[hpsdr] FFT latency

[G3XJP]

gm Simon,
1) I don't have and don't want a waterfall/spectrum display and
2) my SDR does not run on a PC let alone Windows.  It runs on a 
dedicated radio. 
I do have to have Fourier and his inverse in the real-time signal path - 
because I need to get into the freq domain, do the Noise Reduction stuff 
and then get back to the time domain.  In that sense, FFT and IFFT are 
pure overheads, a means to an end.  And I would have to forget the whole 
idea if they produced inherent delays that would make ANY radio on ANY 
platform unuseable.  20ms is acceptable.  Only just.  Peter G3XJP

Simon Brown wrote:
> Peter,
>
> You don't have to perform FWD / INV FFT in the demodulation path at all.
> Essentially there are two IQ paths in a generic design:
>
> 1) For the waterfall / spectrum display,
> 2) For demodulation.
>
> Demodulation can get down to < 20ms on Windows if you're careful, using
> WASAPI audio API helps a lot :) .
>
> Simon Brown G4ELI
> http://v2.sdr-radio.com
>

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