[hpsdr] FFT latency

[Jay Salsburg]

Yes, there is an unavoidable delay. What the SDR Software does is perform
the FFT on the Data stream coming from the Analog to Digital Converters.
Then, to hear the stream, an Inverse FFT is performed and sent to the audio
device. This delay may be reduced with better hardware and dedicated SDR
hardware to pre-process the data stream.

-----Original Message-----
From: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of G3XJP
Sent: Sunday, April 5, 2015 5:55 AM
To: Hpsdr at lists.openhpsdr.org
Subject: [hpsdr] FFT latency

***** High Performance Software Defined Radio Discussion List *****

I need your collective wisdom!  Is it not an inescapable fact that any
serious FFT in the real-time path between your antenna and your ears must
introduce an inherent and inevitable delay that will preclude a
conversational VOX/QSK QSO?  I can see that it would not preclude listening
to a monologue - or to watching spectral pictures on a display.  But
anything more than about 1/5 sec is doomed to feel like Skype on a bad day -
where you often end up having to say "over".  As a generality, am I missing
something fundamental here?  Peter G3XJP
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