GNU Radio 3.5.3.2 C++ API
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00001 /* -*- c++ -*- */ 00002 /* 00003 * Copyright 2011 Free Software Foundation, Inc. 00004 * 00005 * This file is part of GNU Radio 00006 * 00007 * GNU Radio is free software; you can redistribute it and/or modify 00008 * it under the terms of the GNU General Public License as published by 00009 * the Free Software Foundation; either version 3, or (at your option) 00010 * any later version. 00011 * 00012 * GNU Radio is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 * GNU General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU General Public License 00018 * along with GNU Radio; see the file COPYING. If not, write to 00019 * the Free Software Foundation, Inc., 51 Franklin Street, 00020 * Boston, MA 02110-1301, USA. 00021 */ 00022 00023 #ifndef INCLUDED_DIGITAL_CONSTELLATION_RECEIVER_CB_H 00024 #define INCLUDED_DIGITAL_CONSTELLATION_RECEIVER_CB_H 00025 00026 #include <digital_api.h> 00027 #include <gr_block.h> 00028 #include <digital_constellation.h> 00029 #include <gruel/attributes.h> 00030 #include <gri_control_loop.h> 00031 #include <gr_complex.h> 00032 #include <math.h> 00033 #include <fstream> 00034 00035 class digital_constellation_receiver_cb; 00036 typedef boost::shared_ptr<digital_constellation_receiver_cb> digital_constellation_receiver_cb_sptr; 00037 00038 // public constructor 00039 DIGITAL_API digital_constellation_receiver_cb_sptr 00040 digital_make_constellation_receiver_cb (digital_constellation_sptr constellation, 00041 float loop_bw, float fmin, float fmax); 00042 00043 /*! 00044 * \brief This block takes care of receiving generic modulated signals 00045 * through phase, frequency, and symbol synchronization. 00046 * \ingroup sync_blk 00047 * \ingroup demod_blk 00048 * \ingroup digital 00049 * 00050 * This block takes care of receiving generic modulated signals 00051 * through phase, frequency, and symbol synchronization. It performs 00052 * carrier frequency and phase locking as well as symbol timing 00053 * recovery. 00054 * 00055 * The phase and frequency synchronization are based on a Costas loop 00056 * that finds the error of the incoming signal point compared to its 00057 * nearest constellation point. The frequency and phase of the NCO are 00058 * updated according to this error. 00059 * 00060 * The symbol synchronization is done using a modified Mueller and 00061 * Muller circuit from the paper: 00062 * 00063 * G. R. Danesfahani, T.G. Jeans, "Optimisation of modified Mueller 00064 * and Muller algorithm," Electronics Letters, Vol. 31, no. 13, 22 00065 * June 1995, pp. 1032 - 1033. 00066 * 00067 * This circuit interpolates the downconverted sample (using the NCO 00068 * developed by the Costas loop) every mu samples, then it finds the 00069 * sampling error based on this and the past symbols and the decision 00070 * made on the samples. Like the phase error detector, there are 00071 * optimized decision algorithms for BPSK and QPKS, but 8PSK uses 00072 * another brute force computation against all possible symbols. The 00073 * modifications to the M&M used here reduce self-noise. 00074 * 00075 */ 00076 00077 class DIGITAL_API digital_constellation_receiver_cb : public gr_block, public gri_control_loop 00078 { 00079 public: 00080 int general_work (int noutput_items, 00081 gr_vector_int &ninput_items, 00082 gr_vector_const_void_star &input_items, 00083 gr_vector_void_star &output_items); 00084 00085 protected: 00086 00087 /*! 00088 * \brief Constructor to synchronize incoming M-PSK symbols 00089 * 00090 * \param constellation constellation of points for generic modulation 00091 * \param loop_bw Loop bandwidth of the Costas Loop (~ 2pi/100) 00092 * \param fmin minimum normalized frequency value the loop can achieve 00093 * \param fmax maximum normalized frequency value the loop can achieve 00094 * 00095 * The constructor also chooses which phase detector and decision maker to use in the 00096 * work loop based on the value of M. 00097 */ 00098 digital_constellation_receiver_cb (digital_constellation_sptr constellation, 00099 float loop_bw, float fmin, float fmax); 00100 00101 void phase_error_tracking(float phase_error); 00102 00103 private: 00104 unsigned int d_M; 00105 00106 digital_constellation_sptr d_constellation; 00107 unsigned int d_current_const_point; 00108 00109 //! delay line length. 00110 static const unsigned int DLLEN = 8; 00111 00112 //! delay line plus some length for overflow protection 00113 __GR_ATTR_ALIGNED(8) gr_complex d_dl[2*DLLEN]; 00114 00115 //! index to delay line 00116 unsigned int d_dl_idx; 00117 00118 friend DIGITAL_API digital_constellation_receiver_cb_sptr 00119 digital_make_constellation_receiver_cb (digital_constellation_sptr constell, 00120 float loop_bw, float fmin, float fmax); 00121 }; 00122 00123 #endif