<P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; LINE-HEIGHT: 150%"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 12pt; mso-spacerun: yes">&nbsp;&nbsp;&nbsp; 
            </SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳頻系統(tǒng)的特點，在很大程度上取決于它的擴展頻譜機理。跳頻擴展頻譜在機理上與直接序列擴展頻譜大不相同。從圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">－</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">1</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的跳頻圖案上可以看出，每一</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt"><O:P></O:P></SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳頻駐留時間的瞬時所占的信道帶寬是窄帶頻譜，依照跳頻圖案隨時間的變化，這些瞬時窄帶頻譜在一個很寬的頻帶內(nèi)跳變，形成一個跳頻帶寬。由于跳頻速率</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; 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'">很快，從而在宏觀上實現(xiàn)了頻譜的擴展。圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">－</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">5</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示是由頻譜儀上觀察到的跳頻信號的頻譜。</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; LINE-HEIGHT: 150%" 
            align=center><SPAN lang=EN-US style="FONT-SIZE: 12pt">&nbsp;<IMG 
            height=174 src="s06.files/s6-05.gif" width=350 border=0><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; LINE-HEIGHT: 150%" 
            align=center><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">－</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">5<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; LINE-HEIGHT: 150%" 
            align=center><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%; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">圖中箭頭所標(biāo)示的，是載波頻率跳變的過程。載波頻率之間的頻率間隔就是信道帶寬，跳頻的載波數(shù)目乘上信道帶寬就是跳頻帶寬。因此，跳頻系統(tǒng)有如下特點：</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt"><SPAN 
            style="mso-spacerun: yes">&nbsp; </SPAN><O:P></O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><IMG 
            height=10 src="s06.files/green-ret.gif" width=7> <SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><FONT 
            color=#008080>由于它是瞬時窄帶系統(tǒng)，它易于與目前的窄帶通信系統(tǒng)兼容。</FONT></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: 24pt; LINE-HEIGHT: 150%; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">目前的通信系統(tǒng)不論是模擬調(diào)制的還是數(shù)字調(diào)制的，通常都是窄帶的通信系統(tǒng)。如果給現(xiàn)有的窄帶通信系統(tǒng)加裝上能使其載波頻率按照某種跳頻圖案跳變并能實現(xiàn)同步接收的裝置，則可改造成為跳頻通信系統(tǒng)。</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: 24pt; LINE-HEIGHT: 150%"><IMG 
            height=10 src="s06.files/green-ret.gif" width=7> <SPAN 
            style="FONT-SIZE: 12pt; COLOR: teal; FONT-FAMILY: 宋體; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">由于它是宏觀的寬帶系統(tǒng)，它具有擴展頻譜的抗干擾能力。</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt; COLOR: teal"><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: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳頻擴展頻譜具有抗單頻干擾、多頻干擾的能力，還具有抗部分頻帶和寬帶干擾的能力。圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">－</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">給出單頻干擾和部分頻帶干擾對跳頻信號影響的示意圖。</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: 24pt; LINE-HEIGHT: 150%" 
            align=center><SPAN lang=EN-US style="FONT-SIZE: 12pt">&nbsp;<IMG 
            height=244 src="s06.files/s6-06.gif" width=450 border=0><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%" 
            align=center><SPAN lang=EN-US 
            style="FONT-SIZE: 12pt">&nbsp;</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">－</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%" 
            align=center><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: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所謂跳頻抗干擾，是指跳頻的跳頻圖案被敵方發(fā)現(xiàn)、識別的概率，以及跳頻頻率與敵方干擾頻率相一致的概率。這種概率越小，抗干擾能力越強。</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: 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'">表征抗多頻及寬帶干擾能力的跳頻系統(tǒng)參數(shù)叫處理增益</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">G<SUB>H</SUB></SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</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: 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'">跳頻處理增益的定義是：跳頻帶寬內(nèi)的總信道數(shù)</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">N</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">N</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">越大，處理增益越大。但是，不能用處理增益</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">G<SUB>H</SUB></SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">來表征抗跟蹤式干擾的能力。</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: 24pt; LINE-HEIGHT: 150%"><IMG 
            height=10 src="s06.files/green-ret.gif" width=7> <SPAN 
            style="FONT-SIZE: 12pt; COLOR: teal; FONT-FAMILY: 宋體; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">由于它是按照跳頻圖案進行頻率跳變的，它具有碼分多址和頻帶共享的組網(wǎng)通信能力。</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt; COLOR: teal"><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: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">組網(wǎng)能力是現(xiàn)代通信的基本要求之一。跳頻通信組網(wǎng)可分為正交跳頻網(wǎng)和非正交跳頻網(wǎng)。如果多個跳頻通信所采用的跳頻圖案在時頻域“棋盤”上相互不發(fā)生重疊，則稱它們?yōu)檎惶l網(wǎng)；如果發(fā)生重疊，則稱為非正交跳頻網(wǎng)。如圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6-7</SPAN><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所示。</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: 24pt; LINE-HEIGHT: 150%" 
            align=center><SPAN lang=EN-US style="FONT-SIZE: 12pt">&nbsp;<IMG 
            height=265 src="s06.files/s6-07.gif" width=450 border=0><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; TEXT-INDENT: 24pt; LINE-HEIGHT: 150%" 
            align=center><SPAN 
            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">圖</SPAN><SPAN 
            lang=EN-US style="FONT-SIZE: 12pt">6-7<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px; 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'">&nbsp;&nbsp;&nbsp; 
            根據(jù)跳頻網(wǎng)的同步方式，可分為同步網(wǎng)和異步網(wǎng)。正交跳頻網(wǎng)為了保證跳頻圖案的正交，要求全網(wǎng)嚴(yán)格的定時，采用同步網(wǎng)方式，所以它是正交跳頻同步網(wǎng)。由于正交網(wǎng)的跳頻圖案不發(fā)生重疊，所以它不存在因跳頻頻率重合引起的網(wǎng)間