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Diffstat (limited to 'gr-digital/include/digital/constellation_receiver_cb.h')
| -rw-r--r-- | gr-digital/include/digital/constellation_receiver_cb.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/gr-digital/include/digital/constellation_receiver_cb.h b/gr-digital/include/digital/constellation_receiver_cb.h new file mode 100644 index 0000000000..b1c415ea09 --- /dev/null +++ b/gr-digital/include/digital/constellation_receiver_cb.h @@ -0,0 +1,93 @@ +/* -*- 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 */ |