private/sig_tone.h
/*
* SpanDSP - a series of DSP components for telephony
*
* private/sig_tone.h - Signalling tone processing for the 2280Hz, 2400Hz, 2600Hz
* and similar signalling tones used in older protocols.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2004 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#if !defined(_SPANDSP_PRIVATE_SIG_TONE_H_)
#define _SPANDSP_PRIVATE_SIG_TONE_H_
/*! \brief The coefficient set for a pair of cascaded bi-quads that make a signalling notch filter. */
typedef struct
{
#if defined(SPANDSP_USE_FIXED_POINT)
int16_t a1[3];
int16_t b1[3];
int16_t a2[3];
int16_t b2[3];
int postscale;
#else
float a1[3];
float b1[3];
float a2[3];
float b2[3];
#endif
} sig_tone_notch_coeffs_t;
/*! \brief The coefficient set for a bi-quad that makes a signalling flat filter.
Some signalling tone schemes require such a filter, and some don't.
It is termed a flat filter, to distinguish it from the sharp filter,
but obviously it is not actually flat. It is a broad band weighting
filter. */
typedef struct
{
#if defined(SPANDSP_USE_FIXED_POINT)
/*! \brief Flat mode bandpass bi-quad parameters */
int16_t a[3];
/*! \brief Flat mode bandpass bi-quad parameters */
int16_t b[3];
/*! \brief Post filter scaling */
int postscale;
#else
/*! \brief Flat mode bandpass bi-quad parameters */
float a[3];
/*! \brief Flat mode bandpass bi-quad parameters */
float b[3];
#endif
} sig_tone_flat_coeffs_t;
/*!
signalling tone descriptor. This defines the working state for a
single instance of the transmit and receive sides of a signalling
tone processor.
*/
typedef struct
{
/*! \brief The tones used. */
int tone_freq[2];
/*! \brief The high and low tone amplitudes for each of the tones, in dBm0. */
int tone_amp[2][2];
/*! \brief The delay, in audio samples, before the high level tone drops
to a low level tone. Some signalling protocols require the
signalling tone be started at a high level, to ensure crisp
initial detection at the receiver, but require the tone
amplitude to drop by a number of dBs if it is sustained,
to reduce crosstalk levels. */
int high_low_timeout;
/*! \brief Some signalling tone detectors use a sharp initial filter,
changing to a broader, flatter, filter after some delay. This
parameter defines the delay. 0 means it never changes. */
int sharp_flat_timeout;
/*! \brief Parameters to control the behaviour of the notch filter, used
to remove the tone from the voice path in some protocols. The
notch is applied as fast as possible, when the signalling tone
is detected. Its removal is delayed by this timeout, to avoid
clicky noises from repeated switching of the filter on rapid
pulses of signalling tone. */
int notch_lag_time;
/*! \brief The tone on persistence check, in audio samples. */
int tone_on_check_time;
/*! \brief The tone off persistence check, in audio samples. */
int tone_off_check_time;
/*! \brief The number of tones used. */
int tones;
/*! \brief The coefficients for the cascaded bi-quads notch filter. */
const sig_tone_notch_coeffs_t *notch[2];
/*! \brief The coefficients for the single bi-quad flat mode filter. */
const sig_tone_flat_coeffs_t *flat;
/*! \brief Minimum signalling tone to total power ratio, in dB */
int16_t detection_ratio;
/*! \brief Minimum total power for detection in sharp mode, in dB */
int16_t sharp_detection_threshold;
/*! \brief Minimum total power for detection in flat mode, in dB */
int16_t flat_detection_threshold;
} sig_tone_descriptor_t;
/*!
Signalling tone transmit state
*/
struct sig_tone_tx_state_s
{
/*! \brief The callback function used to handle signalling changes. */
tone_report_func_t sig_update;
/*! \brief A user specified opaque pointer passed to the callback function. */
void *user_data;
/*! \brief Tone descriptor */
const sig_tone_descriptor_t *desc;
/*! The phase rates for the one or two tones */
int32_t phase_rate[2];
/*! The phase accumulators for the one or two tones */
uint32_t phase_acc[2];
/*! The scaling values for the one or two tones, and the high and low level of each tone */
int16_t tone_scaling[2][2];
/*! The sample timer, used to switch between the high and low level tones. */
int high_low_timer;
/*! \brief Current transmit tone */
int current_tx_tone;
/*! \brief Current transmit timeout */
int current_tx_timeout;
/*! \brief Time in current signalling state, in samples. */
int signalling_state_duration;
};
/*!
Signalling tone receive state
*/
struct sig_tone_rx_state_s
{
/*! \brief The callback function used to handle signalling changes. */
tone_report_func_t sig_update;
/*! \brief A user specified opaque pointer passed to the callback function. */
void *user_data;
/*! \brief Tone descriptor */
const sig_tone_descriptor_t *desc;
/*! \brief The current receive tone */
int current_rx_tone;
/*! \brief The timeout for switching from the high level to low level tone detector. */
int high_low_timer;
/*! \brief ??? */
int current_notch_filter;
struct
{
#if defined(SPANDSP_USE_FIXED_POINT)
/*! \brief The z's for the notch filter */
int16_t notch_z1[2];
/*! \brief The z's for the notch filter */
int16_t notch_z2[2];
#else
/*! \brief The z's for the notch filter */
float notch_z1[2];
/*! \brief The z's for the notch filter */
float notch_z2[2];
#endif
/*! \brief The power output of the notch. */
power_meter_t power;
} tone[3];
#if defined(SPANDSP_USE_FIXED_POINT)
/*! \brief The z's for the weighting/bandpass filter. */
int16_t flat_z[2];
#else
/*! \brief The z's for the weighting/bandpass filter. */
float flat_z[2];
#endif
/*! \brief The output power of the flat (unfiltered or flat filtered) path. */
power_meter_t flat_power;
/*! \brief Persistence check for tone present */
int tone_persistence_timeout;
/*! \brief The tone pattern on the last audio sample */
int last_sample_tone_present;
/*! \brief The minimum reading from the power meter for detection in flat mode */
int32_t flat_detection_threshold;
/*! \brief The minimum reading from the power meter for detection in sharp mode */
int32_t sharp_detection_threshold;
/*! \brief The minimum ratio between notched power and total power for detection */
int32_t detection_ratio;
/*! \brief TRUE if in flat mode. FALSE if in sharp mode. */
int flat_mode;
/*! \brief TRUE if the notch filter is enabled in the media path */
int notch_enabled;
/*! \brief ??? */
int flat_mode_timeout;
/*! \brief ??? */
int notch_insertion_timeout;
/*! \brief ??? */
int signalling_state;
/*! \brief ??? */
int signalling_state_duration;
};
#endif
/*- End of file ------------------------------------------------------------*/
power_meter_t
Definition power_meter.h:49
sig_tone_descriptor_t
Definition private/sig_tone.h:75
sig_tone_descriptor_t::detection_ratio
int16_t detection_ratio
Minimum signalling tone to total power ratio, in dB.
Definition private/sig_tone.h:115
sig_tone_descriptor_t::tones
int tones
The number of tones used.
Definition private/sig_tone.h:108
sig_tone_descriptor_t::flat_detection_threshold
int16_t flat_detection_threshold
Minimum total power for detection in flat mode, in dB.
Definition private/sig_tone.h:119
sig_tone_descriptor_t::notch_lag_time
int notch_lag_time
Parameters to control the behaviour of the notch filter, used to remove the tone from the voice path ...
Definition private/sig_tone.h:100
sig_tone_descriptor_t::tone_amp
int tone_amp[2][2]
The high and low tone amplitudes for each of the tones, in dBm0.
Definition private/sig_tone.h:79
sig_tone_descriptor_t::tone_on_check_time
int tone_on_check_time
The tone on persistence check, in audio samples.
Definition private/sig_tone.h:103
sig_tone_descriptor_t::high_low_timeout
int high_low_timeout
The delay, in audio samples, before the high level tone drops to a low level tone....
Definition private/sig_tone.h:87
sig_tone_descriptor_t::tone_off_check_time
int tone_off_check_time
The tone off persistence check, in audio samples.
Definition private/sig_tone.h:105
sig_tone_descriptor_t::notch
const sig_tone_notch_coeffs_t * notch[2]
The coefficients for the cascaded bi-quads notch filter.
Definition private/sig_tone.h:110
sig_tone_descriptor_t::tone_freq
int tone_freq[2]
The tones used.
Definition private/sig_tone.h:77
sig_tone_descriptor_t::sharp_flat_timeout
int sharp_flat_timeout
Some signalling tone detectors use a sharp initial filter, changing to a broader, flatter,...
Definition private/sig_tone.h:92
sig_tone_descriptor_t::sharp_detection_threshold
int16_t sharp_detection_threshold
Minimum total power for detection in sharp mode, in dB.
Definition private/sig_tone.h:117
sig_tone_descriptor_t::flat
const sig_tone_flat_coeffs_t * flat
The coefficients for the single bi-quad flat mode filter.
Definition private/sig_tone.h:112
sig_tone_flat_coeffs_t
The coefficient set for a bi-quad that makes a signalling flat filter. Some signalling tone schemes r...
Definition private/sig_tone.h:53
sig_tone_flat_coeffs_t::a
float a[3]
Flat mode bandpass bi-quad parameters.
Definition private/sig_tone.h:63
sig_tone_flat_coeffs_t::b
float b[3]
Flat mode bandpass bi-quad parameters.
Definition private/sig_tone.h:65
sig_tone_notch_coeffs_t
The coefficient set for a pair of cascaded bi-quads that make a signalling notch filter.
Definition private/sig_tone.h:32
sig_tone_rx_state_s
Definition private/sig_tone.h:157
sig_tone_rx_state_s::high_low_timer
int high_low_timer
The timeout for switching from the high level to low level tone detector.
Definition private/sig_tone.h:169
sig_tone_rx_state_s::user_data
void * user_data
A user specified opaque pointer passed to the callback function.
Definition private/sig_tone.h:161
sig_tone_rx_state_s::last_sample_tone_present
int last_sample_tone_present
The tone pattern on the last audio sample.
Definition private/sig_tone.h:204
sig_tone_rx_state_s::notch_enabled
int notch_enabled
TRUE if the notch filter is enabled in the media path.
Definition private/sig_tone.h:216
sig_tone_rx_state_s::flat_mode_timeout
int flat_mode_timeout
???
Definition private/sig_tone.h:218
sig_tone_rx_state_s::flat_mode
int flat_mode
TRUE if in flat mode. FALSE if in sharp mode.
Definition private/sig_tone.h:214
sig_tone_rx_state_s::notch_z1
float notch_z1[2]
The z's for the notch filter.
Definition private/sig_tone.h:182
sig_tone_rx_state_s::flat_power
power_meter_t flat_power
The output power of the flat (unfiltered or flat filtered) path.
Definition private/sig_tone.h:199
sig_tone_rx_state_s::tone_persistence_timeout
int tone_persistence_timeout
Persistence check for tone present.
Definition private/sig_tone.h:202
sig_tone_rx_state_s::sig_update
tone_report_func_t sig_update
The callback function used to handle signalling changes.
Definition private/sig_tone.h:159
sig_tone_rx_state_s::desc
const sig_tone_descriptor_t * desc
Tone descriptor.
Definition private/sig_tone.h:164
sig_tone_rx_state_s::flat_detection_threshold
int32_t flat_detection_threshold
The minimum reading from the power meter for detection in flat mode.
Definition private/sig_tone.h:207
sig_tone_rx_state_s::current_notch_filter
int current_notch_filter
???
Definition private/sig_tone.h:171
sig_tone_rx_state_s::notch_z2
float notch_z2[2]
The z's for the notch filter.
Definition private/sig_tone.h:184
sig_tone_rx_state_s::sharp_detection_threshold
int32_t sharp_detection_threshold
The minimum reading from the power meter for detection in sharp mode.
Definition private/sig_tone.h:209
sig_tone_rx_state_s::signalling_state
int signalling_state
???
Definition private/sig_tone.h:223
sig_tone_rx_state_s::notch_insertion_timeout
int notch_insertion_timeout
???
Definition private/sig_tone.h:220
sig_tone_rx_state_s::signalling_state_duration
int signalling_state_duration
???
Definition private/sig_tone.h:225
sig_tone_rx_state_s::power
power_meter_t power
The power output of the notch.
Definition private/sig_tone.h:188
sig_tone_rx_state_s::current_rx_tone
int current_rx_tone
The current receive tone.
Definition private/sig_tone.h:167
sig_tone_rx_state_s::detection_ratio
int32_t detection_ratio
The minimum ratio between notched power and total power for detection.
Definition private/sig_tone.h:211
sig_tone_rx_state_s::flat_z
float flat_z[2]
The z's for the weighting/bandpass filter.
Definition private/sig_tone.h:196
sig_tone_tx_state_s
Definition private/sig_tone.h:126
sig_tone_tx_state_s::high_low_timer
int high_low_timer
Definition private/sig_tone.h:143
sig_tone_tx_state_s::phase_acc
uint32_t phase_acc[2]
Definition private/sig_tone.h:138
sig_tone_tx_state_s::current_tx_timeout
int current_tx_timeout
Current transmit timeout.
Definition private/sig_tone.h:148
sig_tone_tx_state_s::user_data
void * user_data
A user specified opaque pointer passed to the callback function.
Definition private/sig_tone.h:130
sig_tone_tx_state_s::sig_update
tone_report_func_t sig_update
The callback function used to handle signalling changes.
Definition private/sig_tone.h:128
sig_tone_tx_state_s::signalling_state_duration
int signalling_state_duration
Time in current signalling state, in samples.
Definition private/sig_tone.h:150
sig_tone_tx_state_s::current_tx_tone
int current_tx_tone
Current transmit tone.
Definition private/sig_tone.h:146
sig_tone_tx_state_s::desc
const sig_tone_descriptor_t * desc
Tone descriptor.
Definition private/sig_tone.h:133
sig_tone_tx_state_s::tone_scaling
int16_t tone_scaling[2][2]
Definition private/sig_tone.h:141
sig_tone_tx_state_s::phase_rate
int32_t phase_rate[2]
Definition private/sig_tone.h:136