tinymodem::MFSKEncoder Class Reference

Multi-tone FSK modulator: converts the written bytes into 16 bit PCM audio. Each symbol is one of MFSKConfig::tones tones and carries log2(tones) bits (Gray coded, most significant bit first). More...

#include <MFSKEncoder.h>

Inheritance diagram for tinymodem::MFSKEncoder:

Collaboration diagram for tinymodem::MFSKEncoder:

Public Member Functions
	MFSKEncoder ()=default
	MFSKEncoder (Print &out)
MFSKConfig	defaultConfig ()
	Provides a default configuration: mfsk16.
void	setAudioInfo (audio_tools::AudioInfo info) override
	Defines the sample rate and number of channels of the generated audio.
audio_tools::AudioInfo	audioInfo () override
bool	begin (MFSKConfig config)
	Starts the processing with the indicated configuration.
bool	begin () override
void	end () override
size_t	write (const uint8_t *data, size_t len) override
	Modulates the bytes.
bool	endTransmission (size_t silence_samples=0) override
bool	isTransmitting () override
	true between the first byte and endTransmission()
float	symbolRate () override
	Symbols per second.
MFSKConfig &	config ()
	The configuration which was provided in begin().
	operator bool () override
Public Member Functions inherited from tinymodem::ModemEncoder
void	setOutput (Print &out) override
void	setGenerator (audio_tools::SoundGenerator< int16_t > &generator)
audio_tools::SoundGenerator< int16_t > &	getGenerator ()
	Provides the active tone generator.
virtual bool	writeIdle (size_t nsamples)
	Sends an idle carrier: returns false if this is not supported.
void	writeSilence (size_t nsamples)
	Writes the indicated number of samples of silence.
void	writeTone (float freq, size_t nsamples)
	Writes a tone for the indicated number of samples.
void	flush ()
	Ends the transmission.
const char *	mime () override

Protected Member Functions
void	startTransmission ()
void	writeBits ()
	Writes the next bits_per_symbol bits from the bit buffer.
void	writeSymbol (int tone)

Protected Attributes
MFSKConfig	cfg
bool	is_active = false
bool	transmitting = false
int	bits_per_symbol = 4
double	samples_per_symbol = 0
uint32_t	symbol_index = 0
uint32_t	bit_buffer = 0
int	bit_count = 0
Protected Attributes inherited from tinymodem::ModemEncoder
ToneOutput	tones

Static Protected Attributes
static constexpr int	TRAILER_SYMBOLS = 2

Detailed Description

Multi-tone FSK modulator: converts the written bytes into 16 bit PCM audio. Each symbol is one of MFSKConfig::tones tones and carries log2(tones) bits (Gray coded, most significant bit first).

A transmission starts with a preamble (alternating lowest and highest tone) for the receiver's timing, followed by the sync symbols (see MFSKConfig::syncSymbol()) and the data. Call endTransmission() (or flush()) when the data is complete: the last symbol is padded with 0 bits and 2 symbols of silence mark the end.

Copyright

GPLv3

Constructor & Destructor Documentation

MFSKEncoder() [1/2]

tinymodem::MFSKEncoder::MFSKEncoder ( )

default

MFSKEncoder() [2/2]

tinymodem::MFSKEncoder::MFSKEncoder ( Print & out )

inline

Member Function Documentation

audioInfo()

audio_tools::AudioInfo tinymodem::MFSKEncoder::audioInfo ( )

inlineoverride

begin() [1/2]

bool tinymodem::MFSKEncoder::begin ( )

inlineoverride

begin() [2/2]

bool tinymodem::MFSKEncoder::begin ( MFSKConfig config )

inline

Starts the processing with the indicated configuration.

config()

MFSKConfig & tinymodem::MFSKEncoder::config ( )

inline

The configuration which was provided in begin().

defaultConfig()

MFSKConfig tinymodem::MFSKEncoder::defaultConfig ( )

inline

Provides a default configuration: mfsk16.

end()

void tinymodem::MFSKEncoder::end ( )

inlineoverride

endTransmission()

bool tinymodem::MFSKEncoder::endTransmission ( size_t silence_samples = 0 )

inlineoverridevirtual

Sends the remaining bits and the end marker (and optional silence): returns true if a transmission was ended.

Implements tinymodem::ModemEncoder.

isTransmitting()

bool tinymodem::MFSKEncoder::isTransmitting ( )

inlineoverridevirtual

true between the first byte and endTransmission()

Implements tinymodem::ModemEncoder.

operator bool()

tinymodem::MFSKEncoder::operator bool ( )

inlineoverride

setAudioInfo()

void tinymodem::MFSKEncoder::setAudioInfo ( audio_tools::AudioInfo info )

inlineoverride

Defines the sample rate and number of channels of the generated audio.

startTransmission()

void tinymodem::MFSKEncoder::startTransmission ( )

inlineprotected

symbolRate()

float tinymodem::MFSKEncoder::symbolRate ( )

inlineoverridevirtual

Symbols per second.

Implements tinymodem::ModemEncoder.

write()

size_t tinymodem::MFSKEncoder::write ( const uint8_t * data, size_t len )

inlineoverride

Modulates the bytes.

writeBits()

void tinymodem::MFSKEncoder::writeBits ( )

inlineprotected

Writes the next bits_per_symbol bits from the bit buffer.

writeSymbol()

void tinymodem::MFSKEncoder::writeSymbol ( int tone )

inlineprotected

Writes the tone with the indicated index (-1 = silence). The symbol boundaries are rounded from the exact (fractional) symbol length.

Member Data Documentation

bit_buffer

uint32_t tinymodem::MFSKEncoder::bit_buffer = 0

protected

bit_count

int tinymodem::MFSKEncoder::bit_count = 0

protected

bits_per_symbol

int tinymodem::MFSKEncoder::bits_per_symbol = 4

protected

cfg

MFSKConfig tinymodem::MFSKEncoder::cfg

protected

is_active

bool tinymodem::MFSKEncoder::is_active = false

protected

samples_per_symbol

double tinymodem::MFSKEncoder::samples_per_symbol = 0

protected

symbol_index

uint32_t tinymodem::MFSKEncoder::symbol_index = 0

protected

TRAILER_SYMBOLS

int tinymodem::MFSKEncoder::TRAILER_SYMBOLS = 2

staticconstexprprotected

transmitting

bool tinymodem::MFSKEncoder::transmitting = false

protected

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

• src/modem/MFSKEncoder.h