cw.c

来自「Time-Frequency Toolbox,其中包含很常用的MATLAB程序」· C语言 代码 · 共 439 行 · 第 1/2 页

/* EXISTS AN INTERFACE PROGRAM TO MATLAB : CTFRCW.C                           *
 *============================================================================*
 * Name of the function : cw.c (void)                                         *
 * Authors              : Emmanuel Roy - Manuel DAVY                          *
 * Date of creation     : 10 - 02 - 1999                                      *
 *----------------------------------------------------------------------------*
 * THE ALGORITHM                                                              *
 *                                                                            *
 * Given a signal to analyze in time and frequency, computes the Choi-Williams*
 * Distribution (CW) :                                                        *
 *                                                                            *
 *                 //                                                         *
 *                 ||     sqrt(sigma)     -mu^2 *sigma / (16 tau^2)           *
 *      CW(t,f) =  || -----------------  e                           .../... *
 *                 ||  2 sqrt(pi)|tau |                                       *
 *                //                                                          *
 *                                                                            *
 *                                                 -j2pi f tau                *
 *                     x(t+mu+tau/2)x*(t+mu-tau/2)e            dmu dtau       *
 *                                                                            *
 *                                                                            *
 * This function is real valued. Its computation requires a real or complex   *
 * signal, a vector containing time instants, the number of frequency bins, a *
 * time smoothing window, a frequency smoothing window and the kernel width.  *
 *                                                                            *
 *============================================================================*
 * INPUT VARIABLES                                                            *
 * Name                |              role                                    *
 * Signal              | The signal to analyze. No field modified             *
 *                     |                                                      *
 * WindowT             | Vector containing the points of the time moothing    *
 *                     | window                                               *
 * WindowT_Length      | Number of points of the time window (ODD number !)   *
 *                     |                                                      *
 * WindowF             | Vector containing the points of the frequency window *
 * WindowF_Length      | Number of points of the window (ODD number !)        *
 *                     |                                                      *
 * tfr                 | Matrix containing the resulting TFR (real)           *
 * tfr.time_instants   | positions of the smoothing window                    *
 * tfr.N_time          | length of '.time_instants' = number of cols.         *
 *                     | in the tfr matrix                                    *
 * tfr.N_freq          | number of frequency bins = number of rows in the tfr *
 *                     | matrix                                               *
 * tfr.is_complex      | must be set to FALSE (a CW tfr is real-valued)       *
 *                     |                                                      *
 * sigma               | the kernel width                                     *
 *                     |                                                      *
 *----------------------------------------------------------------------------*
 * OUTPUT VARIABLES                                                           *
 * Name                |                role                                  *
 * tfr.real_part       | the output tfr matrix  (real_part)                   *
 * tfr.freq_bins       | vector of frequency bins (freqs where the tfr matrix *
 *                     | is computed)                                         *
 *----------------------------------------------------------------------------*
 * INTERNAL VARIABLES                                                         *
 * Name                |                 role                                 *
 *                     |                                                      *
 * Nfft                | Next power of two to tfr.N_freq                      *
 * column, row         | variables of displacement in the matrices            *
 * time                | local time-instant variable to compute the tfr       *
 *                     |                                                      *
 * half_WindowT_Length | half-length of the time smoothing window             *
 *                     |                                                      *
 * half_WindowF_Length | half-length of the frequency smoothing window        *
 * normF               | normalization factor for the frequency window        *
 *                     |                                                      *
 * CWKernel            | variable to compute the Choi-Williams Kernel         *
 * normK               | normalization factor for the Kernel                  *
 * spreadfac           | factor = 16/sigma                                    *
 * index               | variable to locate position in the kernel matrix     *
 *                     |                                                      *
 * tau                 | time-lag variable                                    *
 * taumin              | local time-lag variable bounds. Used to take into    *
 * taumax              | accound the beginning and the end of the             *
 *                     | signal, where the window is cut                      *
 *                     |                                                      *
 * mu                  | time-smoothing variable                              *
 * mumin               | local time-smoothing variable bounds. Used to take   *
 * mumax               | into accound the beginning and the end of time       *
 *                     | smoothing procedure                                  *
 *                     |                                                      *
 * lacf_real           | real and imaginary parts of the local autocorrelation*
 * lacf_imag           | function of the signal                               *
 *                     |                                                      *
 * R1_real R1_imag     | used to compute real and imaginary parts of the time *
 * R2_real R2_imag     | smoothed-windowed local autocorrelation function     *
 *                     |                                                      *
 *============================================================================*
 * SUBROUTINES USED HERE                                                      *
 *----------------------------------------------------------------------------*
 * Name   | int idx(int i_row, int j_col, int nb_row)                         *
 * Action | computes the vector index for an element in a matrix given the row*
 *        | and column indices (i,j) and the total number of row              *
 * Place  | divers.c                                                          *
 *----------------------------------------------------------------------------*
 * Name   | void fft(int n, int m, double *x, double *y)                      *
 * Action | Computes the fft                                                  *
 * Place  | divers.c                                                          *
 *----------------------------------------------------------------------------*
 * Name   | int po2(int x)                                                    *
 * Action | Computes the next power of two of x                               *
 * Place  | divers.c                                                          *
 *============================================================================*/

void
cw (type_signal Signal,
    double *WindowT, int WindowT_Length,
    double *WindowF, int WindowF_Length,
    double sigma,
    type_TFR tfr)

{
  int            Nfft, column, row, time;
  int            half_WindowT_Length, half_WindowF_Length;
  int            taumin, taumax, tau;
  int            mumin, mumax, mu, index;
  double        *lacf_real, *lacf_imag;/* local autocorrelation function */
  double         normK, normF, spreadfac;
  double         R1_real, R1_imag, R2_real, R2_imag;
  double        *CWKernel;

 /*--------------------------------------------------------------------------*/
 /*                        Test the input variables                          */
 /*--------------------------------------------------------------------------*/


   if (tfr.is_complex == TRUE)
    {
      printf ("cw.c : The tfr matrix must be real valued\n");
      exit(0);
    }

  if (tfr.N_freq <= 0)
    {
      printf ("cw.c : The field tfr.N_freq is not correctly set\n");
      exit(0);
    }

  if (tfr.N_time <= 0)
    {
      printf ("cw.c : The field tfr.N_time is not correctly set\n");
      exit(0);
    }

  if (ISODD(WindowT_Length) == 0)
    {
      printf ("cw.c : The time-window Length must be an ODD number\n");
      exit(0);
    }

  if (ISODD(WindowF_Length) == 0)
    {
      printf ("cw.c : The frequency-window Length must be an ODD number\n");
      exit(0);
    }

 /*--------------------------------------------------------------------------*/
 /*                    Determines some internal constants                    */
 /*--------------------------------------------------------------------------*/

  half_WindowT_Length = (WindowT_Length - 1) / 2;
  
  half_WindowF_Length = (WindowF_Length - 1) / 2;
  normF=WindowF[half_WindowF_Length];
  /* normalization of the frequency smoothing window */
  for(row = 0; row < WindowF_Length; row++)
    {
      WindowF[row]=WindowF[row]/normF;
    }

 /*--------------------------------------------------------------------------*/
 /*          Memory allocation and computation of  the kernel                */
 /*--------------------------------------------------------------------------*/
  CWKernel = (double * )ALLOC (MIN(tfr.N_freq,half_WindowF_Length)
			                                    * WindowT_Length,sizeof(double));

  spreadfac = 16.0/sigma;
  taumax=MIN(tfr.N_freq,half_WindowF_Length);

  for(tau=1;tau<=taumax;tau++)
      {
      for(mu=-half_WindowT_Length;mu<=+half_WindowT_Length;mu++)
	  {
	  CWKernel[idx(tau-1,half_WindowT_Length+mu,taumax)] = 
                                   exp(-1.0/(spreadfac * tau * tau) * mu * mu)
	                                * WindowT[half_WindowT_Length + mu];
	}
    }  
 /*--------------------------------------------------------------------------*/
 /*           creation of the vector of frequency bins  (output)             */
 /*--------------------------------------------------------------------------*/
  Nfft = po2 (tfr.N_freq);

  for (row = 0; row < tfr.N_freq; row++)
    {
      tfr.freq_bins[row] = (double) (0.5 * row) / tfr.N_freq;
    }

 /*--------------------------------------------------------------------------*/
 /*     memory allocation and init. of the local autocorrelation fuction     */
 /*--------------------------------------------------------------------------*/
  lacf_real = (double *) ALLOC (tfr.N_freq , sizeof (double));
  lacf_imag = (double *) ALLOC (tfr.N_freq , sizeof (double));

 /* initialization of the intermediary vectors */
 for (row = 0; row < tfr.N_freq ; row++)
   {
    lacf_real[row] = 0.0;
    lacf_imag[row] = 0.0;
   }

 /*--------------------------------------------------------------------------*/
 /*      computation of the fft for the local autocorrelation function       */
 /*--------------------------------------------------------------------------*/
  for (column = 0; column < tfr.N_time; column++)
    {
      /* time instants of interest to compute the tfr */
      time = ((int) tfr.time_instants[column]) - 1;

      /* maximum value of the delay in order to take the edges