数字信号处理：级联一阶滤波器实现二阶滤波器

#include "stdafx.h" #include'J:\信号处理与工程实践\xhclgcyy\x_math.cpp' #include'J:\信号处理与工程实践\xhclgcyy\x_graph.cpp' double Y[40];

void plotgri2(COLORREF gridcolor,COLORREF linecolor,double p[],int N) //用来画矩形框 { int i; HPEN pen1=CreatePen(PS_SOLID,1,gridcolor),oldpen=(HPEN)SelectObject(win3.hdc,pen1); HPEN pen2=CreatePen(PS_SOLID,1,linecolor); for(i=0;i<N;i++)line2(i,0,i,p[i]); SelectObject(win2.hdc,pen2); moveto2(0,p[0]); SelectObject(win2.hdc,oldpen); DeleteObject(pen1); for(i=0;i<N;i++)lineto2(i,p[i]); DeleteObject(pen2); }

void f1(double a0,double b0,double b1,double X[],int N)//通用一阶数字滤波器函数工具 { int n; for(n=0;n<N;n++) Y[n]=0; for(n=0;n<N;n++) Y[n]=b0X[n]+b1X[n-1]+a0*Y[n-1]; }

void f2(double a0,double a1,double b0,double b1,double b2,double X[],int N)//通用二阶数字滤波器函数工具 { int n; for(n=0;n<N;n++) Y[n]=0; for(n=0;n<N;n++) Y[n]=b0X[n]+b1X[n-1]+b2X[n-2]+a0Y[n-1]+a1*Y[n-2]; }

void f3(double a0,double b0,double b1, double a1, double b2, double X[], int N) //级联两个一阶滤波器 { int n; for(n=0;n<N;n++) Y[n]=0; for(n=0;n<N;n++) Y[n]=b0X[n]+b1X[n-1]+a0Y[n-1]; //第一个一阶滤波器 for(n=0;n<N;n++) Y[n]=b2Y[n]+b1Y[n-1]+a1Y[n-2]; //第二个一阶滤波器 }

int main(int argc, char* argv[]) { int i,n; double X1[40],X4[40], X2[40], delta[40]; ////////////矩形序列////////////// X1[-1]=0; for(i=0;i<12;i++){X1[i]=1;} for(i=12;i<38;i++){X1[i]=0;} window2(L"X1",-10,-1,30,5,"x","y"); xy2(BLUE); plotgri2(GREEN,BLUE,X1,30); _getch(); f1(0.4,1,0.2,X1,40); plotgri2(GREEN,RED,Y,30); _getch(); ////////////二阶///////////// X4[0]=1; for(i=-19;i<0;i++){X4[i]=0;} for(i=1;i<40;i++){X4[i]=0;} window2(L"X4",-1,-2,20,5,"x","y"); xy2(BLUE); plotgri2(GREEN,BLUE,X4,30); _getch(); f2(1.5,-0.5,0,1,0,X4,40); plotgri2(RED,BLUE,Y,30); _getch(); ////////////级联////////////// for(i=0;i<40;i++){X2[i]=0;} f1(0.4,1,0.2,X4,40); f1(0.4,1,0.2,Y,40); for(i=0;i<40;i++){X2[i]=Y[i];} window2(L"级联滤波图像",-1,-2,20,5,"x","y"); xy2(BLUE); plotgri2(GREEN,BLUE,X2,30); _getch(); f2(1.5,-0.5,0,1,0,X2,40); plotgri2(RED,BLUE,Y,30); _getch(); ////////////级联后再次滤波////////////// double a0 = 1.4, b0 = 1.2, b1 = -0.4; for(i=0;i<40;i++){delta[i]=0;} delta[0]=1; f1(a0, b0, b1, delta, 40); window2(L"级联后再次滤波图像",-1,-2,20,5,"x","y"); xy2(BLUE); plotgri2(GREEN,BLUE,delta,30); _getch(); f2(1.5,-0.5,0,1,0,delta,40); plotgri2(RED,BLUE,Y,30); _getch(); ////////////级联后再次滤波////////////// f3(0.4, 1, 0.2, 0.4, 1, delta, 40); // 将两个一阶滤波器级联 window2(L"级联两个一阶滤波器",-1,-2,20,5,"x","y"); xy2(BLUE); plotgri2(GREEN,BLUE,Y,30); _getch();

return 0;

}