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I was wondering if anyone had any input to this theory/problem I am having with down imaging quality on lakes.I get great returns from my HB999 on side imagining.Attachment 193575As far as down imaging goes I don't get any good returns at Mark Twain Lake (blurred image), but when on the MO river it is good. Why would this be? I would think with the silt/mud in the river it would hurt the image, even though MTL is a muddy lake at middle fork I don't get the same return.
Maybe you could explain some more. Are the DI and SI seperate units? Are the transducers in different locations on the boat? Can you include examples and show depth and speed.
You answered your own question. Silt has an impact on image quality.
What is sonar?
SOund
Navigation
And
Ranging
Silt if rather thick and cut down on image quality. It interferes with the signals. The transducers pings a signal out away from the boat. The returning ping signal is captured at the transducer and the unit interprets the information into a series of dots and produces an image. So, anything between you and the returned signal will play an affect on the quality.
I get little blips on the left side of my side scan. Simply because my standard low frequency sonar transducer is slightly higher than my side imaging transducer and the noise or interference is creating the blips on my graph. If I turn off the sonar and only use side imaging, blips disapper.
Same if I have the motor trimmed down all the way, my images on the left side are not as far ranging. Trim up my motor and I can see equally on both sides of the screen on side scan. Little things make a difference.
Hope this helps! :-)
Vic .... he's using a HB999, so he's likely talking about not getting good DI images from that unit. Doesn't HB use the SI to create the DI image, since it doesn't have a dedicated DI crystal ... or has HB changed with these newer models ??Quote:
Originally Posted by vic n
... cp :kewl
All the HB core SI units paint DI images from data received from the "side pointing" SI piezoes ...Quote:
Originally Posted by CrappiePappy
Only the HB DI units and Onix use a dedicated "down pointing" DI piezo ...
It is not uncommon for DI images in the HB SI units to be less detailed as DI images from dedicated DI units ...
Set the "DI Width" setting under the Sonar tab to "Wide" and then crank up the DI Sensitivity in the DI Xpress menu (1 menu button press when viewing DI) ...
(Setting the "Imaging Frequency" under the Sonar tab to 800kHz can also bring out more detail from echoes directly under the boat) ...
Rickie
http://www.crappie.com/crappie/attac...s-fish-427-jpg
Looks like a 68 Camaro ...
Rickie
Yes-that's why I was asking for more explanation and whether he was using one unit or two....then we would be better able to figure out what might be going on.
800 is better definition but it's a narrower cone angle. I almost never use 800. But I have a Lowrance. Not sure it would be different for a bird but frequency is frequency. Should be a narrower cone and yes, increasing sensitivity is needed when switching to 800.
That's what I was thinking, but didn't know if HB's newer SI/DI units had twin crystals in their tdx's or were still using the SI image data.Quote:
Originally Posted by rnvinc
... cp :kewl
I rarely fish below 20ft deep ... so I keep my Lowrance DI unit set on 800 kHz. :RoflQuote:
Originally Posted by OzarkAngler
But ... I do believe I've seen where the degree of angle of the 800 & 455 kHz signals ARE slightly different between the HB & Lowrance units. :dono
... cp :kewl
I do not have any DI pictures to post to show what I am talking about. On SI I get high resolutions of trees at MTL but I would like to fish some submerged trees and look at a clear DI of what I am fishing and if it is holding fish in that structure. I have been running the sensitivity between 8 and 12 on DI.
That's what I thought as well.Quote:
Originally Posted by rnvinc
You get somewhat better DI images with a HB SI unit by scanning structure with the boat just to the left of known structure ...
This will orient the structure more towards the "Main Axis" (strongest part) of the right SI beam ...
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And crank the DI Sensitivity up as high as you can stand it without blowing out the detail ...
Rickie
Stoney ... at what speed are you moving when you get the hi-rez SI images, and what speed are you moving when getting the "less than acceptable" DI images ??Quote:
Originally Posted by Stoney79
You do realize that both DI & SI require a speed of up to a couple of miles per hour to get good images, right ?? So, if you're trying to "fish" those trees that you got good images of on SI, using the DI screen, are you hovering over those trees trying to spot fish among the branches ?? Could that be the reason why your DI images are less than the SI images of the same thing ... you're not moving fast enough ??
... cp :kewl