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[Discuss-gnuradio] SSB demodulation

From: cswiger
Subject: [Discuss-gnuradio] SSB demodulation
Date: Wed, 8 Sep 2004 09:07:11 -0400 (EDT)

Hi All - I'm making wild stabs are writing modules to demod SSB
with REAL+IMAG or REAL-IMAG for upper and lower sideband, simply
by cloning David Carr's gr_complex_mag module:


  for (int i = 0; i < noutput_items; i++){
    float ans = std::abs (in[i]);
    out[i] = ans;

I have compiled gr_complex_sum:

  for (int i = 0; i < noutput_items; i++){
    gr_complex in_c = in[i];
    float ans = in_c.real() + in_c.imag();
    out[i] = ans;

and gr_complex_dif is same except for in_c.real() - in_c.imag();

Now testing those out I'm getting a lot of noise and getting audio
out on both sidebands, setting the radio for 950Khz and listening
to an unmodulated sine 1K above and below 950Khz I get these:


Anything obviously wrong that accounts for the noise and signal
on both sidebands? The tones are correct, 1Khz (32 points/cycle
at 32Ksps).



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