【摘要】 在水声数字通信中,严重的多径衰落和多普勒频移是影响通信性能的两个主要因素。研究了一种分数间隔判决反馈盲均衡结构,以有效地克服水声信道多径衰落的不利影响。同时,针对水声信道的时变多普勒特性,在分数间隔判决反馈结构的基础上,提出了一种修正常数模分数间隔判决反馈盲均衡与二阶数字锁相环相结合的盲均衡算法,以纠正信道引入的载波相位旋转。最后通过计算机仿真,将该算法与常数模波特间隔判决反馈盲均衡算法进行了性能对比,仿真结果证明了该算法的有效性。因此,该算法具有良好的实用性和应用前景。更多还原

【Abstract】 In underwater acoustic digital communications, two main factors which affect the performance of communication systems seriously are multipath fading and Doppler frequency shift. A blind equalizer based on fractionally-spaced decision-feedback structure, which efficiently combats the multipath fading effects of underwater acoustic channels, is discussed. Towards the time-varying Doppler underwater acoustic channels, a modified constant modulus fractionally-spaced decision- feedback equalization and second-order digital phase-locked loop combined algorithm, which can efficiently correct the channel-introduced carrier phase rotation, is proposed. Finally the performance of the proposed algorithm is compared with a constant modulus baud-spaced decision-feedback blind equalization algorithm by computer simulation, and the simulation results confirm the effectiveness of the proposed algorithm.更多还原