spandsp 3.0.0
v22bis.h
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1/*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * v22bis.h - ITU V.22bis modem
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2004 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/*! \file */
27
28/*! \page v22bis_page The V.22bis modem
29\section v22bis_page_sec_1 What does it do?
30The V.22bis modem is a duplex modem for general data use on the PSTN, at rates
31of 1200 and 2400 bits/second. It is a compatible extension of the V.22 modem,
32which is a 1200 bits/second only design. It is a band-split design, using carriers
33of 1200Hz and 2400Hz. It is the fastest PSTN modem in general use which does not
34use echo-cancellation.
35
36\section v22bis__page_sec_2 How does it work?
37V.22bis uses 4PSK modulation at 1200 bits/second or 16QAM modulation at 2400
38bits/second. At 1200bps the symbols are so long that a fixed compromise equaliser
39is sufficient to recover the 4PSK signal reliably. At 2400bps an adaptive
40equaliser is necessary.
41
42The V.22bis training sequence includes sections which allow the modems to determine
43if the far modem can support (or is willing to support) 2400bps operation. The
44modems will automatically use 2400bps if both ends are willing to use that speed,
45or 1200bps if one or both ends to not acknowledge that 2400bps is OK.
46*/
47
48#if !defined(_SPANDSP_V22BIS_H_)
49#define _SPANDSP_V22BIS_H_
50
51#if defined(SPANDSP_USE_FIXED_POINT)
52#define V22BIS_CONSTELLATION_SCALING_FACTOR 1024.0
53#else
54#define V22BIS_CONSTELLATION_SCALING_FACTOR 1.0
55#endif
56
57/* The bottom bits of the option field define which guard tone to use. Guard tones were a compatibility
58 mechanism to prevent a high band modem signal from interferring with billing systems. Only the
59 answering modem sends them.
60
61 Other options can be OR'ed with the guard tone option. */
62typedef enum
63{
64 /* No guard tone is the norm is some areas, such a North America */
65 V22BIS_GUARD_TONE_NONE = 0,
66 /* 550Hz guard tone is the norm is some areas, such as Scandinavia */
67 V22BIS_GUARD_TONE_550HZ = 1,
68 /* 1800Hz guard tone is the norm is some areas, such as the UK and much of the Commonwealth */
69 V22BIS_GUARD_TONE_1800HZ = 2,
70 /* Change the operation of the modem to follow the original Bell212A spec, from which V.22bis was
71 developed. This is basically for old systems in North America. */
72 V22BIS_BELL212A_COMPATIBILITY_MODE = 0x100,
73 /* Use unscrambled 00 instead of unscrambled 11 during the handshake. This is not something you
74 should use day to day. Its here to allow testing that receivers will function correctly with
75 either 11 or 00, as V.22bis says they should. */
76 V22BIS_USE_U00 = 0x200
77} v22bis_options_t;
78
79/*!
80 V.22bis modem descriptor. This defines the working state for a single instance
81 of a V.22bis modem.
82*/
84
85#if defined(__cplusplus)
86extern "C"
87{
88#endif
89
90/*! Process a block of received V.22bis modem audio samples.
91 \brief Process a block of received V.22bis modem audio samples.
92 \param s The modem context.
93 \param amp The audio sample buffer.
94 \param len The number of samples in the buffer.
95 \return The number of samples unprocessed. */
96SPAN_DECLARE(int) v22bis_rx(v22bis_state_t *s, const int16_t amp[], int len);
97
98/*! Fake processing of a missing block of received V.22bis modem audio samples.
99 (e.g due to packet loss).
100 \brief Fake processing of a missing block of received V.22bis modem audio samples.
101 \param s The modem context.
102 \param len The number of samples to fake.
103 \return The number of samples unprocessed. */
104SPAN_DECLARE(int) v22bis_rx_fillin(v22bis_state_t *s, int len);
105
106/*! Get a snapshot of the current equalizer coefficients.
107 \brief Get a snapshot of the current equalizer coefficients.
108 \param coeffs The vector of complex coefficients.
109 \return The number of coefficients in the vector. */
110#if defined(SPANDSP_USE_FIXED_POINT)
111SPAN_DECLARE(int) v22bis_rx_equalizer_state(v22bis_state_t *s, complexi16_t **coeffs);
112#else
113SPAN_DECLARE(int) v22bis_rx_equalizer_state(v22bis_state_t *s, complexf_t **coeffs);
114#endif
115
116/*! Get the current received carrier frequency.
117 \param s The modem context.
118 \return The frequency, in Hertz. */
119SPAN_DECLARE(float) v22bis_rx_carrier_frequency(v22bis_state_t *s);
120
121/*! Get the current symbol timing correction since startup.
122 \param s The modem context.
123 \return The correction. */
125
126/*! Get a current received signal power.
127 \param s The modem context.
128 \return The signal power, in dBm0. */
129SPAN_DECLARE(float) v22bis_rx_signal_power(v22bis_state_t *s);
130
131/*! Set the power level at which the carrier detection will cut in
132 \param s The modem context.
133 \param cutoff The signal cutoff power, in dBm0. */
134SPAN_DECLARE(void) v22bis_rx_set_signal_cutoff(v22bis_state_t *s, float cutoff);
135
136/*! Set a handler routine to process QAM status reports
137 \param s The modem context.
138 \param handler The handler routine.
139 \param user_data An opaque pointer passed to the handler routine. */
140SPAN_DECLARE(void) v22bis_rx_set_qam_report_handler(v22bis_state_t *s, qam_report_handler_t handler, void *user_data);
141
142/*! Generate a block of V.22bis modem audio samples.
143 \brief Generate a block of V.22bis modem audio samples.
144 \param s The modem context.
145 \param amp The audio sample buffer.
146 \param len The number of samples to be generated.
147 \return The number of samples actually generated. */
148SPAN_DECLARE(int) v22bis_tx(v22bis_state_t *s, int16_t amp[], int len);
149
150/*! Adjust a V.22bis modem transmit context's power output.
151 \brief Adjust a V.22bis modem transmit context's output power.
152 \param s The modem context.
153 \param power The power level, in dBm0 */
154SPAN_DECLARE(void) v22bis_tx_power(v22bis_state_t *s, float power);
155
156/*! Reinitialise an existing V.22bis modem context, so it may be reused.
157 \brief Reinitialise an existing V.22bis modem context.
158 \param s The modem context.
159 \param bit_rate The bit rate of the modem. Valid values are 1200 and 2400.
160 \return 0 for OK, -1 for bad parameter. */
161SPAN_DECLARE(int) v22bis_restart(v22bis_state_t *s, int bit_rate);
162
163/*! Request a retrain for a V.22bis modem context. A rate change may also be requested.
164 \brief Request a retrain for a V.22bis modem context.
165 \param s The modem context.
166 \param bit_rate The bit rate of the modem. Valid values are 1200 and 2400.
167 \return 0 for OK, -1 for request rejected. */
168SPAN_DECLARE(int) v22bis_request_retrain(v22bis_state_t *s, int bit_rate);
169
170/*! Request a loopback 2 for a V.22bis modem context.
171 \brief Request a loopback 2 for a V.22bis modem context.
172 \param s The modem context.
173 \param enable True to enable loopback, or false to disable it.
174 \return 0 for OK, -1 for request reject. */
175SPAN_DECLARE(int) v22bis_remote_loopback(v22bis_state_t *s, bool enable);
176
177/*! Report the current operating bit rate of a V.22bis modem context.
178 \brief Report the current operating bit rate of a V.22bis modem context
179 \param s The modem context. */
180SPAN_DECLARE(int) v22bis_get_current_bit_rate(v22bis_state_t *s);
181
182/*! Initialise a V.22bis modem context. This must be called before the first
183 use of the context, to initialise its contents.
184 \brief Initialise a V.22bis modem context.
185 \param s The modem context.
186 \param bit_rate The bit rate of the modem. Valid values are 1200 and 2400.
187 \param options Guard tone and other options.
188 \param calling_party True if this is the calling modem.
189 \param get_bit The callback routine used to get the data to be transmitted.
190 \param get_bit_user_data An opaque pointer, passed in calls to the get_bit routine.
191 \param put_bit The callback routine used to put the data received.
192 \param put_bit_user_data An opaque pointer, passed in calls to the put_bit routine.
193 \return A pointer to the modem context, or NULL if there was a problem. */
194SPAN_DECLARE(v22bis_state_t *) v22bis_init(v22bis_state_t *s,
195 int bit_rate,
196 int options,
197 bool calling_party,
198 span_get_bit_func_t get_bit,
199 void *get_bit_user_data,
200 span_put_bit_func_t put_bit,
201 void *put_bit_user_data);
202
203/*! Release a V.22bis modem receive context.
204 \brief Release a V.22bis modem receive context.
205 \param s The modem context.
206 \return 0 for OK */
207SPAN_DECLARE(int) v22bis_release(v22bis_state_t *s);
208
209/*! Free a V.22bis modem receive context.
210 \brief Free a V.22bis modem receive context.
211 \param s The modem context.
212 \return 0 for OK */
213SPAN_DECLARE(int) v22bis_free(v22bis_state_t *s);
214
215/*! Get the logging context associated with a V.22bis modem context.
216 \brief Get the logging context associated with a V.22bis modem context.
217 \param s The modem context.
218 \return A pointer to the logging context */
220
221/*! Change the get_bit function associated with a V.22bis modem context.
222 \brief Change the get_bit function associated with a V.22bis modem context.
223 \param s The modem context.
224 \param get_bit The callback routine used to get the data to be transmitted.
225 \param user_data An opaque pointer. */
226SPAN_DECLARE(void) v22bis_set_get_bit(v22bis_state_t *s, span_get_bit_func_t get_bit, void *user_data);
227
228/*! Change the get_bit function associated with a V.22bis modem context.
229 \brief Change the put_bit function associated with a V.22bis modem context.
230 \param s The modem context.
231 \param put_bit The callback routine used to process the data received.
232 \param user_data An opaque pointer. */
233SPAN_DECLARE(void) v22bis_set_put_bit(v22bis_state_t *s, span_put_bit_func_t put_bit, void *user_data);
234
235/*! Change the modem status report function associated with a V.22bis modem receive context.
236 \brief Change the modem status report function associated with a V.22bis modem receive context.
237 \param s The modem context.
238 \param handler The callback routine used to report modem status changes.
239 \param user_data An opaque pointer. */
240SPAN_DECLARE(void) v22bis_set_modem_status_handler(v22bis_state_t *s, span_modem_status_func_t handler, void *user_data);
241
242#if defined(__cplusplus)
243}
244#endif
245
246#endif
247/*- End of file ------------------------------------------------------------*/
int(* span_get_bit_func_t)(void *user_data)
Definition async.h:127
void(* span_modem_status_func_t)(void *user_data, int status)
Definition async.h:131
void(* span_put_bit_func_t)(void *user_data, int bit)
Definition async.h:123
struct logging_state_s logging_state_t
Definition logging.h:72
Definition complex.h:43
Definition complex.h:89
Definition private/v22bis.h:80
void * put_bit_user_data
A user specified opaque pointer passed to the put_bit callback routine.
Definition private/v22bis.h:94
int options
Guard tone and sundry flags.
Definition private/v22bis.h:84
void * get_bit_user_data
A user specified opaque pointer passed to the get_bit callback routine.
Definition private/v22bis.h:90
int v22bis_remote_loopback(v22bis_state_t *s, bool enable)
Request a loopback 2 for a V.22bis modem context.
Definition v22bis_tx.c:844
void v22bis_tx_power(v22bis_state_t *s, float power)
Adjust a V.22bis modem transmit context's output power.
Definition v22bis_tx.c:695
int v22bis_get_current_bit_rate(v22bis_state_t *s)
Report the current operating bit rate of a V.22bis modem context.
Definition v22bis_tx.c:851
int v22bis_rx(v22bis_state_t *s, const int16_t amp[], int len)
Process a block of received V.22bis modem audio samples.
Definition v22bis_rx.c:827
void v22bis_set_get_bit(v22bis_state_t *s, span_get_bit_func_t get_bit, void *user_data)
Change the get_bit function associated with a V.22bis modem context.
Definition v22bis_tx.c:760
struct v22bis_state_s v22bis_state_t
Definition v22bis.h:83
void v22bis_set_modem_status_handler(v22bis_state_t *s, span_modem_status_func_t handler, void *user_data)
Change the modem status report function associated with a V.22bis modem receive context.
Definition v22bis_tx.c:774
v22bis_state_t * v22bis_init(v22bis_state_t *s, int bit_rate, int options, bool calling_party, span_get_bit_func_t get_bit, void *get_bit_user_data, span_put_bit_func_t put_bit, void *put_bit_user_data)
Initialise a V.22bis modem context.
Definition v22bis_tx.c:857
void v22bis_set_put_bit(v22bis_state_t *s, span_put_bit_func_t put_bit, void *user_data)
Change the put_bit function associated with a V.22bis modem context.
Definition v22bis_tx.c:767
float v22bis_rx_carrier_frequency(v22bis_state_t *s)
Definition v22bis_rx.c:142
int v22bis_restart(v22bis_state_t *s, int bit_rate)
Reinitialise an existing V.22bis modem context.
Definition v22bis_tx.c:787
int v22bis_free(v22bis_state_t *s)
Free a V.22bis modem receive context.
Definition v22bis_tx.c:928
int v22bis_rx_fillin(v22bis_state_t *s, int len)
Fake processing of a missing block of received V.22bis modem audio samples.
Definition v22bis_rx.c:982
int v22bis_release(v22bis_state_t *s)
Release a V.22bis modem receive context.
Definition v22bis_tx.c:922
void v22bis_rx_set_signal_cutoff(v22bis_state_t *s, float cutoff)
Definition v22bis_rx.c:160
float v22bis_rx_signal_power(v22bis_state_t *s)
Definition v22bis_rx.c:154
int v22bis_request_retrain(v22bis_state_t *s, int bit_rate)
Request a retrain for a V.22bis modem context.
Definition v22bis_tx.c:807
int v22bis_tx(v22bis_state_t *s, int16_t amp[], int len)
Generate a block of V.22bis modem audio samples.
Definition v22bis_tx.c:626
void v22bis_rx_set_qam_report_handler(v22bis_state_t *s, qam_report_handler_t handler, void *user_data)
Definition v22bis_rx.c:1058
float v22bis_rx_symbol_timing_correction(v22bis_state_t *s)
Definition v22bis_rx.c:148
int v22bis_rx_equalizer_state(v22bis_state_t *s, complexf_t **coeffs)
Get a snapshot of the current equalizer coefficients.
Definition v22bis_rx.c:180
logging_state_t * v22bis_get_logging_state(v22bis_state_t *s)
Get the logging context associated with a V.22bis modem context.
Definition v22bis_tx.c:781