fftdisp.~cpp

串口数据采集的上位机源码

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "FFTDisp.h"
#include "math.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TFFTform *FFTform;
void TFFTform::kbfft(float pr[],float pi[],int n,int k,float fr[],float fi[],float al[],float ph[])
{
	/*after FFT, real and image parts: fr fi    */
        double PI=3.1415926;
	int i,it,m,is,j,nv,l0;
	double p,q,s,vr,vi,poddr,poddi;
	for (it=0;it<=n-1;it++)
	{
		m=it;
		is=0;
		for(i=0;i<=k-1;i++)
		{
			j=m/2;
			is=2*is+(m-2*j);
			m=j;
		}
		fr[it]=pr[is];
		fi[it]=pi[is];
	}
	pr[0]=1.0;pi[0]=0.0;
	p=2*PI/(1.0*n);
	pr[1]=cos(p);
	pi[1]=-sin(p);
	for(i=2;i<=n-1;i++)
	{
		p=pr[i-1]*pr[1];
		q=pi[i-1]*pi[1];
		s=(pr[i-1]+pi[i-1])*(pr[1]+pi[1]);
		pr[i]=p-q;
		pi[i]=s-p-q;
	}
	for (it=0;it<=n-2;it=it+2)
	{
		vr=fr[it];
		vi=fi[it];
		fr[it]=vr+fr[it+1];
		fi[it]=vi+fi[it+1];
		fr[it+1]=vr-fr[it+1];
		fi[it+1]=vi-fi[it+1];
	}
	m=n/2;
	nv=2;
	for (l0=k-2;l0>=0;l0--)
	{
	  m=m/2;
	  nv=2*nv;
	  for (it=0;it<=(m-1)*nv;it=it+nv)
		 for(j=0;j<=(nv/2)-1;j++)
		 {
			 p=pr[m*j]*fr[it+j+nv/2];
			 q=pi[m*j]*fi[it+j+nv/2];
			 s=pr[m*j]+pi[m*j];
			 s=s*(fr[it+j+nv/2]+fi[it+j+nv/2]);
			 poddr=p-q;
			 poddi=s-p-q;
			 fr[it+j+nv/2]=fr[it+j]-poddr;
			 fi[it+j+nv/2]=fi[it+j]-poddi;
			 fr[it+j]=fr[it+j]+poddr;
			 fi[it+j]=fi[it+j]+poddi;
		 }
	}
        /*
	for(i=0;i<=n-1;i++)
	{
		al[i]=sqrt(fr[i]*fr[i]+fi[i]*fi[i]);
		ph[i]=atan2(fi[i],fr[i]);
	} */
}
//---------------------------------------------------------------------------
__fastcall TFFTform::TFFTform(TComponent* Owner)
        : TForm(Owner)
{
//DATALENGTH
kbfft(pr,pi,DATALENGTH,5,fr,fi,al,ph);
}
//---------------------------------------------------------------------------