/* -*- c++ -*- */
/*
 * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
 *
 *  Copyright (C) 2016,2019 Libre Space Foundation <http://libre.space>
 *
 *  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_DOPPLER_CORRECTION_CC_H
#define INCLUDED_SATNOGS_DOPPLER_CORRECTION_CC_H

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

namespace gr {
namespace satnogs {

/*!
 * \brief This block corrects the doppler effect between the ground
 * station and the satellite. It takes the input stream in baseband
 * and applies proper corrections to keep the carrier at the desired
 * frequency. To achieve that it uses messages containing the absolute
 * predicted frequency of the satellite from software like Gpredict.
 *
 * \ingroup satnogs
 *
 */
class SATNOGS_API doppler_correction_cc : virtual public gr::sync_block {
public:
  typedef boost::shared_ptr<doppler_correction_cc> sptr;

  /*!
   * The doppler correction block. The input is the complex signal at
   * baseband as it comes from the SDR device. The message input \p freq
   * received periodically messages containing the predicted absolute
   * frequency of the satellite at that specific time.
   * @param target_freq the absolute frequency of the satellite
   * @param offset the frequency offset from the actual target frequency.
   * This is very common on SDR receivers to avoid DC spikes at the center
   * frequency. This block can automatically compensate this offset
   * @param sampling_rate the sampling rate of the signal
   * @param corrections_per_sec the number of the corrections every second
   * that the block should perform
   */
  static sptr
  make(double target_freq, double offset, double sampling_rate,
       size_t corrections_per_sec = 1000);
};

} // namespace satnogs
} // namespace gr

#endif /* INCLUDED_SATNOGS_DOPPLER_CORRECTION_CC_H */