iir_bcf.c

实现了巴特沃斯滤波。用C语言写的。实现了巴特沃斯滤波。用C语言写的。

#include <stdio.h>
#include "iirbcf.c"
#include "gainc.c"

int main(int argc, char *argv[])               //带通滤波器
{
	int i,k,n,ns;                              //n是每级滤波器的级数（取4）；ns是级联数（取2）
	double a[50],b[50],x[1000],y[1000]         //a，b是滤波器系数存放数组（二维）；x，y是输入输出序列的存放数组
	double f1,f2,f3,f4,fs,flc,fls,fhc,fhs,freq,db  //flc:通带下边界频率；fhc:通带上边界频率；flc:阻带下边界频率；flc:阻带上边界频率；
	                                               //fs:采样频率;db:阻带衰减
    char fname[40];
	FILE *fp;
    db=50;
	ns=2;
	n=4;
	flc=10;
	fhc=500;
	f1=0;
	f2=flc;
	f3=fhc;
	f4=0;
	fs=2000;
	f1=f1/fs;
    f2=f2/fs;
	f3=f3/fs;
	f4=f4/fs;
	iirbcfpass(ns,n,f1,f2,f3,f4,db,b,a);
	for (k=0;k<ns ;k++ )
	{
		printf("\nsection %d\n\n",k+1);
		for (i=0;i<=n ;i++ )
		{
			printf("b[%d][%d]=%10.7if",k,i,b[k*(n+1)+i]);
			if (((i%2==0)&&(i!=0))
			{
				printf("\n");
			}
		}
		printf("\n");
	}
	printf("\nenter file name f magnitude response\n");        //输入响应
	scanf（"%s,fname"）;
	if((fp=fopen(fname,"w"))==NULL)
	{
		printf("cannot open file %s\n",fname);
		exit(0);
	}
	gainc(b,a,n,ns,x,y,1000,2)                                          //2代表是幅频响应+相频响应
	for (i=0;i<100 ;i++ )
	{
		freq=i*0.5/1000.0;
		fprintf(fp,"%if    %if\n",freq,x[i]);
	}
	fclose(fp);
}