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📁 Input/Data Acquisition System Design for Human Computer Interfacing
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.2//EN"><!--Converted with LaTeX2HTML 96.1 (Feb 5, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --><HTML><HEAD><TITLE>4.2 Additional Requirements for Signal Conditioning</TITLE><META NAME="description" CONTENT="4.2 Additional Requirements for Signal Conditioning"><META NAME="keywords" CONTENT="sensors"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><LINK REL=STYLESHEET HREF="sensors.css" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/sensors.css"></HEAD><BODY BGCOLOR="#FFFFFF" TEXT="#000000" LANG="EN"> <A NAME="tex2html228" HREF="node15.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node15.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="next_motif.gif" tppabs="http://ccrma.stanford.edu/Images//next_motif.gif"></A> <A NAME="tex2html226" HREF="node12.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node12.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="up_motif.gif" tppabs="http://ccrma.stanford.edu/Images//up_motif.gif"></A> <A NAME="tex2html220" HREF="node13.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node13.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif" tppabs="http://ccrma.stanford.edu/Images//previous_motif.gif"></A>   <BR><B> Next:</B> <A NAME="tex2html229" HREF="node15.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node15.html">4.3 Voltage to Voltage</A><B>Up:</B> <A NAME="tex2html227" HREF="node12.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node12.html">4 Signal Conditioning</A><B> Previous:</B> <A NAME="tex2html221" HREF="node13.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node13.html">4.1 Requirements for A-D </A><BR> <P><H2><A NAME="SECTION00042000000000000000">4.2 Additional Requirements for Signal Conditioning</A></H2><P>There are many other uses for the signal conditioning circuitry depending on the particular 
HCI application.  Some of these are:
<DL ><DT><STRONG>Signal isolation</STRONG><DD> In many applications it is necessary to isolate the sensor from the 
power supply of the computer.  This is done in one of two ways: magnetic isolation or 
optical isolation. Magnetic isolation is primarily used for coupling power from the 
computer or the wall outlet to the sensor.  This is done through the use of a 
transformer.  Optical isolation is used for coupling the sensor signal to the data 
acquisition input.  This is usually done through the use of a light emitting diode and a 
photodetector. This can be integrated into a single IC package such as the 6N139.
<DT><STRONG>Signal preprocessing</STRONG><DD> Many times it is desirable to perform preprocessing on the 
sensor signal before data acquisition. Depending on the application, this can help lower 
the required computer processing time, lower the necessary system sampling rate, or 
even perform functions that will enable the use of a much simpler data acquisition 
system entirely.  For example, while an accelerometer system can output a voltage 
proportional to acceleration, it may be desired to only tell the computer when the 
acceleration is greater than a certain amount. This can be accomplished in the analog 
signal conditioning circuitry.  Thus, the data acquisition system is reduced to only 
having a single binary input (no need for an ADC).
<DT><STRONG>Removal of undesired signals</STRONG><DD> Many sensors output signals that have many different 
components to them.  It may be desirable or even necessary to remove such 
components before the signal is digitized.  Additional other signals may corrupt the 
sensor output. This ``noise'' can also be removed using analog circuitry.  For example, 
60Hz interference can distort the output of low output sensors.  The signal 
conditioning circuitry can remove this before it is amplified and digitized.<P> </DL><HR><A NAME="tex2html228" HREF="node15.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node15.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="next_motif.gif" tppabs="http://ccrma.stanford.edu/Images//next_motif.gif"></A> <A NAME="tex2html226" HREF="node12.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node12.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="up_motif.gif" tppabs="http://ccrma.stanford.edu/Images//up_motif.gif"></A> <A NAME="tex2html220" HREF="node13.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node13.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif" tppabs="http://ccrma.stanford.edu/Images//previous_motif.gif"></A>   <BR><B> Next:</B> <A NAME="tex2html229" HREF="node15.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node15.html">4.3 Voltage to Voltage</A><B>Up:</B> <A NAME="tex2html227" HREF="node12.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node12.html">4 Signal Conditioning</A><B> Previous:</B> <A NAME="tex2html221" HREF="node13.html" tppabs="http://ccrma.stanford.edu/CCRMA/Courses/252/sensors/node13.html">4.1 Requirements for A-D </A><P><ADDRESS><I>Tim Stilson <BR>Thu Oct 17 16:32:33 PDT 1996</I></ADDRESS></BODY></HTML>
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