<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE document PUBLIC "-//CNX//DTD CNXML 0.5 plus MathML//EN" "http://cnx.rice.edu/cnxml/0.5/DTD/cnxml_mathml.dtd">
<document xmlns="http://cnx.rice.edu/cnxml" xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="m11080">
  <name xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Two-Channel Analysis Filter Bank</name>
  <metadata xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">
  <md:version xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">2.2</md:version>
  <md:created xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">2003/03/19</md:created>
  <md:revised xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">2003/03/31</md:revised>
  <md:authorlist xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">
      <md:author xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="selesi">
      <md:firstname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Ivan</md:firstname>
      
      <md:surname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Selesnick</md:surname>
      <md:email xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">selesi@taco.poly.edu</md:email>
    </md:author>
  </md:authorlist>

  <md:maintainerlist xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">
    <md:maintainer xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="emaloney">
      <md:firstname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Erin</md:firstname>
      
      <md:surname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Maloney</md:surname>
      <md:email xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">emaloney@rice.edu</md:email>
    </md:maintainer>
    <md:maintainer xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="selesi">
      <md:firstname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Ivan</md:firstname>
      
      <md:surname xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Selesnick</md:surname>
      <md:email xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">selesi@taco.poly.edu</md:email>
    </md:maintainer>
  </md:maintainerlist>
  
  <md:keywordlist xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">
    <md:keyword xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">bank</md:keyword>
    <md:keyword xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">filter</md:keyword>
    <md:keyword xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">Filterbank</md:keyword>
  </md:keywordlist>

  <md:abstract xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/"/>
</metadata>

  <content xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/">
    <para xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="para1">
      Consider a two-channel analysis filter bank (<cnxn xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" target="fig1" strength="9"/>).
    </para>

    <figure xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="fig1">
      <media xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" type="image/png" src="sec5fig1.png"/>
    </figure>

    <para xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="para2">
      What is the transpose of this system? We can find it by finding
      first the matrix representation. To find the matrix
      representation, note that we already know the matrix
      representation of the two branches individually.

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:ci>
	    <m:msub>
	      <m:mi>s</m:mi>
	      <m:mn>0</m:mn>
	    </m:msub>
	  </m:ci>
	  <m:apply>
	    <m:times/>
	    <m:ci>
	      <m:msub>
		<m:mi>Q</m:mi>
		<m:mn>0</m:mn>
	      </m:msub>
	    </m:ci>
	    <m:ci>x</m:ci>
	  </m:apply>
	</m:apply>
      </m:math>

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:ci>
	    <m:msub>
	      <m:mi>s</m:mi>
	      <m:mn>1</m:mn>
	    </m:msub>
	  </m:ci>
	  <m:apply>
	    <m:times/>
	    <m:ci>
	      <m:msub>
		<m:mi>Q</m:mi>
		<m:mn>1</m:mn>
	      </m:msub>
	    </m:ci>
	    <m:ci>x</m:ci>
	  </m:apply>
	</m:apply>
      </m:math>

      So total system can be represented as a single matrix:

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:vector>
	    <m:ci>
	      <m:msub>
		<m:mi>s</m:mi>
		<m:mn>0</m:mn>
	      </m:msub>
	    </m:ci>
	    <m:ci>
	      <m:msub>
		<m:mi>s</m:mi>
		<m:mn>1</m:mn>
	      </m:msub>
	    </m:ci>
	  </m:vector>
	  <m:vector>
	    <m:apply>
	      <m:times/>
	      <m:ci>
		<m:msub>
		  <m:mi>Q</m:mi>
		  <m:mn>0</m:mn>
		</m:msub>
	      </m:ci>
	      <m:ci>x</m:ci>
	    </m:apply>
	    <m:apply>
	      <m:times/>
	      <m:ci>
		<m:msub>
		  <m:mi>Q</m:mi>
		  <m:mn>1</m:mn>
		</m:msub>
	      </m:ci>
	      <m:ci>x</m:ci>
	    </m:apply>
	  </m:vector>
	  <m:apply>
	    <m:times/>
	    <m:vector>
	      <m:ci>
		<m:msub>
		  <m:mi>Q</m:mi>
		  <m:mn>0</m:mn>
		</m:msub>
	      </m:ci>
	      <m:ci>
		<m:msub>
		  <m:mi>Q</m:mi>
		  <m:mn>1</m:mn>
		</m:msub>
	      </m:ci>
	    </m:vector>
	    <m:ci>x</m:ci>
	  </m:apply>
	  <m:apply>
	    <m:times/>
	    <m:ci type="matrix">Q</m:ci>
	    <m:ci>x</m:ci>
	  </m:apply>
	</m:apply>
      </m:math>

      where

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:ci type="matrix">Q</m:ci>
	  <m:vector>
	    <m:ci>
	      <m:msub>
		<m:mi>Q</m:mi>
		<m:mn>0</m:mn>
	      </m:msub>
	    </m:ci>
	    <m:ci>
	      <m:msub>
		<m:mi>Q</m:mi>
		<m:mn>1</m:mn>
	      </m:msub>
	    </m:ci>
	  </m:vector>
	</m:apply>
      </m:math>

      The transpose of the two-channel analysis filter bank is therefore:

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:apply>
	    <m:transpose/>
	    <m:ci type="matrix">Q</m:ci>
	  </m:apply>
	  <m:matrix>
	    <m:matrixrow>
	      <m:apply>
		<m:transpose/>
		<m:ci>
		  <m:msub>
		    <m:mi>Q</m:mi>
		    <m:mn>0</m:mn>
		  </m:msub>
		</m:ci>
	      </m:apply>
	      <m:apply>
		<m:transpose/>
		<m:ci>
		  <m:msub>
		    <m:mi>Q</m:mi>
		    <m:mn>1</m:mn>
		  </m:msub>
		</m:ci>
	      </m:apply>
	    </m:matrixrow>
	  </m:matrix>
	</m:apply>
      </m:math>

      and

      <m:math display="block">
	<m:apply>
	  <m:eq/>
	  <m:ci>y</m:ci>
	  <m:apply>
	    <m:times/>
	    <m:apply>
	      <m:transpose/>
	      <m:ci type="matrix">Q</m:ci>
	    </m:apply>
	    <m:vector>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>0</m:mn>
		</m:msub>
	      </m:ci>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>1</m:mn>
		</m:msub>
	      </m:ci>
	    </m:vector>
	  </m:apply>
	  <m:apply>
	    <m:times/>
	    <m:matrix>
	      <m:matrixrow>
		<m:apply>
		  <m:transpose/>
		  <m:ci>
		    <m:msub>
		      <m:mi>Q</m:mi>
		      <m:mn>0</m:mn>
		    </m:msub>
		  </m:ci>
		</m:apply>
		<m:apply>
		  <m:transpose/>
		  <m:ci>
		    <m:msub>
		      <m:mi>Q</m:mi>
		      <m:mn>1</m:mn>
		    </m:msub>
		  </m:ci>
		</m:apply>
	      </m:matrixrow>
	    </m:matrix>
	    <m:vector>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>0</m:mn>
		</m:msub>
	      </m:ci>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>1</m:mn>
		</m:msub>
	      </m:ci>
	    </m:vector>
	  </m:apply>
	  <m:apply>
	    <m:plus/>
	    <m:apply>
	      <m:times/>
	      <m:apply>
		<m:transpose/>
		<m:ci>
		  <m:msub>
		    <m:mi>Q</m:mi>
		    <m:mn>0</m:mn>
		  </m:msub>
		</m:ci>
	      </m:apply>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>0</m:mn>
		</m:msub>
	      </m:ci>
	    </m:apply>
	    <m:apply>
	      <m:times/>
	      <m:apply>
		<m:transpose/>
		<m:ci>
		  <m:msub>
		    <m:mi>Q</m:mi>
		    <m:mn>1</m:mn>
		  </m:msub>
		</m:ci>
	      </m:apply>
	      <m:ci>
		<m:msub>
		  <m:mi>s</m:mi>
		  <m:mn>1</m:mn>
		</m:msub>
	      </m:ci>
	    </m:apply>
	  </m:apply>
	</m:apply>
      </m:math>

      This corresponds to the diagram in <cnxn xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" target="fig2" strength="9"/>:
    </para>

    <figure xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" id="fig2">
      <media xmlns:md="http://cnx.rice.edu/mdml/0.4" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:bib="http://bibtexml.sf.net/" type="image/png" src="sec5fig2.png"/>
    </figure>

  </content>
</document>
