radproc.c

dsp AD公司ADSP21的代码,里面有FFT FIR IIR EQULIZER G722_21F 等可以在项目中直接应用的代码.此代码的来源是ADI公司自己出版的书籍,此书在美国购得

#include <stdlib.h>
#include <math.h>
#include "rtdspc.h"

/*********************************************************************

RADPROC.C - Real-Time Radar Processing

This program subtracts successive complex echo signals to
remove stationary targets from a radar signal and then
does power spectral estimation on the resulting samples.
The mean frequency is then estimated by finding the peak of the 
FFT spectrum.

Requires complex input (stored real,imag) with 12
consecutive samples representing 12 range locations from
each echo.

*********************************************************************/

/* FFT length must be a power of 2 */
#define FFT_LENGTH 16
#define M 4            /* must be log2(FFT_LENGTH) */
#define ECHO_SIZE 12

void main()
{
  int            i,j,k;
  float          tempflt,rin,iin,p1,p2;
  static float   mag[FFT_LENGTH];
  static COMPLEX echos[ECHO_SIZE][FFT_LENGTH];
  static COMPLEX last_echo[ECHO_SIZE];

/* read in the first echo */
  for(i = 0 ; i < ECHO_SIZE ; i++) {
     last_echo[i].real = getinput();
     last_echo[i].imag = getinput();
  }

  for(;;) {
    for (j=0; j< FFT_LENGTH; j++){

/* remove stationary targets by subtracting pairs (highpass filter) */
      for (k=0; k< ECHO_SIZE; k++){
        rin = getinput();
        iin = getinput();
        echos[k][j].real = rin - last_echo[k].real;
        echos[k][j].imag = iin - last_echo[k].imag;
        last_echo[k].real = rin;
        last_echo[k].imag = iin;
      }
    }
/* do FFTs on each range sample */
    for (k=0; k< ECHO_SIZE; k++) {

      fft(echos[k],M);

      for(j = 0 ; j < FFT_LENGTH ; j++) {
        tempflt  = echos[k][j].real * echos[k][j].real;
        tempflt += echos[k][j].imag * echos[k][j].imag;
        mag[j] = tempflt;
      }
/* find the biggest magnitude spectral bin and output */
      tempflt = mag[0];
      i=0;
      for(j = 1 ; j < FFT_LENGTH ; j++) {
        if(mag[j] > tempflt) {
          tempflt = mag[j];
          i=j;
        }
      }
/* interpolate the peak loacation */
      p1 = mag[i] - mag[i-1];
      p2 = mag[i] - mag[i+1];
      sendout((float)i + (p1-p2)/(2*(p1+p2+1e-30)));
    }
  }
}