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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from ssbdemod.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="ssbdemod" xml:lang="en"
xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:ns3="http://www.w3.org/1999/xhtml"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:scilab="http://www.scilab.org"
xmlns:db="http://docbook.org/ns/docbook">
<refnamediv>
<refname>ssbdemod</refname>
<refpurpose>This function performs Single Side Band Amplitude Demodulation</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
Z = SSBDEMOD(Y,Fc,Fs)
demodulates the single sideband amplitude modulated signal Y
with the carrier frequency Fc (Hz).
Sample frequency Fs (Hz). zero initial phase (ini_phase).
The modulated signal can be an upper or lower sideband signal.
A lowpass butterworth filter is used in the demodulation.
</para>
<para>
Z = SSBDEMOD(Y,Fc,Fs,INI_PHASE)
adds an extra argument the initial phase (rad) of the modulated signal.
</para>
<para>
Z = SSBDEMOD(Y,Fc,Fs,INI_PHASE,NUM,DEN)
adds extra arguments about the filter specifications
i.e., the numerator and denominator of the lowpass filter.
</para>
<para>
Fs must satisfy Fs >2*(Fc + BW), where BW is the bandwidth of the
modulating signal.
</para>
<para>
</para>
<para>
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
Fs =200;
t = [0:2*Fs+1]'/Fs;
ini_phase = 5;
Fc = 20;
fm1= 2;
fm2= 3
x =sin(2*fm1*%pi*t)+sin(2*fm2*%pi*t);
y = ssbmod(x,Fc,Fs,ini_phase);
o = ssbdemod(y,Fc,Fs,ini_phase);
z = fft(y);
zz =abs(z(1:length(z)/2+1 ));
axis = (0:Fs/length(zz):Fs -(Fs/length(zz)))/2;
figure
subplot(3,1,1); plot(x);
title(' Message signal');
subplot(3,1,2); plot(y);
title('Amplitude modulated signal');
subplot(3,1,3); plot(axis,zz);
title('Spectrum of amplitude modulated signal');
z1 =fft(o);
zz1 =abs(z1(1:length(z1)/2+1 ));
axis = (0:Fs/length(zz1):Fs -(Fs/length(zz1)))/2;
figure
subplot(3,1,1); plot(y);
title(' Modulated signal');
subplot(3,1,2); plot(o);
title('Demodulated signal');
subplot(3,1,3); plot(axis,zz1);
title('Spectrum of Demodulated signal');
]]></programlisting>
</refsection>
<refsection>
<title>Authors</title>
<simplelist type="vert">
<member>Pola Lakshmi Priyanka, IIT Bombay</member>
</simplelist>
</refsection>
</refentry>
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