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Re: [Discuss-gnuradio] Problems running example audio_fft.py


From: Eric Blossom
Subject: Re: [Discuss-gnuradio] Problems running example audio_fft.py
Date: Tue, 24 Oct 2006 13:10:48 -0700
User-agent: Mutt/1.5.9i

On Tue, Oct 24, 2006 at 08:48:27AM -0700, Jonathan Jacky wrote:
> 
> On Mon, 23 Oct 2006, Dave hartzell wrote:
> 
> >OK, that is interesting....are these things (G4s) really that slow?
> 
> Yes.  It seems that wxPython is the rate-limiting step.  A GNU Radio
> flowgraph can process samples much much faster than wxPython can display 
> them, at least on a G4.  I've used Linux also and it seems that wxPython 
> is appreciably slower, relative to the flow graph, on OS X compared to 
> Linux.
> 
> >I know how to limit FFT CPU utilization via the window sizes, but is
> >there a way to limit the WxPython window updates to something lower?
> 
> Yes.  In scope_sink_f and _c there is a parameter frame_decim, when
> frame_decim = 2 scope_sink only tries to display every other buffer of 
> data that comes from the flow graph, etc.  Start with frame_decim at 20 or 
> 30, then reduce it until you get a reasonable refresh rate.  When you run 
> scopesink from the command line, the first command line argument (with no 
> option flag in front of it) is frame_decim.  This makes it easy to 
> experiment to find a reasonable value for your system.  For more details 
> see
> 
>  http://staff.washington.edu/~jon/gr-osx/scopesink.html
> 
> In fft_sink there is a parameter fft_rate that has a similar effect.
> 
> Jon Jacky

FYI,

You can set the defaults for these in your ~/.gnuradio/config.conf

E.g.,

# This file contains system wide configuration data for GNU Radio.
# You may override any setting on a per-user basis by editing
# ~/.gnuradio/config.conf

[wxgui]
fft_rate = 15     # fftsink and waterfallsink
frame_decim = 1   # scopesink




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