bell_r2_mf.h

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00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * bell_r2_mf.h - Bell MF and MFC/R2 tone generation and detection.
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2001 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: bell_r2_mf.h,v 1.24 2009/02/10 13:06:47 steveu Exp $
00026  */
00027 
00028 /*! \file */
00029 
00030 #if !defined(_SPANDSP_BELL_R2_MF_H_)
00031 #define _SPANDSP_BELL_R2_MF_H_
00032 
00033 /*! \page mfc_r2_tone_generation_page MFC/R2 tone generation
00034 \section mfc_r2_tone_generation_page_sec_1 What does it do?
00035 The MFC/R2 tone generation module provides for the generation of the
00036 repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol. 
00037 
00038 \section mfc_r2_tone_generation_page_sec_2 How does it work?
00039 */
00040 
00041 /*! \page bell_mf_tone_generation_page Bell MF tone generation
00042 \section bell_mf_tone_generation_page_sec_1 What does it do?
00043 The Bell MF tone generation module provides for the generation of the
00044 repertoire of 15 dual tones needs for various Bell MF signalling protocols. 
00045 
00046 \section bell_mf_tone_generation_page_sec_2 How does it work?
00047 Basic Bell MF tone generation specs:
00048     - Tone on time = KP: 100+-7ms. All other signals: 68+-7ms
00049     - Tone off time (between digits) = 68+-7ms
00050     - Frequency tolerance +- 1.5%
00051     - Signal level -7+-1dBm per frequency
00052 */
00053 
00054 /*! \page mfc_r2_tone_rx_page MFC/R2 tone receiver
00055 
00056 \section mfc_r2_tone_rx_page_sec_1 What does it do?
00057 The MFC/R2 tone receiver module provides for the detection of the
00058 repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol. 
00059 It is compliant with ITU-T Q.441D.
00060 
00061 \section mfc_r2_tone_rx_page_sec_2 How does it work?
00062 Basic MFC/R2 tone detection specs:
00063     - Receiver response range: -5dBm to -35dBm
00064     - Difference in level for a pair of frequencies
00065         - Adjacent tones: <5dB
00066         - Non-adjacent tones: <7dB
00067     - Receiver not to detect a signal of 2 frequencies of level -5dB and
00068       duration <7ms.
00069     - Receiver not to recognise a signal of 2 frequencies having a difference
00070       in level >=20dB.
00071     - Max received signal frequency error: +-10Hz
00072     - The sum of the operate and release times of a 2 frequency signal not to
00073       exceed 80ms (there are no individual specs for the operate and release
00074       times).
00075     - Receiver not to release for signal interruptions <=7ms.
00076     - System malfunction due to signal interruptions >7ms (typically 20ms) is
00077       prevented by further logic elements.
00078 */
00079 
00080 /*! \page bell_mf_tone_rx_page Bell MF tone receiver
00081 
00082 \section bell_mf_tone_rx_page_sec_1 What does it do?
00083 The Bell MF tone receiver module provides for the detection of the
00084 repertoire of 15 dual tones needs for various Bell MF signalling protocols. 
00085 It is compliant with ITU-T Q.320, ITU-T Q.322, ITU-T Q.323B.
00086 
00087 \section bell_mf_tone_rx_page_sec_2 How does it work?
00088 Basic Bell MF tone detection specs:
00089     - Frequency tolerance +- 1.5% +-10Hz
00090     - Signal level -14dBm to 0dBm
00091     - Perform a "two and only two tones present" test.
00092     - Twist <= 6dB accepted
00093     - Receiver sensitive to signals above -22dBm per frequency
00094     - Test for a minimum of 55ms if KP, or 30ms of other signals.
00095     - Signals to be recognised if the two tones arrive within 8ms of each other.
00096     - Invalid signals result in the return of the re-order tone.
00097 
00098 Note: Above -3dBm the signal starts to clip. We can detect with a little clipping,
00099       but not up to 0dBm, which the above spec seems to require. There isn't a lot
00100       we can do about that. Is the spec. incorrectly worded about the dBm0 reference
00101       point, or have I misunderstood it?
00102 */
00103 
00104 /*! The maximum number of Bell MF digits we can buffer. */
00105 #define MAX_BELL_MF_DIGITS 128
00106 
00107 /*!
00108     Bell MF generator state descriptor. This defines the state of a single
00109     working instance of a Bell MF generator.
00110 */
00111 typedef struct bell_mf_tx_state_s bell_mf_tx_state_t;
00112 
00113 /*!
00114     Bell MF digit detector descriptor.
00115 */
00116 typedef struct bell_mf_rx_state_s bell_mf_rx_state_t;
00117 
00118 /*!
00119     MFC/R2 tone detector descriptor.
00120 */
00121 typedef struct r2_mf_tx_state_s r2_mf_tx_state_t;
00122 
00123 /*!
00124     MFC/R2 tone detector descriptor.
00125 */
00126 typedef struct r2_mf_rx_state_s r2_mf_rx_state_t;
00127 
00128 #if defined(__cplusplus)
00129 extern "C"
00130 {
00131 #endif
00132 
00133 /*! \brief Generate a buffer of Bell MF tones.
00134     \param s The Bell MF generator context.
00135     \param amp The buffer for the generated signal.
00136     \param max_samples The required number of generated samples.
00137     \return The number of samples actually generated. This may be less than 
00138             max_samples if the input buffer empties. */
00139 SPAN_DECLARE(int) bell_mf_tx(bell_mf_tx_state_t *s, int16_t amp[], int max_samples);
00140 
00141 /*! \brief Put a string of digits in a Bell MF generator's input buffer.
00142     \param s The Bell MF generator context.
00143     \param digits The string of digits to be added.
00144     \param len The length of the string of digits. If negative, the string is
00145            assumed to be a NULL terminated string.
00146     \return The number of digits actually added. This may be less than the
00147             length of the digit string, if the buffer fills up. */
00148 SPAN_DECLARE(int) bell_mf_tx_put(bell_mf_tx_state_t *s, const char *digits, int len);
00149 
00150 /*! \brief Initialise a Bell MF generator context.
00151     \param s The Bell MF generator context.
00152     \return A pointer to the Bell MF generator context.*/
00153 SPAN_DECLARE(bell_mf_tx_state_t *) bell_mf_tx_init(bell_mf_tx_state_t *s);
00154 
00155 /*! \brief Release a Bell MF generator context.
00156     \param s The Bell MF generator context.
00157     \return 0 for OK, else -1. */
00158 SPAN_DECLARE(int) bell_mf_tx_release(bell_mf_tx_state_t *s);
00159 
00160 /*! \brief Free a Bell MF generator context.
00161     \param s The Bell MF generator context.
00162     \return 0 for OK, else -1. */
00163 SPAN_DECLARE(int) bell_mf_tx_free(bell_mf_tx_state_t *s);
00164 
00165 /*! \brief Generate a block of R2 MF tones.
00166     \param s The R2 MF generator context.
00167     \param amp The buffer for the generated signal.
00168     \param samples The required number of generated samples.
00169     \return The number of samples actually generated. */
00170 SPAN_DECLARE(int) r2_mf_tx(r2_mf_tx_state_t *s, int16_t amp[], int samples);
00171 
00172 /*! \brief Generate a block of R2 MF tones.
00173     \param s The R2 MF generator context.
00174     \param digit The digit to be generated.
00175     \return 0 for OK, or -1 for a bad request. */
00176 SPAN_DECLARE(int) r2_mf_tx_put(r2_mf_tx_state_t *s, char digit);
00177 
00178 /*! \brief Initialise an R2 MF tone generator context.
00179     \param s The R2 MF generator context.
00180     \param fwd TRUE if the context is for forward signals. FALSE if the
00181            context is for backward signals.
00182     \return A pointer to the MFC/R2 generator context.*/
00183 SPAN_DECLARE(r2_mf_tx_state_t *) r2_mf_tx_init(r2_mf_tx_state_t *s, int fwd);
00184 
00185 /*! \brief Release an R2 MF tone generator context.
00186     \param s The R2 MF tone generator context.
00187     \return 0 for OK, else -1. */
00188 SPAN_DECLARE(int) r2_mf_tx_release(r2_mf_tx_state_t *s);
00189 
00190 /*! \brief Free an R2 MF tone generator context.
00191     \param s The R2 MF tone generator context.
00192     \return 0 for OK, else -1. */
00193 SPAN_DECLARE(int) r2_mf_tx_free(r2_mf_tx_state_t *s);
00194 
00195 /*! Process a block of received Bell MF audio samples.
00196     \brief Process a block of received Bell MF audio samples.
00197     \param s The Bell MF receiver context.
00198     \param amp The audio sample buffer.
00199     \param samples The number of samples in the buffer.
00200     \return The number of samples unprocessed. */
00201 SPAN_DECLARE(int) bell_mf_rx(bell_mf_rx_state_t *s, const int16_t amp[], int samples);
00202 
00203 /*! \brief Get a string of digits from a Bell MF receiver's output buffer.
00204     \param s The Bell MF receiver context.
00205     \param buf The buffer for the received digits.
00206     \param max The maximum  number of digits to be returned,
00207     \return The number of digits actually returned. */
00208 SPAN_DECLARE(size_t) bell_mf_rx_get(bell_mf_rx_state_t *s, char *buf, int max);
00209 
00210 /*! \brief Initialise a Bell MF receiver context.
00211     \param s The Bell MF receiver context.
00212     \param callback An optional callback routine, used to report received digits. If
00213            no callback routine is set, digits may be collected, using the bell_mf_rx_get()
00214            function.
00215     \param user_data An opaque pointer which is associated with the context,
00216            and supplied in callbacks.
00217     \return A pointer to the Bell MF receiver context.*/
00218 SPAN_DECLARE(bell_mf_rx_state_t *) bell_mf_rx_init(bell_mf_rx_state_t *s,
00219                                                    digits_rx_callback_t callback,
00220                                                    void *user_data);
00221 
00222 /*! \brief Release a Bell MF receiver context.
00223     \param s The Bell MF receiver context.
00224     \return 0 for OK, else -1. */
00225 SPAN_DECLARE(int) bell_mf_rx_release(bell_mf_rx_state_t *s);
00226 
00227 /*! \brief Free a Bell MF receiver context.
00228     \param s The Bell MF receiver context.
00229     \return 0 for OK, else -1. */
00230 SPAN_DECLARE(int) bell_mf_rx_free(bell_mf_rx_state_t *s);
00231 
00232 /*! Process a block of received R2 MF audio samples.
00233     \brief Process a block of received R2 MF audio samples.
00234     \param s The R2 MF receiver context.
00235     \param amp The audio sample buffer.
00236     \param samples The number of samples in the buffer.
00237     \return The number of samples unprocessed. */
00238 SPAN_DECLARE(int) r2_mf_rx(r2_mf_rx_state_t *s, const int16_t amp[], int samples);
00239 
00240 /*! \brief Get the current digit from an R2 MF receiver.
00241     \param s The R2 MF receiver context.
00242     \return The number digits being received. */
00243 SPAN_DECLARE(int) r2_mf_rx_get(r2_mf_rx_state_t *s);
00244 
00245 /*! \brief Initialise an R2 MF receiver context.
00246     \param s The R2 MF receiver context.
00247     \param fwd TRUE if the context is for forward signals. FALSE if the
00248            context is for backward signals.
00249     \param callback An optional callback routine, used to report received digits. If
00250            no callback routine is set, digits may be collected, using the r2_mf_rx_get()
00251            function.
00252     \param user_data An opaque pointer which is associated with the context,
00253            and supplied in callbacks.
00254     \return A pointer to the R2 MF receiver context. */
00255 SPAN_DECLARE(r2_mf_rx_state_t *) r2_mf_rx_init(r2_mf_rx_state_t *s,
00256                                                int fwd,
00257                                                tone_report_func_t callback,
00258                                                void *user_data);
00259 
00260 /*! \brief Release an R2 MF receiver context.
00261     \param s The R2 MF receiver context.
00262     \return 0 for OK, else -1. */
00263 SPAN_DECLARE(int) r2_mf_rx_release(r2_mf_rx_state_t *s);
00264 
00265 /*! \brief Free an R2 MF receiver context.
00266     \param s The R2 MF receiver context.
00267     \return 0 for OK, else -1. */
00268 SPAN_DECLARE(int) r2_mf_rx_free(r2_mf_rx_state_t *s);
00269 
00270 #if defined(__cplusplus)
00271 }
00272 #endif
00273 
00274 #endif
00275 /*- End of file ------------------------------------------------------------*/

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