Folks
I am trying to use a complex fft (the green FFT block) for a spectrum analyzer
application.
I would like to use a 512 point FFT to compute on read time data. I need the
FFT to compute in less than 512 samples. I am using 4 taps in the input, and
running the FPGA at 128MHz. In this case
hi tim,
the casper fft's are maximized to handle high bandwidths with
low resource utilization, but they are not optimized for low latency,
as astronomers use them in streaming applications where latency
is not important.
there are other FFT architectures - some 512 input FFT's can
convert from t
I appreciate your response Dan.
Tim
From: dan.werthi...@gmail.com [dan.werthi...@gmail.com] on behalf of Dan
Werthimer [d...@ssl.berkeley.edu]
Sent: Friday, May 02, 2014 11:26 AM
To: Madden, Timothy J.
Cc: casper@lists.berkeley.edu
Subject: Re: [casper] FFT
tim,
one more thought:
the PFB FIR in front of the FFT dominates the latency of the PFB/FFT.
the PFB has latency of (Ntaps-1) x FFTlength / Nparallelinputs.
a four tap PFB has about three times the latency of the FFT,
so if you remove the PFB you will cut latency down by about a factor of
three
Dear Tim,
You are aware that the CASPER FFTs are streaming, right? By this, I mean
that they can accept data input at the full clock rate with no pausing
between FFT windows. Everything Dan says is correct about latency, but
historically there have been very few applications that have strict lim
Hi Tim,
>
> Also, if we supply ONE and only ONE sync pulse, should the fft block compute
> indefinately? My simulink seems to require a series of sync pulses to get
> the FFt to work more than once.
>
>
That's right, one and only one sync pulse is sufficient to keep the
FFT operating indefinitely
From: Jack Hickish [jackhick...@gmail.com]
Sent: Friday, May 02, 2014 2:15 PM
To: Madden, Timothy J.
Cc: casper@lists.berkeley.edu
Subject: Re: [casper] FFT compute time
Hi Tim,
>
> Also, if we supply ONE and only ONE sync pulse, should the fft block compute
> indefinately? My simulink
4 2:15 PM
> To: Madden, Timothy J.
> Cc: casper@lists.berkeley.edu
> Subject: Re: [casper] FFT compute time
>
> Hi Tim,
> >
> > Also, if we supply ONE and only ONE sync pulse, should the fft block
> compute
> > indefinately? My simulink seems to require a serie
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