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TOPIC: First Attempt Side-Scan Is Nothing But Noise

First Attempt Side-Scan Is Nothing But Noise 1 week 2 days ago #11670

  • ndoggac
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First time attempting side-scan data collection using a Lowrance Elite5-TI with the totalscan transducer.

Collected SL2 files, in left pane of RM, show "Channels: Primary, Secondary, DownscanSidescanBoth" when hovered over. Same tracks added to downscan depth map project work as expected. When added to my first Sidescan Mosaic, the tracks look like entirely noise. (See image).

Wondering if I need to change settings in the Lowrance? Perhaps only collect side-scan frequencies, and not downscan at the same time....is that possible? Something I'm doing wrong in RM?

The swathes shown are roughly 28 feet across. I've tried noise reduction setting changes in RM with no effect. Collection was in fresh water, 5-40 feet deep. Collection boat speed approximately 5 miles per hour. Lowrance set to 433 Khz setting, max ping rate and data size.

Thanks in advance for any help you can provide.
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First Attempt Side-Scan Is Nothing But Noise 1 week 2 days ago #11671

  • Matt
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What depth are you in there? 28 feet for both channels or per side? That is a very low range. How do the files look in the standard SV, with water column showing?
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First Attempt Side-Scan Is Nothing But Noise 1 week 1 day ago #11673

  • ndoggac
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Thanks Matt! I'm fairly experienced in the downscan depth map, but this is my first foray into sidescan mosaic, so I'm bit lost. I'm no sure how to do the things you asked. What does "low range" mean, or "SV". Not sure how to view the water column?

Water depth shown in the first picture is 6-10 feet. When I measure the swath from edge to edge in RM, it measures 28 feet. However, collections were done in up to 30 feet of water with the same results.

Another thing that is odd, is that the side-scan swath tracks are a roughly "one half" subset of the total length of tracks for the downscan 200KHz collection. Almost like the sidescan collection was turning on & off while the downscan continued on throughout the entire trip.

Is there a guide or "best practices" to Lowrance settings with respect to achieving the best RM side-scan mosaic mapping?
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Last Edit: 1 week 1 day ago by ndoggac. Reason: fix2
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First Attempt Side-Scan Is Nothing But Noise 1 week 1 day ago #11674

  • Matt
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My guess with the "disappearing" sidescan in the map view is that you are running on a fixed range, and the water in the areas without sidescan is deeper than this range - so you have a sidescan swath that consists only of water column. Because the sidescan image in the map view has the water column removed, there is nothing left to view. The way to check this is to open the sonar viewer and view the unmodified sidescan channel there. Long story short, you are running with a very low range - try setting the range manually in the 50-100 ft range per side.
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First Attempt Side-Scan Is Nothing But Noise 1 week 22 hours ago #11675

  • ndoggac
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Thanks Matt! Will try again this weekend with your "Range" set manually to the range you specified, and I'll try it at "Auto" too, and let you know how it goes.

Once I get my feet wet a bit on collecting sidescan data, I'd be willing to put together a settings guide for Lowrance Elite TI units if there's interest.
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