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  • Committer: Package Import Robot
  • Author(s): Sylvestre Ledru
  • Date: 2012-08-30 14:42:38 UTC
  • mfrom: (1.4.7)
  • Revision ID: package-import@ubuntu.com-20120830144238-c1y2og7dbm7m9nig
Tags: 5.4.0-beta-3-1~exp1
* New upstream release
* Update the scirenderer dep
* Get ride of libjhdf5-java dependency

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modules/signal_processing/help/en_US/hilb.xml
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<?xml version="1.0" encoding="UTF-8"?>
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<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:lang="en" xml:id="hilb">
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  <refnamediv>
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    <refname>hilb</refname>
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    <refpurpose>FIR approximation to a Hilbert transform filter</refpurpose>
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  </refnamediv>
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  <refsynopsisdiv>
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    <title>Calling Sequence</title>
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    <synopsis>xh=hilb(n [,wtype [,par]])</synopsis>
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  </refsynopsisdiv>
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  <refsection>
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    <title>Arguments</title>
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    <variablelist>
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      <varlistentry>
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        <term>n</term>
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        <listitem>
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          <para>odd integer : number of points in filter</para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term>wtype</term>
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        <listitem>
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          <para>
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            string : window type <literal>('re','tr','hn','hm','kr','ch')</literal> (default <literal>='re'</literal>)
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          </para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term>par</term>
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        <listitem>
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          <para>
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            window parameter for <literal>wtype='kr' or 'ch'</literal> default <literal>par=[0 0]</literal> see the function window for more help
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          </para>
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        </listitem>
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      </varlistentry>
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      <varlistentry>
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        <term>xh</term>
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        <listitem>
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          <para>Hilbert transform</para>
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        </listitem>
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      </varlistentry>
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    </variablelist>
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  </refsection>
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  <refsection>
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    <title>Description</title>
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    <para>Returns the first n points of an FIR approximation to a Hilbert transform filter centred around the origin.</para>
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    <para> The FIR filter is designed by appropraitely windowing the ideal impulse response 
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      <literal>h(n)=(2/(n*pi))*(sin(n*pi/2))^2</literal> for <literal>n</literal> not equal 0 and <literal>h(0)=0</literal>.
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    </para>
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    <para>
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      An approximation to an analytic signal generator can be built by
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      designing an FIR (Finite Impulse Response) filter approximation to
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      the Hilbert transform operator. The analytic signal can then be computed
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      by adding the appropriately time-shifted real signal to the imaginary
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      part generated by the Hilbert filter.     
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    </para>
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  </refsection>
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  <refsection>
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    <title>References</title>
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    <para>
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      <literal>
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        <ulink url="http://ieeexplore.ieee.org/iel4/78/7823/00330385.pdf?tp=&amp;arnumber=330385&amp;isnumber=7823">http://ieeexplore.ieee.org/iel4/78/7823/00330385.pdf?tp=&amp;arnumber=330385&amp;isnumber=7823</ulink>
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      </literal>
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    </para>
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    <para>
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      A. Reilly, G. Frazer, and B. Boashash, "Analytic signal generation Tips and traps", IEEE Trans. Signal Processing, vol. 42,
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      pp.3241-3245, Nov. 1994. 
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    </para>
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  </refsection>
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  <refsection role="see also">
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    <title>See Also</title>
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    <simplelist type="inline">
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      <member>
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        <link linkend="window">window</link>
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      </member>
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      <member>
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        <link linkend="hilbert">hilbert</link>
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      </member>
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    </simplelist>
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  </refsection>
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  <refsection>
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    <title>Examples</title>
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    <programlisting role="example"><![CDATA[ 
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plot(hilb(51))
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 ]]></programlisting>
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  </refsection>
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</refentry>