plankton, etc. Can be reduced by the clutter control.

current The horizontal movement of water caused by tidal or other forces.

default A choice made automatically by the echo sounder; some defaults can be overridden in partial automatic mode.

echo The sound returned by either an object below the water’s sur- face or by the seabed, when this object or seabed is detected by a sound wave.

echo sounder An instrument that uses sound waves to measure the depth of a body of water or an object (such as a school of fish) below the water’s surface.

fathom A depth measurement that equals six feet or 1.83 meters of water.

gain The amount of amplification given to the received echo before it is displayed.

GPS Global Positioning System. hue The gradations of a color.

interference The electromagnetic interruption of a radio signal that causes a poor signal reception. Interference may originate from exter- nal sources, such as another nearby echo sounder, or from the vessel itself, such as alternator noise.

latitude Imaginary lines on the earth's surface running East/West and expressed in degrees (0-90) north or south of the Equator. Used in conjunction with the North/South lines of longitude to determine position.

491 Echo Sounder Operations Manual

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Contents Northstar Echo Sounder Contents Troubleshooting 491 Operations Reviewing past echoes using SoundTracPage 1Welcome Using this manual Welcome to the NorthstarOrganization Conventions Service and repair Technical supportHearing from you How echo sounding works 961/962 echo sounder system components Powering the 491 on and off Setting upUsing 491 with the 961/962 Press the Port Setup Options key Using the 491 with the 957/958961/962 echo sounder menu structure 957/958 echo sounder menu structure 2Quick Start Using the Echo Sounder Illustrated Echo screen Displaying the echo sounder’s pictureIllustrated Soundtrac screen Using demo mode At the Chart Overlay Selection window, pressChart Overlay screen Navigation Status tabs Depth and temperatureIntroducing the displayed information Echo soundingCruising or ﬁshing Using automatic modeManually overriding automatic mode Changing the frequency of echoes50 kHz 200 kHz Echo screen with both frequencies displayed Choosing a zoom mode Zooming in and outChoosing the zoom scale Using bottom lock zoom Using bottom zoomUsing bottom lock/ center zoom Accessing the setup screen Setup functionsEntering numerical values Number of special waypoints Changing the temperature graph’s units and scaleTransducer depth Changing the depth units961/962 sensor setup screen Speed and temperature sensor setup957958/ sensor setup screen 3Adjusting the Echo Sounder Picture Picture menu Adjusting the gain strong echoesGain window Adjusting the clutter weak echoesClutter window Adjusting the signal level weak echoesSuppressing interference the noise limiter Understanding the color bar Selecting the color bar hue and white levelHue and white level window Setting the white levelEcho Sounder Operations Manual 4Understanding Depth Settings Changing the depth settings Viewing the seabed depthViewing the depth marker Shift window Setting the picture’s shift starting depthSetting the picture’s range Range window Echo Sounder Operations Manual 5Other Functions Using the More key Changing the advance speed Using the More keyScope on single-frequency echo screen Displaying the A-scopeSetting the Echo screen data Using the A-scope with dual frequenciesScope on dual-frequency echo screen Echo screen data selections Bottom depth box Temperature boxTaking and storing a snapshot Temperature graphIntroducing snapshots Speed through the waterSnapshot screen 961/962 only Archiving and restoring a snapshot with a ﬂoppy diskArchiving snapshots screen 961/962 only Archiving and restoring snapshots with a Zip diskSetting up the video image overlay Echo Sounder Operations Manual 6Reviewing past echoes using SoundTrac SoundTrac screen Viewing past echoes using SoundTracNavigating to a past echo position Marking ﬁsh as waypointsSelected Cursor Position window appears Going directly to a past echo position7Setting the Alarms Setting the ﬁsh alarm Understanding the alarmsFish alarm window Setting the upper and lower marker depthsTurning the ﬁsh alarm on and off Setting the bottom alarmSetting inside or outside ﬁsh markers AlarmBottom alarm window Setting the bottom levelSetting the temperature alarm Turning the bottom alarm on and offTemperature alarm window Upper limit window is highlighted in black Turning the temperature alarm on and offWhen the temperature alarm sounds, an alert message is Troubleshooting the echo sounder Checking the transducer 8Troubleshooting 491 OperationsNo echoes displayed when Star key is pressed Troubleshooting the echo sounderOFF Checking the transducerMaintaining a transducer Manufacturer Model Power Northstar P/NPerformance characteristics A491 Features and SpeciﬁcationsInterfacing Physical characteristicsEnvironmental characteristics Screen notationsON/OFF Manual controlsEcho Sounder Operations Manual Glossary Echo Sounder Operations Manual