NorthStar Navigation NorthStar 491 A491 Features and Speciﬁcations, Performance characteristics

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A491 Features and Speciﬁcations

Table 4: 491 echo sounder features

Performance characteristics

Output	Single/Dual Channel, 50/200kHz, 600W

Alarms	Fish, seabed, temperature

Update rate	10 Hz maximum (depends on water depth)

Auto modes	Fishing and cruising

Zoom modes	Marker, bottom, bottom lock, bottom lock/center

Features	Mark present or past echo as waypoint (961/962)
	Go directly to any past echo
	A-scope analyzes present or past echoes
	Navigation data shown at bottom of screen
	Demo mode for training

491 Echo Sounder Operations Manual

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Contents Northstar Echo Sounder Contents Troubleshooting 491 Operations Reviewing past echoes using SoundTracPage 1Welcome Organization Using this manualWelcome to the Northstar Conventions Hearing from you Service and repairTechnical support How echo sounding works 961/962 echo sounder system components Using 491 with the 961/962 Powering the 491 on and offSetting up 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 Chart Overlay screen Using demo modeAt the Chart Overlay Selection window, press Navigation Status tabs Depth and temperatureIntroducing the displayed information Echo soundingCruising or ﬁshing Using automatic mode50 kHz 200 kHz Manually overriding automatic modeChanging the frequency of echoes Echo screen with both frequencies displayed Choosing the zoom scale Choosing a zoom modeZooming in and out 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 Viewing the depth marker Changing the depth settingsViewing the seabed depth 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-scopeScope on dual-frequency echo screen Setting the Echo screen dataUsing the A-scope with dual frequencies 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 levelTemperature alarm window Setting the temperature alarmTurning the bottom alarm on and off 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