NorthStar Navigation NorthStar 491 manual Using bottom zoom, Using bottom lock zoom

Page 24

Using bottom zoom

Using bottom lock zoom

•marker zoom

The original unzoomed echoes are on the right side, and the magnified area is shown on the left side of the screen.

A tab below the ZOOM key shows which zoom mode is in use.

When you select bottom zoom, the contour of the bottom is magnified, clearly displaying canyon edges and echoes near the seabed. The 491 automatically locates the seabed and displays it on the lower left side of the screen (normal echoes are displayed on the right side).

If the seabed moves out of the lower half of the screen (for example, if you travel into deeper water), the 491 automatically repositions the bottom back into the lower half. You’ll see the zoomed image jump up or down from time to time, as the 491 keeps the seabed displayed on the screen.

When you select bottom lock zoom, the magnified sea bottom is flattened out and displayed on the left side of the screen at the lower edge. You can see any fish that are swimming near the bottom.

Page 20

491 Echo Sounder Operations Manual

Image 24

Contents Northstar Echo Sounder Contents Reviewing past echoes using SoundTrac Troubleshooting 491 OperationsPage 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 Using the 491 with the 957/958 Press the Port Setup Options key961/962 echo sounder menu structure 957/958 echo sounder menu structure 2Quick Start Using the Echo Sounder Displaying the echo sounder’s picture Illustrated Echo screenIllustrated Soundtrac screen Using demo mode At the Chart Overlay Selection window, pressChart Overlay screen Depth and temperature Introducing the displayed informationEcho sounding Navigation Status tabsUsing automatic mode Cruising or ﬁshingManually 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 zoom Using bottom lock zoomUsing bottom lock/ center zoom Setup functions Accessing the setup screenEntering numerical values Changing the temperature graph’s units and scale Transducer depthChanging the depth units Number of special waypointsSpeed and temperature sensor setup 961/962 sensor setup screen957958/ sensor setup screen 3Adjusting the Echo Sounder Picture Adjusting the gain strong echoes Picture menuAdjusting the clutter weak echoes Gain windowAdjusting the signal level weak echoes Clutter windowSuppressing interference the noise limiter Selecting the color bar hue and white level Understanding the color barSetting the white level Hue and white level windowEcho Sounder Operations Manual 4Understanding Depth Settings Changing the depth settings Viewing the seabed depthViewing the depth marker Setting the picture’s shift starting depth Shift windowSetting the picture’s range Range window Echo Sounder Operations Manual 5Other Functions Using the More key Using the More key Changing the advance speedDisplaying the A-scope Scope on single-frequency echo screenSetting the Echo screen data Using the A-scope with dual frequenciesScope on dual-frequency echo screen Bottom depth box Temperature box Echo screen data selectionsTemperature graph Introducing snapshotsSpeed through the water Taking and storing a snapshotArchiving and restoring a snapshot with a ﬂoppy disk Snapshot screen 961/962 onlyArchiving and restoring snapshots with a Zip disk Archiving snapshots screen 961/962 onlySetting up the video image overlay Echo Sounder Operations Manual 6Reviewing past echoes using SoundTrac Viewing past echoes using SoundTrac SoundTrac screenMarking ﬁsh as waypoints Navigating to a past echo positionGoing directly to a past echo position Selected Cursor Position window appears7Setting the Alarms Understanding the alarms Setting the ﬁsh alarmSetting the upper and lower marker depths Fish alarm windowSetting the bottom alarm Setting inside or outside ﬁsh markersAlarm Turning the ﬁsh alarm on and offSetting the bottom level Bottom alarm windowSetting the temperature alarm Turning the bottom alarm on and offTemperature alarm window Turning the temperature alarm on and off Upper limit window is highlighted in blackWhen the temperature alarm sounds, an alert message is 8Troubleshooting 491 Operations Troubleshooting the echo sounder Checking the transducerTroubleshooting the echo sounder No echoes displayed when Star key is pressedChecking the transducer OFFManufacturer Model Power Northstar P/N Maintaining a transducerA491 Features and Speciﬁcations Performance characteristicsPhysical characteristics Environmental characteristicsScreen notations InterfacingManual controls ON/OFFEcho Sounder Operations Manual Glossary Echo Sounder Operations Manual