基于Farrow结构的分数时延滤波器

Fractional Delay Filter Based on Farrow Structure

在宽带数字阵列雷达的波束形成中,传统的窄带移相方法存在主瓣展宽和扫描不准的情况,为此现阶段多采用实延时(TTD)补偿单元来代替移相器。模拟时延补偿存在诸多缺点,为实现宽带数字阵列各阵元传输时延的精确补偿,引入声纳学中广泛使用的Farrow结构来实现时延滤波器;为降低FPGA资源消耗,引入滤波器的系数求取优化方法;为提高速度,提出了Farrow结构的优化方法。仿真以及实际运行结果都表明了该方法的有效性,与传统移相方法相比,更适用于数字阵列雷达T/R组件。

Compared with conventional narrow-band phased array radar,true time delay（TTD） is used in wide-band digital array to replace the phase shifter.As the analog way exists many defects,so Farrow structure is introduced to achieve accurate variable time-delay.To reduce the resource consumption of FPGA,the solving and optimizing of filter coefficients are proposed;and the optimized Farrow structure is proposed to speed up the FPGA.Compared with classical phase shifter,the method is more applicable to digital array radar.