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<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="None">
  <name>Angle dependencies of speed detection</name>
  <metadata>
  <md:version>1.1</md:version>
  <md:created>2004/12/17 02:34:01 US/Central</md:created>
  <md:revised>2004/12/22 15:36:50.006 US/Central</md:revised>
  <md:authorlist>
      <md:author id="lynnbl">
      <md:firstname>Lynn</md:firstname>
      
      <md:surname>Le</md:surname>
      <md:email>lynnbl@rice.edu</md:email>
    </md:author>
  </md:authorlist>

  <md:maintainerlist>
    <md:maintainer id="lynnbl">
      <md:firstname>Lynn</md:firstname>
      
      <md:surname>Le</md:surname>
      <md:email>lynnbl@rice.edu</md:email>
    </md:maintainer>
  </md:maintainerlist>
  
  <md:keywordlist>
    <md:keyword>angle</md:keyword>
    <md:keyword>dependencies</md:keyword>
    <md:keyword>speeding</md:keyword>
  </md:keywordlist>

  <md:abstract>This module explains what effects different angles have on the detection of moving objects.</md:abstract>
</metadata>

  <content>
    <para id="radar_guns">
A radar gun can only read the portion of the speed which is parallel to the beam.  Thus, at different angles, we will get different Doppler shifts and different speed readings as shown below:
<figure id="angle0">
	<media type="image/gif" src="noangle.gif"/>
</figure>
<figure id="angle30">
	<media type="image/gif" src="angle30.gif"/>
</figure>
<figure id="angle60">
	<media type="image/gif" src="angle60.gif"/>
</figure>
<figure id="angle90">
	<media type="image/gif" src="angle90.gif"/>
</figure>
As shown above, the closer the angle is to 90, the less visible the peak of the second pulse that is reflected back.  That is why a radar gun has to be shot within a specific angle range to get accurate readings.
    </para>
  </content>
  
</document>
