chirp.c

通过visual DSP

#include <def21161.h>
#include <stdio.h>
#include <math.h>

#define  BandWidth  2.0e6    //发射信号带宽
#define  TimeWidth  42.0e-6    //发射信号时宽
#define  Fs  2.0e6               //采样频率
#define  pi  3.14
//#define  num 420               //num=0.5*Fs*TimeWidth;   // 采样点数
//#define  N1   840        //N1=2*num+1;
#define  M  2048

 float dm  lfmreal[M];	
 float  dm lfmimag[M];
 extern float echo_re_fft[M];
 extern float echo_im_fft[M];
 
extern float dsp_re_fft[M];
 
extern float dsp_im_fft[M];
 
 
extern float dsp_re[M];
extern float dsp_im[M];
extern float echo_re[M];
extern float echo_im[M];
extern float refft[M];
extern float imfft[M];
extern float coeffreal[M];
 
extern float coeffimag[M];
/* float dsp_re_fft[M];
 float dsp_im_fft[M];
 float dsp_re[M];
 float dsp_im[M];
 float echo_re[M];
 float echo_im[M];
 float refft[M];
 float imfft[M];
 float coeffreal[M];
 float coeffimag[M];*/

float result[M];
 
void _fft(float*,float*);
void _module(float*,float*);

  
void main()
{
 
  /* float u;
 

  u=pi*(BandWidth/TimeWidth);  //调制斜率
  
  */
  //这里r4,r8作为c与汇编的接口寄存器
 int i,u,k,n; 
 for (i=1;i<=1920;i++)
  {
    
    
   echo_re[i] =lfmreal[i];
    echo_im[i] =lfmimag[i];         
    
  }    
  
  for(i=1921;i<=2048;i++)  
  {
     echo_re[i]=0;
     echo_im[i]=0;    
  }

  
  fft(echo_re,echo_im);
  module(refft,imfft);

for(u=1;u<=2048;u++)
{
  echo_re_fft[u]=refft[u];
  echo_im_fft[u]=imfft[u];
  }  

 
 for(k=1;k<=2048;k++)
 {
 dsp_re_fft[k]=echo_re_fft[k]*coeffreal[k]-echo_im_fft[k]*coeffimag[k];
 dsp_im_fft[k]=echo_im_fft[k]*coeffreal[k]+echo_re_fft[k]*coeffimag[k];
 } 
 
 fft(dsp_re_fft,dsp_im_fft);
 for(n=1;n<=2048;n++)
{
  dsp_re[n]=refft[n]/M;
  dsp_im[n]=imfft[n]/M;
  }  

 
 module(refft,imfft);
    
    
   exit(0) ;  
}