A simple (Audio) Frequency Shift Keying (AFSK) demodulator. More...

#include <afsk.hh>

Inheritance diagram for sdr::AFSK:

Public Types
enum	Mode { NORMAL, TRANSITION }
	Possible bit decoding modes. More...

Public Member Functions
	AFSK (double baud=1200.0, double Fmark=1200.0, double Fspace=2200.0, Mode mode=TRANSITION)
	Constructs a AFSK node with the specified `baud` rate and `Fmark`, `Fspace` frequencies. More...

virtual	~AFSK ()
	Destructor. More...

virtual void	config (const Config &src_cfg)
	Configures the node. More...

virtual void	process (const Buffer< int16_t > &buffer, bool allow_overwrite)
	Processes the given buffer. More...

Public Member Functions inherited from sdr::Sink< int16_t >
	Sink ()
	Constructor. More...

virtual	~Sink ()
	Drestructor. More...

virtual void	handleBuffer (const RawBuffer &buffer, bool allow_overwrite)
	Re-implemented from `SinkBase`. More...

Public Member Functions inherited from sdr::SinkBase
	SinkBase ()
	Constructor. More...

virtual	~SinkBase ()
	Destructor. More...

Public Member Functions inherited from sdr::Source
	Source ()
	Constructor. More...

virtual	~Source ()
	Destructor. More...

virtual void	send (const RawBuffer &buffer, bool allow_overwrite=false)
	Sends the given buffer to all connected sinks. More...

void	connect (SinkBase *sink, bool direct=false)
	Connect this source to a sink. More...

void	disconnect (SinkBase *sink)
	Disconnect a sink again. More...

virtual void	setConfig (const Config &config)
	Stores the configuration and propergates it if the configuration has been changed. More...

virtual double	sampleRate () const
	Returns the configured sample rate or `0` otherwise. More...

virtual Config::Type	type () const
	Returns the configured source type or `Config::Type_UNDEFINED` otherwise. More...

template<class T >
void	addEOS (T instance, void(T::function)())
	Adds a callback to the end-of-stream signal of the source. More...

Protected Member Functions
double	_getSymbol ()
	Performs the convolution filtering of the mark & space frequencies. More...

Protected Member Functions inherited from sdr::Source
void	signalEOS ()
	Signals the EOS. More...

void	propagateConfig (const Config &config)
	Propagates the given configuration to all connected sinks. More...

Protected Attributes
float	_sampleRate
	The sample rate of the input signal. More...

float	_symbolRate
	A multiple of the baud rate. More...

float	_baud
	The baud rate. More...

float	_Fmark
	Mark "tone" frequency. More...

float	_Fspace
	Space "tone" frequency. More...

Mode	_mode
	Bit encoding mode. More...

uint32_t	_corrLen
	Correlation length, the number of "symbols" per bit. More...

uint32_t	_lutIdx
	The current FIR filter LUT index. More...

Buffer< std::complex< float > >	_markLUT
	Mark frequency FIR filter LUT. More...

Buffer< std::complex< float > >	_spaceLUT
	Space frequency FIR filter LUT. More...

Buffer< std::complex< float > >	_markHist
	FIR filter buffer. More...

Buffer< std::complex< float > >	_spaceHist
	FIR filter buffer. More...

float	_mu
	Symbol subsampling counter. More...

float	_muIncr
	Symbol subsampling. More...

Buffer< float >	_dl
	Delay line for the 8-pole interpolation filter. More...

size_t	_dl_idx
	Delay line index. More...

Buffer< int16_t >	_symbols
	Ring buffer of the last `_corrLen` symbols. More...

size_t	_symbolIdx
	Insertion index. More...

int32_t	_symSum
	Sum of the current `_corrLen` symbols. More...

int32_t	_lastSymSum
	Sum of the last `_corrLen` symbols. More...

uint32_t	_lastBits
	Last received bits. More...

float	_phase
	Current PLL phase. More...

float	_omega
	PLL phase speed. More...

float	_omegaMin
	Maximum PLL phase speed. More...

float	_omegaMax
	Minimum PLL phase speed. More...

float	_gainOmega
	PLL gain. More...

Buffer< uint8_t >	_buffer
	Output buffer. More...

Protected Attributes inherited from sdr::Source
Config	_config
	Holds the source configuration, this can be updated by calling `setConfig`. More...

std::map< SinkBase *, bool >	_sinks
	The connected sinks. More...

std::list< DelegateInterface * >	_eos
	The connected EOS singal handlers. More...

Detailed Description

A simple (Audio) Frequency Shift Keying (AFSK) demodulator.

This node consists of two convolution peak-filters at the mark and space frequencies, a interpolating sub-sampler to match the baud-rate exactly and a PLL to lock to the symbol transitions. The node will decode the (A)FSK signal and will send a bit-stream (uint8_t).

Constructor & Destructor Documentation

AFSK::AFSK	(	double	baud = `1200.0`,
		double	Fmark = `1200.0`,
		double	Fspace = `2200.0`,
		Mode	mode = `TRANSITION`
	)

Constructs a AFSK node with the specified baud rate and Fmark, Fspace frequencies.

The default valuse corresponds to those used for 1200 baud packet radio.

AFSK::~AFSK ( )

virtual

Destructor.

Member Function Documentation

double sdr::AFSK::_getSymbol ( )

inlineprotected

Performs the convolution filtering of the mark & space frequencies.

void AFSK::config ( const Config & src_cfg )

virtual

Configures the node.

Implements sdr::SinkBase.

void AFSK::process	(	const Buffer< int16_t > &	buffer,
		bool	allow_overwrite
	)

virtual

Processes the given buffer.

std::cerr << "Transition at phi=" << _phase << std::endl << " update omega from " << _omega << " to ";

Implements sdr::Sink< int16_t >.

Member Data Documentation

float sdr::AFSK::_baud

protected

The baud rate.

Buffer<uint8_t> sdr::AFSK::_buffer

protected

Output buffer.

uint32_t sdr::AFSK::_corrLen

protected

Correlation length, the number of "symbols" per bit.

Buffer< float > sdr::AFSK::_dl

protected

Delay line for the 8-pole interpolation filter.

size_t sdr::AFSK::_dl_idx

protected

Delay line index.

float sdr::AFSK::_Fmark

protected

Mark "tone" frequency.

float sdr::AFSK::_Fspace

protected

Space "tone" frequency.

float sdr::AFSK::_gainOmega

protected

PLL gain.

uint32_t sdr::AFSK::_lastBits

protected

Last received bits.

int32_t sdr::AFSK::_lastSymSum

protected

Sum of the last _corrLen symbols.

uint32_t sdr::AFSK::_lutIdx

protected

The current FIR filter LUT index.

Buffer< std::complex<float> > sdr::AFSK::_markHist

protected

FIR filter buffer.

Buffer< std::complex<float> > sdr::AFSK::_markLUT

protected

Mark frequency FIR filter LUT.

Mode sdr::AFSK::_mode

protected

Bit encoding mode.

float sdr::AFSK::_mu

protected

Symbol subsampling counter.

float sdr::AFSK::_muIncr

protected

Symbol subsampling.

float sdr::AFSK::_omega

protected

PLL phase speed.

float sdr::AFSK::_omegaMax

protected

Minimum PLL phase speed.

float sdr::AFSK::_omegaMin

protected

Maximum PLL phase speed.

float sdr::AFSK::_phase

protected

Current PLL phase.

float sdr::AFSK::_sampleRate

protected

The sample rate of the input signal.

Buffer< std::complex<float> > sdr::AFSK::_spaceHist

protected

FIR filter buffer.

Buffer< std::complex<float> > sdr::AFSK::_spaceLUT

protected

Space frequency FIR filter LUT.

size_t sdr::AFSK::_symbolIdx

protected

Insertion index.

float sdr::AFSK::_symbolRate

protected

A multiple of the baud rate.

Buffer<int16_t> sdr::AFSK::_symbols

protected

Ring buffer of the last _corrLen symbols.

int32_t sdr::AFSK::_symSum

protected

Sum of the current _corrLen symbols.

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

/Users/hannes/Uni/Elektronik/sdr/libsdr/src/afsk.hh
/Users/hannes/Uni/Elektronik/sdr/libsdr/src/afsk.cc

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation