【摘要】 线性调频(Chirp)信号由于其独特的脉冲压缩特性,作为一个宽带信号在水声通信中拥有窄带信号所不能替代的优势,具体表现为时宽带宽积增益所带来的抗多普勒扩展性能,以及时频域的能量聚集性能,有利于抵抗频率选择性衰落.利用Chirp信号在其分数阶Fourier变换(fractional fourier transform,FrFT)的最佳分数阶变换域的冲激特性,使用二进制正交键控的调制方式,提出了一个用FrFT作为解调方法的多载波Chirp水声通信方案.该系统的特点是充分利用Chirp信号的性质,省去均衡环节,大大简化通信系统接收端结构,同时保证足够的强壮性.通过在计算机仿真、实验室水池实验以及海洋实验验证了该方案的性能.在通信距离为10km,平均水深为18m的浅海水声环境中,系统的通信速率为553bit/s时,系统的误码率达到了10-4量级.更多还原

【Abstract】 As a wideband signal,Chirp signal enjoys distinguished advantages over narrowband signals in underwater acoustic communication systems because of its unique properties of pulse compressions.Large time-bandwidth product resists Doppler spread and,at the same time,the energy aggregation resists the frequency selective fading.In this paper,a multicarrier Chirp underwater acoustic communication system is proposed based on a binary orthogonal shift key modulation and a fractional Fourier transform(FrFT)detection.The major advantage of the proposed system is to make use of the property of the Chirp signal,so that the equalization could be omitted in the system,while the system stays robust at the same time.Results of computer simulations,pool experiments,and outfield experiments show that the proposed multicarrier Chirp underwater acoustic communication system exhibits greater bit error rate(BER)performance.Outfield experiments carried out in Xiamen Port show that the BER performance of the proposed system is in the order of 10-4,when the data rate of the system is 553bit/s and the communication range is approximately10km.更多还原