00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * v27ter_rx.h - ITU V.27ter modem receive part 00005 * 00006 * Written by Steve Underwood <steveu@coppice.org> 00007 * 00008 * Copyright (C) 2003 Steve Underwood 00009 * 00010 * All rights reserved. 00011 * 00012 * This program is free software; you can redistribute it and/or modify 00013 * it under the terms of the GNU General Public License as published by 00014 * the Free Software Foundation; either version 2 of the License, or 00015 * (at your option) any later version. 00016 * 00017 * This program is distributed in the hope that it will be useful, 00018 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00019 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00020 * GNU General Public License for more details. 00021 * 00022 * You should have received a copy of the GNU General Public License 00023 * along with this program; if not, write to the Free Software 00024 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00025 * 00026 * $Id: v27ter_rx.h,v 1.23 2005/12/09 19:36:00 steveu Exp $ 00027 */ 00028 00029 /*! \file */ 00030 00031 #if !defined(_V27TER_RX_H_) 00032 #define _V27TER_RX_H_ 00033 00034 /*! \page v27ter_rx_page The V.27ter receiver 00035 00036 \section v27ter_rx_page_sec_1 What does it do? 00037 00038 \section v27ter_rx_page_sec_2 How does it work? 00039 */ 00040 00041 #define V27TER_EQUALIZER_LEN 7 /* this much to the left and this much to the right */ 00042 #define V27TER_EQUALIZER_MASK 15 /* one less than a power of 2 >= (2*V27TER_EQUALIZER_LEN + 1) */ 00043 00044 #define V27TER_RX_4800_FILTER_STEPS 27 00045 #define V27TER_RX_2400_FILTER_STEPS 27 00046 00047 #if V27TER_RX_4800_FILTER_STEPS > V27TER_RX_2400_FILTER_STEPS 00048 #define V27TER_RX_FILTER_STEPS V27TER_RX_4800_FILTER_STEPS 00049 #else 00050 #define V27TER_RX_FILTER_STEPS V27TER_RX_2400_FILTER_STEPS 00051 #endif 00052 00053 /*! 00054 V.27ter modem receive side descriptor. This defines the working state for a 00055 single instance of a V.27ter modem receiver. 00056 */ 00057 typedef struct 00058 { 00059 /*! \brief The bit rate of the modem. Valid values are 2400 and 4800. */ 00060 int bit_rate; 00061 /*! \brief The callback function used to put each bit received. */ 00062 put_bit_func_t put_bit; 00063 /*! \brief A user specified opaque pointer passed to the put_bit routine. */ 00064 void *user_data; 00065 /*! \brief A callback function which may be enabled to report every symbol's 00066 constellation position. */ 00067 qam_report_handler_t *qam_report; 00068 /*! \brief A user specified opaque pointer passed to the qam_report callback 00069 routine. */ 00070 void *qam_user_data; 00071 00072 /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */ 00073 complex_t rrc_filter[2*V27TER_RX_FILTER_STEPS]; 00074 /*! \brief Current offset into the RRC pulse shaping filter buffer. */ 00075 int rrc_filter_step; 00076 00077 /*! \brief The register for the training and data scrambler. */ 00078 unsigned int scramble_reg; 00079 /*! \brief A counter for the number of consecutive bits of repeating pattern through 00080 the scrambler. */ 00081 int scrambler_pattern_count; 00082 int in_training; 00083 int training_bc; 00084 int training_count; 00085 float training_error; 00086 int carrier_present; 00087 00088 /*! \brief The current phase of the carrier (i.e. the DDS parameter). */ 00089 uint32_t carrier_phase; 00090 /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */ 00091 int32_t carrier_phase_rate; 00092 float carrier_track_p; 00093 float carrier_track_i; 00094 00095 power_meter_t power; 00096 int32_t carrier_on_power; 00097 int32_t carrier_off_power; 00098 float agc_scaling; 00099 00100 int constellation_state; 00101 00102 float eq_delta; 00103 /*! \brief The adaptive equalizer coefficients */ 00104 complex_t eq_coeff[2*V27TER_EQUALIZER_LEN + 1]; 00105 complex_t eq_buf[V27TER_EQUALIZER_MASK + 1]; 00106 /*! \brief Current offset into equalizer buffer. */ 00107 int eq_step; 00108 int eq_put_step; 00109 int eq_skip; 00110 00111 /*! \brief Integration variable for damping the Gardner algorithm tests. */ 00112 int gardner_integrate; 00113 /*! \brief Current step size of Gardner algorithm integration. */ 00114 int gardner_step; 00115 /*! \brief The total gardner timing correction, since the carrier came up. 00116 This is only for performance analysis purposes. */ 00117 int gardner_total_correction; 00118 /*! \brief The current fractional phase of the baud timing. */ 00119 int baud_phase; 00120 00121 /*! \brief Starting phase angles for the coarse carrier aquisition step. */ 00122 int32_t start_angles[2]; 00123 /*! \brief History list of phase angles for the coarse carrier aquisition step. */ 00124 int32_t angles[16]; 00125 /*! \brief Error and flow logging control */ 00126 logging_state_t logging; 00127 } v27ter_rx_state_t; 00128 00129 #ifdef __cplusplus 00130 extern "C" { 00131 #endif 00132 00133 /*! Initialise a V.27ter modem receive context. 00134 \brief Initialise a V.27ter modem receive context. 00135 \param s The modem context. 00136 \param rate The bit rate of the modem. Valid values are 2400 and 4800. 00137 \param put_bit The callback routine used to put the received data. 00138 \param user_data An opaque pointer passed to the put_bit routine. 00139 \return A pointer to the modem context, or NULL if there was a problem. */ 00140 v27ter_rx_state_t *v27ter_rx_init(v27ter_rx_state_t *s, int rate, put_bit_func_t put_bit, void *user_data); 00141 00142 /*! Reinitialise an existing V.27ter modem receive context. 00143 \brief Reinitialise an existing V.27ter modem receive context. 00144 \param s The modem context. 00145 \param rate The bit rate of the modem. Valid values are 2400 and 4800. 00146 \return 0 for OK, -1 for bad parameter */ 00147 int v27ter_rx_restart(v27ter_rx_state_t *s, int rate); 00148 00149 /*! Release a V.27ter modem receive context. 00150 \brief Release a V.27ter modem receive context. 00151 \param s The modem context. 00152 \return 0 for OK */ 00153 int v27ter_rx_release(v27ter_rx_state_t *s); 00154 00155 /*! Change the put_bit function associated with a V.27ter modem receive context. 00156 \brief Change the put_bit function associated with a V.27ter modem receive context. 00157 \param s The modem context. 00158 \param put_bit The callback routine used to handle received bits. 00159 \param user_data An opaque pointer. */ 00160 void v27ter_rx_set_put_bit(v27ter_rx_state_t *s, put_bit_func_t put_bit, void *user_data); 00161 00162 /*! Process a block of received V.27ter modem audio samples. 00163 \brief Process a block of received V.27ter modem audio samples. 00164 \param s The modem context. 00165 \param amp The audio sample buffer. 00166 \param len The number of samples in the buffer. 00167 \return The number of samples unprocessed. 00168 */ 00169 int v27ter_rx(v27ter_rx_state_t *s, const int16_t *amp, int len); 00170 00171 /*! Get a snapshot of the current equalizer coefficients. 00172 \brief Get a snapshot of the current equalizer coefficients. 00173 \param coeffs The vector of complex coefficients. 00174 \return The number of coefficients in the vector. */ 00175 int v27ter_rx_equalizer_state(v27ter_rx_state_t *s, complex_t **coeffs); 00176 00177 /*! Get the current received carrier frequency. 00178 \param s The modem context. 00179 \return The frequency, in Hertz. */ 00180 float v27ter_rx_carrier_frequency(v27ter_rx_state_t *s); 00181 00182 /*! Get the current symbol timing correction since startup. 00183 \param s The modem context. 00184 \return The correction. */ 00185 float v27ter_rx_symbol_timing_correction(v27ter_rx_state_t *s); 00186 00187 /*! Get a current received signal power. 00188 \param s The modem context. 00189 \return The signal power, in dBm0. */ 00190 float v27ter_rx_signal_power(v27ter_rx_state_t *s); 00191 00192 /*! Set the power level at which the carrier detection will cut in 00193 \param s The modem context. 00194 \param cutoff The signal cutoff power, in dBm0. */ 00195 void v27ter_rx_signal_cutoff(v27ter_rx_state_t *s, float cutoff); 00196 00197 /*! Set a handler routine to process QAM status reports 00198 \param s The modem context. 00199 \param handler The handler routine. 00200 \param user_data An opaque pointer passed to the handler routine. */ 00201 void v27ter_rx_set_qam_report_handler(v27ter_rx_state_t *s, qam_report_handler_t *handler, void *user_data); 00202 00203 #ifdef __cplusplus 00204 } 00205 #endif 00206 00207 #endif 00208 /*- End of file ------------------------------------------------------------*/