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 1.21 2008/10/13 14:19:18 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 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 size_t 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 bell_mf_tx_state_t *bell_mf_tx_init(bell_mf_tx_state_t *s); 00154 00155 /*! \brief Free a Bell MF generator context. 00156 \param s The Bell MF generator context. 00157 \return 0 for OK, else -1. */ 00158 int bell_mf_tx_free(bell_mf_tx_state_t *s); 00159 00160 /*! \brief Generate a block of R2 MF tones. 00161 \param s The R2 MF generator context. 00162 \param amp The buffer for the generated signal. 00163 \param samples The required number of generated samples. 00164 \return The number of samples actually generated. */ 00165 int r2_mf_tx(r2_mf_tx_state_t *s, int16_t amp[], int samples); 00166 00167 /*! \brief Generate a block of R2 MF tones. 00168 \param s The R2 MF generator context. 00169 \param digit The digit to be generated. 00170 \return 0 for OK, or -1 for a bad request. */ 00171 int r2_mf_tx_put(r2_mf_tx_state_t *s, char digit); 00172 00173 /*! \brief Initialise an R2 MF tone generator context. 00174 \param s The R2 MF generator context. 00175 \param fwd TRUE if the context is for forward signals. FALSE if the 00176 context is for backward signals. 00177 \return A pointer to the MFC/R2 generator context.*/ 00178 r2_mf_tx_state_t *r2_mf_tx_init(r2_mf_tx_state_t *s, int fwd); 00179 00180 /*! \brief Free an R2 MF tone generator context. 00181 \param s The R2 MF tone generator context. 00182 \return 0 for OK, else -1. */ 00183 int r2_mf_tx_free(r2_mf_tx_state_t *s); 00184 00185 /*! Process a block of received Bell MF audio samples. 00186 \brief Process a block of received Bell MF audio samples. 00187 \param s The Bell MF receiver context. 00188 \param amp The audio sample buffer. 00189 \param samples The number of samples in the buffer. 00190 \return The number of samples unprocessed. */ 00191 int bell_mf_rx(bell_mf_rx_state_t *s, const int16_t amp[], int samples); 00192 00193 /*! \brief Get a string of digits from a Bell MF receiver's output buffer. 00194 \param s The Bell MF receiver context. 00195 \param buf The buffer for the received digits. 00196 \param max The maximum number of digits to be returned, 00197 \return The number of digits actually returned. */ 00198 size_t bell_mf_rx_get(bell_mf_rx_state_t *s, char *buf, int max); 00199 00200 /*! \brief Initialise a Bell MF receiver context. 00201 \param s The Bell MF receiver context. 00202 \param callback An optional callback routine, used to report received digits. If 00203 no callback routine is set, digits may be collected, using the bell_mf_rx_get() 00204 function. 00205 \param user_data An opaque pointer which is associated with the context, 00206 and supplied in callbacks. 00207 \return A pointer to the Bell MF receiver context.*/ 00208 bell_mf_rx_state_t *bell_mf_rx_init(bell_mf_rx_state_t *s, 00209 digits_rx_callback_t callback, 00210 void *user_data); 00211 00212 /*! \brief Free a Bell MF receiver context. 00213 \param s The Bell MF receiver context. 00214 \return 0 for OK, else -1. */ 00215 int bell_mf_rx_free(bell_mf_rx_state_t *s); 00216 00217 /*! Process a block of received R2 MF audio samples. 00218 \brief Process a block of received R2 MF audio samples. 00219 \param s The R2 MF receiver context. 00220 \param amp The audio sample buffer. 00221 \param samples The number of samples in the buffer. 00222 \return The number of samples unprocessed. */ 00223 int r2_mf_rx(r2_mf_rx_state_t *s, const int16_t amp[], int samples); 00224 00225 /*! \brief Get the current digit from an R2 MF receiver. 00226 \param s The R2 MF receiver context. 00227 \return The number digits being received. */ 00228 int r2_mf_rx_get(r2_mf_rx_state_t *s); 00229 00230 /*! \brief Initialise an R2 MF receiver context. 00231 \param s The R2 MF receiver context. 00232 \param fwd TRUE if the context is for forward signals. FALSE if the 00233 context is for backward signals. 00234 \param callback An optional callback routine, used to report received digits. If 00235 no callback routine is set, digits may be collected, using the r2_mf_rx_get() 00236 function. 00237 \param user_data An opaque pointer which is associated with the context, 00238 and supplied in callbacks. 00239 \return A pointer to the R2 MF receiver context. */ 00240 r2_mf_rx_state_t *r2_mf_rx_init(r2_mf_rx_state_t *s, 00241 int fwd, 00242 tone_report_func_t callback, 00243 void *user_data); 00244 00245 /*! \brief Free an R2 MF receiver context. 00246 \param s The R2 MF receiver context. 00247 \return 0 for OK, else -1. */ 00248 int r2_mf_rx_free(r2_mf_rx_state_t *s); 00249 00250 #if defined(__cplusplus) 00251 } 00252 #endif 00253 00254 #endif 00255 /*- End of file ------------------------------------------------------------*/