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<span class="path" dir="ltr"><a href="index.html">FOSSEE_Communication_Systems_Toolbox</a> >> <a href="section_1f049b1e3111e3d1d538e7603f77f589.html">FOSSEE_Communication_Systems_Toolbox</a> > ssbdemod</span>
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<div class="refnamediv"><h1 class="refname">ssbdemod</h1>
<p class="refpurpose">This function performs Single Side Band Amplitude Demodulation</p></div>
<div class="refsection"><h3 class="title">Description</h3>
<p class="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.</p>
<p class="para">Z = SSBDEMOD(Y,Fc,Fs,INI_PHASE)
adds an extra argument the initial phase (rad) of the modulated signal.</p>
<p class="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.</p>
<p class="para">Fs must satisfy Fs >2*(Fc + BW), where BW is the bandwidth of the
modulating signal.</p>
<p class="para"></p>
<p class="para"></p></div>
<div class="refsection"><h3 class="title">Examples</h3>
<div class="programlisting"><table border="0" width="100%"><tr><td width="98%"><pre class="scilabcode"><span class="scilabid">Fs</span> <span class="scilaboperator">=</span><span class="scilabnumber">200</span><span class="scilabdefault">;</span>
<span class="scilabid">t</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">[</span><span class="scilabnumber">0</span><span class="scilabspecial">:</span><span class="scilabnumber">2</span><span class="scilaboperator">*</span><span class="scilabid">Fs</span><span class="scilaboperator">+</span><span class="scilabnumber">1</span><span class="scilabopenclose">]</span><span class="scilaboperator">'</span><span class="scilaboperator">/</span><span class="scilabid">Fs</span><span class="scilabdefault">;</span>
<span class="scilabid">ini_phase</span> <span class="scilaboperator">=</span> <span class="scilabnumber">5</span><span class="scilabdefault">;</span>
<span class="scilabid">Fc</span> <span class="scilaboperator">=</span> <span class="scilabnumber">20</span><span class="scilabdefault">;</span>
<span class="scilabid">fm1</span><span class="scilaboperator">=</span> <span class="scilabnumber">2</span><span class="scilabdefault">;</span>
<span class="scilabid">fm2</span><span class="scilaboperator">=</span> <span class="scilabnumber">3</span>
<span class="scilabid">x</span> <span class="scilaboperator">=</span><a class="scilabcommand" href="scilab://sin">sin</a><span class="scilabopenclose">(</span><span class="scilabnumber">2</span><span class="scilaboperator">*</span><span class="scilabid">fm1</span><span class="scilaboperator">*</span><span class="scilabconstants">%pi</span><span class="scilaboperator">*</span><span class="scilabid">t</span><span class="scilabopenclose">)</span><span class="scilaboperator">+</span><a class="scilabcommand" href="scilab://sin">sin</a><span class="scilabopenclose">(</span><span class="scilabnumber">2</span><span class="scilaboperator">*</span><span class="scilabid">fm2</span><span class="scilaboperator">*</span><span class="scilabconstants">%pi</span><span class="scilaboperator">*</span><span class="scilabid">t</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">y</span> <span class="scilaboperator">=</span> <span class="scilabid">ssbmod</span><span class="scilabopenclose">(</span><span class="scilabid">x</span><span class="scilabdefault">,</span><span class="scilabid">Fc</span><span class="scilabdefault">,</span><span class="scilabid">Fs</span><span class="scilabdefault">,</span><span class="scilabid">ini_phase</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">o</span> <span class="scilaboperator">=</span> <span class="scilabid">ssbdemod</span><span class="scilabopenclose">(</span><span class="scilabid">y</span><span class="scilabdefault">,</span><span class="scilabid">Fc</span><span class="scilabdefault">,</span><span class="scilabid">Fs</span><span class="scilabdefault">,</span><span class="scilabid">ini_phase</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">z</span> <span class="scilaboperator">=</span> <a class="scilabcommand" href="scilab://fft">fft</a><span class="scilabopenclose">(</span><span class="scilabid">y</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">zz</span> <span class="scilaboperator">=</span><a class="scilabcommand" href="scilab://abs">abs</a><span class="scilabopenclose">(</span><span class="scilabid">z</span><span class="scilabopenclose">(</span><span class="scilabnumber">1</span><span class="scilabspecial">:</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">z</span><span class="scilabopenclose">)</span><span class="scilaboperator">/</span><span class="scilabnumber">2</span><span class="scilaboperator">+</span><span class="scilabnumber">1</span> <span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">axis</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">(</span><span class="scilabnumber">0</span><span class="scilabspecial">:</span><span class="scilabid">Fs</span><span class="scilaboperator">/</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">zz</span><span class="scilabopenclose">)</span><span class="scilabspecial">:</span><span class="scilabid">Fs</span> <span class="scilaboperator">-</span><span class="scilabopenclose">(</span><span class="scilabid">Fs</span><span class="scilaboperator">/</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">zz</span><span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilaboperator">/</span><span class="scilabnumber">2</span><span class="scilabdefault">;</span>
<a class="scilabcommand" href="scilab://figure">figure</a>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">x</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring"> Message signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">2</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">y</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring">Amplitude modulated signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">3</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">axis</span><span class="scilabdefault">,</span><span class="scilabid">zz</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring">Spectrum of amplitude modulated signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">z1</span> <span class="scilaboperator">=</span><a class="scilabcommand" href="scilab://fft">fft</a><span class="scilabopenclose">(</span><span class="scilabid">o</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">zz1</span> <span class="scilaboperator">=</span><a class="scilabcommand" href="scilab://abs">abs</a><span class="scilabopenclose">(</span><span class="scilabid">z1</span><span class="scilabopenclose">(</span><span class="scilabnumber">1</span><span class="scilabspecial">:</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">z1</span><span class="scilabopenclose">)</span><span class="scilaboperator">/</span><span class="scilabnumber">2</span><span class="scilaboperator">+</span><span class="scilabnumber">1</span> <span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<span class="scilabid">axis</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">(</span><span class="scilabnumber">0</span><span class="scilabspecial">:</span><span class="scilabid">Fs</span><span class="scilaboperator">/</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">zz1</span><span class="scilabopenclose">)</span><span class="scilabspecial">:</span><span class="scilabid">Fs</span> <span class="scilaboperator">-</span><span class="scilabopenclose">(</span><span class="scilabid">Fs</span><span class="scilaboperator">/</span><a class="scilabcommand" href="scilab://length">length</a><span class="scilabopenclose">(</span><span class="scilabid">zz1</span><span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilabopenclose">)</span><span class="scilaboperator">/</span><span class="scilabnumber">2</span><span class="scilabdefault">;</span>
<a class="scilabcommand" href="scilab://figure">figure</a>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">y</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring"> Modulated signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">2</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">o</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring">Demodulated signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://subplot">subplot</a><span class="scilabopenclose">(</span><span class="scilabnumber">3</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">3</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <a class="scilabmacro" href="scilab://plot">plot</a><span class="scilabopenclose">(</span><span class="scilabid">axis</span><span class="scilabdefault">,</span><span class="scilabid">zz1</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span>
<a class="scilabmacro" href="scilab://title">title</a><span class="scilabopenclose">(</span><span class="scilabstring">'</span><span class="scilabstring">Spectrum of Demodulated signal</span><span class="scilabstring">'</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span></pre></td><td valign="top"><a href="scilab://scilab.execexample/"><img src="ScilabExecute.png" border="0"/></a></td><td valign="top"><a href="scilab://scilab.editexample/"><img src="ScilabEdit.png" border="0"/></a></td><td></td></tr></table></div></div>
<div class="refsection"><h3 class="title">Authors</h3>
<ul class="itemizedlist"><li class="member">Pola Lakshmi Priyanka, IIT Bombay</li></ul></div>
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