PSK demodulator (BPSK, QPSK and 8PSK compatible with fldigi): the PCM audio data is written to the decoder and the decoded bytes are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only PSKConfig::channel is evaluated). More...

#include <PSKDecoder.h>

Inheritance diagram for tinymodem::PSKDecoder:

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Collaboration diagram for tinymodem::PSKDecoder:

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Public Member Functions
	PSKDecoder ()=default
	PSKDecoder (Print &out)
PSKConfig	defaultConfig ()
	Provides a default configuration: psk31.
void	setAudioInfo (audio_tools::AudioInfo info) override
	Defines the format of the input audio data.
audio_tools::AudioInfo	audioInfo () override
bool	begin (PSKConfig config)
	Starts the processing with the indicated configuration.
bool	begin () override
void	end () override
	Processes the remaining samples and reports the end of the carrier.
void	flush () override
	Processes the remaining samples (e.g. at the end of the input).
size_t	write (const uint8_t *data, size_t len) override
	Provide PCM data to the decoder.
bool	isCarrier () override
	true while a transmission is received
bool	isFinished () override
	true if the decoding was stopped (rx_one)
float	frequencyOffset ()
	Current frequency offset of the received signal in Hz.
PSKConfig &	config ()
	The configuration which was provided in begin().
	operator bool () override
Public Member Functions inherited from tinymodem::ModemDecoder
void	setStatusOutput (Print &out)
	Defines the output for the ### CARRIER / ### NOCARRIER messages.
void	setQuiet (bool quiet)
	Suppresses the status messages.
const char *	mime () override

Protected Member Functions
void	resetState ()
void	setFrequencyOffset (float offset)
float	noise ()
	uniform random value in the range -0.5 to 0.5
void	addSample (float x, bool add_noise)
void	recalculate ()
	Avoids the accumulation of rounding errors.
void	updateTiming ()
	The decision time is the circular center of the energy distribution.
int	positions ()
	number of phase positions
void	decide ()
	Bit decision from the phase difference to the previous symbol.
void	mfskVaricode (int bit)
	MFSK Varicode (8PSK): a character ends with "001".
void	releaseHeld ()
void	output (uint8_t ch)
void	varicode (int bit)
	Collects the bits of a character: characters are separated by "00".
void	startOfCarrier (float amplitude)
void	endOfCarrier ()
Protected Member Functions inherited from tinymodem::ModemDecoder
void	status (const char *fmt,...)

Protected Attributes
PSKConfig	cfg
bool	is_active = false
bool	is_finished = false
PcmInput	input
uint32_t	noise_seed = 1
float	samples_per_symbol = 0
int	window = 0
float	nco_re = 1
float	nco_im = 0
float	step_re = 1
float	step_im = 0
float	freq_offset = 0
audio_tools::Vector< float >	history
int	pos = 0
float	sum_i = 0
float	sum_q = 0
float	sum_power = 0
uint32_t	sample_count = 0
float	phase = 0
float	target = 0.5f
float	countdown = 0
float	bin_sum [BINS]
int	bin_count [BINS]
float	hist [BINS]
float	prev_i = 0
float	prev_q = 0
float	quality = 0
float	quality_m = 0
bool	carrier = false
int	zeros = 0
int	ones = 0
int	weak = 0
int	last_bit = 1
uint16_t	code = 0
QPSKCode	qpsk
uint32_t	mfsk_code = 0
uint8_t	held [MAX_ONES]
int	nheld = 0
float	track_amplitude = 0
unsigned	ndata = 0
unsigned	nsymbols = 0
float	quality_total = 0
float	amplitude_total = 0
Protected Attributes inherited from tinymodem::ModemDecoder
Print *	p_status = nullptr
bool	is_quiet = false

Static Protected Attributes
static constexpr int	BINS = 16
static constexpr int	MIN_PREAMBLE = 8
static constexpr int	MAX_ONES = 20
static constexpr int	MAX_WEAK = 3
	the signal is lost after MAX_WEAK symbols below LOST_LEVEL
static constexpr float	LOST_LEVEL = 0.3f
static constexpr float	AFC_GAIN = 0.1f
static constexpr float	TIMING_SMOOTHING = 0.15f
static constexpr float	TIMING_GAIN = 0.5f
static constexpr float	MAX_CORRECTION = 0.125f

Detailed Description

PSK demodulator (BPSK, QPSK and 8PSK compatible with fldigi): the PCM audio data is written to the decoder and the decoded bytes are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only PSKConfig::channel is evaluated).

The signal is mixed to the baseband and integrated over one symbol. The symbol timing is determined from the energy distribution over the symbol period, the bits from the phase difference of consecutive symbols: QPSK uses a soft decision Viterbi decoder. An automatic frequency control tracks frequency offsets of up to a quarter of the symbol rate (QPSK: 1/8, 8PSK: 1/16). The receiver starts with a run of phase reversals (preamble) and stops when the signal is lost or with a long steady carrier (postamble of BPSK and 8PSK).

Copyright: GPLv3

Constructor & Destructor Documentation

◆ PSKDecoder() [1/2]

tinymodem::PSKDecoder::PSKDecoder ( )

default

◆ PSKDecoder() [2/2]

tinymodem::PSKDecoder::PSKDecoder ( Print & out )

inline

Member Function Documentation

◆ addSample()

void tinymodem::PSKDecoder::addSample	(	float	x,
		bool	add_noise )

inlineprotected

◆ audioInfo()

audio_tools::AudioInfo tinymodem::PSKDecoder::audioInfo ( )

inlineoverride

◆ begin() [1/2]

bool tinymodem::PSKDecoder::begin ( )

inlineoverride

◆ begin() [2/2]

bool tinymodem::PSKDecoder::begin ( PSKConfig config )

inline

Starts the processing with the indicated configuration.

◆ config()

PSKConfig & tinymodem::PSKDecoder::config ( )

inline

The configuration which was provided in begin().

◆ decide()

void tinymodem::PSKDecoder::decide ( )

inlineprotected

Bit decision from the phase difference to the previous symbol.

◆ defaultConfig()

PSKConfig tinymodem::PSKDecoder::defaultConfig ( )

inline

Provides a default configuration: psk31.

◆ end()

void tinymodem::PSKDecoder::end ( )

inlineoverride

Processes the remaining samples and reports the end of the carrier.

◆ endOfCarrier()

void tinymodem::PSKDecoder::endOfCarrier ( )

inlineprotected

◆ flush()

void tinymodem::PSKDecoder::flush ( )

inlineoverridevirtual

Processes the remaining samples (e.g. at the end of the input).

Implements tinymodem::ModemDecoder.

◆ frequencyOffset()

float tinymodem::PSKDecoder::frequencyOffset ( )

inline

Current frequency offset of the received signal in Hz.

◆ isCarrier()

bool tinymodem::PSKDecoder::isCarrier ( )

inlineoverridevirtual

true while a transmission is received

Implements tinymodem::ModemDecoder.

◆ isFinished()

bool tinymodem::PSKDecoder::isFinished ( )

inlineoverridevirtual

true if the decoding was stopped (rx_one)

Implements tinymodem::ModemDecoder.

◆ mfskVaricode()

void tinymodem::PSKDecoder::mfskVaricode ( int bit )

inlineprotected

MFSK Varicode (8PSK): a character ends with "001".

◆ noise()

float tinymodem::PSKDecoder::noise ( )

inlineprotected

uniform random value in the range -0.5 to 0.5

◆ operator bool()

tinymodem::PSKDecoder::operator bool ( )

inlineoverride

◆ output()

void tinymodem::PSKDecoder::output ( uint8_t ch )

inlineprotected

◆ positions()

int tinymodem::PSKDecoder::positions ( )

inlineprotected

number of phase positions

◆ recalculate()

void tinymodem::PSKDecoder::recalculate ( )

inlineprotected

Avoids the accumulation of rounding errors.

◆ releaseHeld()

void tinymodem::PSKDecoder::releaseHeld ( )

inlineprotected

◆ resetState()

void tinymodem::PSKDecoder::resetState ( )

inlineprotected

◆ setAudioInfo()

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

inlineoverride

Defines the format of the input audio data.

◆ setFrequencyOffset()

void tinymodem::PSKDecoder::setFrequencyOffset ( float offset )

inlineprotected

◆ startOfCarrier()

void tinymodem::PSKDecoder::startOfCarrier ( float amplitude )

inlineprotected

◆ updateTiming()

void tinymodem::PSKDecoder::updateTiming ( )

inlineprotected

The decision time is the circular center of the energy distribution.

◆ varicode()

void tinymodem::PSKDecoder::varicode ( int bit )

inlineprotected

Collects the bits of a character: characters are separated by "00".

◆ write()

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

inlineoverride

Provide PCM data to the decoder.

Member Data Documentation

◆ AFC_GAIN

float tinymodem::PSKDecoder::AFC_GAIN = 0.1f

staticconstexprprotected

◆ amplitude_total

float tinymodem::PSKDecoder::amplitude_total = 0

protected

◆ bin_count

int tinymodem::PSKDecoder::bin_count[BINS]

protected

◆ bin_sum

float tinymodem::PSKDecoder::bin_sum[BINS]

protected

◆ BINS

int tinymodem::PSKDecoder::BINS = 16

staticconstexprprotected

◆ carrier

bool tinymodem::PSKDecoder::carrier = false

protected

◆ cfg

PSKConfig tinymodem::PSKDecoder::cfg

protected

◆ code

uint16_t tinymodem::PSKDecoder::code = 0

protected

◆ countdown

float tinymodem::PSKDecoder::countdown = 0

protected

◆ freq_offset

float tinymodem::PSKDecoder::freq_offset = 0

protected

◆ held

uint8_t tinymodem::PSKDecoder::held[MAX_ONES]

protected

◆ hist

float tinymodem::PSKDecoder::hist[BINS]

protected

◆ history

audio_tools::Vector<float> tinymodem::PSKDecoder::history

protected

◆ input

PcmInput tinymodem::PSKDecoder::input

protected

◆ is_active

bool tinymodem::PSKDecoder::is_active = false

protected

◆ is_finished

bool tinymodem::PSKDecoder::is_finished = false

protected

◆ last_bit

int tinymodem::PSKDecoder::last_bit = 1

protected

◆ LOST_LEVEL

float tinymodem::PSKDecoder::LOST_LEVEL = 0.3f

staticconstexprprotected

◆ MAX_CORRECTION

float tinymodem::PSKDecoder::MAX_CORRECTION = 0.125f

staticconstexprprotected

◆ MAX_ONES

int tinymodem::PSKDecoder::MAX_ONES = 20

staticconstexprprotected

◆ MAX_WEAK

int tinymodem::PSKDecoder::MAX_WEAK = 3

staticconstexprprotected

the signal is lost after MAX_WEAK symbols below LOST_LEVEL

◆ mfsk_code

uint32_t tinymodem::PSKDecoder::mfsk_code = 0

protected

◆ MIN_PREAMBLE

int tinymodem::PSKDecoder::MIN_PREAMBLE = 8

staticconstexprprotected

◆ nco_im

float tinymodem::PSKDecoder::nco_im = 0

protected

◆ nco_re

float tinymodem::PSKDecoder::nco_re = 1

protected

◆ ndata

unsigned tinymodem::PSKDecoder::ndata = 0

protected

◆ nheld

int tinymodem::PSKDecoder::nheld = 0

protected

◆ noise_seed

uint32_t tinymodem::PSKDecoder::noise_seed = 1

protected

◆ nsymbols

unsigned tinymodem::PSKDecoder::nsymbols = 0

protected

◆ ones

int tinymodem::PSKDecoder::ones = 0

protected

◆ phase

float tinymodem::PSKDecoder::phase = 0

protected

◆ pos

int tinymodem::PSKDecoder::pos = 0

protected

◆ prev_i

float tinymodem::PSKDecoder::prev_i = 0

protected

◆ prev_q

float tinymodem::PSKDecoder::prev_q = 0

protected

◆ qpsk

QPSKCode tinymodem::PSKDecoder::qpsk

protected

◆ quality

float tinymodem::PSKDecoder::quality = 0

protected

◆ quality_m

float tinymodem::PSKDecoder::quality_m = 0

protected

◆ quality_total

float tinymodem::PSKDecoder::quality_total = 0

protected

◆ sample_count

uint32_t tinymodem::PSKDecoder::sample_count = 0

protected

◆ samples_per_symbol

float tinymodem::PSKDecoder::samples_per_symbol = 0

protected

◆ step_im

float tinymodem::PSKDecoder::step_im = 0

protected

◆ step_re

float tinymodem::PSKDecoder::step_re = 1

protected

◆ sum_i

float tinymodem::PSKDecoder::sum_i = 0

protected

◆ sum_power

float tinymodem::PSKDecoder::sum_power = 0

protected

◆ sum_q

float tinymodem::PSKDecoder::sum_q = 0

protected

◆ target

float tinymodem::PSKDecoder::target = 0.5f

protected

◆ TIMING_GAIN

float tinymodem::PSKDecoder::TIMING_GAIN = 0.5f

staticconstexprprotected

◆ TIMING_SMOOTHING

float tinymodem::PSKDecoder::TIMING_SMOOTHING = 0.15f

staticconstexprprotected

◆ track_amplitude

float tinymodem::PSKDecoder::track_amplitude = 0

protected

◆ weak

int tinymodem::PSKDecoder::weak = 0

protected

◆ window

int tinymodem::PSKDecoder::window = 0

protected

◆ zeros

int tinymodem::PSKDecoder::zeros = 0

protected

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

src/modem/PSKDecoder.h

Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ PSKDecoder() [1/2]

◆ PSKDecoder() [2/2]

Member Function Documentation

◆ addSample()

◆ audioInfo()

◆ begin() [1/2]

◆ begin() [2/2]

◆ config()

◆ decide()

◆ defaultConfig()

◆ end()

◆ endOfCarrier()

◆ flush()

◆ frequencyOffset()

◆ isCarrier()

◆ isFinished()

◆ mfskVaricode()

◆ noise()

◆ operator bool()

◆ output()

◆ positions()

◆ recalculate()

◆ releaseHeld()

◆ resetState()

◆ setAudioInfo()

◆ setFrequencyOffset()

◆ startOfCarrier()

◆ updateTiming()

◆ varicode()

◆ write()

Member Data Documentation

◆ AFC_GAIN

◆ amplitude_total

◆ bin_count

◆ bin_sum

◆ BINS

◆ carrier

◆ cfg

◆ code

◆ countdown

◆ freq_offset

◆ held

◆ hist

◆ history

◆ input

◆ is_active

◆ is_finished

◆ last_bit

◆ LOST_LEVEL

◆ MAX_CORRECTION

◆ MAX_ONES

◆ MAX_WEAK

◆ mfsk_code

◆ MIN_PREAMBLE

◆ nco_im

◆ nco_re

◆ ndata

◆ nheld

◆ noise_seed

◆ nsymbols

◆ ones

◆ phase

◆ pos

◆ prev_i

◆ prev_q

◆ qpsk

◆ quality

◆ quality_m

◆ quality_total

◆ sample_count

◆ samples_per_symbol

◆ step_im

◆ step_re

◆ sum_i