THD+N measurement with AES17-2015 notch filter

Re: THD+N measurement with AES17-2015 notch filter

Postby RJA4000 » Mon Jul 25, 2022 3:53 pm

Thanks for your answer !

Of course !
I should have thought that the accuracy of the substraction method would be problematic.
Thanks for sharing the bandwidth used for HD computing: I'll adapt and use the same.

A lot of (other) work this week, but I hope to work on this during next week-end.
More to come then.

Thanks again !
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Re: THD+N measurement with AES17-2015 notch filter

Postby RJA4000 » Sun Jul 31, 2022 9:22 pm

Thanks once again !

It works, of course.

I'm now consistently getting the exact same figure than REW with "AES17-2015 standard notch" distortion setting.
I also get exactly the same THD by computing from Band Energy than the "official" THD DDP.

2022-07-31 15_18_48-Greenshot.png
2022-07-31 15_18_48-Greenshot.png (168.71 KiB) Viewed 166 times

2022-07-31 15_20_02-Greenshot.png
2022-07-31 15_20_02-Greenshot.png (253.57 KiB) Viewed 166 times


Of course, there is anoise benefit to this Notch
It is quite constant with level
Chart_00007_20220731_1507.png
Chart_00007_20220731_1507.png (143.17 KiB) Viewed 166 times
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Re: THD+N measurement with AES17-2015 notch filter

Postby VirtinsTech » Fri Aug 19, 2022 3:02 am

Thanks for the report.

RJA4000 wrote:I also get exactly the same THD by computing from Band Energy than the "official" THD DDP.


The "official" THD cannot be seen from your screenshot, but it should be nearly the same as the one with AES notch filter, that is, the increase of fundamental energy due to the much wider bandwidth of AES notch filter should be negligibly small when the fundamental is well above the noise floor.

It can be seen in the your screenshots that the fundamental has a quite wide skirt, probably because the ADC is RME ADI-2 Pro but the DAC is not?
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