## PSN-L Email List Message

**
Subject: Re: WinQuake question for Larry**

From: Brett Nordgren brett3nt@.............

Date: Sat, 28 Mar 2009 09:54:54 -0400

Larry,
Many thanks. I downloaded the (very) new WinQuake and now have the FFT
data exported. I think that it is exactly what I was looking for.
Now to get educated on spectral density stuff.
Brett
At 11:29 PM 3/27/2009 -0700, you wrote:
>Brett,
>
>Brett Nordgren wrote:
>>Larry,
>>When I do an FFT on a PSN file, the result is normalized to fill the
>>screen vertically. Is there any way to extract the normalization factor
>>so that I could use the results to generate a calibrated noise spectrum?
>
>Not within WinQuake. With the current version of WQ you can export the raw
>FFT data so you can analyze the FFT data using other programs like MATLAB
>or Excel. To do this create an FFT Window and use the File / Export menu
>items. The resulting file will look like this:
>
>Freq,Real,Imaginary,Magnitude
>0.000190735,-0.0925326,0.182551,0.409328
>0.00038147,-0.17057,-0.0860256,0.38207
>0.000572205,0.110639,-0.0927722,0.288774
>0.000762939,-0.0952175,0.178415,0.404466
>0.000953674,-0.15761,-0.0518402,0.331834
>0.00114441,0.0554941,-0.136885,0.295412
>0.00133514,0.02051,0.0920337,0.188583
>...
>
>The first number is the frequency then the real and imaginary numbers from
>the FFT function and then the magnitude. The magnitude is calculated using
>the following C code
>
>mag = hypot(Real[i] , Imag[i] );
>
>Regards,
>Larry Cochrane
>Webtronics
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