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TOPIC: Downscan or Primary for Depth Accuracy?

Downscan or Primary for Depth Accuracy? 1 year 10 months ago #11291

  • chadp
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Hi there,

I'm trying to nail down which Sonar scan I should be trusting more for accurate depths. In the attached screenshot you'll see I have both the Primary and Downscan Depth Correction windows open, and on the top (Primary, 200KHz, 8.7Pings/s) I see the circled dip bottom out at around 9.3ft, while the bottom (Downscan, 455KHz 11.6Pings/s) bottoms out at around 8.2 ft. I'm looking for accurate depths, does anyone have any insight as to which I should trust more?


Last Edit: 1 year 10 months ago by chadp.
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Downscan or Primary for Depth Accuracy? 1 year 9 months ago #11314

  • Heiko
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Hi!

I had the some problem, i decided for me that the downscan should be the scan with the highest accuracy.
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Downscan or Primary for Depth Accuracy? 1 year 9 months ago #11317

  • Foxes
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chadp wrote:
Hi there,

I'm trying to nail down which Sonar scan I should be trusting more for accurate depths. In the attached screenshot you'll see I have both the Primary and Downscan Depth Correction windows open, and on the top (Primary, 200KHz, 8.7Pings/s) I see the circled dip bottom out at around 9.3ft, while the bottom (Downscan, 455KHz 11.6Pings/s) bottoms out at around 8.2 ft. I'm looking for accurate depths, does anyone have any insight as to which I should trust more?
Have you set a keel offset (depth) for your tranceducer? I suspect the difference can be that the 2D-sonar depth is measured taking account the keel offset in order to show the distance from surface to bottom and the downscan is measured only tranceducer->bottom.
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Downscan or Primary for Depth Accuracy? 1 year 9 months ago #11318

  • Mark Meierotto
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Even with a Lowrance 3 in 1 transducer depth readings differ slightly from broadband vs High frequency scan. I just stick with the broadband values.
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Downscan or Primary for Depth Accuracy? 1 year 9 months ago #11319

  • Team Colibri
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The coneangle varies between 2D and DownScan, and as a result both digital depth and how the bottom is drawn varies as well. Both are wrong, and both are correct. :D
Last Edit: 1 year 9 months ago by Team Colibri.
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