Thread: Jumping into the SI market?

Originally Posted by Humminbird_Greg

True CP, not many crappie in salty water, but I was pointing out that some fishermen still prefer to buy the NVB units. Mainly the salt water guys since their maps have not changed at all or have not changed much. I should have also pointed out that on some lakes the Navionics maps will not cover up into the shallow waters which the NVB maps may since they are based on some of the older Navionics map card data that included this.

As for the shadows we won’t know for sure until the Di software is released and it is more fully explained. My guess is that these are the same shadows shown in the left-right Si data. If I understand it right; the Di data is a blend of what is shown in the Si data. I think that if Jason were running his unit with a 30 foot Si Range that you would be able to more clearly see the shadow that that last fish crib on the (upper) left made and these would match up.

So, what you are saying is that the down imaging is just an expansion of the side image envelope using the SI crystals?

What I am saying is that our Di sonar will use the data from the Si elements that are already in the transducer. All it will be doing is show some of this data in a different format (more like the conventional 2D sonar that most are familiar with.

Originally Posted by Humminbird_Greg

What I am saying is that our Di sonar will use the data from the Si elements that are already in the transducer. All it will be doing is show some of this data in a different format (more like the conventional 2D sonar that most are familiar with.

I believe we are shuffling the same cards. Seems to me that the 86* SI butterfly angle coverage would have to overlap the 2d coverage to get true down imaging. That would be 90* per side with respect to the horizon..

I could be wrong, but I doubt it.

Originally Posted by Cane Pole

I believe we are shuffling the same cards. Seems to me that the 86* SI butterfly angle coverage would have to overlap the 2d coverage to get true down imaging. That would be 90* per side with respect to the horizon..

I could be wrong, but I doubt it.

I can't seem to find it now but there was a discussion on one of the other sideimaging forums talking about the "gap" straight down under the boat and between the 86* coverage areas of the side beams......

That discussion alluded to the idea that there really is no "gap" and possibly could actually overlap to a minute degree..

Factual side images were actually shown of objects on the bottom showing on both sides of the Si image..

It was even reported to have an Si image of a submerged verticle standing tree that showed half of the treetrunk on the left and the other half of the treetrunk on the right....

If it is true that there is actually no "gap" then it would seem that all the information needed to display the Di image is already embedded in the Si image...and then it's just a matter of "rearranging" the data into creating the Di image...

Although I can't prove the idea of the "gap" either way...I do think it makes interesting discussion...

Originally Posted by rnvinc

I can't seem to find it now but there was a discussion on one of the other sideimaging forums talking about the "gap" straight down under the boat and between the 86* coverage areas of the side beams......

That discussion alluded to the idea that there really is no "gap" and possibly could actually overlap to a minute degree..

Factual side images were actually shown of objects on the bottom showing on both sides of the Si image..

It was even reported to have an Si image of a submerged verticle standing tree that showed half of the treetrunk on the left and the other half of the treetrunk on the right....

If it is true that there is actually no "gap" then it would seem that all the information needed to display the Di image is already embedded in the Si image...and then it's just a matter of "rearranging" the data into creating the Di image...

Although I can't prove the idea of the "gap" either way...I do think it makes interesting discussion...

Yep. This is what I believe about the coverage and imaging. I haven't read any particulars on the subject, justa SWAG on my part.

Remember that the 86 degree specification was taken in a laboratory at the -10db point. What Humminbird Si users have found in actual use is that the beams are wider than this and do overlap. Now water conditions depth and some other factors will influence this but there have been many images posted by Si owners that show this.

“If it is true that there is actually no "gap" then it would seem that all the information needed to display the Di image is already embedded in the Si image...and then it's just a matter of "rearranging" the data into creating the Di image...”
Yep, that’s the way I understand how the Di sonar works.

I understand. This would be a sensitivity setting for the more pronounced overlap then.

To get my simple mind to understand it.... the way I have to picture it my head is...

in 2D sonar there is a conical downward looking sonar that the processor turns "sideways" to show the image on the screen...

in Di sonar there is a thin slice sideways looking sonar that the processor leaves sideways to show the image on the screen...the processor just changes the color of the pixels (and with more detail because of the Si element being used)...

Rnvinc,
Okay I’ll mostly agree with that. The 2D sonar beam is somewhat conical in nature while the Si beam is narrow (forwards-backwards) while it is extremely wide (side-to-side), so it makes a slice as you say. The Si sonar can show better detail due to the shape of the sonar beam and because of its use of a higher frequency. The mpu is programmed to assign different colors (for 2D sonar) or shades of a color for certain returned sonar signal strengths.

The part I don’t agree with is the turning or leaving of the image. The programmers can have the sonar displayed in any direction they want. I guess it’s just because I’ve been around this for so many years now but when I think 2D or conventional sonar I think ‘downwards’ for showing depth or distance. So showing the 2D sonar in this orientation looks right to me. I think left-right when thinking about Si sonar. Those who have not been using Si sonar usually think ‘down’ for depth/distance since that is how it has been shown to them on 2D sonar.


CP,
“This would be a sensitivity setting for the more pronounced overlap then.”
Not a sensitivity setting from the perspective of the Si Sensitivity menu (although this menu should affect what the Di sonar shows just like it does the Si sonar), but sensitivity from the standpoint of the overall Si sonar being able to show sonar returns from outside the laboratory -10db point.

Originally Posted by Humminbird_Greg

Rnvinc,
Okay I’ll mostly agree with that. The 2D sonar beam is somewhat conical in nature while the Si beam is narrow (forwards-backwards) while it is extremely wide (side-to-side), so it makes a slice as you say. The Si sonar can show better detail due to the shape of the sonar beam and because of its use of a higher frequency. The mpu is programmed to assign different colors (for 2D sonar) or shades of a color for certain returned sonar signal strengths.

The part I don’t agree with is the turning or leaving of the image. The programmers can have the sonar displayed in any direction they want. I guess it’s just because I’ve been around this for so many years now but when I think 2D or conventional sonar I think ‘downwards’ for showing depth or distance. So showing the 2D sonar in this orientation looks right to me. I think left-right when thinking about Si sonar. Those who have not been using Si sonar usually think ‘down’ for depth/distance since that is how it has been shown to them on 2D sonar.

I'm understanding more about this stuff everyday...Thanks for the explaination Greg....