Free FFT source code? 
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 Free FFT source code?

Hello
I am looking for a free 2048-point FFT source code. I know Xilinx has a free
core available but it won't fit in a part smaller than a 300 000 gates chip (not
because of the gate count but because of the geometry of the RPM). I don't need
very high performance since it will be used to compute audio spectrum (not more
than 100ksample/second).
I have searched opencores, free-ip... I have used Google but didn't find
anythong interesting.
Thanks in advance
--
Nicolas MATRINGE           IPricot European Headquarters
Conception electronique    10-12 Avenue de Verdun
Tel +33 1 46 52 53 11      F-92250 LA GARENNE-COLOMBES - FRANCE
Fax +33 1 46 52 53 01       http://www.*-*-*.com/


Sat, 03 Jul 2004 16:32:24 GMT  
 Free FFT source code?

The important thing to know is your data format id. complex or real?
                                                    input size?
                                                    output size?
                                                    and precision
not really the speed.

Quote:
> Hello
> I am looking for a free 2048-point FFT source code. I know Xilinx has a free
> core available but it won't fit in a part smaller than a 300 000 gates chip (not
> because of the gate count but because of the geometry of the RPM). I don't need
> very high performance since it will be used to compute audio spectrum (not more
> than 100ksample/second).
> I have searched opencores, free-ip... I have used Google but didn't find
> anythong interesting.
> Thanks in advance



Mon, 05 Jul 2004 04:40:56 GMT  
 Free FFT source code?

Quote:

> I am looking for a free 2048-point FFT source code. I know Xilinx has a free
> core available but it won't fit in a part smaller than a 300 000 gates chip (not
> because of the gate count but because of the geometry of the RPM). I don't need
> very high performance since it will be used to compute audio spectrum (not more
> than 100ksample/second).

The main resources would occupy the RAM.
For example, I can generate you such a core freely
as a single EDIF file without RPMs,
with the data/coefficient width =10
and it will occupy 510 CLB slices, and 20 Block RAMs.
1 Block RAM is equal ca.10000-20000 gates.
Therefore you would have the very 300000 gates.

Regards,
A.Sergyienko



Sat, 10 Jul 2004 19:16:09 GMT  
 Free FFT source code?
The available memory is going to drive the device size unless you wish to use an
external memory.  SInce you don't need much in the way of performance, you could
easily get away with a radix2 or radix 4 kernel and make multiple passes.  That
kernel, will fit into any device that has enough memory to store the inter-pass
data.

Quote:

> Hello
> I am looking for a free 2048-point FFT source code. I know Xilinx has a free
> core available but it won't fit in a part smaller than a 300 000 gates chip (not
> because of the gate count but because of the geometry of the RPM). I don't need
> very high performance since it will be used to compute audio spectrum (not more
> than 100ksample/second).
> I have searched opencores, free-ip... I have used Google but didn't find
> anythong interesting.
> Thanks in advance
> --
> Nicolas MATRINGE           IPricot European Headquarters
> Conception electronique    10-12 Avenue de Verdun
> Tel +33 1 46 52 53 11      F-92250 LA GARENNE-COLOMBES - FRANCE
> Fax +33 1 46 52 53 01      http://www.IPricot.com/

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930     Fax 401/884-7950

http://www.andraka.com

 "They that give up essential liberty to obtain a little
  temporary safety deserve neither liberty nor safety."
                                          -Benjamin Franklin, 1759



Sat, 10 Jul 2004 21:41:09 GMT  
 Free FFT source code?
Ray Andraka a crit :

Quote:

> The available memory is going to drive the device size unless
> you wish to use an external memory.

I haven't looked at the memory size yet... (I'm afraid an XCV50 won't allow a
"big" FFT)

Quote:
>  SInce you don't need much in the way of performance, you could
> easily get away with a radix2 or radix 4 kernel and make
> multiple passes. That kernel, will fit into any device that has
> enough memory to store the inter-pass data.

Hum... My problem is that I don't know much about signal processing and the FFT
algorithm.
This is a personal project (no business at all :o) and I would like to avoid
having to spend a lot of time learning all this stuff. I think I won't get away
without, though...

--
Nicolas MATRINGE           IPricot European Headquarters
Conception electronique    10-12 Avenue de Verdun
Tel +33 1 46 52 53 11      F-92250 LA GARENNE-COLOMBES - FRANCE
Fax +33 1 46 52 53 01      http://www.IPricot.com/



Sat, 10 Jul 2004 23:12:51 GMT  
 Free FFT source code?
You could use an XCV50 plus an external memory provided you have enough time to run
thrugh the data between memory and the FPGA either 6 or 11 times (depending on the
radix of your kernel).  If you look at the Xilinx core, I think you'll find that it
uses a radix 4 kernel which in most cases is instantiated twice with a phase
rotator (implemented as 3 multipliers and a few adders) to get a radix 16 FFT per
pass, then it is run as many times through memory as needed to get the larger size
FFTs.  The parallel multipliers in the Xilinx design are what make the kernel too
big for an XCV50.  If you data rate is low enough, there is nothing preventing use
of serial by parallel multipliers, which would get the design small enough for an
XC2S50, provided you have external storage for the inter-pass storage.  You might
also look at  using CORDIC to do the phase rotations, as it avoids the sin/cos
tables and may be more compact than the multplier based rotator.

The FFT algorithms, at least for the most common Cooley-Tukey algorithm, are not
that difficult.  I doubt you will find what you are looking for in the form of a
free core, especially one with source.  Since this is a hobby project, why not bite
the bullet and try writing your own.  I guarantee you'll find it rewarding.  You
might get a copy of one of the FFT books such as Smith & Smith to use a s a guide
(The smith & smith book is listed in the bookstore page on my website).

Quote:

> Ray Andraka a crit :

> > The available memory is going to drive the device size unless
> > you wish to use an external memory.

> I haven't looked at the memory size yet... (I'm afraid an XCV50 won't allow a
> "big" FFT)

> >  SInce you don't need much in the way of performance, you could
> > easily get away with a radix2 or radix 4 kernel and make
> > multiple passes. That kernel, will fit into any device that has
> > enough memory to store the inter-pass data.

> Hum... My problem is that I don't know much about signal processing and the FFT
> algorithm.
> This is a personal project (no business at all :o) and I would like to avoid
> having to spend a lot of time learning all this stuff. I think I won't get away
> without, though...

> --
> Nicolas MATRINGE           IPricot European Headquarters
> Conception electronique    10-12 Avenue de Verdun
> Tel +33 1 46 52 53 11      F-92250 LA GARENNE-COLOMBES - FRANCE
> Fax +33 1 46 52 53 01      http://www.IPricot.com/

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930     Fax 401/884-7950

http://www.andraka.com

 "They that give up essential liberty to obtain a little
  temporary safety deserve neither liberty nor safety."
                                          -Benjamin Franklin, 1759



Sun, 11 Jul 2004 00:53:14 GMT  
 Free FFT source code?
Ray Andraka a crit :

Quote:

[...]
> The FFT algorithms, at least for the most common Cooley-Tukey
> algorithm, are not that difficult.  I doubt you will find what
> you are looking for in the form of a free core, especially one
> with source.

Actually, I didn't find anything so I started looking for books and articles.

Quote:
>  Since this is a hobby project, why not bite the bullet and try
> writing your own.

That's what I'll finally do.

Quote:
> You might get a copy of one of the FFT books such as Smith &
> Smith to use a s a guide (The smith & smith book is listed in
> the bookstore page on my website).

I downloaded "The scientists and engineer's guide to digital signal processing"
by S.W. Smith (http://www.dspguide.com/) and started with it.

Thanks for your help
--
Nicolas MATRINGE           IPricot European Headquarters
Conception electronique    10-12 Avenue de Verdun
Tel +33 1 46 52 53 11      F-92250 LA GARENNE-COLOMBES - FRANCE
Fax +33 1 46 52 53 01      http://www.IPricot.com/



Sun, 11 Jul 2004 17:22:12 GMT  
 
 [ 7 post ] 

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