ofdm_synchronizer_cc.h

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/* -*- c++ -*- */
/*
 * Copyright 2019 Free Software Foundation, Inc..
 *
 * This 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.
 *
 * This software 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 software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDED_INSPECTOR_OFDM_SYNCHRONIZER_CC_H
#define INCLUDED_INSPECTOR_OFDM_SYNCHRONIZER_CC_H

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

namespace gr {
namespace inspector {

/*!
 * \brief OFDM frequency synchronizer and timing estimator
 * \ingroup inspector
 *
 * \details
 * This block can be inserted downstream to the OFDM parameter
 * estimation block. It performs a frequency offset estimation and
 * symbol timing estimation according to [1]. Frequency offsets smaller than the
 * subcarrier spacing will be corrected to obtain orthogonality of
 * the carriers. Output is a stream with stream tags at the estimated
 * OFDM symbol beginnings (PMT symbol "symbol").
 *
 * Connect output of OFDM parameter estimator to message port and
 * signal itself to the stream input.
 *
 * [1] J. J. van de Beek, M. Sandell, and P. O. Borjesson,
 * “ML estimation of time and frequency offset in OFDM systems,”
 * IEEE Transactions on Signal Processing, vol. 45, no. 7, pp.
 * 1800–1805, 1997. [Online]. Available:
 * http://pure.ltu.se/portal/files/1612155/Article.pdf.
 */
class INSPECTOR_API ofdm_synchronizer_cc : virtual public gr::sync_block
{
public:
    typedef boost::shared_ptr<ofdm_synchronizer_cc> sptr;

    /*!
     * \brief Return a shared_ptr to a new instance of inspector::ofdm_synchronizer_cc.
     *
     * To avoid accidental use of raw pointers, inspector::ofdm_synchronizer_cc's
     * constructor is in a private implementation
     * class. inspector::ofdm_synchronizer_cc::make is the public interface for
     * creating new instances.
     *
     * \param min_items Set minimum items required for each work call. Should be several
     * FFT lengths.
     */
    static sptr make(int min_items);
};

} // namespace inspector
} // namespace gr

#endif /* INCLUDED_INSPECTOR_OFDM_SYNCHRONIZER_CC_H */