Re: [Discuss-gnuradio] VRAudioSource question (was Parallel Port Interface)

[Joseph DiVerdi]

At 8:22 PM +0000 1/20/03, Matt Ettus wrote:
><snip>
>
>Going back to my soundcard suggestion, you could buy a 96ks/s stereo soundcard
>for less than $100 these days.  Take your input signal, mix it (multiply) by a
>48 kHz sine and cosine wave, lowpass filter those 2 outputs, and feed to the
>soundcard stereo inputs.  You'll have sampled the spectrum from 0 to 96kHz at 
>24
>bits per sample.
>
>Matt

Thanks, Matt, for your suggestion above. I have built a frequency translator 
out of discrete parts from my junk box and been experimenting with an 
inexpensive sound card (two channels, 48ksamples/s). It was surprisingly easy 
to build (VLF is a treat that way) and works equally surprisingly well. I will 
be documenting the translator on my VLF web site shortly for anyone who's 
interested. 

As I proceed, I am learning how to use the GNU-radio software suite and have a 
question. It is not clear to me how to set up two sources from the audio card, 
one for the left and one for the right channel. A code snippet from one of the 
example programs which sets up a single source follows:

  VrSource<short> *source = new VrAudioSource<short>(SAMPLING_FREQUENCY);

I've examined the VRAudioSource.h file and haven't figured out (as yet) how to 
accomplish this seemingly simple feat.

BTW, after running down the Parallel Port Interface questions I'm limiting 
future work on that interface to much slower stuff. Thanks to all for the 
helpful comments on that thread.

Best regards,
Joseph
-- 
Joseph A. DiVerdi, Ph.D., M.B.A.          
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