NorthStar Navigation NorthStar 491 manual Zooming in and out, Choosing the zoom scale

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When using the zoom feature (which also splits the screen into halves), both sides of the screen always display the same frequency.

Zooming in and out

Choosing the zoom scale

On the ECHO screen, the echo sounder’s zoom feature expands a portion of the echoes. You can examine closely any part of the water column, to determine the composition of the bottom or look at the echoes of fish, rocks, or wrecks. When fishing, the zoom function is useful for showing a detailed view of any echoes below the vessel.

Press IN to zoom in and increase the magnification of the echoes you see below the top edge of the marker. Press OUT to zoom out and increase the amount of water seen.

You can choose from any of six depth scales for the magnified echoes. These scales cover the same depths regardless of the scale of the original echoes.

The available scales are: 15’, 30’, 60’, 120’, 240’ and 480’ when using units of “feet.” Similar scales are available for the other depth units.

NOTE:

When zoom is in use, only a single frequency is displayed. Unzoomed echoes are on the right, and the same frequency is shown magnified on the left. Whatever frequency was previously shown on the left is replaced by a magnified view of the right side.

NOTE:

You cannot zoom out to a scale that shows more water than the original picture. For example, if the original picture is set to a scale of 50’, the only zoom scales available will be 15’ and 30’.

Choosing a zoom mode

Press ZOOM on the ECHO screen to cycle through the four zoom modes (and choose the one you want):

•bottom zoom

•bottom lock

•bottom lock/center

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