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<html> <head> <meta content="en-us" http-equiv="Content-Language"> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> <link type="text/css" rel="stylesheet" href="../../../../../css/ccna.css"> <script src="../../../../../js/framesetHelper.js" language="JavaScript"></script><script language="JavaScript"> window.scrollTo(0,0); function newPage(pageID) { alert("COMMING SOON!!\nThis feature is currently in development."); } function launchMoreInfo(oid) { dash = oid.indexOf('-'); sub1 = oid.substring(0,dash); sub2 = oid.substring(dash+1); // this is an URL base on the // system that generated the static // download of the curriculum. httpref = "http://nomar.sdf.cisco.com/servlet/org.cli.delivery.rendering.servlet.MIServlet/Static=true,LMSID=DTUI,Engine=dynamic,Theme=cnamstheme,Style=ccna,Language=en,Version=2,RootID=knet-v214aCV47051/CHAPID=null/RLOID=null/RIOID=null/"; newref = httpref + sub1 +"/"+ sub2 +"/moreinfoframeset.html"; //alert("new newref :\n" + newref); window.open(newref,'MoreInfo','toolbar=no,status=yes,menubar=no,location=no,scrollbars=yes,height=442,width=756,left=20,top=20,resizable=yes') } function launchContentResource(contentID) { top.currentSupport = 0; 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The most common varieties of Ethernet use Manchester encoding (though the newer, faster varieties use more complex encoding schemes). Again, the point for the students is that a particular technology has a particular way of putting signals on the medium.</p> </span></td> </tr> </table> </td> </tr> </table> </td> </tr> </table><p>Signal encoding is a way of combining both clock and data information into a stream of signals over a medium.<img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47674/RIOID=knet-v214aRIO121633/knet/v214adataimage1/1.gif" width="12" height="12"> The rules of Manchester encoding define a 0 (zero) as a signal that is high for the first half of the period and low for the second half. It defines a 1 as a signal that is low for the first half of the period and high for the second half.</p><p><img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47674/RIOID=knet-v214aRIO121633/knet/v214adataimage2/2.gif" width="12" height="12"> 10BASE-T transceivers are designed to send and receive signals over a segment that consists of four wires. One pair of wires for transmitting data, and one pair of wires for receiving data.</p><table cellpadding="0" cellspacing="0" border="0"> <tr> <td width="100%"><img height="10" width="1" border="0" src="../../../../../images/ccna/common/transdot.gif"></td> </tr> <tr> <td width="100%"> <table bgcolor="#000000" bordercolor="#000000" cellspacing="0" bordercolorlight="#000000" width="100%" border="0"> <tr> <td width="100%"> <table bgcolor="#FFFFFF" width="100%" cellspacing="0" cellpadding="3" border="0"> <tr> <td><span class="note"><b>NOTE:</b><p>Manchester encoding results in 0 (zero) being encoded as a high-to-low transition and 1 being encoded as a low-to-high transition. Because both 0s (zeros) and 1s result in a transition to the signal, the clock can be effectively recovered at the receiver.</p></span></td> </tr> </table> </td> </tr> </table> </td> </tr> </table></td> </tr> </table> </td> </tr></table> <p> </p> <table width="100%" cellspacing="0" cellpadding="2" border="0" valign="bottom"> <tr> <td></td> </tr> </table> </body></html>⌨️ 快捷键说明
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