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<TD borderColor=#6699ff><FONT
size=2>您的位置：技術(shù)園地>技術(shù)講座-GSM蜂窩移動(dòng)通信系統(tǒng) </FONT></TD></TR>
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lang=EN-US>第三講 GSM關(guān)鍵技術(shù)</SPAN></SPAN></B></FONT></DIV></TD></TR>
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style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><B>3.10<SPAN
style="mso-spacerun: yes"> </SPAN>跳頻技術(shù)<O:P>
</O:P></B></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-ALIGN: justify"><SPAN
lang=EN-US
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"> </SPAN><SPAN
lang=EN-US
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
size=3><FONT face=楷體_GB2312
color=#000066>采用跳頻技術(shù)是為了確保通信的秘密性和抗干擾性，它首先被用于軍事通信，<BR>后來(lái)在GSM標(biāo)準(zhǔn)中也被采納。<O:P>
</O:P></FONT><FONT face=楷體_GB2312><O:P></O:P></FONT><FONT
face=楷體_GB2312><O:P></O:P></FONT><O:P></O:P></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-ALIGN: justify"><SPAN
lang=EN-US
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
size=3><SPAN
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</SPAN><FONT face=楷體_GB2312 color=#000066>跳頻功能主要是：<O:P>
</O:P></FONT></FONT></SPAN></P>
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style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-ALIGN: justify"><FONT
size=3><SPAN style="mso-hansi-font-family: Times New Roman"><SPAN
lang=EN-US
style="FONT-FAMILY: 宋體; mso-hansi-font-family: Times New Roman; mso-spacerun: yes">
</SPAN><FONT face=楷體_GB2312 color=#000066>(1) 改善衰落。</FONT><O:P>
</O:P></SPAN></FONT></SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-ALIGN: justify"><FONT
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</SPAN><SPAN lang=EN-US
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face=楷體_GB2312 color=#000066>(2)
處于多徑環(huán)境中的漫速移動(dòng)的移動(dòng)臺(tái)通過(guò)采用跳頻技術(shù)，大大改善移動(dòng)臺(tái)的通信質(zhì)量，相當(dāng)于頻率分集。</FONT><O:P>
</O:P></SPAN></SPAN></FONT></P>
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style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-ALIGN: justify"><FONT
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</SPAN><FONT face=楷體_GB2312 color=#000066>(3) 跳頻相當(dāng)于頻率分集<O:P>
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lang=EN-US
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face=楷體_GB2312 color=#000066 size=3>GSM系統(tǒng)中的跳頻分為基帶跳頻和射頻跳頻兩種。<O:P>
</O:P></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; TEXT-JUSTIFY: inter-ideograph; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21pt; TEXT-ALIGN: justify"><SPAN
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
face=楷體_GB2312 color=#000066
size=3>基帶跳頻的原理是將話音信號(hào)隨著時(shí)間的變換使用不同頻率發(fā)射機(jī)發(fā)射，其原理圖如圖<SPAN
lang=EN-US>3-35所示，實(shí)施的方框圖如圖3-36所示。</SPAN></FONT><FONT size=3><SPAN
lang=EN-US><O:P> </O:P></SPAN></FONT></SPAN></P>
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size=3><SPAN lang=EN-US><O:P></O:P></SPAN></FONT></SPAN></P>
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size=3>
<IMG height=113 src="g3-10.files/g3-10.1.gif" width=321
v:shapes="_x0000_i1025"><O:P> </O:P></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21pt"
align=center><SPAN
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
face=楷體_GB2312 color=#000066 size=3>圖<SPAN lang=EN-US>3-35
基帶跳頻原理<O:P> </SPAN></FONT></SPAN></P>
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align=center><SPAN
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
size=3><SPAN lang=EN-US> </SPAN></FONT></SPAN></P>
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style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21pt"
align=center><SPAN
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
size=3><SPAN lang=EN-US></SPAN></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21pt"
align=center><SPAN lang=EN-US
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
size=3><IMG height=127
src="g3-10.files/g3-10.2.gif" width=347
v:shapes="_x0000_i1026"><O:P> </O:P></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 21pt"
align=center><SPAN
style="FONT-FAMILY: 宋體; mso-hansi-font-family: 'Times New Roman'"><FONT
face=楷體_GB2312 color=#000066 size=3>圖<SPAN lang=EN-US>3-36
基帶跳頻實(shí)施框圖<O:P> </O:P></SPAN></FONT></SPAN></P>
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