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Re: [Discuss-gnuradio] Help Needed: ValueError: itemsize mismatch: audio


From: Johnathan Corgan
Subject: Re: [Discuss-gnuradio] Help Needed: ValueError: itemsize mismatch: audio_alsa_source(1):0 using 4, flex_demod(2):0 using 8
Date: Fri, 4 Apr 2008 08:13:04 -0600

On Thu, Apr 3, 2008 at 10:51 PM, Darryl Ross <address@hidden> wrote:

>  I'm having a problem trying to use the flex_demod() method of
>  gnuradio.pager:

The FLEX demodulator/decoder is designed to operate on a stream of
complex baseband samples received from the USRP; it was not designed
to work with audio from a sound card.

You could use the output of an FM discriminator (but not the external
audio output) in a scanner or other receiver by building your own
hierarchical block using the low-level blocks in gnuradio.pager.  The
flex_sync() block expects a 25000 sample per second stream of [-1.0,
1.0] audio samples.  Since most sound cards don't create samples at
this rate, you'll need to use the gr.rational_resampler block to
convert your stream from some other rate (like 32000 or 48000).

-- 
Johnathan Corgan
Corgan Enterprises LLC
http://corganenterprises.com/




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