On Tue, May 10, 2011 at 9:13 AM, Andrew Elder wrote:
> Also, see
>
> <
>
http://processors.wiki.ti.com/index.php/Efficient_FFT_Computation_of_Real_Input
> > Not sure if it uses decimation in freq.
>
> - Andrew
> ----- Original Message ----
> From: Jeff Brower
> To: a...
> Cc: f...@gmail.com
> Sent: Tue, May 10, 2011 12:03:54 PM
> Subject: Re: [audiodsp] Real FFT implementation
>
> Fezi-
>
> > I need assistance in computing FFT of real valued
> > data. Googling, i found that sorensen has developed and
> > implemented an algorithm. But i couldnt find the steps to
> > code it. Moreover above said algorithm is
> > decimation in time. My requirement is decimation in
> > frequency. Any help(c code\algorithm) is deeply
> > appreciated!
>
> Try this book:
>
> http://www.amazon.com/Fast-Fourier-Transform-Its-Applications/dp/0133075052
>
> Look for section "Transform of 2 N Samples with an N-Sample Transform". The
>
> source code is given in BASIC, but easily
> ported to C.
>
> -Jeff
>
>
>
Why i need a DIF RFFT is that i am trying to do an algorithm level
optimisation. The bit reversal portion in DIT is to be avoided. Taking DIF and
then inverse DIT can help me do this i guess.
Most of the links and references you people gave were those i read
earlier. Out of which , efficient computing by TI wiki is a common one. I have
coded it. But it still requires a re-ordering or output extraction at the end of
algorithm. fftw is much more complex as told.
Do you guys have a hands on experience with FFT on real data and quote the step
by step procedure to calculate it?
Reply by Andrew Elder●May 10, 20112011-05-10
Also, see
Not sure if it uses decimation in freq.
- Andrew
----- Original Message ----
From: Jeff Brower
To: a...
Cc: f...@gmail.com
Sent: Tue, May 10, 2011 12:03:54 PM
Subject: Re: [audiodsp] Real FFT implementation
Fezi-
> I need assistance in computing FFT of
real valued
> data. Googling, i found that sorensen has developed and
> implemented an algorithm. But i couldnt find the steps to
> code it. Moreover above said algorithm is
> decimation in time. My requirement is decimation in
> frequency. Any help(c code\algorithm) is deeply
> appreciated!
Look for section "Transform of 2 N Samples with an N-Sample Transform". The
source code is given in BASIC, but easily
ported to C.
-Jeff
Reply by Brant Jameson●May 10, 20112011-05-10
Hi Fezi,
You could look into KISSFFT (http://sourceforge.net/projects/kissfft/)
and FFTW (http://www.fftw.org/). KISSFFT is more general, as it supports
fixed point transforms (after a re-compile), but FFTW is a little more
sophisticated and offers some more options for the transform.
Good Luck,
-Brant
On Tue, May 10, 2011 at 9:03 AM, Jeff Brower wrote:
> Fezi-
> > I need assistance in computing FFT of real valued
> > data. Googling, i found that sorensen has developed and
> > implemented an algorithm. But i couldnt find the steps to
> > code it. Moreover above said algorithm is
> > decimation in time. My requirement is decimation in
> > frequency. Any help(c code\algorithm) is deeply
> > appreciated!
>
> Try this book:
>
> http://www.amazon.com/Fast-Fourier-Transform-Its-Applications/dp/0133075052
>
> Look for section "Transform of 2 N Samples with an N-Sample Transform". The
> source code is given in BASIC, but easily
> ported to C.
>
> -Jeff
>
>
>
> I need assistance in computing FFT of
real valued
> data. Googling, i found that sorensen has developed and
> implemented an algorithm. But i couldnt find the steps to
> code it. Moreover above said algorithm is
> decimation in time. My requirement is decimation in
> frequency. Any help(c code\algorithm) is deeply
> appreciated!
Look for section "Transform of 2 N Samples with an N-Sample Transform". The
source code is given in BASIC, but easily
ported to C.
-Jeff
Reply by fezi...@gmail.com●May 10, 20112011-05-10
Hi everyone,
I need assistance in computing FFT of real valued data. Googling, i
found that sorensen has developed and implemented an algorithm. But i couldnt
find the steps to code it. Moreover above said algorithm is decimation in time.
My requirement is decimation in frequency. Any help(c code\algorithm) is deeply
appreciated!