Mercurial > hg > audiostuff

comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/bell_r2_mf.h @ 5:f762bf195c4b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
parents
children
comparison
equal deleted inserted replaced
4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * bell_r2_mf.h - Bell MF and MFC/R2 tone generation and detection.
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2001 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 General Public License version 2, as
14 * 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 General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: bell_r2_mf.h,v 1.5 2006/10/24 13:22:01 steveu Exp $
26 */
27
28 /*! \file */
29
30 #if !defined(_BELL_R2_MF_H_)
31 #define _BELL_R2_MF_H_
32
33 /*! \page mfc_r2_tone_generation_page MFC/R2 tone generation
34 \section mfc_r2_tone_generation_page_sec_1 What does it do?
35 The MFC/R2 tone generation module provides for the generation of the
36 repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol.
37
38 \section mfc_r2_tone_generation_page_sec_2 How does it work?
39 */
40
41 /*! \page bell_mf_tone_generation_page Bell MF tone generation
42 \section bell_mf_tone_generation_page_sec_1 What does it do?
43 The Bell MF tone generation module provides for the generation of the
44 repertoire of 15 dual tones needs for various Bell MF signalling protocols.
45
46 \section bell_mf_tone_generation_page_sec_2 How does it work?
47 Basic Bell MF tone generation specs:
48 - Tone on time = KP: 100+-7ms. All other signals: 68+-7ms
49 - Tone off time (between digits) = 68+-7ms
50 - Frequency tolerance +- 1.5%
51 - Signal level -7+-1dBm per frequency
52 */
53
54 /*! \page mfc_r2_tone_rx_page MFC/R2 tone receiver
55
56 \section mfc_r2_tone_rx_page_sec_1 What does it do?
57 The MFC/R2 tone receiver module provides for the detection of the
58 repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol.
59 It is compliant with ITU-T Q.441D.
60
61 \section mfc_r2_tone_rx_page_sec_2 How does it work?
62 Basic MFC/R2 tone detection specs:
63 - Receiver response range: -5dBm to -35dBm
64 - Difference in level for a pair of frequencies
65 - Adjacent tones: <5dB
66 - Non-adjacent tones: <7dB
67 - Receiver not to detect a signal of 2 frequencies of level -5dB and
68 duration <7ms.
69 - Receiver not to recognise a signal of 2 frequencies having a difference
70 in level >=20dB.
71 - Max received signal frequency error: +-10Hz
72 - The sum of the operate and release times of a 2 frequency signal not to
73 exceed 80ms (there are no individual specs for the operate and release
74 times).
75 - Receiver not to release for signal interruptions <=7ms.
76 - System malfunction due to signal interruptions >7ms (typically 20ms) is
77 prevented by further logic elements.
78 */
79
80 /*! \page bell_mf_tone_rx_page Bell MF tone receiver
81
82 \section bell_mf_tone_rx_page_sec_1 What does it do?
83 The Bell MF tone receiver module provides for the detection of the
84 repertoire of 15 dual tones needs for various Bell MF signalling protocols.
85 It is compliant with ITU-T Q.320, ITU-T Q.322, ITU-T Q.323B.
86
87 \section bell_mf_tone_rx_page_sec_2 How does it work?
88 Basic Bell MF tone detection specs:
89 - Frequency tolerance +- 1.5% +-10Hz
90 - Signal level -14dBm to 0dBm
91 - Perform a "two and only two tones present" test.
92 - Twist <= 6dB accepted
93 - Receiver sensitive to signals above -22dBm per frequency
94 - Test for a minimum of 55ms if KP, or 30ms of other signals.
95 - Signals to be recognised if the two tones arrive within 8ms of each other.
96 - Invalid signals result in the return of the re-order tone.
97
98 Note: Above -3dBm the signal starts to clip. We can detect with a little clipping,
99 but not up to 0dBm, which the above spec seems to require. There isn't a lot
100 we can do about that. Is the spec. incorrectly worded about the dBm0 reference
101 point, or have I misunderstood it?
102 */
103
104 #define MAX_BELL_MF_DIGITS 128
105
106 typedef enum
107 {
108 BELL_MF_TONES,
109 R2_MF_TONES,
110 SOCOTEL_TONES
111 } mf_tone_types_e;
112
113 /*!
114 Bell MF generator state descriptor. This defines the state of a single
115 working instance of a Bell MF generator.
116 */
117 typedef struct
118 {
119 tone_gen_descriptor_t *tone_descriptors;
120 tone_gen_state_t tones;
121 char digits[MAX_BELL_MF_DIGITS + 1];
122 int current_sample;
123 size_t current_digits;
124 } bell_mf_tx_state_t;
125
126 /*!
127 Bell MF digit detector descriptor.
128 */
129 typedef struct
130 {
131 /*! Optional callback funcion to deliver received digits. */
132 void (*callback)(void *data, const char *digits, int len);
133 /*! An opaque pointer passed to the callback function. */
134 void *callback_data;
135 /*! Tone detector working states */
136 goertzel_state_t out[6];
137 /*! Short term history of results from the tone detection, using in persistence checking */
138 uint8_t hits[5];
139 /*! The current sample number within a processing block. */
140 int current_sample;
141
142 /*! The received digits buffer. This is a NULL terminated string. */
143 char digits[MAX_BELL_MF_DIGITS + 1];
144 /*! The number of digits currently in the digit buffer. */
145 int current_digits;
146 /*! The number of digits which have been lost due to buffer overflows. */
147 int lost_digits;
148 } bell_mf_rx_state_t;
149
150 /*!
151 MFC/R2 tone detector descriptor.
152 */
153 typedef struct
154 {
155 tone_gen_state_t tone;
156 } r2_mf_tx_state_t;
157
158 /*!
159 MFC/R2 tone detector descriptor.
160 */
161 typedef struct
162 {
163 /*! TRUE is we are detecting forward tones. FALSE if we are detecting backward tones */
164 int fwd;
165 /*! Tone detector working states */
166 goertzel_state_t out[6];
167 int samples;
168 int current_sample;
169 } r2_mf_rx_state_t;
170
171 #ifdef __cplusplus
172 extern "C" {
173 #endif
174
175 /*! \brief Generate a buffer of Bell MF tones.
176 \param s The Bell MF generator context.
177 \param amp The buffer for the generated signal.
178 \param max_samples The required number of generated samples.
179 \return The number of samples actually generated. This may be less than
180 samples if the input buffer empties. */
181 int bell_mf_tx(bell_mf_tx_state_t *s, int16_t amp[], int max_samples);
182
183 /*! \brief Put a string of digits in a Bell MF generator's input buffer.
184 \param s The Bell MF generator context.
185 \param digits The string of digits to be added.
186 \return The number of digits actually added. This may be less than the
187 length of the digit string, if the buffer fills up. */
188 size_t bell_mf_tx_put(bell_mf_tx_state_t *s, const char *digits);
189
190 /*! \brief Initialise a Bell MF generator context.
191 \param s The Bell MF generator context.
192 \return A pointer to the Bell MF generator context.*/
193 bell_mf_tx_state_t *bell_mf_tx_init(bell_mf_tx_state_t *s);
194
195 /*! \brief Generate a block of R2 MF tones.
196 \param s The R2 MF generator context.
197 \param amp The buffer for the generated signal.
198 \param samples The required number of generated samples.
199 \param fwd TRUE to use the forward tone set. FALSE to use the reverse tone set.
200 \param digit The digit to be generated. When continuing to generate the same
201 digit as during the last call to this function, digit should be set to 0x7F.
202 \return The number of samples actually generated. */
203 int r2_mf_tx(r2_mf_tx_state_t *s, int16_t amp[], int samples, int fwd, char digit);
204
205 /*! \brief Initialise an MFC/R2 tone generator context.
206 \param s The R2 MF generator context.
207 \return A pointer to the MFC/R2 generator context.*/
208 r2_mf_tx_state_t *r2_mf_tx_init(r2_mf_tx_state_t *s);
209
210 /*! Process a block of received Bell MF audio samples.
211 \brief Process a block of received Bell MF audio samples.
212 \param s The Bell MF receiver context.
213 \param amp The audio sample buffer.
214 \param samples The number of samples in the buffer.
215 \return The number of samples unprocessed. */
216 int bell_mf_rx(bell_mf_rx_state_t *s, const int16_t amp[], int samples);
217
218 /*! \brief Get a string of digits from a Bell MF receiver's output buffer.
219 \param s The Bell MF receiver context.
220 \param digits The buffer for the received digits.
221 \param max The maximum number of digits to be returned,
222 \return The number of digits actually returned. */
223 size_t bell_mf_rx_get(bell_mf_rx_state_t *s, char *buf, int max);
224
225 /*! \brief Initialise a Bell MF receiver context.
226 \param s The Bell MF receiver context.
227 \param callback An optional callback routine, used to report received digits. If
228 no callback routine is set, digits may be collected, using the bell_mf_rx_get()
229 function.
230 \param user_data An opaque pointer which is associated with the context,
231 and supplied in callbacks.
232 \return A pointer to the Bell MF receiver context.*/
233 bell_mf_rx_state_t *bell_mf_rx_init(bell_mf_rx_state_t *s,
234 void (*callback)(void *user_data, const char *digits, int len),
235 void *user_data);
236
237 /*! Process a block of received R2 MF audio samples.
238 \brief Process a block of received R2 MF audio samples.
239 \param s The R2 MF receiver context.
240 \param amp The audio sample buffer.
241 \param samples The number of samples in the buffer.
242 \return The number of samples unprocessed. */
243 int r2_mf_rx(r2_mf_rx_state_t *s, const int16_t amp[], int samples);
244
245 /*! \brief Initialise an R2 MF receiver context.
246 \param s The R2 MF receiver context.
247 \param fwd TRUE if the context is for forward signals. FALSE if the
248 context is for backward signals.
249 \return A pointer to the R2 MF receiver context. */
250 r2_mf_rx_state_t *r2_mf_rx_init(r2_mf_rx_state_t *s, int fwd);
251
252 #ifdef __cplusplus
253 }
254 #endif
255
256 #endif
257 /*- End of file ------------------------------------------------------------*/

Repositories maintained by Peter Meerwald, pmeerw@pmeerw.net.