三阶带通数字滤波器系统函数的快速求法及其理论模型试验

在模拟滤波器设计的基础上，利用C语言快速实现了中心频率为50Hz，带宽为4Hz，通带内衰减不超过3dB，45H以下和55Hz以上为阻带，阻带内最小衰减为20dB的三阶窄数字滤波器以及系统的差分方程，并进行了仿真．理论模型的试算表明，设计方法是可行的，设计结果基本能达到要求。

The Design of Narrow Bandpass Digital Filter

On the basis of simulative filters design, we fabricated a three-rank experimental digital filter and its differential equation with center frequency of 50Hz and with the largest attenuation of 3dB in 4dB-width bandpass, with the lest attenuation of 20dB in the stopband which is less than 45Hz and more than 55Hz. C language is used in the whole process .Results from simulation of the design are presented. The synthetic results suggest that the design method is effective and can satisfy the demand for high sampling rate.