PTones Class Reference

This class can be used to generate PCM data for tones (such as telephone calling tones and DTMF) at a sample rate of 8khz. More...

#include <dtmf.h>

Inheritance diagram for PTones:

List of all members.

Public Types
	MaxVolume = 100
	DefaultSampleRate = 8000
	MinFrequency = 30
	MinModulation = 5
	SineScale = 1000
enum	{   MaxVolume = 100, DefaultSampleRate = 8000, MinFrequency = 30, MinModulation = 5,   SineScale = 1000 }
Public Member Functions
	PTones (unsigned masterVolume=MaxVolume, unsigned sampleRate=DefaultSampleRate)
	Create an empty tone buffer.
	PTones (const PString &descriptor, unsigned masterVolume=MaxVolume, unsigned sampleRate=DefaultSampleRate)
	Create a filled tone buffer using the specified descriptor.
bool	Generate (const PString &descriptor)
	Generate a tone using the specified descriptor.
bool	Generate (char operation, unsigned frequency1, unsigned frequency2, unsigned milliseconds, unsigned volume=MaxVolume)
	Generate a tone using the specified values.
Protected Member Functions
void	Construct ()
bool	Juxtapose (unsigned frequency1, unsigned frequency2, unsigned milliseconds, unsigned volume)
bool	Modulate (unsigned frequency, unsigned modulate, unsigned milliseconds, unsigned volume)
bool	PureTone (unsigned frequency, unsigned milliseconds, unsigned volume)
bool	Silence (unsigned milliseconds)
unsigned	CalcSamples (unsigned milliseconds, unsigned frequency1, unsigned frequency2=0)
void	AddSample (int sample, unsigned volume)
Protected Attributes
unsigned	m_sampleRate
unsigned	m_maxFrequency
unsigned	m_masterVolume
char	m_lastOperation
unsigned	m_lastFrequency1
unsigned	m_lastFrequency2
int	m_angle1
int	m_angle2

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Detailed Description

This class can be used to generate PCM data for tones (such as telephone calling tones and DTMF) at a sample rate of 8khz.

The class contains a master volume which is applied as well as the individual tone volumes. Thus a master volume ot 50% and a tone voluem of 50% would result in a net volume of 25%.

Tones may be described via a list of descriptor strings based on an ITU-T "semi-standard", one used within various standard documents but not a standard in itself. This format was enhanced to allow for multiple tones and volume indications.

The basic format is:

[volume % ] frequency ':' cadence [ '/' ... ]

where frequency is one of frequency single frequency tone freq1 '+' freq2 two frequency juxtaposed (simple mixing) freq1 'x' freq2 first frequency modulated by second frequency freq1 '-' freq2 Alternate frequencies, generated tone is freq1 used for compatibility with tone filters and cadence is mintime ontime '-' offtime [ '-' ontime '-' offtime [ ... ] ]

and volume is a percentage of full volume

examples: 300:0.25 300Hz for minimum 250ms 1100:0.4-0.4 1100Hz with cadence 400ms on, 400ms off 900-1300:1.5 900Hz for 1.5 seconds 350+440:1 350Hz superimposed with 440Hz (US dial tone) for 1 second 425x15:0.4-0.2-0.4-2 425Hz modulated with 15Hz (Aus ring back tone) with cadence 400ms on, 200ms off, 400ms on, 2s off 425:0.4-0.1/50425:0.4-0.1 425Hz with cadence 400ms on, 100ms off, 400ms on, 100ms off, where second tone is reduced in volume by 50%

A database of tones for all contries in the worls is available at: http://www.3amsystems.com/wireline/tone-search.htm

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Member Enumeration Documentation

anonymous enum

Enumerator:

MaxVolume
DefaultSampleRate
MinFrequency
MinModulation
SineScale

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Constructor & Destructor Documentation

PTones::PTones	(	unsigned	masterVolume = MaxVolume,
		unsigned	sampleRate = DefaultSampleRate
	)

Create an empty tone buffer.

Tones added will use the specified master volume.

Parameters:

masterVolume	Percentage volume
sampleRate	Sample rate of generated data

PTones::PTones	(	const PString &	descriptor,
		unsigned	masterVolume = MaxVolume,
		unsigned	sampleRate = DefaultSampleRate
	)

Create a filled tone buffer using the specified descriptor.

Parameters:

descriptor	Descriptor string for tone(s). See class notes.
masterVolume	Percentage volume
sampleRate	Sample rate of generated data

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Member Function Documentation

void PTones::AddSample	(	int	sample,
		unsigned	volume
	)			[protected]

unsigned PTones::CalcSamples	(	unsigned	milliseconds,
		unsigned	frequency1,
		unsigned	frequency2 = 0
	)			[protected]

void PTones::Construct

(

)

[protected]

bool PTones::Generate	(	char	operation,
		unsigned	frequency1,
		unsigned	frequency2,
		unsigned	milliseconds,
		unsigned	volume = MaxVolume
	)

Generate a tone using the specified values.

The operation parameter may be '+', 'x', '-' or ' ' for summing, modulation, pure tone or silence resepctively. The tones duration is always rounded up to the nearest even multiple of the tone cycle to assure correct zero crossing when tones change.

Parameters:

operation	Operation for mixing frequency
frequency1	Primary frequency for tone
frequency2	Secondary frequency for summing or modulation
milliseconds	Duration of tone
volume	Percentage volume

bool PTones::Generate

(

const PString &

descriptor

)

Generate a tone using the specified descriptor.

See class general notes for format of the descriptor string.

Parameters:

descriptor

Descriptor string for tone(s). See class notes.

bool PTones::Juxtapose	(	unsigned	frequency1,
		unsigned	frequency2,
		unsigned	milliseconds,
		unsigned	volume
	)			[protected]

bool PTones::Modulate	(	unsigned	frequency,
		unsigned	modulate,
		unsigned	milliseconds,
		unsigned	volume
	)			[protected]

bool PTones::PureTone	(	unsigned	frequency,
		unsigned	milliseconds,
		unsigned	volume
	)			[protected]

bool PTones::Silence

(

unsigned

milliseconds

)

[protected]

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Member Data Documentation

int PTones::m_angle1 [protected]

int PTones::m_angle2 [protected]

unsigned PTones::m_lastFrequency1 [protected]

unsigned PTones::m_lastFrequency2 [protected]

char PTones::m_lastOperation [protected]

unsigned PTones::m_masterVolume [protected]

unsigned PTones::m_maxFrequency [protected]

unsigned PTones::m_sampleRate [protected]

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The documentation for this class was generated from the following file:

• dtmf.h

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