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为了提高差分跳频系统的抗噪声性能,提出了一种基于多接收天线的空间分集差分跳频系统,系统采用平方率检测线性合并准则进行合并接收。采用矩生成函数法分析了该系统在瑞利衰落信道下的抗噪声性能,得到了系统误符号率的闭式表达式。分析中考虑了各分集支路信号衰落参数及背景噪声不同的一般情况。数值和仿真结果表明,应用接收分集技术可以显著改善差分跳频系统的抗噪声性能,在误符号率为10-4时,采用双天线分集时即可使系统性能较无分集系统改善达约7 dB;性能改善量随天线数量的增多而增大,但改善幅度逐步降低;信噪比过低的分集支路应从分集中排除,否则可能使系统性能低于没有这些天线时的系统性能。
In order to improve the anti-noise performance of differential frequency hopping system, a space diversity differential frequency hopping system based on multi-receive antennas is proposed. The system adopts the linear combination criterion of square-rate detection to combine and receive. The anti-noise performance of the system under Rayleigh fading channel is analyzed by the moment generation function method, and the closed form expression of system symbol error rate is obtained. In the analysis, the signal fading parameters and background noise of each diversity branch are taken into account. The numerical and simulation results show that the application of receive diversity technology can significantly improve the anti-noise performance of differential frequency hopping system. When the symbol error rate is 10-4, the system performance can be improved by about 7% dB; performance improvement increases with the number of antennas, but the improvement amplitude decreases gradually; diversity branches with low signal-to-noise ratio should be excluded from the diversity, otherwise the performance of the system may be lower than the performance of the system without these antennas.