基于频域插值的信道化原型滤波器设计

Design of Channelized Prototype Filter Based on Frequency Domain Interpolation

针对信道化原型滤波器设计复杂度较高的问题,提出一种满足线性相位要求的原型滤波器频域插值设计算法。该算法采用无约束迭代优化办法获得了阻带衰减较高的低阶滤波器模型,然后根据所推导的频域插值模型构建满足线性相位特性的原型滤波器频谱,最后通过快速傅里叶逆变换获得了满足信道化滤波器组完全重构特性要求的原型滤波器。所提设计算法将频域插值与迭代优化相结合,有效地解决了设计高阻带衰减的原型滤波器时待优化参数数目较大的问题,并且不会产生镜像频谱,省去了镜像抑制滤波器的设计。仿真结果表明,所提算法相比传统的时域插值设计算法具有显著的性能改善,并且降低了设计复杂度。

A novel method of designing channelized prototype filter based on interpolation in frequency domain is proposed in view of high complexity in existing design method. A low-order filter model with high stopband attenuation was obtained by the proposed algorithm for employing unconstrained iterative processing, then the discrete spectrum of prototype filter with linear phase can be constructed based on the spectrum interpolation model derivated by us. Finally, the IFFT transform is performed to get the prototype filter which is suitable for the character of perfect reconstruction of ehannelized filter bank. Moreover, the afore mentioned algorithm uses the interpolation of frequency domain in combination with iterative optimizing, which avoids a large number of parameters to be optimized when the prototype filter is designed with a high stopband attenuation. Besides, the image spectrum is saved, which avoids the filter design of image suppressor. Simulation results reveal that the proposed method embraces favorable porformance improvements compared with the conventional algorithm of time domain interpolation, and relieves the complexity of design.