/* -*- c++ -*- */
/*
 * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
 *
 *  Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
 *
 *  This program 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 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_SATNOGS_CW_TO_SYMBOL_H
#define INCLUDED_SATNOGS_CW_TO_SYMBOL_H

#include <satnogs/api.h>
#include <gnuradio/sync_block.h>

#define MIN_WPM 5
#define MAX_WPM 50

namespace gr
{
  namespace satnogs
  {

    /*!
     * \brief The CW to Symbol block tries to translate the input signal
     * into Morse symbols. The input signal should have been already properly
     * filtered and processed. A possible DSP on the input signal may be the
     * squared magnitude or the amplitude of the autocorrelation. Proper filtering
     * that take cares possible spikes may drastically increase the performance
     * of this block.
     *
     * \ingroup satnogs
     */
    class SATNOGS_API cw_to_symbol : virtual public gr::sync_block
    {
    public:
      typedef boost::shared_ptr<cw_to_symbol> sptr;

      /*!
       * The CW to Symbol block tries to translate the received signal
       * power time-series into Morse symbols.
       *
       * The input stream is the energy of the signal in the time domain.
       * For best results, a proper moving average filter should be applied
       * before.
       *
       * Upon a successful recovery of a symbol it produces an appropriate
       * asynchronous message that can directly be used by the Morse decoder
       * block.
       *
       * @param sampling_rate the sampling rate of the signal
       * @param threshold the activation threshold
       * @param conf_level the confidence level, for the decisions made by
       * the decoder. Higher values, means that the decoder would be more
       * conservative, whereas lower may help in noisy environments but may
       * trigger false alarms too, especially for the case of short pauses
       * symbols
       *
       * @param wpm Morse code Words per Minute
       *
       * @param hysteresis this value represents the hysteresis of a possible
       * filter used before the CW to Symbol block. For example if there is
       * a moving average filter with x taps, the full power of the signal
       * will be available after x samples. The total length of samples with
       * maximum power will be 2*x less. Because the block searches for plateaus
       * with proper durations, this filtering hysteresis should be known.
       * If no such a filter is used, the hysteresis value should be set to zero.
       */
      static cw_to_symbol::sptr
      make (double sampling_rate, float threshold, float conf_level = 0.9,
            size_t wpm = 20,
            size_t hysteresis = 0);

      virtual void
      set_act_threshold (float thrld) = 0;
    };

  } // namespace satnogs
} // namespace gr

#endif /* INCLUDED_SATNOGS_CW_TO_SYMBOL_H */