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Klippel Near Field Scanner on a Shoestring
Klippel Near Field Scanner on a Shoestring
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Old Yesterday, 07:19 AM   #371
3ll3d00d is offline 3ll3d00d  United Kingdom
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Quote:
Originally Posted by gedlee View Post
Looks like it is swinging too fast, the angle has to be in radians and it can be any angle, but best is 0 to P/2 every 2 degrees
ok this looks more sensible now I think. Note that an arbitrary 60dB range applied & still need to add that preferred colour scheme. Lines are drawn every
2dB for first 6dB though there is only one colour for that 6dB atm, do you recommend the colours and lines use the same spacing?

modal_rads.png

Do we need to be able to see a graph for the output from CalSpatial (i.e. the previously shown line chart of modal response vs frequency) or do we just want to see the output of CalPolar?

If this looks ok then let me know what the next steps are and I can crack on with that over the weekend.
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Old Yesterday, 07:20 AM   #372
Dave Zan is offline Dave Zan  Australia
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Originally Posted by aslepekis View Post
I believe that is why the initial hardware concept proposed in this thread was to have the microphone move around a stationary speaker; then the same piece of hardware could be used for each new step of the software, from 2D measurements (as is being worked out now), to full 3D and then 3D with sound field separation...
Yes, that was exactly the idea for my proposal.
The thread title is "Klippel Near Field Scanner..." so I took it as read that we planned to do near field with cancellation of the room modes.
It seemed clear that we need to hold the speaker stationary, at least one of Klippel's presentations mentions this explicitly IIRC.
I still will do the Bessel / Hankel function write up as context for the move to 3d.
Just waited to see how the 2d works out.


Best wishes
David

Last edited by Dave Zan; Yesterday at 07:23 AM.
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Old Yesterday, 08:22 AM   #373
3ll3d00d is offline 3ll3d00d  United Kingdom
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One other point re CalPolar, this is the only function that returns a value it has created itself so far.

I think this means the DLL must have allocated the memory for that value, memory it can never free, aka a memory leak.

I have worked around the lack of a complex primitive in ctypes (with a solution that I think is platform specific but then this is a windows only app so not a big deal atm) & this isn't an enormous memory leak so no pressing need to change the function. Nevertheless, assuming my understanding of the python ffi is correct, it would be preferable to allocate on the python side and let the function write to that location.
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Old Yesterday, 03:15 PM   #374
aslepekis is offline aslepekis  United States
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Quote:
Originally Posted by 3ll3d00d View Post
exporting an FRD is easy enough, I don't know that an IR is possible. How do you plan to use that data though?
Just having FRD would be fine by me. When using this system for speaker design, my plan was to import the data into VituixCAD, since that's the software that I've been using.
Quote:
Originally Posted by Dave Zan View Post
Yes, that was exactly the idea for my proposal.
The thread title is "Klippel Near Field Scanner..." so I took it as read that we planned to do near field with cancellation of the room modes.
It seemed clear that we need to hold the speaker stationary, at least one of Klippel's presentations mentions this explicitly IIRC.
I still will do the Bessel / Hankel function write up as context for the move to 3d.
Just waited to see how the 2d works out.


Best wishes
David
That's what I thought. And yes, it was/is the plan to get to field separation eventually.

I don't remember which document it is, but I remember that from Klippel's papers too. The necessity of keeping the source stationary makes sense since separating the two sound fields would mean that the focus of the measurement would need to be on the sound field and changing the orientation of the source will change that sound field.

And thanks! I'll be looking forward to it, and I'm pretty excited about how 2D is coming along.
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Old Yesterday, 06:36 PM   #375
3ll3d00d is offline 3ll3d00d  United Kingdom
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Quote:
Originally Posted by aslepekis View Post
Just having FRD would be fine by me. When using this system for speaker design, my plan was to import the data into VituixCAD, since that's the software that I've been using.
is that going to work when summing multiple ways?
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Old Yesterday, 10:17 PM   #376
3ll3d00d is offline 3ll3d00d  United Kingdom
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attempting to use smooth and finding it is producing quite a few NaNs in the middle of the returned array, it seems 1/3 1/6 and Narrow return reasonable results but 1/12 Zwicker and Moore have a bunch of NaNs in the middle of the returned array. The NaNs are at different points for each algorithm, for example

1/12

12.png

Zwicker

zwicker.png

the fact that some calls yield sane data indicate that I am calling it correctly to me so this would appear to be a data issue.
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Old Yesterday, 10:22 PM   #377
3ll3d00d is offline 3ll3d00d  United Kingdom
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refactored assorted bits and pieces to make the codebase a bit simpler/more consistent and to make it easier to dump out FRDs as an output, I think I'll add some sort of export graph button next (unless the next steps in the analysis come along)

At some point soon I'll need to tackle making an exe for it but I know that is going to be extremely tedious (used pyinstaller once, is a bear to debug) so prefer to do something more interesting if at all possible
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