Re: [oc] fft on hardware??or DSP??

[gsg43@rediffmail.com]

Hi John,
Are you implemeting pipelined fft?? The word real time fft is giving this meaning...
which algorithm you are using and why?
Shall we get enough speed with pipeline fft on FPGA? I mean routing delays may effect the design...
IF not so which FPGA will be suitable...
Is opencores giving code for free??

I am trying to get brief idea on the fft implementation... I am planning to simulate(Integer C code) pipelined fft.
Thank you,
gayathri :-)

----- Original Message ----- 
From: jdalton at asiaonline dot net dot au 
To: cores at opencores dot org 
CC: jdalton at asiaonline dot net dot au 
Date: 17 Sep 2001 21:03:23 -0700 
Subject: Re: [oc] fft on hardware??or DSP?? 

> > Hi folks, 
> 
> Hello 
> 
> > 1. What is the speed of fastest FFT availabe in the 
> market till now? 
> 
> Not sure. 
> 
> > 2. I have seen few xilinx FFT documents for virtex 
> FPGAs saying 1024 
> > FFT in arround 60us. Other DSP vendors giving much 
> speed FFTs than 
> > FPGAs. 
> > So which is suitable for fastest FFT, either DSP or 
> FPGA or dedicated 
> > chip. 
> > what are the limitations in both. 
> 
> The FFT I am designing for opencores should do around 1 
> point 
> every 10ns in an FPGA. This translates to 10us for 1024 
> points. 
> Essentially it will be 'real time', allowing a continuous 
> stream of data 
> to be processed. 
> 
> > 3. Can I get faster FFTs in FPGA than DSPs? 
> 
> My guess is for long transforms, an FPGA will generally 
> have a higher thoughput, as it can do more in parallel. 
> A DSP could potentially have a shorter latency due to 
> more highly optimised multipliers. For very short 
> transforms 
> a DSP with multiple ALUs might be faster than an FPGA as 
> it can do 
> everything in parallel with optimised multipliers. 
> 
> > 4. What are the advantages of FFT on FPGA than in 
> DSP? 
> 
> See previous answer. 
> 
> Best wishes 
> John 
> 
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