spandsp 0.0.6
private/v29rx.h
00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * private/v29rx.h - ITU V.29 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_V29RX_H_)
00027 #define _SPANDSP_PRIVATE_V29RX_H_
00028 
00029 /* Target length for the equalizer is about 63 taps, to deal with the worst stuff
00030    in V.56bis. */
00031 /*! The length of the equalizer buffer */
00032 #define V29_EQUALIZER_LEN       33
00033 /*! Samples before the target position in the equalizer buffer */
00034 #define V29_EQUALIZER_PRE_LEN   16
00035 
00036 /*! The number of taps in the pulse shaping/bandpass filter */
00037 #define V29_RX_FILTER_STEPS     27
00038 
00039 /*!
00040     V.29 modem receive side descriptor. This defines the working state for a
00041     single instance of a V.29 modem receiver.
00042 */
00043 struct v29_rx_state_s
00044 {
00045     /*! \brief The bit rate of the modem. Valid values are 4800, 7200 and 9600. */
00046     int bit_rate;
00047     /*! \brief The callback function used to put each bit received. */
00048     put_bit_func_t put_bit;
00049     /*! \brief A user specified opaque pointer passed to the put_bit routine. */
00050     void *put_bit_user_data;
00051 
00052     /*! \brief The callback function used to report modem status changes. */
00053     modem_rx_status_func_t status_handler;
00054     /*! \brief A user specified opaque pointer passed to the status function. */
00055     void *status_user_data;
00056 
00057     /*! \brief A callback function which may be enabled to report every symbol's
00058                constellation position. */
00059     qam_report_handler_t qam_report;
00060     /*! \brief A user specified opaque pointer passed to the qam_report callback
00061                routine. */
00062     void *qam_user_data;
00063 
00064     /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
00065 #if defined(SPANDSP_USE_FIXED_POINT)
00066     int16_t rrc_filter[V29_RX_FILTER_STEPS];
00067 #else
00068     float rrc_filter[V29_RX_FILTER_STEPS];
00069 #endif
00070     /*! \brief Current offset into the RRC pulse shaping filter buffer. */
00071     int rrc_filter_step;
00072 
00073     /*! \brief The register for the data scrambler. */
00074     uint32_t scramble_reg;
00075     /*! \brief The register for the training scrambler. */
00076     uint8_t training_scramble_reg;
00077     /*! \brief The current step in the table of CD constellation positions. */
00078     int training_cd;
00079     /*! \brief TRUE if the previous trained values are to be reused. */
00080     int old_train;
00081     /*! \brief The section of the training data we are currently in. */
00082     int training_stage;
00083     /*! \brief A count of how far through the current training step we are. */
00084     int training_count;
00085     /*! \brief A measure of how much mismatch there is between the real constellation,
00086         and the decoded symbol positions. */
00087     float training_error;
00088     /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
00089     int16_t last_sample;
00090     /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.29 signal. */
00091     int signal_present;
00092     /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
00093     int carrier_drop_pending;
00094     /*! \brief A count of the current consecutive samples below the carrier off threshold. */
00095     int low_samples;
00096     /*! \brief A highest magnitude sample seen. */
00097     int16_t high_sample;
00098 
00099     /*! \brief The position of the current symbol in the constellation, used for
00100                differential decoding. */
00101     int constellation_state;
00102 
00103     /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
00104     uint32_t carrier_phase;
00105     /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
00106     int32_t carrier_phase_rate;
00107     /*! \brief The carrier update rate saved for reuse when using short training. */
00108     int32_t carrier_phase_rate_save;
00109 #if defined(SPANDSP_USE_FIXED_POINT)
00110     /*! \brief The proportional part of the carrier tracking filter. */
00111     int32_t carrier_track_p;
00112     /*! \brief The integral part of the carrier tracking filter. */
00113     int32_t carrier_track_i;
00114 #else
00115     /*! \brief The proportional part of the carrier tracking filter. */
00116     float carrier_track_p;
00117     /*! \brief The integral part of the carrier tracking filter. */
00118     float carrier_track_i;
00119 #endif
00120 
00121     /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */    
00122     power_meter_t power;
00123     /*! \brief The power meter level at which carrier on is declared. */
00124     int32_t carrier_on_power;
00125     /*! \brief The power meter level at which carrier off is declared. */
00126     int32_t carrier_off_power;
00127 
00128     /*! \brief Current read offset into the equalizer buffer. */
00129     int eq_step;
00130     /*! \brief Current write offset into the equalizer buffer. */
00131     int eq_put_step;
00132     /*! \brief Symbol counter to the next equalizer update. */
00133     int eq_skip;
00134 
00135     /*! \brief The current half of the baud. */
00136     int baud_half;
00137 
00138 #if defined(SPANDSP_USE_FIXED_POINT)
00139     /*! \brief The scaling factor accessed by the AGC algorithm. */
00140     int16_t agc_scaling;
00141     /*! \brief The previous value of agc_scaling, needed to reuse old training. */
00142     int16_t agc_scaling_save;
00143 
00144     /*! \brief The current delta factor for updating the equalizer coefficients. */
00145     int16_t eq_delta;
00146     /*! \brief The adaptive equalizer coefficients. */
00147     complexi16_t eq_coeff[V29_EQUALIZER_LEN];
00148     /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
00149     complexi16_t eq_coeff_save[V29_EQUALIZER_LEN];
00150     /*! \brief The equalizer signal buffer. */
00151     complexi16_t eq_buf[V29_EQUALIZER_LEN];
00152 
00153     /*! Low band edge filter for symbol sync. */
00154     int32_t symbol_sync_low[2];
00155     /*! High band edge filter for symbol sync. */
00156     int32_t symbol_sync_high[2];
00157     /*! DC filter for symbol sync. */
00158     int32_t symbol_sync_dc_filter[2];
00159     /*! Baud phase for symbol sync. */
00160     int32_t baud_phase;
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[V29_EQUALIZER_LEN];
00171     /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
00172     complexf_t eq_coeff_save[V29_EQUALIZER_LEN];
00173     /*! \brief The equalizer signal buffer. */
00174     complexf_t eq_buf[V29_EQUALIZER_LEN];
00175 
00176     /*! Low band edge filter for symbol sync. */
00177     float symbol_sync_low[2];
00178     /*! High band edge filter for symbol sync. */
00179     float symbol_sync_high[2];
00180     /*! DC filter for symbol sync. */
00181     float symbol_sync_dc_filter[2];
00182     /*! Baud phase for symbol sync. */
00183     float baud_phase;
00184 #endif
00185 
00186     /*! \brief The total symbol timing correction since the carrier came up.
00187                This is only for performance analysis purposes. */
00188     int total_baud_timing_correction;
00189 
00190     /*! \brief Starting phase angles for the coarse carrier aquisition step. */
00191     int32_t start_angles[2];
00192     /*! \brief History list of phase angles for the coarse carrier aquisition step. */
00193     int32_t angles[16];
00194     /*! \brief Error and flow logging control */
00195     logging_state_t logging;
00196 };
00197 
00198 #endif
00199 /*- End of file ------------------------------------------------------------*/