spandsp  0.0.6
private/v17rx.h
1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * private/v17rx.h - ITU V.17 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_V17RX_H_)
27 #define _SPANDSP_PRIVATE_V17RX_H_
28 
29 /* Target length for the equalizer is about 63 taps, to deal with the worst stuff
30  in V.56bis. */
31 /*! The length of the equalizer buffer */
32 //#define V17_EQUALIZER_LEN 33
33 #define V17_EQUALIZER_LEN 17
34 /*! Samples before the target position in the equalizer buffer */
35 //#define V17_EQUALIZER_PRE_LEN 16
36 #define V17_EQUALIZER_PRE_LEN 8
37 
38 /*! The number of taps in the pulse shaping/bandpass filter */
39 #define V17_RX_FILTER_STEPS 27
40 
41 /* We can store more trellis depth that we look back over, so that we can push out a group
42  of symbols in one go, giving greater processing efficiency, at the expense of a bit more
43  latency through the modem. */
44 /* Right now we don't take advantage of this optimisation. */
45 /*! The depth of the trellis buffer */
46 #define V17_TRELLIS_STORAGE_DEPTH 16
47 /*! How far we look back into history for trellis decisions */
48 #define V17_TRELLIS_LOOKBACK_DEPTH 16
49 
50 /*!
51  V.17 modem receive side descriptor. This defines the working state for a
52  single instance of a V.17 modem receiver.
53 */
55 {
56  /*! \brief The bit rate of the modem. Valid values are 7200 9600, 12000 and 14400. */
57  int bit_rate;
58  /*! \brief The callback function used to put each bit received. */
60  /*! \brief A user specified opaque pointer passed to the put_but routine. */
62 
63  /*! \brief The callback function used to report modem status changes. */
65  /*! \brief A user specified opaque pointer passed to the status function. */
67 
68  /*! \brief A callback function which may be enabled to report every symbol's
69  constellation position. */
70  qam_report_handler_t qam_report;
71  /*! \brief A user specified opaque pointer passed to the qam_report callback
72  routine. */
74 
75 #if 1 //defined(RESCALER_TEST)
76  /* Experimental data for AGC tolerance */
77  int16_t power_window[40];
78  int power_window_ptr;
79  int64_t window_power;
80  int64_t window_power_save;
81 #endif
82 #if defined(SPANDSP_USE_FIXED_POINTx)
83  /*! \brief The scaling factor accessed by the AGC algorithm. */
84  float agc_scaling;
85  /*! \brief The previous value of agc_scaling, needed to reuse old training. */
86  float agc_scaling_save;
87 
88  /*! \brief The current delta factor for updating the equalizer coefficients. */
89  float eq_delta;
90  /*! \brief The adaptive equalizer coefficients. */
91  complexi16_t eq_coeff[V17_EQUALIZER_LEN];
92  /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
93  complexi16_t eq_coeff_save[V17_EQUALIZER_LEN];
94  /*! \brief The equalizer signal buffer. */
95  complexi16_t eq_buf[V17_EQUALIZER_LEN];
96 
97  /*! Low band edge filter for symbol sync. */
98  int32_t symbol_sync_low[2];
99  /*! High band edge filter for symbol sync. */
100  int32_t symbol_sync_high[2];
101  /*! DC filter for symbol sync. */
102  int32_t symbol_sync_dc_filter[2];
103  /*! Baud phase for symbol sync. */
104  int32_t baud_phase;
105 
106  /*! \brief A measure of how much mismatch there is between the real constellation,
107  and the decoded symbol positions. */
108  float training_error;
109 
110  /*! \brief The proportional part of the carrier tracking filter. */
111  float carrier_track_p;
112  /*! \brief The integral part of the carrier tracking filter. */
113  float carrier_track_i;
114  /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
115  int16_t rrc_filter[V17_RX_FILTER_STEPS];
116 
117  /*! \brief A pointer to the current constellation. */
119 #else
120  /*! \brief The scaling factor accessed by the AGC algorithm. */
121  float agc_scaling;
122  /*! \brief The previous value of agc_scaling, needed to reuse old training. */
124 
125  /*! \brief The current delta factor for updating the equalizer coefficients. */
126  float eq_delta;
127  /*! \brief The adaptive equalizer coefficients. */
128  complexf_t eq_coeff[V17_EQUALIZER_LEN];
129  /*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
130  complexf_t eq_coeff_save[V17_EQUALIZER_LEN];
131  /*! \brief The equalizer signal buffer. */
132  complexf_t eq_buf[V17_EQUALIZER_LEN];
133 
134  /*! Low band edge filter for symbol sync. */
135  float symbol_sync_low[2];
136  /*! High band edge filter for symbol sync. */
138  /*! DC filter for symbol sync. */
140  /*! Baud phase for symbol sync. */
141  float baud_phase;
142 
143  /*! \brief A measure of how much mismatch there is between the real constellation,
144  and the decoded symbol positions. */
146 
147  /*! \brief The proportional part of the carrier tracking filter. */
149  /*! \brief The integral part of the carrier tracking filter. */
151  /*! \brief The root raised cosine (RRC) pulse shaping filter buffer. */
152  float rrc_filter[V17_RX_FILTER_STEPS];
153 
154  /*! \brief A pointer to the current constellation. */
156 #endif
157  /*! \brief Current offset into the RRC pulse shaping filter buffer. */
159 
160  /*! \brief The current state of the differential decoder */
161  int diff;
162  /*! \brief The register for the data scrambler. */
163  uint32_t scramble_reg;
164  /*! \brief Scrambler tap */
165  //int scrambler_tap;
166 
167  /*! \brief TRUE if the short training sequence is to be used. */
169  /*! \brief The section of the training data we are currently in. */
171  /*! \brief A count of how far through the current training step we are. */
173  /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
174  int16_t last_sample;
175  /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.17 signal. */
177  /*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
179  /*! \brief A count of the current consecutive samples below the carrier off threshold. */
181  /*! \brief A highest magnitude sample seen. */
182  int16_t high_sample;
183 
184  /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
185  uint32_t carrier_phase;
186  /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
188  /*! \brief The carrier update rate saved for reuse when using short training. */
190 
191  /*! \brief A power meter, to measure the HPF'ed signal power in the channel. */
193  /*! \brief The power meter level at which carrier on is declared. */
195  /*! \brief The power meter level at which carrier off is declared. */
197 
198  /*! \brief Current read offset into the equalizer buffer. */
199  int eq_step;
200  /*! \brief Current write offset into the equalizer buffer. */
202  /*! \brief Symbol count to the next equalizer update. */
203  int eq_skip;
204 
205  /*! \brief The current half of the baud. */
207 
208  /*! \brief The total symbol timing correction since the carrier came up.
209  This is only for performance analysis purposes. */
211 
212  /*! \brief Starting phase angles for the coarse carrier aquisition step. */
213  int32_t start_angles[2];
214  /*! \brief History list of phase angles for the coarse carrier aquisition step. */
215  int32_t angles[16];
216  /*! \brief A pointer to the current space map. There is a space map for
217  each trellis state. */
219  /*! \brief The number of bits in each symbol at the current bit rate. */
221 
222  /*! \brief Current pointer to the trellis buffers */
224  /*! \brief The trellis. */
225  int full_path_to_past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
226  /*! \brief The trellis. */
227  int past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
228 #if defined(SPANDSP_USE_FIXED_POINTx)
229  /*! \brief Euclidean distances (actually the squares of the distances)
230  from the last states of the trellis. */
231  uint32_t distances[8];
232 #else
233  /*! \brief Euclidean distances (actually the squares of the distances)
234  from the last states of the trellis. */
235  float distances[8];
236 #endif
237  /*! \brief Error and flow logging control */
239 };
240 
241 #endif
242 /*- End of file ------------------------------------------------------------*/
v17_rx_state_s::power
power_meter_t power
A power meter, to measure the HPF'ed signal power in the channel.
Definition: private/v17rx.h:192
v17_rx_state_s::eq_coeff_save
complexf_t eq_coeff_save[17]
A saved set of adaptive equalizer coefficients for use after restarts.
Definition: private/v17rx.h:130
v17_rx_state_s::angles
int32_t angles[16]
History list of phase angles for the coarse carrier aquisition step.
Definition: private/v17rx.h:215
dds_advance
void dds_advance(uint32_t *phase_acc, int32_t phase_rate)
Advance the phase, without returning any new signal sample.
Definition: dds_int.c:362
v17_rx_state_s::eq_coeff
complexf_t eq_coeff[17]
The adaptive equalizer coefficients.
Definition: private/v17rx.h:128
v17_rx_state_s::eq_buf
complexf_t eq_buf[17]
The equalizer signal buffer.
Definition: private/v17rx.h:132
v17_rx_state_s::carrier_track_p
float carrier_track_p
The proportional part of the carrier tracking filter.
Definition: private/v17rx.h:148
v17_rx_state_s::eq_delta
float eq_delta
The current delta factor for updating the equalizer coefficients.
Definition: private/v17rx.h:126
modem_status_func_t
void(* modem_status_func_t)(void *user_data, int status)
Definition: async.h:114
v17_rx_set_qam_report_handler
void v17_rx_set_qam_report_handler(v17_rx_state_t *s, qam_report_handler_t handler, void *user_data)
Definition: v17rx.c:1563
complexf_t
Definition: complex.h:43
SIG_STATUS_CARRIER_UP
@ SIG_STATUS_CARRIER_UP
The carrier signal is up. This merely indicates that carrier energy has been seen....
Definition: async.h:58
dds_advancef
void dds_advancef(uint32_t *phase_acc, int32_t phase_rate)
Advance the phase, without returning any new signal sample.
Definition: dds_float.c:2133
async.h
power_meter_current_dbm0
float power_meter_current_dbm0(power_meter_t *s)
Get the current power meter reading, in dBm0.
Definition: power_meter.c:120
v17_rx_state_s::symbol_sync_high
float symbol_sync_high[2]
Definition: private/v17rx.h:137
SIG_STATUS_TRAINING_IN_PROGRESS
@ SIG_STATUS_TRAINING_IN_PROGRESS
The modem is training. This is an early indication that the signal seems to be of the right type....
Definition: async.h:63
v17_rx_state_s::start_angles
int32_t start_angles[2]
Starting phase angles for the coarse carrier aquisition step.
Definition: private/v17rx.h:213
v17_rx_signal_power
float v17_rx_signal_power(v17_rx_state_t *s)
Definition: v17rx.c:182
v17_rx_state_s::eq_skip
int eq_skip
Symbol count to the next equalizer update.
Definition: private/v17rx.h:203
v17_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/v17rx.h:145
v17_rx_state_s::rrc_filter_step
int rrc_filter_step
Current offset into the RRC pulse shaping filter buffer.
Definition: private/v17rx.h:158
put_bit_func_t
void(* put_bit_func_t)(void *user_data, int bit)
Definition: async.h:105
power_meter_update
int32_t power_meter_update(power_meter_t *s, int16_t amp)
Update a power meter.
Definition: power_meter.c:84
complexi_t::im
int im
Imaginary part.
Definition: complex.h:82
vec_circular_dot_prodf
float vec_circular_dot_prodf(const float x[], const float y[], int n, int pos)
Find the dot product of two float vectors, where the first is a circular buffer with an offset for th...
Definition: vector_float.c:852
v17_rx_state_s::carrier_track_i
float carrier_track_i
The integral part of the carrier tracking filter.
Definition: private/v17rx.h:150
v17_rx_restart
int v17_rx_restart(v17_rx_state_t *s, int bit_rate, int short_train)
Reinitialise an existing V.17 modem receive context.
Definition: v17rx.c:1380
SPAN_DECLARE_NONSTD
SPAN_DECLARE_NONSTD(int) async_tx_get_bit(void *user_data)
Get the next bit of a transmitted serial bit stream.
v17_rx_state_s::baud_half
int baud_half
The current half of the baud.
Definition: private/v17rx.h:206
v17_rx_state_s::symbol_sync_dc_filter
float symbol_sync_dc_filter[2]
Definition: private/v17rx.h:139
v17rx.h
power_meter_t
Definition: power_meter.h:49
complex.h
complexf_t::im
float im
Imaginary part.
Definition: complex.h:47
EQUALIZER_SLOW_ADAPTION_DELTA
#define EQUALIZER_SLOW_ADAPTION_DELTA
Definition: v17rx.c:95
v17_rx_state_s::status_user_data
void * status_user_data
A user specified opaque pointer passed to the status function.
Definition: private/v17rx.h:66
v17_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/v17rx.h:174
v17_rx_state_s::low_samples
int low_samples
A count of the current consecutive samples below the carrier off threshold.
Definition: private/v17rx.h:180
v17_rx_state_s::logging
logging_state_t logging
Error and flow logging control.
Definition: private/v17rx.h:238
v17_rx_carrier_frequency
float v17_rx_carrier_frequency(v17_rx_state_t *s)
Definition: v17rx.c:170
v17_rx_state_s::high_sample
int16_t high_sample
A highest magnitude sample seen.
Definition: private/v17rx.h:182
V17_TRAINING_SHORT_SEG_2_LEN
#define V17_TRAINING_SHORT_SEG_2_LEN
Definition: v17rx.c:103
v17_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/v17rx.h:70
v17_rx_state_s::training_count
int training_count
A count of how far through the current training step we are.
Definition: private/v17rx.h:172
saturated.h
V17_TRAINING_SEG_3_LEN
#define V17_TRAINING_SEG_3_LEN
Definition: v17rx.c:105
v17_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/v17rx.h:187
v17_rx_state_s::carrier_phase
uint32_t carrier_phase
The current phase of the carrier (i.e. the DDS parameter).
Definition: private/v17rx.h:185
SIG_STATUS_TRAINING_FAILED
@ SIG_STATUS_TRAINING_FAILED
The modem has failed to train.
Definition: async.h:67
v17_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/v17rx.h:210
v17_rx_state_s::symbol_sync_low
float symbol_sync_low[2]
Definition: private/v17rx.h:135
v17_rx_state_s::rrc_filter
float rrc_filter[27]
The root raised cosine (RRC) pulse shaping filter buffer.
Definition: private/v17rx.h:152
v17_rx_state_s::eq_put_step
int eq_put_step
Current write offset into the equalizer buffer.
Definition: private/v17rx.h:201
complexi32_t
Definition: complex.h:100
v17_rx_state_s::constellation
const complexf_t * constellation
A pointer to the current constellation.
Definition: private/v17rx.h:155
v17_rx_state_s::eq_step
int eq_step
Current read offset into the equalizer buffer.
Definition: private/v17rx.h:199
V17_TRAINING_SEG_1_LEN
#define V17_TRAINING_SEG_1_LEN
Definition: v17rx.c:99
SIG_STATUS_CARRIER_DOWN
@ SIG_STATUS_CARRIER_DOWN
The carrier signal has dropped.
Definition: async.h:54
v17_rx_equalizer_state
int v17_rx_equalizer_state(v17_rx_state_t *s, complexf_t **coeffs)
Get a snapshot of the current equalizer coefficients.
Definition: v17rx.c:208
dds_lookup_complexf
complexf_t dds_lookup_complexf(uint32_t phase)
Lookup the complex value of a specified phase.
Definition: dds_float.c:2176
v17_rx_state_s::carrier_off_power
int32_t carrier_off_power
The power meter level at which carrier off is declared.
Definition: private/v17rx.h:196
complexi32_t::im
int32_t im
Imaginary part.
Definition: complex.h:104
v17_rx_get_logging_state
logging_state_t * v17_rx_get_logging_state(v17_rx_state_t *s)
Get the logging context associated with a V.17 modem receive context.
Definition: v17rx.c:1374
complexi32_t::re
int32_t re
Real part.
Definition: complex.h:102
vec_circular_dot_prodi16
int32_t vec_circular_dot_prodi16(const int16_t x[], const int16_t y[], int n, int pos)
Find the dot product of two int16_t vectors, where the first is a circular buffer with an offset for ...
Definition: vector_int.c:261
v17tx.h
v17_rx_state_s::full_path_to_past_state_locations
int full_path_to_past_state_locations[16][8]
The trellis.
Definition: private/v17rx.h:225
cvec_circular_dot_prodf
complexf_t cvec_circular_dot_prodf(const complexf_t x[], const complexf_t y[], int n, int pos)
Find the dot product of two complex float vectors, where the first is a circular buffer with an offse...
Definition: complex_vector_float.c:173
v17_rx_state_s::agc_scaling_save
float agc_scaling_save
The previous value of agc_scaling, needed to reuse old training.
Definition: private/v17rx.h:123
EQUALIZER_FAST_ADAPTION_DELTA
#define EQUALIZER_FAST_ADAPTION_DELTA
Definition: v17rx.c:91
v17_rx_state_s::carrier_on_power
int32_t carrier_on_power
The power meter level at which carrier on is declared.
Definition: private/v17rx.h:194
v17_rx_state_s::scramble_reg
uint32_t scramble_reg
The register for the data scrambler.
Definition: private/v17rx.h:163
complexi16_t
Definition: complex.h:89
v17_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/v17rx.h:178
span_log
int span_log(logging_state_t *s, int level, const char *format,...)
Generate a log entry.
Definition: logging.c:84
v17_rx_state_s::qam_user_data
void * qam_user_data
A user specified opaque pointer passed to the qam_report callback routine.
Definition: private/v17rx.h:73
V17_TRAINING_SEG_4A_LEN
#define V17_TRAINING_SEG_4A_LEN
Definition: v17rx.c:107
v17_rx_state_s::bits_per_symbol
int bits_per_symbol
The number of bits in each symbol at the current bit rate.
Definition: private/v17rx.h:220
v29rx.h
EQUALIZER_MEDIUM_ADAPTION_DELTA
#define EQUALIZER_MEDIUM_ADAPTION_DELTA
Definition: v17rx.c:93
CARRIER_NOMINAL_FREQ
#define CARRIER_NOMINAL_FREQ
Definition: v17rx.c:87
dds_frequencyf
float dds_frequencyf(int32_t phase_rate)
Find the frequency, in Hz, equivalent to a phase rate.
Definition: dds_float.c:2115
complexi16_t::im
int16_t im
Imaginary part.
Definition: complex.h:93
v17_rx_set_modem_status_handler
void v17_rx_set_modem_status_handler(v17_rx_state_t *s, modem_status_func_t handler, void *user_data)
Change the modem status report function associated with a V.17 modem receive context.
Definition: v17rx.c:1367
v17_rx_state_s::put_bit_user_data
void * put_bit_user_data
A user specified opaque pointer passed to the put_but routine.
Definition: private/v17rx.h:61
v17_rx_state_s::training_stage
int training_stage
The section of the training data we are currently in.
Definition: private/v17rx.h:170
V17_BRIDGE_WORD
#define V17_BRIDGE_WORD
Definition: v17rx.c:112
v17_rx_state_s::distances
float distances[8]
Euclidean distances (actually the squares of the distances) from the last states of the trellis.
Definition: private/v17rx.h:235
v17_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.17 signal.
Definition: private/v17rx.h:176
power_meter_level_dbm0
int32_t power_meter_level_dbm0(float level)
Get the current power meter reading, in dBm0.
Definition: power_meter.c:91
logging.h
v17_rx_state_s::short_train
int short_train
Scrambler tap.
Definition: private/v17rx.h:168
v17_rx_state_s::diff
int diff
The current state of the differential decoder.
Definition: private/v17rx.h:161
complexf_t::re
float re
Real part.
Definition: complex.h:45
v17_rx_state_s::status_handler
modem_status_func_t status_handler
The callback function used to report modem status changes.
Definition: private/v17rx.h:64
v17_rx_init
v17_rx_state_t * v17_rx_init(v17_rx_state_t *s, int bit_rate, put_bit_func_t put_bit, void *user_data)
Initialise a V.17 modem receive context.
Definition: v17rx.c:1517
complexi16_t::re
int16_t re
Real part.
Definition: complex.h:91
v17_rx_release
int v17_rx_release(v17_rx_state_t *s)
Release a V.17 modem receive context.
Definition: v17rx.c:1550
arctan2.h
power_meter_init
power_meter_t * power_meter_init(power_meter_t *s, int shift)
Initialise a power meter context.
Definition: power_meter.c:50
V17_TRAINING_SEG_2_LEN
#define V17_TRAINING_SEG_2_LEN
Definition: v17rx.c:101
SIG_STATUS_TRAINING_SUCCEEDED
@ SIG_STATUS_TRAINING_SUCCEEDED
The modem has trained, and is ready for data exchange.
Definition: async.h:65
v17_rx_state_s::trellis_ptr
int trellis_ptr
Current pointer to the trellis buffers.
Definition: private/v17rx.h:223
v17_rx_state_s::past_state_locations
int past_state_locations[16][8]
The trellis.
Definition: private/v17rx.h:227
logging_state_s
Definition: private/logging.h:34
v17_rx_set_put_bit
void v17_rx_set_put_bit(v17_rx_state_t *s, put_bit_func_t put_bit, void *user_data)
Change the put_bit function associated with a V.17 modem receive context.
Definition: v17rx.c:1360
v17_rx_state_s::space_map
int space_map
A pointer to the current space map. There is a space map for each trellis state.
Definition: private/v17rx.h:218
v17_rx_signal_cutoff
void v17_rx_signal_cutoff(v17_rx_state_t *s, float cutoff)
Definition: v17rx.c:188
v17_rx_state_s::put_bit
put_bit_func_t put_bit
The callback function used to put each bit received.
Definition: private/v17rx.h:59
complexi_t::re
int re
Real part.
Definition: complex.h:80
v17_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/v17rx.h:189
v17_rx_state_s
Definition: private/v17rx.h:55
v17_rx_state_s::baud_phase
float baud_phase
Definition: private/v17rx.h:141
V17_TRAINING_SEG_4_LEN
#define V17_TRAINING_SEG_4_LEN
Definition: v17rx.c:109
v17_rx_symbol_timing_correction
float v17_rx_symbol_timing_correction(v17_rx_state_t *s)
Definition: v17rx.c:176
v17_rx_state_s::bit_rate
int bit_rate
The bit rate of the modem. Valid values are 7200 9600, 12000 and 14400.
Definition: private/v17rx.h:57
v17_rx_state_s::agc_scaling
float agc_scaling
The scaling factor accessed by the AGC algorithm.
Definition: private/v17rx.h:121
dds.h
complexi_t
Definition: complex.h:78
v17_rx_free
int v17_rx_free(v17_rx_state_t *s)
Free a V.17 modem receive context.
Definition: v17rx.c:1556