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/* -*- c++ -*- */
/*
* Copyright 2011,2012 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_DIGITAL_CONSTELLATION_RECEIVER_CB_H
#define INCLUDED_DIGITAL_CONSTELLATION_RECEIVER_CB_H
#include <digital/api.h>
#include <digital/constellation.h>
#include <gr_block.h>
namespace gr {
namespace digital {
/*!
* \brief This block takes care of receiving generic modulated signals
* through phase, frequency, and symbol synchronization.
* \ingroup sync_blk
* \ingroup demod_blk
* \ingroup digital
*
* This block takes care of receiving generic modulated signals
* through phase, frequency, and symbol synchronization. It
* performs carrier frequency and phase locking as well as symbol
* timing recovery.
*
* The phase and frequency synchronization are based on a Costas
* loop that finds the error of the incoming signal point compared
* to its nearest constellation point. The frequency and phase of
* the NCO are updated according to this error.
*
* The symbol synchronization is done using a modified Mueller and
* Muller circuit from the paper:
*
* "G. R. Danesfahani, T.G. Jeans, "Optimisation of modified
* Mueller and Muller algorithm," Electronics Letters, Vol. 31,
* no. 13, 22 June 1995, pp. 1032 - 1033."
*
* This circuit interpolates the downconverted sample (using the
* NCO developed by the Costas loop) every mu samples, then it
* finds the sampling error based on this and the past symbols and
* the decision made on the samples. Like the phase error
* detector, there are optimized decision algorithms for BPSK and
* QPKS, but 8PSK uses another brute force computation against all
* possible symbols. The modifications to the M&M used here reduce
* self-noise.
*/
class DIGITAL_API constellation_receiver_cb
: virtual public gr_block
{
public:
// gr::digital::constellation_receiver_cb::sptr
typedef boost::shared_ptr<constellation_receiver_cb> sptr;
/*!
* \brief Constructor to synchronize incoming M-PSK symbols
*
* \param constellation constellation of points for generic modulation
* \param loop_bw Loop bandwidth of the Costas Loop (~ 2pi/100)
* \param fmin minimum normalized frequency value the loop can achieve
* \param fmax maximum normalized frequency value the loop can achieve
*
* The constructor chooses which phase detector and decision
* maker to use in the work loop based on the value of M.
*/
static sptr make(constellation_sptr constellation,
float loop_bw, float fmin, float fmax);
virtual void phase_error_tracking(float phase_error) = 0;
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_DIGITAL_CONSTELLATION_RECEIVER_CB_H */
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