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   1 /* -*- c++ -*- */
   2 /*
   3  * Copyright 2007 Free Software Foundation, Inc.
   4  *
   5  * This file is part of GNU Radio
   6  *
   7  * GNU Radio is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3, or (at your option)
  10  * any later version.
  11  *
  12  * GNU Radio is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with GNU Radio; see the file COPYING.  If not, write to
  19  * the Free Software Foundation, Inc., 51 Franklin Street,
  20  * Boston, MA 02110-1301, USA.
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include <gr_peak_detector2_fb.h>
  28 #include <gr_io_signature.h>
  29
  30 gr_peak_detector2_fb_sptr
  31 gr_make_peak_detector2_fb (float threshold_factor_rise,
  32                            int look_ahead, float alpha)
  33 {
  34   return gr_peak_detector2_fb_sptr (new gr_peak_detector2_fb (threshold_factor_rise,
  35                                   look_ahead, alpha));
  36 }
  37
  38 gr_peak_detector2_fb::gr_peak_detector2_fb (float threshold_factor_rise,
  39                                             int look_ahead, float alpha)
  40   : gr_sync_block ("peak_detector2_fb",
  41                    gr_make_io_signature (1, 1, sizeof(float)),
  42                    gr_make_io_signature2 (1, 2, sizeof(char), sizeof(float))),
  43     d_threshold_factor_rise(threshold_factor_rise),
  44     d_look_ahead(look_ahead), d_alpha(alpha), d_avg(0.0f), d_found(false)
  45 {
  46 }
  47
  48 int
  49 gr_peak_detector2_fb::work (int noutput_items,
  50                             gr_vector_const_void_star &input_items,
  51                             gr_vector_void_star &output_items) {
  52   float *iptr = (float *) input_items[0];
  53   char *optr = (char *) output_items[0];
  54
  55   assert(noutput_items >= 2);
  56
  57   memset(optr, 0, noutput_items*sizeof(char));
  58
  59   for (int i = 0; i < noutput_items; i++) {
  60
  61     if (!d_found) {
  62       // Have not yet detected presence of peak
  63       if (iptr[i] > d_avg * (1.0f + d_threshold_factor_rise)) {
  64         d_found = true;
  65         d_look_ahead_remaining = d_look_ahead;
  66         d_peak_val = -(float)INFINITY;
  67       }
  68       else {
  69         d_avg = d_alpha*iptr[i] + (1.0f - d_alpha)*d_avg;
  70       }
  71     }
  72     else {
  73       // Detected presence of peak
  74       if (iptr[i] > d_peak_val) {
  75         d_peak_val = iptr[i];
  76         d_peak_ind = i;
  77       }
  78       else if (d_look_ahead_remaining <= 0) {
  79         optr[d_peak_ind] = 1;
  80         d_found = false;
  81         d_avg = iptr[i];
  82       }
  83
  84       // Have not yet located peak, loop and keep searching.
  85       d_look_ahead_remaining--;
  86     }
  87
  88     // Every iteration of the loop, write debugging signal out if
  89     // connected:
  90     if (output_items.size() == 2) {
  91       float *sigout = (float *) output_items[1];
  92       sigout[i] = d_avg;
  93     }
  94   } // loop
  95
  96   if (!d_found)
  97     return noutput_items;
  98
  99   // else if detected presence, keep searching during the next call to work.
 100   int tmp = d_peak_ind;
 101   d_peak_ind = 1;
 102
 103   return tmp - 1;
 104 }
 105
 106