GNU Radio 3.5.3.2 C++ API
gri_agc2_cc.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2006 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 #ifndef _GRI_AGC2_CC_H_
24 #define _GRI_AGC2_CC_H_
25 
26 #include <gr_core_api.h>
27 #include <math.h>
28 
29 /*!
30  * \brief high performance Automatic Gain Control class
31  *
32  * For Power the absolute value of the complex number is used.
33  */
35 
36  public:
37  gri_agc2_cc (float attack_rate = 1e-1, float decay_rate = 1e-2, float reference = 1.0,
38  float gain = 1.0, float max_gain = 0.0)
39  : _attack_rate(attack_rate), _decay_rate(decay_rate), _reference(reference),
40  _gain(gain), _max_gain(max_gain) {};
41 
42  float decay_rate () const { return _decay_rate; }
43  float attack_rate () const { return _attack_rate; }
44  float reference () const { return _reference; }
45  float gain () const { return _gain; }
46  float max_gain() const { return _max_gain; }
47 
48  void set_decay_rate (float rate) { _decay_rate = rate; }
49  void set_attack_rate (float rate) { _attack_rate = rate; }
50  void set_reference (float reference) { _reference = reference; }
51  void set_gain (float gain) { _gain = gain; }
52  void set_max_gain(float max_gain) { _max_gain = max_gain; }
53 
55  gr_complex output = input * _gain;
56 
57  float tmp = -_reference + sqrt(output.real()*output.real() +
58  output.imag()*output.imag());
59  float rate = _decay_rate;
60  if((tmp) > _gain)
61  rate = _attack_rate;
62  _gain -= tmp*rate;
63 
64 #if 0
65  fprintf(stdout, "rate = %f\ttmp = %f\t gain = %f\n", rate, tmp, _gain);
66 #endif
67 
68  // Not sure about this; will blow up if _gain < 0 (happens when rates are too high),
69  // but is this the solution?
70  if (_gain < 0.0)
71  _gain = 10e-5;
72 
73  if (_max_gain > 0.0 && _gain > _max_gain)
74  _gain = _max_gain;
75  return output;
76  }
77 
78  void scaleN (gr_complex output[], const gr_complex input[], unsigned n){
79  for (unsigned i = 0; i < n; i++)
80  output[i] = scale (input[i]);
81  }
82 
83  protected:
84  float _attack_rate; // attack rate for fast changing signals
85  float _decay_rate; // decay rate for slow changing signals
86  float _reference; // reference value
87  float _gain; // current gain
88  float _max_gain; // max allowable gain
89 };
90 
91 #endif /* _GRI_AGC2_CC_H_ */