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Expert Talk: What Is Bandwidth and Why Do I Care?

j_j

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This is an interesting topic.
I am not sure if I can attend.
Is it best for those that cannot commit to abstain from registering to avoid taking a slot from another?

- Rich
Probably, we have a seat limit. And you can always peruse the archives afterwards.
 

j_j

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This should cover some of the basics for people:

This is a pretty good talk, as well. I have no urge to make fancy videos, the recording is thanks to zoom recording for me.

WAY the (*&(*& back in the PNW archives is a powerpoint deck of a 3 hour tutorial on ADC/DAC functioning, directed more at people who have to use them or spec them. That was given at the AES, but only tape-recorded, and I gave it again at PNW long, long before we had the ability to record a talk. Oddly, it's not even remotely obsolete.
 

JSmith

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Could not join the meeting due to time zone issues.
It hasn't happened yet... it's 4:36am PST right now, so approx. 13.5 hours to go;

Thursday, November 17th, 2022, 6pm PST (UTC -8)
Meeting Presentation Slides Available Pre-Meeting Below
Download Meeting Presentation Slides, 939KB Power Point File


JSmith
 

AdamG

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DonH56

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I registered, looking forward to it but may not be able to make it (found out last night I need to work tonight, joy). Should be a nice presentation!

p.s. I am not sure how technically saavy the audience will be... Hope they have coffee! My efforts online and in-person to an "audiophile" audience have had mixed results but I do not claim the knowledge nor presentation skills of @j_j . Even with pictures my attempts to distinguish between digital numbers (having effectively infinite bandwidth, impulses), the step response from a sample (track) and hold or DAC, and filtered output met with glazed eyes and cries of "But there are still steps, even if they are filtered, they are still in the signal!" Sigh. Maybe I can steal leverage some of this...
 
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AdamG

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pma

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There is an interesting example of 1 impulse placed between 2 samples, and quite a lot of explanations related, in the presentation. However, such scenario violates necessary condition of the sampling theorem, i.e. the input signal bandwidth must be limited to <Fs/2. So, for proper sampling, one narrow impulse between the samples may never happen. The input signal must be band limited with an input LPF. The scenario is purely hypothetical. It would be enough to say that the input signal must not violate the Nyquist theorem, IMO.
 
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pseudoid

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The slide deck is now up at www.aes.org/sections/pnw if you want a preview.
I can upload/post the Bandwidth.PDF version of your slides (Bandwidth.PPPX) for those who do not have access for PowerPoint.
If it is not too late... but will need your permission!
I am surprised that AES does not use pdf as a standard...
 

danadam

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There is an interesting example of 1 impulse placed between 2 samples, and quite a lot of explanations related, in the presentation. However, such scenario violates necessary condition of the sampling theorem, i.e. the input signal bandwidth must be limited to <Fs/2. So, for proper sampling, one narrow impulse between the samples may never happen. The input signal must be band limited with an input LPF. The scenario is purely hypothetical. It would be enough to say that the input signal must not violate the Nyquist theorem, IMO.
Seems to me that is exactly the point (or one of them) of the presentation, to explain why and how it violates the theorem.
 

j_j

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I can upload/post the Bandwidth.PDF version of your slides (Bandwidth.PPPX) for those who do not have access for PowerPoint.
If it is not too late... but will need your permission!
I am surprised that AES does not use pdf as a standard...
Please feel free to do so. The intent is not obscurity!
 

j_j

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There is an interesting example of 1 impulse placed between 2 samples, and quite a lot of explanations related, in the presentation. However, such scenario violates necessary condition of the sampling theorem, i.e. the input signal bandwidth must be limited to <Fs/2. So, for proper sampling, one narrow impulse between the samples may never happen. The input signal must be band limited with an input LPF. The scenario is purely hypothetical. It would be enough to say that the input signal must not violate the Nyquist theorem, IMO.

The goal in in fact to show just how that "between samples" simply can not exist within the sampled bandwidth. That's the point, and one that is missed, over and over and over again.
 

j_j

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I registered, looking forward to it but may not be able to make it (found out last night I need to work tonight, joy). Should be a nice presentation!

p.s. I am not sure how technically saavy the audience will be... Hope they have coffee! My efforts online and in-person to an "audiophile" audience have had mixed results but I do not claim the knowledge nor presentation skills of @j_j . Even with pictures my attempts to distinguish between digital numbers (having effectively infinite bandwidth, impulses), the step response from a sample (track) and hold or DAC, and filtered output met with glazed eyes and cries of "But there are still steps, even if they are filtered, they are still in the signal!" Sigh. Maybe I can steal leverage some of this...

Take it. It's there for educational purposes. So take it.
 

pseudoid

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DonH56

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Take it. It's there for educational purposes. So take it.
Thanks, I shall! I always give credit for references when I use them. I tend to write mostly "off the cuff" but referencing an expert always helps.
 
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