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<TD borderColor=#6699ff><FONT size=2>您的位置：技术园地>技术讲座-扩频通信</FONT></TD></TR>
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<DIV align=center><FONT color=#000080 size=5><B><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">第四讲 </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">扩频通信的工作原理及工作方式</SPAN></B></FONT><FONT
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<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; LINE-HEIGHT: 150%"><FONT
color=#800080 size=4><B><SPAN lang=EN-US><A
name="4.1 工作原理">4.1<SPAN style="mso-spacerun: yes">
</SPAN></A></SPAN><A name="4.1 工作原理"><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">工作原理</SPAN></A></B></FONT><SPAN
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<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">扩频通信的一般工作原理如图</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">4.1</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示。</SPAN></P>
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align=center><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">4.1<SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">扩频通信工作原理</SPAN><SPAN
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<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21.75pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在发端输入的信息先经信息调制形成数字信号，然后由扩频码发生器产生的扩频码序列去调制数字信号以展宽信号的频谱。展宽后的信号再调制到射频发送出去。</SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21.75pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在接收端收到的宽带射频信号，变频至中频，然后由本地产生的与发端相</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">同的扩频码序列去相关解扩。再经信息解调、恢复成原始信息输出。</SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21.75pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">由此可见，—般的扩频通信系统都要进行三次调制和相应的解调。一次调制为信息调制，二次调制为扩频调制，三次调制为射频调制，以及相应的信息解调、解扩和射频解调。</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21.75pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">与一般通信系统比较，扩频通信就是多了扩频调制和解扩部分。</SPAN><SPAN
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<P class=MsoNormal
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size=4><A name="4.2 扩频通信的几种工作方式"><B><FONT color=#800080><SPAN
lang=EN-US>4.2<SPAN style="mso-spacerun: yes">
</SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">扩频通信的几种工作方式</SPAN></FONT></B></A></FONT><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">按照扩展频谱的方式不同，现有的扩频通信系统可以分为：</SPAN></P>
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lang=EN-US style="FONT-SIZE: 12pt"><FONT color=#0080c0><B><A
name="4.2.1 直接序列扩频(Direct Sequence Spread Spectrum)工作方式，简称直扩(DS)方式">4.2.1<SPAN
style="mso-spacerun: yes"> </SPAN></A></B></FONT></SPAN><FONT
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