模块法设计FIR数字滤波器的一种新方法

在模块法设计FIR数字滤波器的基础上,提出一种设计FIR数值滤波器的新方法.该方法将数字滤波器等效成一个全通滤波器减去一个由基本单元构成的点通滤波器,进而推导出计算数字滤波器冲激响应的数学公式.该方法具有公式简单,物理概念清晰,滤波点频率不受模块数取整的约束,便于连续控制滤波点频率的优点.与窗口法设计相比,在同等凹口宽度下具有阶数减半的优点.同时,该方法可以推广至带阻滤波器的设计.

A new design method for FIR digital trap filter by use of building blocks

On the base of FIR digital filter design using building blocks, a new design method for FIR digital filter is presented. As the trap filter is equal to an all-pass filter minus a point-pass filter composed of approximate triangle shaped elementary frequency unit, the formula of calculating the impulse response of digital trap filter is induced. This method has several merits such as simple formula, clear physical conception, continuously controlled trap frequency that is independent on integral block number. Compared with windows method, this method can save half order number in condition of the same gap width. Meanwhile, this method can be extended to the design of band-stop filter.