<sect1 id='designfilter-manual'>
	<title><command>design_filter</command></title>

    <toc depth='1'></toc>
    <para>
    </para>
    <sect2>
      <title>Synopsis</title>
      <para>
      </para>
        <!-- /amd/projects/festival/versions/v_mpiro/speech_tools_linux/bin/design_filter -sgml_synopsis -->
        <para>
<cmdsynopsis><command>design_filter</command>[input file0] -o [output file]<arg>-h </arg>
<arg>-forder <replaceable>int</replaceable></arg>
<arg>-double </arg>
<arg>-o <replaceable>ofile</replaceable></arg>
</cmdsynopsis>
        </para>
        <!-- DONE /amd/projects/festival/versions/v_mpiro/speech_tools_linux/bin/design_filter -sgml_synopsis -->
      <para>

<command>designfilter</command> computes the coefficients of a FIR
filter with a given frequency response. The user supplies the
frequency response as a vector of evenly spaced gains ranging from 0
to half the sampling frequency. The length of this vector must be a
power of 2. The filter coefficients can be used by the \Ref{sigfilter}
program.
      </para>
    </sect2>
    <sect2>
      <title>Options</title>
      <para>
      </para>
        <!-- /amd/projects/festival/versions/v_mpiro/speech_tools_linux/bin/design_filter -sgml_options -->
        <para>
<variablelist>
<varlistentry><term>-h</term>
<LISTITEM><PARA>

Options help 
</PARA></LISTITEM>
</varlistentry>

<varlistentry><term>-forder</term>
<LISTITEM><PARA>
<replaceable>int</replaceable>

Order of FIR filter. This must be ODD. 
Sensible values range 
from 19 (quick but with a shallow rolloff) to 199 
(slow but with a steep rolloff). The default is 199. 
</PARA></LISTITEM>
</varlistentry>

<varlistentry><term>-double</term>
<LISTITEM><PARA>

Design a filter suitable for double (zero-phase) 
filtering 
</PARA></LISTITEM>
</varlistentry>

<varlistentry><term>-o</term>
<LISTITEM><PARA>
<replaceable>ofile</replaceable>

output filter file </PARA></LISTITEM>
</varlistentry>
</variablelist>
        </para>
        <!-- DONE /amd/projects/festival/versions/v_mpiro/speech_tools_linux/bin/design_filter -sgml_options -->
    </sect2>
    <sect2>
      <title>Example</title>
      <para>
<title>Designing a bandpass filter</title>
The frequency response vector must be placed in a file, in either
ascii of EST headered format. For example:
<screen>
<para>EST_File fvector</para>
<para>version 1</para>
<para>DataType ascii</para>
<para>length 128</para>
<para>EST_Header_End</para>
<para>0.0</para>
<para>0.0</para>
<para>.....[etc]</para>
<para>1.0</para>
<para>1.0</para>
<para>1.0</para>
<para>.....[etc]</para>
<para>0.0</para>
<para>0.0</para>
<para>0.0</para>
<para>.....[etc]</para>
</screen>
And the filter is simply designed using
</para>
<para>
<screen>
$ design_filter -o filter.coefficients filter.freq_response
</screen>
</para>
<para>
where filter.freq_response is the above file, and filter.coefficients
is the output file which can be used by \Ref{sigfilter}.
</para>
      </para>
    </sect2>
  </sect1>