Description: 数字通信系统的设计及其性能和所传输的数字信号的统计特性有关。所谓 加扰技术，就是不增加多余度而扰乱信号，改变数字信号的统计特性，使其近 似于白噪声统计特性的一种技术。这种技术的基础是建立在反馈移位寄存器序 列（伪随机序列）理论之上的。解扰是加扰的逆过程，恢复原始的数字信号。 如果数字信号具有周期性，则信号频谱为离散的谱线，由于电路的非线 性，在多路通信系统中，这些谱线对相邻信道的信号造成串扰。而短周期信号 经过扰码器后，周期序列变长，谱线频率变低，产生的非线性分量落入相邻信
道之外，因此干扰减小。 在有些数字通信设备中，从码元“0”和“1”的交变点提取定时信息，若
传输的数字信号中经常出现长的“1”或“0”游程，将影响位同步的建立和保 持。而扰码器输出的周期序列有足够多的“0”、“1”交变点，能够保证同步 定时信号的提取。
-digital communication system design and performance and the transmission of digital signals on the statistical characteristics. The so-called scrambling technology is not to increase the degree to disrupt redundant signal, digital signal change the statistical properties it is similar to white noise statistical characteristics of a technology. This technology is based on feedback shift register sequences (pseudo-random sequence) of the above theory. Decryption is the reverse of the scrambling process, the restoration of the original digital signal. If the digital signal is cyclical, the signal spectrum of discrete lines, as the nonlinear circuit, in multi-channel communication system, these lines of the adjacent channel signal causing crosstalk. And the short-cycle signal after scrambling Platform: |
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Author:葛岭泉 |
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