agc.h

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/* -*- c++ -*- */
/*
 * Copyright 2006,2012 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDED_ANALOG_AGC_H
#define INCLUDED_ANALOG_AGC_H

#include <gnuradio/analog/api.h>
#include <gnuradio/gr_complex.h>
#include <cmath>

namespace gr {
  namespace analog {
    namespace kernel {

      /*!
       * \brief high performance Automatic Gain Control class for complex signals.
       * \ingroup level_controllers_blk
       *
       * \details
       * For Power the absolute value of the complex number is used.
       */
      class ANALOG_API agc_cc
      {
      public:
        /*!
         * Construct a complex value AGC loop implementation object.
         *
         * \param rate the update rate of the loop.
         * \param reference reference value to adjust signal power to.
         * \param gain initial gain value.
         * \param max_gain maximum gain value (0 for unlimited).
         */
        agc_cc(float rate = 1e-4, float reference = 1.0,
               float gain = 1.0, float max_gain = 0.0)
          : _rate(rate), _reference(reference),
          _gain(gain), _max_gain(max_gain) {};

        virtual ~agc_cc() {};

        float rate() const      { return _rate; }
        float reference() const { return _reference; }
        float gain() const      { return _gain;  }
        float max_gain() const   { return _max_gain; }

        void set_rate(float rate) { _rate = rate; }
        void set_reference(float reference) { _reference = reference; }
        void set_gain(float gain) { _gain = gain; }
        void set_max_gain(float max_gain) { _max_gain = max_gain; }

        gr_complex scale(gr_complex input)
        {
          gr_complex output = input * _gain;

          _gain +=  _rate * (_reference - std::sqrt(output.real()*output.real() +
                                               output.imag()*output.imag()));
          if(_max_gain > 0.0 && _gain > _max_gain) {
            _gain = _max_gain;
          }
          return output;
        }

        void scaleN(gr_complex output[], const gr_complex input[], unsigned n)
        {
          for(unsigned i = 0; i < n; i++) {
            output[i] = scale (input[i]);
          }
        }

      protected:
        float _rate;            // adjustment rate
        float _reference;       // reference value
        float _gain;            // current gain
        float _max_gain;        // max allowable gain
      };

      /*!
       * \brief high performance Automatic Gain Control class for float signals.
       *
       * Power is approximated by absolute value
       */
      class ANALOG_API agc_ff
      {
      public:
        /*!
         * Construct a floating point value AGC loop implementation object.
         *
         * \param rate the update rate of the loop.
         * \param reference reference value to adjust signal power to.
         * \param gain initial gain value.
         * \param max_gain maximum gain value (0 for unlimited).
         */
        agc_ff(float rate = 1e-4, float reference = 1.0,
               float gain = 1.0, float max_gain = 0.0)
          : _rate(rate), _reference(reference), _gain(gain),
          _max_gain(max_gain) {};

        ~agc_ff() {};

        float rate () const      { return _rate; }
        float reference () const { return _reference; }
        float gain () const      { return _gain;  }
        float max_gain () const  { return _max_gain; }

        void set_rate (float rate) { _rate = rate; }
        void set_reference (float reference) { _reference = reference; }
        void set_gain (float gain) { _gain = gain; }
        void set_max_gain (float max_gain) { _max_gain = max_gain; }

        float scale (float input)
        {
          float output = input * _gain;
          _gain += (_reference - fabsf (output)) * _rate;
          if(_max_gain > 0.0 && _gain > _max_gain)
            _gain = _max_gain;
          return output;
        }

        void scaleN(float output[], const float input[], unsigned n)
        {
          for(unsigned i = 0; i < n; i++)
            output[i] = scale (input[i]);
        }

      protected:
        float _rate;            // adjustment rate
        float _reference;       // reference value
        float _gain;            // current gain
        float _max_gain;        // maximum gain
      };

    } /* namespace kernel */
  } /* namespace analog */
} /* namespace gr */

#endif /* INCLUDED_ANALOG_AGC_H */