mahesh_u2
05-21-2007, 07:43 PM
Hi all..
I would be grateful if more info on the above could be provided with
regards the equations to precompute the twiddle factors for each
stage/butterfly in the FFT. This is to enable me write a piece of code to
generate this ( i have not found much on this on the net).
I am aware that for a DIF radix-2 FFT the total number of butterflies is
(N/2 LogN). The total number of twiddle factors involved is ( N/2 ) for
radix-2 form. Also the last stage involves multiplication by a twiddl
factor of 1. Could this be illustrated for an 8 point FFT for the
stages. How can i
allocate the values for the twiddle factors (cos ra + j sin ra) for the
entire range and relate that to each stage and butterfly. While th
interconnections between each stage more complex is there a pattern tha
can be established for the DIF radix-2 version.
I am currently implementing this in VHDL to generate the equivalen
hardware and any clarifications, pointers on this would be great!
Cheers
Mahesh
_____________________________________
Do you know a company who employs DSP engineers?
Is it already listed at http://dsprelated.com/employers.php ?
I would be grateful if more info on the above could be provided with
regards the equations to precompute the twiddle factors for each
stage/butterfly in the FFT. This is to enable me write a piece of code to
generate this ( i have not found much on this on the net).
I am aware that for a DIF radix-2 FFT the total number of butterflies is
(N/2 LogN). The total number of twiddle factors involved is ( N/2 ) for
radix-2 form. Also the last stage involves multiplication by a twiddl
factor of 1. Could this be illustrated for an 8 point FFT for the
stages. How can i
allocate the values for the twiddle factors (cos ra + j sin ra) for the
entire range and relate that to each stage and butterfly. While th
interconnections between each stage more complex is there a pattern tha
can be established for the DIF radix-2 version.
I am currently implementing this in VHDL to generate the equivalen
hardware and any clarifications, pointers on this would be great!
Cheers
Mahesh
_____________________________________
Do you know a company who employs DSP engineers?
Is it already listed at http://dsprelated.com/employers.php ?