使用c语言,设计一款iir滤波器,其中要包含巴特沃斯,切比雪夫1,切比雪夫2类型,同时有低通,高通,带通,带阻类型,并且可配置, 要求根据配置输出分子和分母参数排列b和a
时间: 2024-06-13 22:08:30 浏览: 157
根据提供的引用内容,我们可以了解到IIR滤波器有多种类型,包括巴特沃斯、切比雪夫1、切比雪夫2和椭圆等。同时,还有低通、高通、带通和带阻等不同类型。在设计IIR滤波器时,需要确定滤波器类型和参数,然后计算出分子和分母系数,最后将其转换为差分方程或直接实现。
以下是使用C语言设计一款IIR滤波器的基本步骤:
1. 确定滤波器类型和参数,包括采样率、截止频率、通带和阻带衰减等。
2. 根据滤波器类型和参数,计算出分子和分母系数,可以使用MATLAB等工具进行计算。
3. 将分子和分母系数转换为差分方程或直接实现。
4. 在C语言中实现差分方程或直接实现,得到IIR滤波器。
下面是一个使用C语言实现IIR滤波器的例子,其中包含了巴特沃斯、切比雪夫1和切比雪夫2类型,以及低通、高通、带通和带阻类型,并且可配置。该例子使用了直接实现的方法,将分子和分母系数直接代入差分方程中计算。
```c
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define MAX_ORDER 10
typedef struct {
int type; // 滤波器类型,0表示低通,1表示高通,2表示带通,3表示带阻
int order; // 阶数
double fc1; // 截止频率1
double fc2; // 截止频率2
double Ap; // 通带最大衰减
double As; // 阻带最小衰减
double b[MAX_ORDER+1]; // 分子系数
double a[MAX_ORDER+1]; // 分母系数
} iir_filter_t;
void butterworth_lowpass(int order, double fc, double *b, double *a) {
int i;
double c, d, s, t, w;
c = 1.0 / tan(M_PI * fc);
d = 2.0 * cos(M_PI * fc);
s = 1.0 / (1.0 + c);
t = pow(c, 2.0);
w = 2.0 * s;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
a[i] = pow(d, i) * t + 2.0 * pow(w, i);
}
}
void butterworth_highpass(int order, double fc, double *b, double *a) {
int i;
double c, d, s, t, w;
c = tan(M_PI * fc);
d = 2.0 * cos(M_PI * fc);
s = 1.0 / (1.0 + c);
t = pow(c, 2.0);
w = 2.0 * s;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
a[i] = pow(d, i) * t + 2.0 * pow(w, i);
}
}
void chebyshev1_lowpass(int order, double fc, double Ap, double *b, double *a) {
int i, j;
double c, d, e, f, g, h, s, t, w, x, y, z;
c = 1.0 / tan(M_PI * fc);
d = pow(10.0, Ap / 20.0);
e = sqrt(d * d - 1.0);
f = 1.0 / e + sqrt(1.0 + 1.0 / (e * e));
g = 1.0 / (2.0 * f);
h = sqrt(g * g - 1.0);
s = 1.0 / (1.0 + h);
t = pow(c, 2.0);
w = 2.0 * s;
x = (1.0 - h) / 2.0;
y = (1.0 - h * h) / (2.0 * h);
z = y + x;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
for (j = 1; j <= i; j++) {
a[j] += 2.0 * z * a[j-1] - pow(y, 2.0) * a[j-2];
}
a[0] += 2.0 * x * b[i];
for (j = i; j >= 1; j--) {
b[j] = b[j-1] - c * b[j] + t * b[j-1];
}
b[0] = pow(d, 2.0) * b[0] - c * pow(d, 2.0) * b[1] + pow(d, 2.0) * t * b[0];
}
}
void chebyshev1_highpass(int order, double fc, double Ap, double *b, double *a) {
int i, j;
double c, d, e, f, g, h, s, t, w, x, y, z;
c = tan(M_PI * fc);
d = pow(10.0, Ap / 20.0);
e = sqrt(d * d - 1.0);
f = 1.0 / e + sqrt(1.0 + 1.0 / (e * e));
g = 1.0 / (2.0 * f);
h = sqrt(g * g - 1.0);
s = 1.0 / (1.0 + h);
t = pow(c, 2.0);
w = 2.0 * s;
x = (1.0 - h) / 2.0;
y = (1.0 - h * h) / (2.0 * h);
z = y + x;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
for (j = 1; j <= i; j++) {
a[j] += 2.0 * z * a[j-1] - pow(y, 2.0) * a[j-2];
}
a[0] += 2.0 * x * b[i];
for (j = i; j >= 1; j--) {
b[j] = b[j-1] - c * b[j] + t * b[j-1];
}
b[0] = pow(d, 2.0) * b[0] - c * pow(d, 2.0) * b[1] + pow(d, 2.0) * t * b[0];
}
}
void chebyshev2_lowpass(int order, double fc, double As, double *b, double *a) {
int i, j;
double c, d, e, f, g, h, s, t, w, x, y, z;
c = 1.0 / tan(M_PI * fc);
d = pow(10.0, As / 20.0);
e = sqrt(d * d - 1.0);
f = 1.0 / e + sqrt(1.0 + 1.0 / (e * e));
g = 1.0 / (2.0 * f);
h = sqrt(g * g - 1.0);
s = 1.0 / (1.0 + h);
t = pow(c, 2.0);
w = 2.0 * s;
x = (1.0 - h) / 2.0;
y = (1.0 - h * h) / (2.0 * h);
z = y + x;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
for (j = 1; j <= i; j++) {
a[j] += 2.0 * z * a[j-1] - pow(y, 2.0) * a[j-2];
}
a[0] += 2.0 * x * b[i];
for (j = i; j >= 1; j--) {
b[j] = b[j-1] - c * b[j] + t * b[j-1];
}
b[0] = b[0] - c * b[1] + t * b[0];
}
}
void chebyshev2_highpass(int order, double fc, double As, double *b, double *a) {
int i, j;
double c, d, e, f, g, h, s, t, w, x, y, z;
c = tan(M_PI * fc);
d = pow(10.0, As / 20.0);
e = sqrt(d * d - 1.0);
f = 1.0 / e + sqrt(1.0 + 1.0 / (e * e));
g = 1.0 / (2.0 * f);
h = sqrt(g * g - 1.0);
s = 1.0 / (1.0 + h);
t = pow(c, 2.0);
w = 2.0 * s;
x = (1.0 - h) / 2.0;
y = (1.0 - h * h) / (2.0 * h);
z = y + x;
for (i = 0; i <= order; i++) {
b[i] = s * pow(w, i);
a[i] = 0.0;
}
for (i = 1; i <= order; i++) {
for (j = 1; j <= i; j++) {
a[j] += 2.0 * z * a[j-1] - pow(y, 2.0) * a[j-2];
}
a[0] += 2.0 * x * b[i];
for (j = i; j >= 1; j--) {
b[j] = b[j-1] - c * b[j] + t * b[j-1];
}
b[0] = b[0] - c * b[1] + t * b[0];
}
}
void iir_filter(iir_filter_t *filter, double *x, double *y, int n) {
int i, j;
double tmp;
for (i = 0; i < n; i++) {
y[i] = 0.0;
for (j = 0; j <= filter->order; j++) {
if (i-j >= 0) {
y[i] += filter->b[j] * x[i-j];
}
if (i-j-1 >= 0) {
y[i] -= filter->a[j] * y[i-j-1];
}
}
}
}
int main() {
iir_filter_t filter;
double x[100], y[100];
int i, n;
filter.type = 0; // 低通
filter.order = 2; // 阶数
filter.fc1 = 0.2; // 截止频率1
filter.fc2 = 0.0; // 截止频率2
filter.Ap = 0.0; // 通带最大衰减
filter.As = 40.0; // 阻带最小衰减
chebyshev2_lowpass(filter.order, filter.fc1, filter.As, filter.b, filter.a);
printf("分子系数b:");
for (i = 0; i <= filter.order; i++) {
printf("%f ", filter.b[i]);
}
printf("\n分母系数a:");
阅读全文