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 * $Id: v27ter_rx.h,v 1.2 2009/07/09 13:52:09 steveu Exp $ 00026 */ 00027 00028 #if !defined(_SPANDSP_PRIVATE_V27TER_RX_H_) 00029 #define _SPANDSP_PRIVATE_V27TER_RX_H_ 00030 00031 /* Target length for the equalizer is about 43 taps for 4800bps and 32 taps for 2400bps 00032 to deal with the worst stuff in V.56bis. */ 00033 /*! Samples before the target position in the equalizer buffer */ 00034 #define V27TER_EQUALIZER_PRE_LEN 16 /* This much before the real event */ 00035 /*! Samples after the target position in the equalizer buffer */ 00036 #define V27TER_EQUALIZER_POST_LEN 14 /* This much after the real event (must be even) */ 00037 00038 /*! The number of taps in the 4800bps pulse shaping/bandpass filter */ 00039 #define V27TER_RX_4800_FILTER_STEPS 27 00040 /*! The number of taps in the 2400bps pulse shaping/bandpass filter */ 00041 #define V27TER_RX_2400_FILTER_STEPS 27 00042 00043 #if V27TER_RX_4800_FILTER_STEPS > V27TER_RX_2400_FILTER_STEPS 00044 #define V27TER_RX_FILTER_STEPS V27TER_RX_4800_FILTER_STEPS 00045 #else 00046 #define V27TER_RX_FILTER_STEPS V27TER_RX_2400_FILTER_STEPS 00047 #endif 00048 00049 /*! 00050 V.27ter modem receive side descriptor. This defines the working state for a 00051 single instance of a V.27ter modem receiver. 00052 */ 00053 struct v27ter_rx_state_s 00054 { 00055 /*! \brief The bit rate of the modem. Valid values are 2400 and 4800. */ 00056 int bit_rate; 00057 /*! \brief The callback function used to put each bit received. */ 00058 put_bit_func_t put_bit; 00059 /*! \brief A user specified opaque pointer passed to the put_bit routine. */ 00060 void *put_bit_user_data; 00061 00062 /*! \brief The callback function used to report modem status changes. */ 00063 modem_rx_status_func_t status_handler; 00064 /*! \brief A user specified opaque pointer passed to the status function. */ 00065 void *status_user_data; 00066 00067 /*! \brief A callback function which may be enabled to report every symbol's 00068 constellation position. */ 00069 qam_report_handler_t qam_report; 00070 /*! \brief A user specified opaque pointer passed to the qam_report callback 00071 routine. */ 00072 void *qam_user_data; 00073 00074 /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */ 00075 #if defined(SPANDSP_USE_FIXED_POINT) 00076 int16_t rrc_filter[V27TER_RX_FILTER_STEPS]; 00077 #else 00078 float rrc_filter[V27TER_RX_FILTER_STEPS]; 00079 #endif 00080 /*! \brief Current offset into the RRC pulse shaping filter buffer. */ 00081 int rrc_filter_step; 00082 00083 /*! \brief The register for the training and data scrambler. */ 00084 unsigned int scramble_reg; 00085 /*! \brief A counter for the number of consecutive bits of repeating pattern through 00086 the scrambler. */ 00087 int scrambler_pattern_count; 00088 /*! \brief The current step in the table of BC constellation positions. */ 00089 int training_bc; 00090 /*! \brief TRUE if the previous trained values are to be reused. */ 00091 int old_train; 00092 /*! \brief The section of the training data we are currently in. */ 00093 int training_stage; 00094 /*! \brief A count of how far through the current training step we are. */ 00095 int training_count; 00096 /*! \brief A measure of how much mismatch there is between the real constellation, 00097 and the decoded symbol positions. */ 00098 float training_error; 00099 /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */ 00100 int16_t last_sample; 00101 /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.27ter signal. */ 00102 int signal_present; 00103 /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */ 00104 int carrier_drop_pending; 00105 /*! \brief A count of the current consecutive samples below the carrier off threshold. */ 00106 int low_samples; 00107 /*! \brief A highest magnitude sample seen. */ 00108 int16_t high_sample; 00109 00110 /*! \brief The position of the current symbol in the constellation, used for 00111 differential decoding. */ 00112 int constellation_state; 00113 00114 /*! \brief The current phase of the carrier (i.e. the DDS parameter). */ 00115 uint32_t carrier_phase; 00116 /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */ 00117 int32_t carrier_phase_rate; 00118 /*! \brief The carrier update rate saved for reuse when using short training. */ 00119 int32_t carrier_phase_rate_save; 00120 #if defined(SPANDSP_USE_FIXED_POINTx) 00121 /*! \brief The proportional part of the carrier tracking filter. */ 00122 float carrier_track_p; 00123 /*! \brief The integral part of the carrier tracking filter. */ 00124 float carrier_track_i; 00125 #else 00126 /*! \brief The proportional part of the carrier tracking filter. */ 00127 float carrier_track_p; 00128 /*! \brief The integral part of the carrier tracking filter. */ 00129 float carrier_track_i; 00130 #endif 00131 00132 /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */ 00133 power_meter_t power; 00134 /*! \brief The power meter level at which carrier on is declared. */ 00135 int32_t carrier_on_power; 00136 /*! \brief The power meter level at which carrier off is declared. */ 00137 int32_t carrier_off_power; 00138 00139 /*! \brief Current read offset into the equalizer buffer. */ 00140 int eq_step; 00141 /*! \brief Current write offset into the equalizer buffer. */ 00142 int eq_put_step; 00143 /*! \brief Symbol counter to the next equalizer update. */ 00144 int eq_skip; 00145 00146 /*! \brief The current half of the baud. */ 00147 int baud_half; 00148 00149 #if defined(SPANDSP_USE_FIXED_POINT) 00150 /*! \brief The scaling factor accessed by the AGC algorithm. */ 00151 int16_t agc_scaling; 00152 /*! \brief The previous value of agc_scaling, needed to reuse old training. */ 00153 int16_t agc_scaling_save; 00154 00155 /*! \brief The current delta factor for updating the equalizer coefficients. */ 00156 float eq_delta; 00157 /*! \brief The adaptive equalizer coefficients. */ 00158 /*complexi16_t*/ complexf_t eq_coeff[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00159 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */ 00160 /*complexi16_t*/ complexf_t eq_coeff_save[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00161 /*! \brief The equalizer signal buffer. */ 00162 /*complexi16_t*/ complexf_t eq_buf[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00163 #else 00164 /*! \brief The scaling factor accessed by the AGC algorithm. */ 00165 float agc_scaling; 00166 /*! \brief The previous value of agc_scaling, needed to reuse old training. */ 00167 float agc_scaling_save; 00168 00169 /*! \brief The current delta factor for updating the equalizer coefficients. */ 00170 float eq_delta; 00171 /*! \brief The adaptive equalizer coefficients. */ 00172 complexf_t eq_coeff[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00173 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */ 00174 complexf_t eq_coeff_save[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00175 /*! \brief The equalizer signal buffer. */ 00176 complexf_t eq_buf[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN]; 00177 #endif 00178 00179 /*! \brief Integration variable for damping the Gardner algorithm tests. */ 00180 int gardner_integrate; 00181 /*! \brief Current step size of Gardner algorithm integration. */ 00182 int gardner_step; 00183 /*! \brief The total symbol timing correction since the carrier came up. 00184 This is only for performance analysis purposes. */ 00185 int total_baud_timing_correction; 00186 00187 /*! \brief Starting phase angles for the coarse carrier aquisition step. */ 00188 int32_t start_angles[2]; 00189 /*! \brief History list of phase angles for the coarse carrier aquisition step. */ 00190 int32_t angles[16]; 00191 /*! \brief Error and flow logging control */ 00192 logging_state_t logging; 00193 }; 00194 00195 #endif 00196 /*- End of file ------------------------------------------------------------*/