Hermite分数时延滤波器在声纳信号源仿真逆波束形成中的应用

针对传统分数时延滤波器的幅频特性与群时延特性在信号高频段性能恶化的现象，提出了基于Hermite插值多项式的时延滤波器来逼近理想非整数延时滤波器的系统函数。搭建Farrow型结构，以解决阵列声纳信号源仿真中信号高频部分衰减失真过大、可变延时等问题。仿真和试验结果表明：Hermite分数时延滤波器的频率响应特性优于同阶传统分数时延滤波器，在整个归一化频带内的均方误差仅为8.18%；在信号波束形成中，Hermite分数时延滤波器高频段衰减较小，使其波束图具有较小的副瓣电平；时延仿真信号与试验实测信号的均方误差保持在0.97%左右，验证了Hermite分数时延滤波器的有效性。

Application of Hermite Fractional Time Delay Filter in Simulation of Inverse Beamforming of Sonar Signal Source

For the phenomena that amplitude-frequency and group delay characteristics of traditional fractional delay filters deteriorate at the high-frequency band of signal, a time delay filter based on the Hermite interpolation polynomial is proposed to approximate the system function of the ideal non-integer delay filter. A Farrow-type structure is established to solve the excessive attenuation and variable delay in the high-frequency part of array sonar signal source simulation. Simulated and experimental results show that the frequency response of Hermite fractional delay filter is better than that of the traditional fractional delay filter, and the mean square error in the entire normalized frequency band is only 8.18%. In beamforming, the Hermite fractional delay filter has a smaller attenuation at the high frequency band, making its beam pattern have a smaller sidelobe level. The mean square errors of simulation and experimental signals are kept in about 0.97%, which verifies the effectiveness of Hermite fractional delay filter.