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Diffstat (limited to 'gr-analog/grc/analog_quadrature_demod_cf.xml')
| -rw-r--r-- | gr-analog/grc/analog_quadrature_demod_cf.xml | 55 |
1 files changed, 0 insertions, 55 deletions
diff --git a/gr-analog/grc/analog_quadrature_demod_cf.xml b/gr-analog/grc/analog_quadrature_demod_cf.xml deleted file mode 100644 index 447acf2ed8..0000000000 --- a/gr-analog/grc/analog_quadrature_demod_cf.xml +++ /dev/null @@ -1,55 +0,0 @@ -<?xml version="1.0"?> -<!-- -################################################### -##Quadrature Demodulator -################################################### - --> -<block> - <name>Quadrature Demod</name> - <key>analog_quadrature_demod_cf</key> - <import>from gnuradio import analog</import> - <import>import math</import> - <make>analog.quadrature_demod_cf($gain)</make> - <callback>set_gain($gain)</callback> - <param> - <name>Gain</name> - <key>gain</key> - <value>samp_rate/(2*math.pi*fsk_deviation_hz/8.0)</value> - <type>real</type> - </param> - <sink> - <name>in</name> - <type>complex</type> - </sink> - <source> - <name>out</name> - <type>float</type> - </source> - <doc> -This can be used to demod FM, FSK, GMSK, etc. The input is complex -baseband, output is the signal frequency in relation to the sample -rated, multiplied with the gain. - -Mathematically, this block calculates the product of the one-sample -delayed input and the conjugate undelayed signal, and then calculates -the argument of the resulting complex number: - -y[n] = \mathrm{arg}\left(x[n] \, \bar x [n-1]\right). - -Let x be a complex sinusoid with amplitude A>0, (absolute) -frequency f\in\mathbb R and phase \phi_0\in[0;2\pi] sampled at -f_s>0 so, without loss of generality, - -x[n]= A e^{j2\pi( \frac f{f_s} n + \phi_0)}\f - -then - -y[n] = \mathrm{arg}\left(A e^{j2\pi\left( \frac f{f_s} n + \phi_0\right)} \overline{A e^{j2\pi( \frac f{f_s} (n-1) + \phi_0)}}\right)\\ - = \mathrm{arg}\left(A^2 e^{j2\pi\left( \frac f{f_s} n + \phi_0\right)} e^{-j2\pi( \frac f{f_s} (n-1) + \phi_0)}\right)\\ - = \mathrm{arg}\left( A^2 e^{j2\pi\left( \frac f{f_s} n + \phi_0 - \frac f{f_s} (n-1) - \phi_0\right)}\right)\\ - = \mathrm{arg}\left( A^2 e^{j2\pi\left( \frac f{f_s} n - \frac f{f_s} (n-1)\right)}\right)\\ - = \mathrm{arg}\left( A^2 e^{j2\pi\left( \frac f{f_s} \left(n-(n-1)\right)\right)}\right)\\ - = \mathrm{arg}\left( A^2 e^{j2\pi \frac f{f_s}}\right) \intertext{$A$ is real, so is $A^2$ and hence only \textit{scales}, therefore $\mathrm{arg}(\cdot)$ is invariant:} = \mathrm{arg}\left(e^{j2\pi \frac f{f_s}}\right)\\ -= \frac f{f_s}\\ - </doc> -</block> |