RE: [Discuss-gnuradio] Can't get input from sound card.

[ematlis]

I just got the audio_fft.py running, and this is how I did it on a Fedora 
Core 6 x86_64 machine, in KDE with a set of earphones/microphone:

1) started kmix, went to the "Input" selection and enabled "capture" 
2) verified that audio_fft.py was responding by starting it in 
Oscilloscope mode, ie "./audio_fft.py -S" with Autorange selected and the 
timescale set to 1ms/div.  I can "see" myself typing this email as the 
microphone picks up the key-clicks.

3) quit audio_fft.py and restarted it without any flags, ie 
"./audio_fft.py"

4) right-clicked on the gui window, and selected the highest db/div 
setting, ie 20 db/div.  Otherwise, there was no visible activity on the 
scale.  An alternative would be to decrement the reference level, again by 
right-clicking and selecting "Decr Ref Level" several times until you see 
graph activity.  I can now see the broadband spectrum as I snack on some 
peanuts, which seems to be centered below 2 kHz.  Incidentally, I can't 
seem to whistle above 2.5 kHz.

eric

On Mon, 19 Mar 2007, Bahn William L Civ USAFA/DFCS wrote:

> > Subject: Re: [Discuss-gnuradio] Can't get input from sound card.
> > LRK
> > address@hidden
> >
> > On Sat, Mar 17, 2007 at 01:15:34AM -0600, Bahn William L Civ
> USAFA/DFCS
> > wrote:
> > > I still can't get any input from the sound card. I have installed
> GNU
> > > Radio on a completely different computer. The dial_tone.py program
> > > works. I get a flat line (it bounces around between -8e-5 and +4e-5)
> > > when I run audio_fft.py in the oscilloscope mode.
> > >
> > > In the hopes of perhaps, possibly getting some kind of a response,
> I'll
> > > try to ask very specific questions.
> > >
> > > 1) Is the signal source for audio_fft.py supposed to default to the
> > > sound card microphone?
> > >
> > > 2) If not, what is the default?
> > >
> > > 3) If not, can I tell it to use the sound card microphone?
> > >
> > > 4) If yes, how?
> >
> >
> > I'm running FreeBSD and the sound cards are controlled by the 'mixer'
> > command. There is a similar command in Linux. Maybe 'amixer'?
> >
> > I have to select the input with the 'mixer', either mic or line. I
> also
> > have a control named 'rec' which sets the input volume level. The
> latest
> > versions of FreeBSD save the mixer settings across re-boots.
> >
> > I have not found a way to set these from GR and I have some soundcards
> > which do show a 'rec' control and do not work. Best I can tell the
> > soundcard world is a 'black art' and there are no standards.
> >
> >
> > Maybe someone can shed more light on this.
>
> Thanks LRK, that helped at least some. In the GNOME GUI I found a mixer
> under "Preferences-Volume Control". By un-muting the microphone I got it
> so that the mike is now live (blow into it and you hear it at the
> speaker) and selected it as the capture device. But the GNUradio apps
> such as audio_fft.py still show no response.
>
> So although I'm half a step closer, I still think I need at least the
> basic answers to the above questions, namely:
>
> 1) Is the signal source for audio_fft.py supposed to default to the
> sound card microphone?
> 2) If not, what is the default?
> 3) If not, can I tell it to use the sound card microphone?
> 4) If yes, how?
>
> Thanks.
>
>
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