s06.htm

关于扩频的一些好资料

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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">干扰方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，依照跳频图案的规律跟踪施放大功率的干扰。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">这些干扰方式和跳频通信的关系正像二人对奕时相互“出子”一样，当双方的“布子”落在时一频域棋盘内的同一小格时，则干扰有效。因此，跟踪跳频图案施放的干扰策略就是最佳的干扰跳频通信的策略了。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">给出了方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的干扰策略与跳频图案的关系。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图中示出一种跳频图案，方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">干扰策略是在时间上连续的施放一个窄带干扰，即第</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个频率段以斜线表示的干扰带；方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">干扰策略是在第一个时间段用第一个频率段进行干扰，第二个时间段用第二个频率段进行干扰，依次下去，就形成了沿时频域模盘对角线上的于扰带。跳频图案中受到这两种干扰时就用全黑色方块来表示。由图中可以看出，干扰方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只干扰了一个跳频驻留时间的通信，而干扰方式</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">则干扰了三个跳频驻留时间的通信。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳频图案的不同，其干扰的效果也不尽相同。当跳频图案的随机性越大时，跳频抗干扰的能力就越强；“棋盘”越大时，即频率和时间的乘积越大时，可容纳的随机图案也越多，跳频图案本身的随机性也越大，从而抗干扰能力也越强。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">所谓抗于扰能力强，实际上是指碰到干扰的概率小。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">现代电子战中，通信方采用跳频技术来分散干扰的影响，干扰方则想截获通信方的信号以减少于扰的盲目性，并尽量作到有的放矢，这就是跟踪式干扰策</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">略。跟踪式干扰的有效干扰是有条件的，这个条件除功率因素外，还应当满足干扰椭圆的要求，如图</SPAN><SPAN 
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            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><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图中的通信方为收、发信机，干扰机用来对通信的信号进行侦听、处理，然后以同样的载波频率施放干扰。为了有效地干扰跳频系统，在通信频率跳到新的频率之前，干扰机必须完成从侦听到施放干扰的全过程。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳频系统更换载频的跳频间隔时间，就是跳频信号在空间驻留的时间。根据收、发信机的距离</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，干扰机与发、收信机的距离</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，以及跳频驻留时间和干扰机施放干扰的处理时间，可以得到以发射机和接收机为两个焦点的椭圆。只有当干扰机设置在这个椭圆内时，才能使干扰有效，如果干扰机设置在椭圆之外时，则此跟踪式干扰策略无效。</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">显然，为了对付跟踪式干扰，希望跳频信号的驻留时间越短越好，让干扰机来不及施放干扰。因此，希望跳频通信的跳速应当尽可能的快才好。这就是目前各国争先研究快速跳频通信装备的原因之一。</SPAN></P>
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            lang=EN-US style="FONT-SIZE: 12pt; COLOR: #333399">6.1.4 
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            style="FONT-SIZE: 12pt; COLOR: #333399; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳频技术指标与抗干扰的关系</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">考察一个系统的跳频技术性能，应注意下列各项指标：</SPAN><SPAN 
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            style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">跳频带宽</SPAN></P>