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Electronic Equipment > Digital Signal Processing (DSP) > Re: FFT spectru...
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Re: FFT spectrum height question

by cs_posting@[EMAIL PROTECTED] Oct 12, 2008 at 07:57 PM

On Oct 12, 10:50 pm, glen herrmannsfeldt <g...@[EMAIL PROTECTED]
>
wrote:

> > Using various windows (Hamming, Bartlett, etc) the V(f) peak amplitude
> > becomes even smaller.

Well yeah, a window function basically "fades" the signal in and out
slowly, so it spends almost all of the time at less than "full
volume".   You'll want to correct for that with the integral of the
window function - essentially the area under the curve.  If it gets
too hard to figure out, just feed it a full scale input (constant
valued if you want) and take the output that produces as a baseline to
figure out an empirical scale factor.

If you at some point implement this in fixed point, you'll have to
think a bit about pre-scaling vs. post-scaling to make sure you don't
overflow your word length at any point in the process.
 




 3 Posts in Topic:
FFT spectrum height question
"Peter123" <  2008-10-12 19:00:12 
Re: FFT spectrum height question
glen herrmannsfeldt <g  2008-10-12 19:50:05 
Re: FFT spectrum height question
cs_posting@[EMAIL PROTECT  2008-10-12 19:57:29 

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tan12V112 Mon Dec 1 16:05:38 CST 2008.