private/v22bis.h

00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * private/v22bis.h - ITU V.22bis modem
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2004 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: v22bis.h,v 1.12 2009/11/04 15:52:06 steveu Exp $
00026  */
00027 
00028 #if !defined(_SPANDSP_PRIVATE_V22BIS_H_)
00029 #define _SPANDSP_PRIVATE_V22BIS_H_
00030 
00031 /*! The number of steps to the left and to the right of the target position in the equalizer buffer. */
00032 #define V22BIS_EQUALIZER_LEN    7
00033 /*! One less than a power of 2 >= (2*V22BIS_EQUALIZER_LEN + 1) */
00034 #define V22BIS_EQUALIZER_MASK   15
00035 
00036 /*! The number of taps in the transmit pulse shaping filter */
00037 #define V22BIS_TX_FILTER_STEPS  9
00038 
00039 /*! The number of taps in the receive pulse shaping/bandpass filter */
00040 #define V22BIS_RX_FILTER_STEPS  37
00041 
00042 /*! Segments of the training sequence on the receive side */
00043 enum
00044 {
00045     V22BIS_RX_TRAINING_STAGE_NORMAL_OPERATION,
00046     V22BIS_RX_TRAINING_STAGE_SYMBOL_ACQUISITION,
00047     V22BIS_RX_TRAINING_STAGE_LOG_PHASE,
00048     V22BIS_RX_TRAINING_STAGE_UNSCRAMBLED_ONES,
00049     V22BIS_RX_TRAINING_STAGE_UNSCRAMBLED_ONES_SUSTAINING,
00050     V22BIS_RX_TRAINING_STAGE_SCRAMBLED_ONES_AT_1200,
00051     V22BIS_RX_TRAINING_STAGE_SCRAMBLED_ONES_AT_1200_SUSTAINING,
00052     V22BIS_RX_TRAINING_STAGE_WAIT_FOR_SCRAMBLED_ONES_AT_2400,
00053     V22BIS_RX_TRAINING_STAGE_PARKED
00054 };
00055 
00056 /*! Segments of the training sequence on the transmit side */
00057 enum
00058 {
00059     V22BIS_TX_TRAINING_STAGE_NORMAL_OPERATION = 0,
00060     V22BIS_TX_TRAINING_STAGE_INITIAL_TIMED_SILENCE,
00061     V22BIS_TX_TRAINING_STAGE_INITIAL_SILENCE,
00062     V22BIS_TX_TRAINING_STAGE_U11,
00063     V22BIS_TX_TRAINING_STAGE_U0011,
00064     V22BIS_TX_TRAINING_STAGE_S11,
00065     V22BIS_TX_TRAINING_STAGE_TIMED_S11,
00066     V22BIS_TX_TRAINING_STAGE_S1111,
00067     V22BIS_TX_TRAINING_STAGE_PARKED
00068 };
00069 
00070 /*!
00071     V.22bis modem descriptor. This defines the working state for a single instance
00072     of a V.22bis modem.
00073 */
00074 struct v22bis_state_s
00075 {
00076     /*! \brief The maximum permitted bit rate of the modem. Valid values are 1200 and 2400. */
00077     int bit_rate;
00078     /*! \brief TRUE is this is the calling side modem. */
00079     int calling_party;
00080     /*! \brief The callback function used to get the next bit to be transmitted. */
00081     get_bit_func_t get_bit;
00082     /*! \brief A user specified opaque pointer passed to the get_bit callback routine. */
00083     void *get_bit_user_data;
00084     /*! \brief The callback function used to put each bit received. */
00085     put_bit_func_t put_bit;
00086     /*! \brief A user specified opaque pointer passed to the put_bit callback routine. */
00087     void *put_bit_user_data;
00088     /*! \brief The callback function used to report modem status changes. */
00089     modem_rx_status_func_t status_handler;
00090     /*! \brief A user specified opaque pointer passed to the status function. */
00091     void *status_user_data;
00092 
00093     int negotiated_bit_rate;
00094 
00095     /* Receive section */
00096     struct
00097     {
00098         /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
00099         float rrc_filter[2*V22BIS_RX_FILTER_STEPS];
00100         /*! \brief Current offset into the RRC pulse shaping filter buffer. */
00101         int rrc_filter_step;
00102 
00103         /*! \brief The register for the data scrambler. */
00104         unsigned int scramble_reg;
00105         /*! \brief A counter for the number of consecutive bits of repeating pattern through
00106                    the scrambler. */
00107         int scrambler_pattern_count;
00108 
00109         /*! \brief 0 if receiving user data. A training stage value during training */
00110         int training;
00111         /*! \brief A count of how far through the current training step we are. */
00112         int training_count;
00113 
00114         /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.22bis signal. */
00115         int signal_present;
00116 
00117         /*! \brief A measure of how much mismatch there is between the real constellation,
00118             and the decoded symbol positions. */
00119         float training_error;
00120 
00121         /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
00122         uint32_t carrier_phase;
00123         /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
00124         int32_t carrier_phase_rate;
00125         /*! \brief The proportional part of the carrier tracking filter. */
00126         float carrier_track_p;
00127         /*! \brief The integral part of the carrier tracking filter. */
00128         float carrier_track_i;
00129         
00130         /*! \brief A callback function which may be enabled to report every symbol's
00131                    constellation position. */
00132         qam_report_handler_t qam_report;
00133         /*! \brief A user specified opaque pointer passed to the qam_report callback
00134                    routine. */
00135         void *qam_user_data;
00136 
00137         /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */    
00138         power_meter_t rx_power;
00139         /*! \brief The power meter level at which carrier on is declared. */
00140         int32_t carrier_on_power;
00141         /*! \brief The power meter level at which carrier off is declared. */
00142         int32_t carrier_off_power;
00143         /*! \brief The scaling factor accessed by the AGC algorithm. */
00144         float agc_scaling;
00145     
00146         int constellation_state;
00147 
00148         /*! \brief The current delta factor for updating the equalizer coefficients. */
00149         float eq_delta;
00150 #if defined(SPANDSP_USE_FIXED_POINTx)
00151         /*! \brief The adaptive equalizer coefficients. */
00152         complexi_t eq_coeff[2*V22BIS_EQUALIZER_LEN + 1];
00153         /*! \brief The equalizer signal buffer. */
00154         complexi_t eq_buf[V22BIS_EQUALIZER_MASK + 1];
00155 #else
00156         complexf_t eq_coeff[2*V22BIS_EQUALIZER_LEN + 1];
00157         complexf_t eq_buf[V22BIS_EQUALIZER_MASK + 1];
00158 #endif
00159         /*! \brief Current offset into the equalizer buffer. */
00160         int eq_step;
00161         /*! \brief Current write offset into the equalizer buffer. */
00162         int eq_put_step;
00163 
00164         /*! \brief Integration variable for damping the Gardner algorithm tests. */
00165         int gardner_integrate;
00166         /*! \brief Current step size of Gardner algorithm integration. */
00167         int gardner_step;
00168         /*! \brief The total symbol timing correction since the carrier came up.
00169                    This is only for performance analysis purposes. */
00170         int total_baud_timing_correction;
00171         /*! \brief The current fractional phase of the baud timing. */
00172         int baud_phase;
00173     
00174         int sixteen_way_decisions;
00175 
00176         int pattern_repeats;
00177         int last_raw_bits;
00178     } rx;
00179 
00180     /* Transmit section */
00181     struct
00182     {
00183         /*! \brief The gain factor needed to achieve the specified output power. */
00184         float gain;
00185 
00186         /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
00187         complexf_t rrc_filter[2*V22BIS_TX_FILTER_STEPS];
00188         /*! \brief Current offset into the RRC pulse shaping filter buffer. */
00189         int rrc_filter_step;
00190 
00191         /*! \brief The register for the data scrambler. */
00192         unsigned int scramble_reg;
00193         /*! \brief A counter for the number of consecutive bits of repeating pattern through
00194                    the scrambler. */
00195         int scrambler_pattern_count;
00196 
00197         /*! \brief 0 if transmitting user data. A training stage value during training */
00198         int training;
00199         /*! \brief A counter used to track progress through sending the training sequence. */
00200         int training_count;
00201         /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
00202         uint32_t carrier_phase;
00203         /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
00204         int32_t carrier_phase_rate;
00205         /*! \brief The current phase of the guard tone (i.e. the DDS parameter). */
00206         uint32_t guard_phase;
00207         /*! \brief The update rate for the phase of the guard tone (i.e. the DDS increment). */
00208         int32_t guard_phase_rate;
00209         float guard_level;
00210         /*! \brief The current fractional phase of the baud timing. */
00211         int baud_phase;
00212         /*! \brief The code number for the current position in the constellation. */
00213         int constellation_state;
00214         /*! \brief An indicator to mark that we are tidying up to stop transmission. */
00215         int shutdown;
00216         /*! \brief The get_bit function in use at any instant. */
00217         get_bit_func_t current_get_bit;
00218     } tx;
00219 
00220     /*! \brief Error and flow logging control */
00221     logging_state_t logging;
00222 };
00223 
00224 #if defined(__cplusplus)
00225 extern "C"
00226 {
00227 #endif
00228 
00229 /*! Reinitialise an existing V.22bis modem receive context.
00230     \brief Reinitialise an existing V.22bis modem receive context.
00231     \param s The modem context.
00232     \return 0 for OK, -1 for bad parameter */
00233 int v22bis_rx_restart(v22bis_state_t *s);
00234 
00235 void v22bis_report_status_change(v22bis_state_t *s, int status);
00236 
00237 void v22bis_equalizer_coefficient_reset(v22bis_state_t *s);
00238 
00239 #if defined(__cplusplus)
00240 }
00241 #endif
00242 
00243 #endif
00244 /*- End of file ------------------------------------------------------------*/

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