【摘要】本文给出了一种基于DSP处理器、通带边界频率连续可调的低通滤波器的新的设计方法。文中证明，当阻带边缘频率与通带边缘频率之比是一个常数且抽样频率与通带边缘频率之比也是一个常数时，FIR低通滤波器的阶数及冲击响应与滤波器的通带宽度无关。以一个通带边界频率调整范围为20KHz至1MHz，调整精度为1Hz，阻带衰减大于为50dB的低通滤波器的设计为例说明了可调滤波器的设计过程。理论推导证明，本设计方案由于采用了调整采样频率的方案而使得计算简单，降低了计算复杂度和计算量，具有较高的实用价值。
关键词：数字信号处理器；可调滤波器；采样频率

ABSTRACT: In this paper, a design method of a passband edge frequency adjustable active filter is presented. The adjustment is controlled by a microprocessor. The passband edge can be tuned from 190KHz to 505KHz. The tuning step is 15KHz. The attenuation of the filter in the stopband is greater than 50dB. The measured result shows that the elements have low sensitivity. The system is built by discrete elements so the cost of the system is low.
Key Words: Digital signal processor(DSP); adjustable filter; Sample frequency

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