183 lines
6.2 KiB
HTML
183 lines
6.2 KiB
HTML
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
||
|
|
|
||
|
|
<!--Converted with LaTeX2HTML 2002-2-1 (1.71)
|
||
|
|
original version by: Nikos Drakos, CBLU, University of Leeds
|
||
|
|
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
|
||
|
|
* with significant contributions from:
|
||
|
|
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
|
||
|
|
<HTML>
|
||
|
|
<HEAD>
|
||
|
|
<TITLE>Prefabricated low-, high-, and band-pass filters</TITLE>
|
||
|
|
<META NAME="description" CONTENT="Prefabricated low-, high-, and band-pass filters">
|
||
|
|
<META NAME="keywords" CONTENT="book">
|
||
|
|
<META NAME="resource-type" CONTENT="document">
|
||
|
|
<META NAME="distribution" CONTENT="global">
|
||
|
|
|
||
|
|
<META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1">
|
||
|
|
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
|
||
|
|
|
||
|
|
<LINK REL="STYLESHEET" HREF="book.css">
|
||
|
|
|
||
|
|
<LINK REL="next" HREF="node157.html">
|
||
|
|
<LINK REL="previous" HREF="node155.html">
|
||
|
|
<LINK REL="up" HREF="node155.html">
|
||
|
|
<LINK REL="next" HREF="node157.html">
|
||
|
|
</HEAD>
|
||
|
|
|
||
|
|
<BODY >
|
||
|
|
<!--Navigation Panel-->
|
||
|
|
<A NAME="tex2html2903"
|
||
|
|
HREF="node157.html">
|
||
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/next.png"></A>
|
||
|
|
<A NAME="tex2html2897"
|
||
|
|
HREF="node155.html">
|
||
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/up.png"></A>
|
||
|
|
<A NAME="tex2html2891"
|
||
|
|
HREF="node155.html">
|
||
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/prev.png"></A>
|
||
|
|
<A NAME="tex2html2899"
|
||
|
|
HREF="node4.html">
|
||
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/contents.png"></A>
|
||
|
|
<A NAME="tex2html2901"
|
||
|
|
HREF="node201.html">
|
||
|
|
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/index.png"></A>
|
||
|
|
<BR>
|
||
|
|
<B> Next:</B> <A NAME="tex2html2904"
|
||
|
|
HREF="node157.html">Prefabricated time-varying band-pass filter</A>
|
||
|
|
<B> Up:</B> <A NAME="tex2html2898"
|
||
|
|
HREF="node155.html">Examples</A>
|
||
|
|
<B> Previous:</B> <A NAME="tex2html2892"
|
||
|
|
HREF="node155.html">Examples</A>
|
||
|
|
<B> <A NAME="tex2html2900"
|
||
|
|
HREF="node4.html">Contents</A></B>
|
||
|
|
<B> <A NAME="tex2html2902"
|
||
|
|
HREF="node201.html">Index</A></B>
|
||
|
|
<BR>
|
||
|
|
<BR>
|
||
|
|
<!--End of Navigation Panel-->
|
||
|
|
|
||
|
|
<H2><A NAME="SECTION001251000000000000000">
|
||
|
|
Prefabricated low-, high-, and band-pass filters</A>
|
||
|
|
</H2>
|
||
|
|
|
||
|
|
<P>
|
||
|
|
Patches H01.low-pass.pd, H02.high-pass.pd, and H03.band-pass.pd (Figure <A HREF="#fig08.28">8.28</A>) show Pd's
|
||
|
|
built-in filters, which implement filter designs described in Sections
|
||
|
|
<A HREF="node140.html#sect08.low-pass">8.3.1</A>, <A HREF="node141.html#sect08.highpass">8.3.2</A> and <A HREF="node143.html#sect8.twopolebandpass">8.3.4</A>.
|
||
|
|
Two of the patches also use a noise generator we have not introduced before.
|
||
|
|
We will need four new Pd objects:
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<BR><!-- MATH
|
||
|
|
$\fbox{\texttt{lop\~}}$
|
||
|
|
-->
|
||
|
|
<IMG
|
||
|
|
WIDTH="47" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
|
||
|
|
SRC="img1014.png"
|
||
|
|
ALT="\fbox{\texttt{lop\~}}">:
|
||
|
|
<A NAME="10842"></A>one-pole low-pass filter. The left inlet takes a signal to be filtered, and
|
||
|
|
the right inlet takes control messages to set the
|
||
|
|
cutoff frequency of the filter. The filter is normalized so that the
|
||
|
|
gain is one at frequency 0.
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<BR><!-- MATH
|
||
|
|
$\fbox{ \texttt{hip\~}}$
|
||
|
|
-->
|
||
|
|
<IMG
|
||
|
|
WIDTH="53" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
|
||
|
|
SRC="img1016.png"
|
||
|
|
ALT="\fbox{ \texttt{hip\~}}">:
|
||
|
|
<A NAME="10843"></A>one-pole, one-zero high-pass filter, with the same inputs and outputs as
|
||
|
|
<TT>lop~</TT>, normalized to have a gain of one at the Nyquist frequency.
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<BR><!-- MATH
|
||
|
|
$\fbox{ \texttt{bp\~}}$
|
||
|
|
-->
|
||
|
|
<IMG
|
||
|
|
WIDTH="44" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
|
||
|
|
SRC="img1017.png"
|
||
|
|
ALT="\fbox{ \texttt{bp\~}}">:
|
||
|
|
<A NAME="10844"></A>resonant filter. The middle inlet takes control messages to set the center
|
||
|
|
frequency, and the right inlet to set ``q".
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<BR><!-- MATH
|
||
|
|
$\fbox{ \texttt{noise\~}}$
|
||
|
|
-->
|
||
|
|
<IMG
|
||
|
|
WIDTH="69" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
|
||
|
|
SRC="img1019.png"
|
||
|
|
ALT="\fbox{ \texttt{noise\~}}">:
|
||
|
|
<A NAME="10845"></A>white noise generator. Each sample is an independent
|
||
|
|
pseudo-random number, uniformly distributed from -1 to 1.
|
||
|
|
|
||
|
|
<P>
|
||
|
|
|
||
|
|
<DIV ALIGN="CENTER"><A NAME="fig08.28"></A><A NAME="10600"></A>
|
||
|
|
<TABLE>
|
||
|
|
<CAPTION ALIGN="BOTTOM"><STRONG>Figure 8.28:</STRONG>
|
||
|
|
Using prefabricated filters in Pd: (a) a low-pass filter, with
|
||
|
|
white noise as a test input; (b) using a high-pass filter to remove a
|
||
|
|
signal component of frequency 0.</CAPTION>
|
||
|
|
<TR><TD><IMG
|
||
|
|
WIDTH="491" HEIGHT="190" BORDER="0"
|
||
|
|
SRC="img1021.png"
|
||
|
|
ALT="\begin{figure}\psfig{file=figs/fig08.28.ps}\end{figure}"></TD></TR>
|
||
|
|
</TABLE>
|
||
|
|
</DIV>
|
||
|
|
|
||
|
|
<P>
|
||
|
|
The first three example patches demonstrate these three filters (see Figure
|
||
|
|
<A HREF="#fig08.28">8.28</A>). The <TT>lop~</TT> and <TT>bp~</TT> objects are demonstrated
|
||
|
|
with noise as input; <TT>hip~</TT> as shown is used to remove the DC (zero
|
||
|
|
frequency) component of a signal.
|
||
|
|
|
||
|
|
<P>
|
||
|
|
<HR>
|
||
|
|
<!--Navigation Panel-->
|
||
|
|
<A NAME="tex2html2903"
|
||
|
|
HREF="node157.html">
|
||
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/next.png"></A>
|
||
|
|
<A NAME="tex2html2897"
|
||
|
|
HREF="node155.html">
|
||
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/up.png"></A>
|
||
|
|
<A NAME="tex2html2891"
|
||
|
|
HREF="node155.html">
|
||
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/prev.png"></A>
|
||
|
|
<A NAME="tex2html2899"
|
||
|
|
HREF="node4.html">
|
||
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/contents.png"></A>
|
||
|
|
<A NAME="tex2html2901"
|
||
|
|
HREF="node201.html">
|
||
|
|
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index"
|
||
|
|
SRC="file:/usr/local/share/lib/latex2html/icons/index.png"></A>
|
||
|
|
<BR>
|
||
|
|
<B> Next:</B> <A NAME="tex2html2904"
|
||
|
|
HREF="node157.html">Prefabricated time-varying band-pass filter</A>
|
||
|
|
<B> Up:</B> <A NAME="tex2html2898"
|
||
|
|
HREF="node155.html">Examples</A>
|
||
|
|
<B> Previous:</B> <A NAME="tex2html2892"
|
||
|
|
HREF="node155.html">Examples</A>
|
||
|
|
<B> <A NAME="tex2html2900"
|
||
|
|
HREF="node4.html">Contents</A></B>
|
||
|
|
<B> <A NAME="tex2html2902"
|
||
|
|
HREF="node201.html">Index</A></B>
|
||
|
|
<!--End of Navigation Panel-->
|
||
|
|
<ADDRESS>
|
||
|
|
Miller Puckette
|
||
|
|
2006-12-30
|
||
|
|
</ADDRESS>
|
||
|
|
</BODY>
|
||
|
|
</HTML>
|