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  * $Id: v29rx.h,v 1.2 2009/07/09 13:52:09 steveu Exp $
00026  */
00027 
00028 #if !defined(_SPANDSP_PRIVATE_V29RX_H_)
00029 #define _SPANDSP_PRIVATE_V29RX_H_
00030 
00031 /* Target length for the equalizer is about 63 taps, to deal with the worst stuff
00032    in V.56bis. */
00033 /*! Samples before the target position in the equalizer buffer */
00034 #define V29_EQUALIZER_PRE_LEN   16
00035 /*! Samples after the target position in the equalizer buffer */
00036 #define V29_EQUALIZER_POST_LEN  14
00037 
00038 /*! The number of taps in the pulse shaping/bandpass filter */
00039 #define V29_RX_FILTER_STEPS     27
00040 
00041 /*!
00042     V.29 modem receive side descriptor. This defines the working state for a
00043     single instance of a V.29 modem receiver.
00044 */
00045 struct v29_rx_state_s
00046 {
00047     /*! \brief The bit rate of the modem. Valid values are 4800, 7200 and 9600. */
00048     int bit_rate;
00049     /*! \brief The callback function used to put each bit received. */
00050     put_bit_func_t put_bit;
00051     /*! \brief A user specified opaque pointer passed to the put_bit routine. */
00052     void *put_bit_user_data;
00053 
00054     /*! \brief The callback function used to report modem status changes. */
00055     modem_rx_status_func_t status_handler;
00056     /*! \brief A user specified opaque pointer passed to the status function. */
00057     void *status_user_data;
00058 
00059     /*! \brief A callback function which may be enabled to report every symbol's
00060                constellation position. */
00061     qam_report_handler_t qam_report;
00062     /*! \brief A user specified opaque pointer passed to the qam_report callback
00063                routine. */
00064     void *qam_user_data;
00065 
00066     /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
00067 #if defined(SPANDSP_USE_FIXED_POINT)
00068     int16_t rrc_filter[V29_RX_FILTER_STEPS];
00069 #else
00070     float rrc_filter[V29_RX_FILTER_STEPS];
00071 #endif
00072     /*! \brief Current offset into the RRC pulse shaping filter buffer. */
00073     int rrc_filter_step;
00074 
00075     /*! \brief The register for the data scrambler. */
00076     unsigned int scramble_reg;
00077     /*! \brief The register for the training scrambler. */
00078     uint8_t training_scramble_reg;
00079     /*! \brief The current step in the table of CD constellation positions. */
00080     int training_cd;
00081     /*! \brief TRUE if the previous trained values are to be reused. */
00082     int old_train;
00083     /*! \brief The section of the training data we are currently in. */
00084     int training_stage;
00085     /*! \brief A count of how far through the current training step we are. */
00086     int training_count;
00087     /*! \brief A measure of how much mismatch there is between the real constellation,
00088         and the decoded symbol positions. */
00089     float training_error;
00090     /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
00091     int16_t last_sample;
00092     /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.29 signal. */
00093     int signal_present;
00094     /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
00095     int carrier_drop_pending;
00096     /*! \brief A count of the current consecutive samples below the carrier off threshold. */
00097     int low_samples;
00098     /*! \brief A highest magnitude sample seen. */
00099     int16_t high_sample;
00100 
00101     /*! \brief The position of the current symbol in the constellation, used for
00102                differential decoding. */
00103     int constellation_state;
00104 
00105     /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
00106     uint32_t carrier_phase;
00107     /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
00108     int32_t carrier_phase_rate;
00109     /*! \brief The carrier update rate saved for reuse when using short training. */
00110     int32_t carrier_phase_rate_save;
00111 #if defined(SPANDSP_USE_FIXED_POINT)
00112     /*! \brief The proportional part of the carrier tracking filter. */
00113     int32_t carrier_track_p;
00114     /*! \brief The integral part of the carrier tracking filter. */
00115     int32_t carrier_track_i;
00116 #else
00117     /*! \brief The proportional part of the carrier tracking filter. */
00118     float carrier_track_p;
00119     /*! \brief The integral part of the carrier tracking filter. */
00120     float carrier_track_i;
00121 #endif
00122 
00123     /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */    
00124     power_meter_t power;
00125     /*! \brief The power meter level at which carrier on is declared. */
00126     int32_t carrier_on_power;
00127     /*! \brief The power meter level at which carrier off is declared. */
00128     int32_t carrier_off_power;
00129 
00130     /*! \brief Current read offset into the equalizer buffer. */
00131     int eq_step;
00132     /*! \brief Current write offset into the equalizer buffer. */
00133     int eq_put_step;
00134     /*! \brief Symbol counter to the next equalizer update. */
00135     int eq_skip;
00136 
00137     /*! \brief The current half of the baud. */
00138     int baud_half;
00139 
00140 #if defined(SPANDSP_USE_FIXED_POINT)
00141     /*! \brief The scaling factor accessed by the AGC algorithm. */
00142     int16_t agc_scaling;
00143     /*! \brief The previous value of agc_scaling, needed to reuse old training. */
00144     int16_t agc_scaling_save;
00145 
00146     /*! \brief The current delta factor for updating the equalizer coefficients. */
00147     int16_t eq_delta;
00148     /*! \brief The adaptive equalizer coefficients. */
00149     complexi16_t eq_coeff[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00150     /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
00151     complexi16_t eq_coeff_save[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00152     /*! \brief The equalizer signal buffer. */
00153     complexi16_t eq_buf[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00154 
00155     /*! Low band edge filter for symbol sync. */
00156     int32_t symbol_sync_low[2];
00157     /*! High band edge filter for symbol sync. */
00158     int32_t symbol_sync_high[2];
00159     /*! DC filter for symbol sync. */
00160     int32_t symbol_sync_dc_filter[2];
00161     /*! Baud phase for symbol sync. */
00162     int32_t baud_phase;
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[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00173     /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
00174     complexf_t eq_coeff_save[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00175     /*! \brief The equalizer signal buffer. */
00176     complexf_t eq_buf[V29_EQUALIZER_PRE_LEN + 1 + V29_EQUALIZER_POST_LEN];
00177 
00178     /*! Low band edge filter for symbol sync. */
00179     float symbol_sync_low[2];
00180     /*! High band edge filter for symbol sync. */
00181     float symbol_sync_high[2];
00182     /*! DC filter for symbol sync. */
00183     float symbol_sync_dc_filter[2];
00184     /*! Baud phase for symbol sync. */
00185     float baud_phase;
00186 #endif
00187 
00188     /*! \brief The total symbol timing correction since the carrier came up.
00189                This is only for performance analysis purposes. */
00190     int total_baud_timing_correction;
00191 
00192     /*! \brief Starting phase angles for the coarse carrier aquisition step. */
00193     int32_t start_angles[2];
00194     /*! \brief History list of phase angles for the coarse carrier aquisition step. */
00195     int32_t angles[16];
00196     /*! \brief Error and flow logging control */
00197     logging_state_t logging;
00198 };
00199 
00200 #endif
00201 /*- End of file ------------------------------------------------------------*/