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gri_agc.h

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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2002,2006 Free Software Foundation, Inc.
00004  * 
00005  * This file is part of GNU Radio
00006  * 
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 2, or (at your option)
00010  * any later version.
00011  * 
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  * 
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
00020  * Boston, MA 02111-1307, USA.
00021  */
00022 
00023 #ifndef _GRI_AGC_H_
00024 #define _GRI_AGC_H_
00025 
00026 #include <math.h>
00027 
00034 class gri_agc {
00035 
00036  public:
00037   gri_agc (float rate = 1e-4, float reference = 1.0, float gain = 1.0, float max_gain = 0.0)
00038     : _rate(rate), _reference(reference), _gain(gain), _max_gain(max_gain) {};
00039 
00040   float rate () const      { return _rate; }
00041   float reference () const { return _reference; }
00042   float gain () const      { return _gain;  }
00043   float max_gain () const  { return _max_gain; }
00044   
00045   void set_rate (float rate) { _rate = rate; }
00046   void set_reference (float reference) { _reference = reference; }
00047   void set_gain (float gain) { _gain = gain; }
00048   void set_max_gain (float max_gain) { _max_gain = max_gain; }
00049   
00050   float scale (float input){
00051     float output = input * _gain;
00052     _gain += (_reference - fabsf (output)) * _rate;
00053     if (_max_gain > 0.0 && _gain > _max_gain)
00054       _gain = _max_gain;
00055     return output;
00056   }
00057 
00058   void scaleN (float output[], const float input[], unsigned n){
00059     for (unsigned i = 0; i < n; i++)
00060       output[i] = scale (input[i]);
00061   }
00062   
00063  protected:
00064   float _rate;                  // adjustment rate
00065   float _reference;             // reference value
00066   float _gain;                  // current gain
00067   float _max_gain;              // maximum gain
00068 };
00069 
00070 #endif /* _GRI_AGC_H_ */

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