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<TD borderColor=#6699ff><FONT size=2>您的位置：技術園地>技術講座-擴頻通信</FONT></TD></TR>
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<DIV align=center><FONT size=4><B><SPAN
style="FONT-FAMILY: 宋體; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><FONT
color=#000080 size=5>第一講 擴頻通信系統概述</FONT></SPAN></B><SPAN lang=EN-US
style="FONT-SIZE: 12pt"> </SPAN></FONT></DIV></TD></TR>
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style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><FONT
face=楷體_GB2312 color=#ff9900 size=4>擴頻通信，</FONT></SPAN></B><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">即擴展頻譜通信</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">(Spread Spectrum
Communication)</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，它與<BR>光纖通信、衛星通信，一同被譽為進入信息時代的三大高技術通信傳輸方式。</SPAN></P>
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style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">擴頻通信是將待傳送的信息數據被偽隨機編碼</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">(</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">擴頻序列：</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">Spread Sequence)</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">調制，實現頻譜擴展后再傳輸；接收端則采用相同的編碼進行解調及相關處理，恢復原始信息數據。</SPAN> </P>
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lang=EN-US style="FONT-SIZE: 12pt"><O:P></O:P></SPAN></P>
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style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">這種通信方式與常規的窄道通信方式是有區別的：</SPAN><SPAN
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style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一是信息的頻譜擴展后形成寬帶傳輸；</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
<P class=MsoNormal
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style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">二是相關處理后恢復成窄帶信息數據。</SPAN> </P>
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style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">正是由于這兩大持點，使擴頻通信有如下的優點：</SPAN><SPAN
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"> 抗干擾</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
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style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; MARGIN-LEFT: 45pt; TEXT-INDENT: -21pt; LINE-HEIGHT: 150%; mso-list: l0 level1 lfo1; tab-stops: list 45.0pt"><IMG
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">抗噪音</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">抗多徑衰落</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">具有保密性</SPAN><SPAN
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">功率譜密度低，具有隱蔽性和低的截獲概率</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可多址復用和任意選址</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
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style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; MARGIN-LEFT: 45pt; TEXT-INDENT: -21pt; LINE-HEIGHT: 150%; mso-list: l0 level1 lfo1; tab-stops: list 45.0pt"><IMG
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</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">高精度測量等</SPAN> </P>
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lang=EN-US style="FONT-SIZE: 12pt"><O:P></O:P></SPAN></P>
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style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">正是由于擴頻通信技術具有上述優點，自</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">50</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">年代中期美國軍方便開始研究，一直為軍事通信所獨占，廣泛應用于軍事通信、電子對抗以及導航、測量等各個領域。直到</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">80</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">年代初才被應用于民用通信領域。為了滿足日益增長的民用通信容量的需求和有效地利用頻譜資源，各國都紛紛提出在數字峰窩移動通信、衛星移動通信和未來的個人通信中采用擴頻技術，擴頻技術已廣泛應用于蜂窩電話、無繩電話、微波通信、無線數據通信、遙測、監控、報警等系統中。</SPAN></P></TD>
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