Auto Range Solution On June 17, 2013

The DownScan has a wider cone than 2D sonar so it can bounce off objects near the transom like a kicker, the main motor, a transducer or anything lower than the LSS transducer. When on auto range the DownScan may interpret the digital depth (DBT depth below the transducer) is the object at 1.2 or 1.4 feet from the transducer. Auto range changes to 5 foot range and you must wait until the digital depth corrects or take it off auto and manually adjust the range to match the depth of water you are presently in. You can select auto after the digital depth locks on the bottom.

The screen looks like this and you think the DownScan is not working, but when you adjust the range manually you will find it is working.

This also happens with 2D sonar on shallow water with weeds and thick schools of baitfish using auto range. The weeds and baitfish block some of the sound and the bottom returns a weaker echo so the sonar has difficulty determining the bottom depth. The digital depth is the software estimate of the distance of the bottom from the transducer some of which is based on the strongest echo and the auto range uses the digital depth to adjust the range.

however there is a huge difference in shallow water since the auto range will go to 5 feet but if you are in 3 feet the sonar screen looks fine even if the digital depth is not working correctly.  

The latest software updates from Lowrance have a solution, the DownScan Auto Range now uses the 2D digital depth which is better for locking on the bottom so this problem is much rarer.

by Bruce Samson under lowrance lowrance downscan

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