时变信道相干部分的修正匹配
A CORRECTED MATCH FOR COHERENT PART OF TIME-VARIANT CHANNEL
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摘要: 由于水声信道的随机时变及多途特性,使得以发射信号作参考的匹配滤波器检测性能的下降。本文提出当多途结构具有相对稳定部分时,可采用以下两种信道匹配方法:(1)脉间相关信道匹配法(参见4);(2)解卷求信道响应法,后一方法要求发射宽带短脉冲,用解卷求出的信道响应h(τ,ι)去修正欲发射的其它声呐信号,并把它当作匹配滤波器的响应函数,以提高匹配滤波器对时变信道的适配能力。本文前一部分对各种设定的信道模型,给出了修正匹配的计算机模拟结果;后一部分给出了经4浬和24浬海洋信道传输的数据的修正匹配,并给出了以上两部分修正前后的计算机结果比较。对大信噪比,修正匹配的效果是十分显著的。Abstract: The detection performance of the matched filter with the transmitted signal as a reference signal will be degraded in an underwater acoustic channel due to the multipath effect and time variability. Two methods of the channel match are presented in this paper:(1) Pulse-to-pulse correlation method for the channel match. (2) Deeonvolution method. In the first method the received signal is used as a reference signal of the matched filter to improve the detection performance of the matched filter to improve the detection performance of the matched filter. In the second method a short pulse is used to excite the channel. To obtain the response function of the channel, the Wiener-Hopf equation in matrix form is used. The equation can be solved by several deconvolution methods. Then the solved response function of the channel is convoluted with the transmitted signal and the result of the convolution is used as a reference signal of the corrected matched filter. In this paper, with the aid of computer the corrected match for several channel models and for the real underwater acoustic propagation channel is given and the comparison between the conventional and corrected matched filters is illustrated.