采用加权叠加结构滤波器组的子带分割与重构系统设计

Design of a Subband Segmentation and Reconstruction System Based on Weighted Overlap-Add Structure Filter Bank

子带分割与重构系统是天线组阵系统的重要组成部分。针对传统子带分割与重构系统参数设置不灵活的问题,提出了采用加权叠加(Weighted Overlap-Add,WOLA)结构滤波器组实现子带分割与重构的方法,对WOLA结构的分析滤波器组和综合滤波器组进行推导,利用窗函数法设计具有重构特性的原型低通滤波器,并利用Matlab进行仿真。仿真结果表明,采用WOLA结构子带分割与重构系统增强了参数设置的灵活性,当输入信号是理想无噪信号时,重构误差在5×10-3以内,与离散傅里叶变换(Discrete Fourier Transform,DFT)多相滤波结构相比,系统重构误差减小了一个量级;当输入带噪信号时,重构误差随着信噪比的增加而降低,当信噪比大于20 dB时重构误差回到5×10-3以内,验证了WOLA结构子带分割与重构系统的可行性和良好的重构特性。

The subband segmentation and reconstruction system is an important part of the antenna array system.In order to solve the problem of inflexible parameter settings in traditional subband segmentation and reconstruction system,a weighted overlap-add(WOLA)filter bank is proposed to implement subband segmentation and reconstruction.The filter bank is deduced and a prototype low-pass filter with reconstruction characteristics is designed by window function method,and emulated through Matlab.The simulation results show that the WOLA structure subband segmentation and reconstruction system enhances the flexibility of parameter setting and the reconstruction error is within 5×10^-3 when the input signal doesn′t contain noise.Comparison between WOLA structure and the discrete Fourier transform(DFT)polyphase filter structure demonstrates that the system reconstruction error is reduced by an order of magnitude.When the input signal contains noise,the reconstruction error decreases with the increase of signal-to-noise ratio(SNR).When the SNR is greater than 20 dB,reconstruction error is within 5×10^-3.The result verifies the feasibility and good reconstruction characteristics of the WOLA structure subband segmentation and reconstruction system.