针对水声通信中所采用的窄带信号传输距离近和抗干扰能力不足的问题,提出一种采用线性调频( LFM)作为载波信号,采用分数阶Fourier变换作为解码方式的水声通信方案.该方案采用在时域进行LFM信号的码元分割,在分数阶变换域借用脉冲位置调制(PPM)进行解码的方法进行通信,并通过Rake接收机进行路径分集接收抑制水声信道多途效应所产生的码间干扰(ISI),该通信方案发挥了分数阶Fourier变换抗干扰能力强的优点,并且相较于传统水声通信方法具有通信速率高的特点,最高通信速率可达800 bit/s.通过大量仿真验证了该方案的可行性和鲁棒性,可应用于远程水声通信.%Aimed at short propagation distance and poor anti-jamming capability of narrow-band signal in underwater acoustic (UWA) communication, a new UWA communication scheme is proposed on the basis of fractional Fourier transform which used LFM signals as carrier signals. LFM signals are divided into groups as coding signals in time domain and the coding signals are decoded by using pulse position modulation ( PPM ) in fractional domain. A Rake receiver is presented to suppress UWA channel' s multi-path effect which could lead to inter-symbol interference ( ISI). Comparing to traditional UWA communication, this scheme has strong anti-interference ability and high communication rate; the maximum communication rate can be up to 800 bit/s. The feasibility and robustness of this system are verified through simulations, and it is helpful to the long range UWA communication.
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