00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * private/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 Lesser General Public License version 2.1, 00014 * as published by the Free Software Foundation. 00015 * 00016 * This program is distributed in the hope that it will be useful, 00017 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00018 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00019 * GNU Lesser General Public License for more details. 00020 * 00021 * You should have received a copy of the GNU Lesser General Public 00022 * License along with this program; if not, write to the Free Software 00023 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00024 */ 00025 00026 #if !defined(_SPANDSP_PRIVATE_V27TER_RX_H_) 00027 #define _SPANDSP_PRIVATE_V27TER_RX_H_ 00028 00029 /* Target length for the equalizer is about 43 taps for 4800bps and 32 taps for 2400bps 00030 to deal with the worst stuff in V.56bis. */ 00031 /*! The length of the equalizer buffer. Must be a power of 2 */ 00032 #define V27TER_EQUALIZER_LEN 32 00033 /*! Samples before the target central position in the equalizer buffer */ 00034 #define V27TER_EQUALIZER_PRE_LEN 16 00035 00036 /*! The number of taps in the 4800bps pulse shaping/bandpass filter */ 00037 #define V27TER_RX_4800_FILTER_STEPS 27 00038 /*! The number of taps in the 2400bps pulse shaping/bandpass filter */ 00039 #define V27TER_RX_2400_FILTER_STEPS 27 00040 00041 #if V27TER_RX_4800_FILTER_STEPS > V27TER_RX_2400_FILTER_STEPS 00042 #define V27TER_RX_FILTER_STEPS V27TER_RX_4800_FILTER_STEPS 00043 #else 00044 #define V27TER_RX_FILTER_STEPS V27TER_RX_2400_FILTER_STEPS 00045 #endif 00046 00047 /*! 00048 V.27ter modem receive side descriptor. This defines the working state for a 00049 single instance of a V.27ter modem receiver. 00050 */ 00051 struct v27ter_rx_state_s 00052 { 00053 /*! \brief The bit rate of the modem. Valid values are 2400 and 4800. */ 00054 int bit_rate; 00055 /*! \brief The callback function used to put each bit received. */ 00056 put_bit_func_t put_bit; 00057 /*! \brief A user specified opaque pointer passed to the put_bit routine. */ 00058 void *put_bit_user_data; 00059 00060 /*! \brief The callback function used to report modem status changes. */ 00061 modem_rx_status_func_t status_handler; 00062 /*! \brief A user specified opaque pointer passed to the status function. */ 00063 void *status_user_data; 00064 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 #if defined(SPANDSP_USE_FIXED_POINT) 00074 int16_t rrc_filter[V27TER_RX_FILTER_STEPS]; 00075 #else 00076 float rrc_filter[V27TER_RX_FILTER_STEPS]; 00077 #endif 00078 /*! \brief Current offset into the RRC pulse shaping filter buffer. */ 00079 int rrc_filter_step; 00080 00081 /*! \brief The register for the training and data scrambler. */ 00082 unsigned int scramble_reg; 00083 /*! \brief A counter for the number of consecutive bits of repeating pattern through 00084 the scrambler. */ 00085 int scrambler_pattern_count; 00086 /*! \brief The current step in the table of BC constellation positions. */ 00087 int training_bc; 00088 /*! \brief TRUE if the previous trained values are to be reused. */ 00089 int old_train; 00090 /*! \brief The section of the training data we are currently in. */ 00091 int training_stage; 00092 /*! \brief A count of how far through the current training step we are. */ 00093 int training_count; 00094 /*! \brief A measure of how much mismatch there is between the real constellation, 00095 and the decoded symbol positions. */ 00096 float training_error; 00097 /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */ 00098 int16_t last_sample; 00099 /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.27ter signal. */ 00100 int signal_present; 00101 /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */ 00102 int carrier_drop_pending; 00103 /*! \brief A count of the current consecutive samples below the carrier off threshold. */ 00104 int low_samples; 00105 /*! \brief A highest magnitude sample seen. */ 00106 int16_t high_sample; 00107 00108 /*! \brief The position of the current symbol in the constellation, used for 00109 differential decoding. */ 00110 int constellation_state; 00111 00112 /*! \brief The current phase of the carrier (i.e. the DDS parameter). */ 00113 uint32_t carrier_phase; 00114 /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */ 00115 int32_t carrier_phase_rate; 00116 /*! \brief The carrier update rate saved for reuse when using short training. */ 00117 int32_t carrier_phase_rate_save; 00118 #if defined(SPANDSP_USE_FIXED_POINTx) 00119 /*! \brief The proportional part of the carrier tracking filter. */ 00120 float carrier_track_p; 00121 /*! \brief The integral part of the carrier tracking filter. */ 00122 float carrier_track_i; 00123 #else 00124 /*! \brief The proportional part of the carrier tracking filter. */ 00125 float carrier_track_p; 00126 /*! \brief The integral part of the carrier tracking filter. */ 00127 float carrier_track_i; 00128 #endif 00129 00130 /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */ 00131 power_meter_t power; 00132 /*! \brief The power meter level at which carrier on is declared. */ 00133 int32_t carrier_on_power; 00134 /*! \brief The power meter level at which carrier off is declared. */ 00135 int32_t carrier_off_power; 00136 00137 /*! \brief Current read offset into the equalizer buffer. */ 00138 int eq_step; 00139 /*! \brief Current write offset into the equalizer buffer. */ 00140 int eq_put_step; 00141 /*! \brief Symbol counter to the next equalizer update. */ 00142 int eq_skip; 00143 00144 /*! \brief The current half of the baud. */ 00145 int baud_half; 00146 00147 #if defined(SPANDSP_USE_FIXED_POINT) 00148 /*! \brief The scaling factor accessed by the AGC algorithm. */ 00149 int16_t agc_scaling; 00150 /*! \brief The previous value of agc_scaling, needed to reuse old training. */ 00151 int16_t agc_scaling_save; 00152 00153 /*! \brief The current delta factor for updating the equalizer coefficients. */ 00154 float eq_delta; 00155 /*! \brief The adaptive equalizer coefficients. */ 00156 /*complexi16_t*/ complexf_t eq_coeff[V27TER_EQUALIZER_LEN]; 00157 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */ 00158 /*complexi16_t*/ complexf_t eq_coeff_save[V27TER_EQUALIZER_LEN]; 00159 /*! \brief The equalizer signal buffer. */ 00160 /*complexi16_t*/ complexf_t eq_buf[V27TER_EQUALIZER_LEN]; 00161 #else 00162 /*! \brief The scaling factor accessed by the AGC algorithm. */ 00163 float agc_scaling; 00164 /*! \brief The previous value of agc_scaling, needed to reuse old training. */ 00165 float agc_scaling_save; 00166 00167 /*! \brief The current delta factor for updating the equalizer coefficients. */ 00168 float eq_delta; 00169 /*! \brief The adaptive equalizer coefficients. */ 00170 complexf_t eq_coeff[V27TER_EQUALIZER_LEN]; 00171 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */ 00172 complexf_t eq_coeff_save[V27TER_EQUALIZER_LEN]; 00173 /*! \brief The equalizer signal buffer. */ 00174 complexf_t eq_buf[V27TER_EQUALIZER_LEN]; 00175 #endif 00176 00177 /*! \brief Integration variable for damping the Gardner algorithm tests. */ 00178 int gardner_integrate; 00179 /*! \brief Current step size of Gardner algorithm integration. */ 00180 int gardner_step; 00181 /*! \brief The total symbol timing correction since the carrier came up. 00182 This is only for performance analysis purposes. */ 00183 int total_baud_timing_correction; 00184 00185 /*! \brief Starting phase angles for the coarse carrier aquisition step. */ 00186 int32_t start_angles[2]; 00187 /*! \brief History list of phase angles for the coarse carrier aquisition step. */ 00188 int32_t angles[16]; 00189 /*! \brief Error and flow logging control */ 00190 logging_state_t logging; 00191 }; 00192 00193 #endif 00194 /*- End of file ------------------------------------------------------------*/