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Using an Average of Overlays as a Normalization Curve
PostPosted: Tue May 24, 2016 7:05 am Reply with quote
ivorykid
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Joined: 24 May 2016
Posts: 2




I am having difficulty using the average of several overlays as the normalization filter. I can use a single measured overlay with no problems. However, if I use my average measurement I get an error message that reads:

Quote:
Could not transform overlay to frequency domain: [name of average]
Could not run Fourier transform! (Intel NSP DLLs missing?)


Is this operation possible?
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PostPosted: Sun Jun 05, 2016 2:00 pm Reply with quote
Niick
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Joined: 07 May 2015
Posts: 25
Location: Portland, OR USA




I'm thinking it is POSSIBLE, however, as I understand it, SysTune uses always both the magnitude and phase information (full IR) in its normalization process.

When you average multiple overlays together, or when you take a multi-mic measurement, SysTune performs what is sometimes called a power average, or referred to in other programs as RMS or Polar averaging.

What this means is that the phase information is "thrown away" in order to allow a power average of the SPL response to occur without phase relationship induced cancellation/summation anomalies in the resulting average.

Being that the normalization function in SysTune takes into consideration the phase and magnitude information, if half of that information is missing, it sees it as invalid data.

I think the trick would be to put the data back by using a spreadsheet and/or text editor.

Compare the text of an overlay that DOES work with the one that doesn't, and fill in for the difference. You can put phase as 0 deg. on all frequencies.

I think that's roughly correct. Hopefully someone from AFMG will chime in and set the record straight. Smile
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PostPosted: Mon Jun 06, 2016 9:42 pm Reply with quote
ivorykid
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Joined: 24 May 2016
Posts: 2




Niick,

I think that you nailed it right on the head. I did notice that the phase info was absent from averaged data, but didn't think anything of it at the time. Manual insertion of zero-phase data makes it work. I just wish that I could do it all from inside of ST. Oh well...

Thanks for the help!

-IK
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Using an Average of Overlays as a Normalization Curve
AFMG Network Forum Index -> EASERA SysTune
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