hilbth.h

三种模拟调制与解调的算法

#include "head.h"

void fht(float *x,int n)
{
	int i,j,k,m,l1,l2,l3,l4,n1,n2,n4;
	float a,e,c,s,t,t1,t2;
	for(j=1,i=1;i<16;i++)
	{
		m=i;
		j=2*j;
		if(j==n)
			break;
	}
	n1=n-1;
	for(j=0,i=0;i<n1;i++)
	{
		if(i<j)
		{
			t=*(x+j);
			*(x+j)=*(x+i);
			*(x+i)=t;
		}
		k=n/2;
		while(k<(j+1))
		{
			j=j-k;
			k=k/2;
		}
		j=j+k;
	}
	for(i=0;i<n;i+=2)
	{
		t=*(x+i);
		*(x+i)=t+(*(x+i+1));
		*(x+i+1)=t-(*(x+i+1));
	}
	n2=1;
	for(k=2;k<=m;k++)
	{
		n4=n2;
		n2=n4+n4;
		n1=n2+n2;
		e=6.283185307179586/n1;
		for(j=0;j<n;j+=n1)
		{
			l2=j+n2;
			l3=j+n4;
			l4=l2+n4;
			t=*(x+j);
			*(x+j)=t+(*(x+l2));
			*(x+l2)=t-(*(x+l2));
			t=*(x+l3);
			*(x+l3)=t+(*(x+l4));
			*(x+l4)=t-(*(x+l4));
			a=e;
			for(i=1;i<n4;i++)
			{
				l1=j+i;
				l2=j-i+n2;
			    l3=l1+n2;
			    l4=l2+n2;
                c=cos(a);
				s=sin(a);
				t1=*(x+l3)*c+(*(x+l4))*s;
				t2=*(x+l3)*s-(*(x+l4))*c;
				a=(i+1)*e;
				t=*(x+l1);
			    *(x+l1)=t+t1;
				*(x+l3)=t-t1;
				t=*(x+l2);
				*(x+l2)=t+t2;
				*(x+l4)=t-t2;
			}
		}
	}
}

void hilbth(float *x,int n)
{
	//希尔波特变换
	int i,n1,n2;
	float t;
	n1=n/2;
	n2=n1+1;
	fht(x,n);
	for(i=1;i<n1;i++)
	{
		t=*(x+i);
		*(x+i)=*(x+n-i);
		*(x+n-i)=t;
	}
	for(i=n2;i<n;i++)
		*(x+i)=-(*(x+i));
	*x=0.0;
	*(x+n1)=0.0;
	fht(x,n);
	t=1.0/n;
	for(i=0;i<n;i++)
		*(x+i)*=t;
}