GNU Radio 3.6.5 C++ API
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00001 /* -*- c++ -*- */ 00002 /* 00003 * Copyright 2006,2011 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 00024 #ifndef INCLUDED_DIGITAL_COSTAS_LOOP_CC_H 00025 #define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H 00026 00027 #include <gr_sync_block.h> 00028 #include <gri_control_loop.h> 00029 #include <stdexcept> 00030 #include <fstream> 00031 #include <digital_api.h> 00032 00033 class digital_costas_loop_cc; 00034 typedef boost::shared_ptr<digital_costas_loop_cc> digital_costas_loop_cc_sptr; 00035 00036 00037 DIGITAL_API digital_costas_loop_cc_sptr 00038 digital_make_costas_loop_cc (float loop_bw, int order 00039 ) throw (std::invalid_argument); 00040 00041 /*! 00042 * \brief A Costas loop carrier recovery module. 00043 * \ingroup synchronizers_blk 00044 * 00045 * \details 00046 * The Costas loop locks to the center frequency of a signal and 00047 * downconverts it to baseband. The second (order=2) order loop is 00048 * used for BPSK where the real part of the output signal is the 00049 * baseband BPSK signal and the imaginary part is the error 00050 * signal. When order=4, it can be used for quadrature modulations 00051 * where both I and Q (real and imaginary) are outputted. 00052 * 00053 * More details can be found online: 00054 * 00055 * J. Feigin, "Practical Costas loop design: Designing a simple and 00056 * inexpensive BPSK Costas loop carrier recovery circuit," RF signal 00057 * processing, pp. 20-36, 2002. 00058 * 00059 * http://rfdesign.com/images/archive/0102Feigin20.pdf 00060 */ 00061 class DIGITAL_API digital_costas_loop_cc : public gr_sync_block, public gri_control_loop 00062 { 00063 friend DIGITAL_API digital_costas_loop_cc_sptr 00064 digital_make_costas_loop_cc (float loop_bw, int order 00065 ) throw (std::invalid_argument); 00066 00067 int d_order; 00068 00069 /*! 00070 * \brief Carrier tracking PLL for QPSK 00071 * input: complex; output: complex 00072 * <br>The Costas loop can have two output streams: 00073 * stream 1 is the baseband I and Q; 00074 * stream 2 is the normalized frequency of the loop 00075 * 00076 * \param loop_bw internal 2nd order loop bandwidth (~ 2pi/100) 00077 * \param order the loop order, either 2, 4, or 8 00078 */ 00079 digital_costas_loop_cc (float loop_bw, int order 00080 ) throw (std::invalid_argument); 00081 00082 /*! \brief the phase detector circuit for 8th-order PSK loops 00083 * \param sample complex sample 00084 * \return the phase error 00085 */ 00086 float phase_detector_8(gr_complex sample) const; // for 8PSK 00087 00088 /*! \brief the phase detector circuit for fourth-order loops 00089 * \param sample complex sample 00090 * \return the phase error 00091 */ 00092 float phase_detector_4(gr_complex sample) const; // for QPSK 00093 00094 /*! \brief the phase detector circuit for second-order loops 00095 * \param sample a complex sample 00096 * \return the phase error 00097 */ 00098 float phase_detector_2(gr_complex sample) const; // for BPSK 00099 00100 00101 float (digital_costas_loop_cc::*d_phase_detector)(gr_complex sample) const; 00102 00103 public: 00104 00105 int work (int noutput_items, 00106 gr_vector_const_void_star &input_items, 00107 gr_vector_void_star &output_items); 00108 }; 00109 00110 #endif