一阶低通滤波器的设计

只看该作者 · 2023-2-23 12:30

h文件

#ifndef _LPF_FIRST_ORDER_H

#define _LPF_FIRST_ORDER_H



typedef struct _lpf_first_order

{

    float fc;   // cut-off frequency

    float uk;

    float alpha; // filter coefficient

    float T;     // samping period

}LpfFirstOderObj;



void lpf_first_order_init(LpfFirstOderObj *filter, float alpha);



float lpf_first_order(LpfFirstOderObj *filter, float k);



void lpf_first_order_fc_set(LpfFirstOderObj *filter, float fc, float T);



#endif

C文件

复制

#include "lpf_first_order.h"



#define LPF_PI  3.1415926



void lpf_first_order_init(LpfFirstOderObj *filter, float alpha)

{

    filter->alpha = alpha;

    filter->fc = 0;

    filter->T = 0;

    filter->uk = 0;

}



float lpf_first_order(LpfFirstOderObj *filter, float k)

{

    float uo;



    uo = filter->alpha * k + (1 - filter->alpha) * filter->uk;

    filter->uk = uo;



    return uo;

}



void lpf_first_order_fc_set(LpfFirstOderObj *filter, float fc, float T)

{

    filter->fc = fc;

    filter->T = T;

    filter->alpha = (2 * LPF_PI * fc * T) / (1 + 2 * LPF_PI * fc * T);

}