spandsp 0.0.6

private/v27ter_rx.h
1/*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * private/v27ter_rx.h - ITU V.27ter modem receive part
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2003 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Lesser General Public License version 2.1,
14 * as published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 */
25
26#if !defined(_SPANDSP_PRIVATE_V27TER_RX_H_)
27#define _SPANDSP_PRIVATE_V27TER_RX_H_
28
29/* Target length for the equalizer is about 43 taps for 4800bps and 32 taps for 2400bps
30 to deal with the worst stuff in V.56bis. */
31/*! The length of the equalizer buffer. Must be a power of 2 */
32#define V27TER_EQUALIZER_LEN 32
33/*! Samples before the target central position in the equalizer buffer */
34#define V27TER_EQUALIZER_PRE_LEN 16
35
36/*! The number of taps in the 4800bps pulse shaping/bandpass filter */
37#define V27TER_RX_4800_FILTER_STEPS 27
38/*! The number of taps in the 2400bps pulse shaping/bandpass filter */
39#define V27TER_RX_2400_FILTER_STEPS 27
40
41#if V27TER_RX_4800_FILTER_STEPS > V27TER_RX_2400_FILTER_STEPS
42#define V27TER_RX_FILTER_STEPS V27TER_RX_4800_FILTER_STEPS
43#else
44#define V27TER_RX_FILTER_STEPS V27TER_RX_2400_FILTER_STEPS
45#endif
46
47/*!
48 V.27ter modem receive side descriptor. This defines the working state for a
49 single instance of a V.27ter modem receiver.
50*/
51 struct v27ter_rx_state_s
52{
53 /*! \brief The bit rate of the modem. Valid values are 2400 and 4800. */
54 int bit_rate;
55 /*! \brief The callback function used to put each bit received. */
56 put_bit_func_t put_bit;
57 /*! \brief A user specified opaque pointer passed to the put_bit routine. */
58 void *put_bit_user_data;
59
60 /*! \brief The callback function used to report modem status changes. */
61 modem_status_func_t status_handler;
62 /*! \brief A user specified opaque pointer passed to the status function. */
63 void *status_user_data;
64
65 /*! \brief A callback function which may be enabled to report every symbol's
66 constellation position. */
67 qam_report_handler_t qam_report;
68 /*! \brief A user specified opaque pointer passed to the qam_report callback
69 routine. */
70 void *qam_user_data;
71
72#if defined(SPANDSP_USE_FIXED_POINT)
73 /*! \brief The scaling factor assessed by the AGC algorithm. */
74 int16_t agc_scaling;
75 /*! \brief The previous value of agc_scaling, needed to reuse old training. */
76 int16_t agc_scaling_save;
77
78 /*! \brief The current delta factor for updating the equalizer coefficients. */
79 float eq_delta;
80 /*! \brief The adaptive equalizer coefficients. */
81 /*complexi16_t*/ complexf_t eq_coeff[V27TER_EQUALIZER_LEN];
82 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
83 /*complexi16_t*/ complexf_t eq_coeff_save[V27TER_EQUALIZER_LEN];
84 /*! \brief The equalizer signal buffer. */
85 /*complexi16_t*/ complexf_t eq_buf[V27TER_EQUALIZER_LEN];
86
87 /*! \brief A measure of how much mismatch there is between the real constellation,
88 and the decoded symbol positions. */
89 float training_error;
90
91 /*! \brief The proportional part of the carrier tracking filter. */
92 float carrier_track_p;
93 /*! \brief The integral part of the carrier tracking filter. */
94 float carrier_track_i;
95 /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
96 int16_t rrc_filter[V27TER_RX_FILTER_STEPS];
97#else
98 /*! \brief The scaling factor assessed by the AGC algorithm. */
99 float agc_scaling;
100 /*! \brief The previous value of agc_scaling, needed to reuse old training. */
101 float agc_scaling_save;
102
103 /*! \brief The current delta factor for updating the equalizer coefficients. */
104 float eq_delta;
105 /*! \brief The adaptive equalizer coefficients. */
106 complexf_t eq_coeff[V27TER_EQUALIZER_LEN];
107 /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
108 complexf_t eq_coeff_save[V27TER_EQUALIZER_LEN];
109 /*! \brief The equalizer signal buffer. */
110 complexf_t eq_buf[V27TER_EQUALIZER_LEN];
111
112 /*! \brief A measure of how much mismatch there is between the real constellation,
113 and the decoded symbol positions. */
114 float training_error;
115
116 /*! \brief The proportional part of the carrier tracking filter. */
117 float carrier_track_p;
118 /*! \brief The integral part of the carrier tracking filter. */
119 float carrier_track_i;
120 /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
121 float rrc_filter[V27TER_RX_FILTER_STEPS];
122#endif
123 /*! \brief Current offset into the RRC pulse shaping filter buffer. */
124 int rrc_filter_step;
125
126 /*! \brief The register for the training and data scrambler. */
127 uint32_t scramble_reg;
128 /*! \brief A counter for the number of consecutive bits of repeating pattern through
129 the scrambler. */
130 int scrambler_pattern_count;
131 /*! \brief The current step in the table of BC constellation positions. */
132 int training_bc;
133 /*! \brief TRUE if the previous trained values are to be reused. */
134 int old_train;
135 /*! \brief The section of the training data we are currently in. */
136 int training_stage;
137 /*! \brief A count of how far through the current training step we are. */
138 int training_count;
139 /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
140 int16_t last_sample;
141 /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.27ter signal. */
142 int signal_present;
143 /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
144 int carrier_drop_pending;
145 /*! \brief A count of the current consecutive samples below the carrier off threshold. */
146 int low_samples;
147 /*! \brief A highest magnitude sample seen. */
148 int16_t high_sample;
149
150 /*! \brief The position of the current symbol in the constellation, used for
151 differential decoding. */
152 int constellation_state;
153
154 /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
155 uint32_t carrier_phase;
156 /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
157 int32_t carrier_phase_rate;
158 /*! \brief The carrier update rate saved for reuse when using short training. */
159 int32_t carrier_phase_rate_save;
160
161 /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */
162 power_meter_t power;
163 /*! \brief The power meter level at which carrier on is declared. */
164 int32_t carrier_on_power;
165 /*! \brief The power meter level at which carrier off is declared. */
166 int32_t carrier_off_power;
167
168 /*! \brief Current read offset into the equalizer buffer. */
169 int eq_step;
170 /*! \brief Current write offset into the equalizer buffer. */
171 int eq_put_step;
172 /*! \brief Symbol counter to the next equalizer update. */
173 int eq_skip;
174
175 /*! \brief The current half of the baud. */
176 int baud_half;
177
178 /*! \brief Integration variable for damping the Gardner algorithm tests. */
179 int gardner_integrate;
180 /*! \brief Current step size of Gardner algorithm integration. */
181 int gardner_step;
182 /*! \brief The total symbol timing correction since the carrier came up.
183 This is only for performance analysis purposes. */
184 int total_baud_timing_correction;
185
186 /*! \brief The previous symbol phase angles for the coarse carrier aquisition step. */
187 int32_t last_angles[2];
188 /*! \brief History list of phase angle differences for the coarse carrier aquisition step. */
189 int32_t diff_angles[16];
190
191 /*! \brief Error and flow logging control */
192 logging_state_t logging;
193};
194
195#endif
196/*- End of file ------------------------------------------------------------*/
modem_status_func_t
void(* modem_status_func_t)(void *user_data, int status)
Definition async.h:114
put_bit_func_t
void(* put_bit_func_t)(void *user_data, int bit)
Definition async.h:105
logging_state_t
struct logging_state_s logging_state_t
Definition logging.h:75
complexf_t
Definition complex.h:43
power_meter_t
Definition power_meter.h:49
v27ter_rx_state_s
Definition private/v27ter_rx.h:52
v27ter_rx_state_s::high_sample
int16_t high_sample
A highest magnitude sample seen.
Definition private/v27ter_rx.h:148
v27ter_rx_state_s::eq_coeff
complexf_t eq_coeff[32]
The adaptive equalizer coefficients.
Definition private/v27ter_rx.h:106
v27ter_rx_state_s::put_bit_user_data
void * put_bit_user_data
A user specified opaque pointer passed to the put_bit routine.
Definition private/v27ter_rx.h:58
v27ter_rx_state_s::carrier_drop_pending
int carrier_drop_pending
Whether or not a carrier drop was detected and the signal delivery is pending.
Definition private/v27ter_rx.h:144
v27ter_rx_state_s::training_stage
int training_stage
The section of the training data we are currently in.
Definition private/v27ter_rx.h:136
v27ter_rx_state_s::eq_delta
float eq_delta
The current delta factor for updating the equalizer coefficients.
Definition private/v27ter_rx.h:104
v27ter_rx_state_s::old_train
int old_train
TRUE if the previous trained values are to be reused.
Definition private/v27ter_rx.h:134
v27ter_rx_state_s::carrier_phase_rate
int32_t carrier_phase_rate
The update rate for the phase of the carrier (i.e. the DDS increment).
Definition private/v27ter_rx.h:157
v27ter_rx_state_s::scrambler_pattern_count
int scrambler_pattern_count
A counter for the number of consecutive bits of repeating pattern through the scrambler.
Definition private/v27ter_rx.h:130
v27ter_rx_state_s::bit_rate
int bit_rate
The bit rate of the modem. Valid values are 2400 and 4800.
Definition private/v27ter_rx.h:54
v27ter_rx_state_s::carrier_track_p
float carrier_track_p
The proportional part of the carrier tracking filter.
Definition private/v27ter_rx.h:117
v27ter_rx_state_s::carrier_track_i
float carrier_track_i
The integral part of the carrier tracking filter.
Definition private/v27ter_rx.h:119
v27ter_rx_state_s::training_error
float training_error
A measure of how much mismatch there is between the real constellation, and the decoded symbol positi...
Definition private/v27ter_rx.h:114
v27ter_rx_state_s::status_handler
modem_status_func_t status_handler
The callback function used to report modem status changes.
Definition private/v27ter_rx.h:61
v27ter_rx_state_s::eq_put_step
int eq_put_step
Current write offset into the equalizer buffer.
Definition private/v27ter_rx.h:171
v27ter_rx_state_s::power
power_meter_t power
A power meter, to measure the HPF'ed signal power in the channel.
Definition private/v27ter_rx.h:162
v27ter_rx_state_s::carrier_on_power
int32_t carrier_on_power
The power meter level at which carrier on is declared.
Definition private/v27ter_rx.h:164
v27ter_rx_state_s::low_samples
int low_samples
A count of the current consecutive samples below the carrier off threshold.
Definition private/v27ter_rx.h:146
v27ter_rx_state_s::last_angles
int32_t last_angles[2]
The previous symbol phase angles for the coarse carrier aquisition step.
Definition private/v27ter_rx.h:187
v27ter_rx_state_s::eq_skip
int eq_skip
Symbol counter to the next equalizer update.
Definition private/v27ter_rx.h:173
v27ter_rx_state_s::put_bit
put_bit_func_t put_bit
The callback function used to put each bit received.
Definition private/v27ter_rx.h:56
v27ter_rx_state_s::gardner_integrate
int gardner_integrate
Integration variable for damping the Gardner algorithm tests.
Definition private/v27ter_rx.h:179
v27ter_rx_state_s::gardner_step
int gardner_step
Current step size of Gardner algorithm integration.
Definition private/v27ter_rx.h:181
v27ter_rx_state_s::constellation_state
int constellation_state
The position of the current symbol in the constellation, used for differential decoding.
Definition private/v27ter_rx.h:152
v27ter_rx_state_s::rrc_filter
float rrc_filter[27]
The root raised cosine (RRC) pulse shaping filter buffer.
Definition private/v27ter_rx.h:121
v27ter_rx_state_s::carrier_phase
uint32_t carrier_phase
The current phase of the carrier (i.e. the DDS parameter).
Definition private/v27ter_rx.h:155
v27ter_rx_state_s::agc_scaling
float agc_scaling
The scaling factor assessed by the AGC algorithm.
Definition private/v27ter_rx.h:99
v27ter_rx_state_s::rrc_filter_step
int rrc_filter_step
Current offset into the RRC pulse shaping filter buffer.
Definition private/v27ter_rx.h:124
v27ter_rx_state_s::diff_angles
int32_t diff_angles[16]
History list of phase angle differences for the coarse carrier aquisition step.
Definition private/v27ter_rx.h:189
v27ter_rx_state_s::carrier_phase_rate_save
int32_t carrier_phase_rate_save
The carrier update rate saved for reuse when using short training.
Definition private/v27ter_rx.h:159
v27ter_rx_state_s::eq_coeff_save
complexf_t eq_coeff_save[32]
A saved set of adaptive equalizer coefficients for use after restarts.
Definition private/v27ter_rx.h:108
v27ter_rx_state_s::baud_half
int baud_half
The current half of the baud.
Definition private/v27ter_rx.h:176
v27ter_rx_state_s::agc_scaling_save
float agc_scaling_save
The previous value of agc_scaling, needed to reuse old training.
Definition private/v27ter_rx.h:101
v27ter_rx_state_s::qam_user_data
void * qam_user_data
A user specified opaque pointer passed to the qam_report callback routine.
Definition private/v27ter_rx.h:70
v27ter_rx_state_s::training_count
int training_count
A count of how far through the current training step we are.
Definition private/v27ter_rx.h:138
v27ter_rx_state_s::training_bc
int training_bc
The current step in the table of BC constellation positions.
Definition private/v27ter_rx.h:132
v27ter_rx_state_s::qam_report
qam_report_handler_t qam_report
A callback function which may be enabled to report every symbol's constellation position.
Definition private/v27ter_rx.h:67
v27ter_rx_state_s::logging
logging_state_t logging
Error and flow logging control.
Definition private/v27ter_rx.h:192
v27ter_rx_state_s::scramble_reg
uint32_t scramble_reg
The register for the training and data scrambler.
Definition private/v27ter_rx.h:127
v27ter_rx_state_s::total_baud_timing_correction
int total_baud_timing_correction
The total symbol timing correction since the carrier came up. This is only for performance analysis p...
Definition private/v27ter_rx.h:184
v27ter_rx_state_s::signal_present
int signal_present
>0 if a signal above the minimum is present. It may or may not be a V.27ter signal.
Definition private/v27ter_rx.h:142
v27ter_rx_state_s::last_sample
int16_t last_sample
The value of the last signal sample, using the a simple HPF for signal power estimation.
Definition private/v27ter_rx.h:140
v27ter_rx_state_s::eq_step
int eq_step
Current read offset into the equalizer buffer.
Definition private/v27ter_rx.h:169
v27ter_rx_state_s::eq_buf
complexf_t eq_buf[32]
The equalizer signal buffer.
Definition private/v27ter_rx.h:110
v27ter_rx_state_s::status_user_data
void * status_user_data
A user specified opaque pointer passed to the status function.
Definition private/v27ter_rx.h:63
v27ter_rx_state_s::carrier_off_power
int32_t carrier_off_power
The power meter level at which carrier off is declared.
Definition private/v27ter_rx.h:166