A simple BPSK31 "demodulator". More...

#include <psk31.hh>

Inheritance diagram for sdr::BPSK31< Scalar >:

Public Member Functions
	BPSK31 (double dF=0.1)
	Constructs a new BPSK31 demodulator. More...

virtual	~BPSK31 ()
	Destructor. More...

virtual void	config (const Config &src_cfg)
	Needs to be implemented by any sub-type to check and perform the configuration of the node. More...

virtual void	process (const Buffer< std::complex< Scalar > > &buffer, bool allow_overwrite)
	Needs to be implemented by any sub-type to process the received data. More...

Public Member Functions inherited from sdr::Sink< std::complex< Scalar > >
	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
bool	_hasTransition () const
	Returns `true` if there is a phase transition at the current sample. More...

int	_currentContellation () const
	Returns the current constellation. More...

float	_phaseError (const std::complex< float > &value) const
	Computes the phase error. More...

void	_updatePLL (const std::complex< float > &sample)
	Updates the PLL (`_F` and `_P`). More...

void	_updateSampler (const std::complex< Scalar > &value)
	Updates the sub-sampler. More...

void	_errorTracking (const std::complex< float > &sample)
	Updates the PPL state (`_mu` and `_omega`). 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
size_t	_superSample
	Holds the number of phase constellations per bit. More...

float	_P
	Phase of the carrier PLL. More...

float	_F
	Frequency of the carrier PLL. More...

float	_Fmin
	Lower frequency limit of the carrier PLL. More...

float	_Fmax
	Upper frequency limit of the carrier PLL. More...

float	_alpha
	Gain factor of the carrier PLL. More...

float	_beta
	Gain factor of the carrier PLL. More...

Buffer< std::complex< float > >	_dl
	The delay line for the interpolating sub-sampler. More...

size_t	_dl_idx
	The current index of the delay line. More...

float	_mu
	Holds the fractional sub-sampling counter. More...

float	_gain_mu
	Gain factor of the sub-sampler. More...

float	_theta
	Constant phase shift between real axis and first constellation. More...

float	_omega
	Current sub-sample rate. More...

float	_omega_rel
	Relative error of the subsample rate. More...

float	_min_omega
	Minimum of the sub-sample rate. More...

float	_max_omega
	Maximum of the sub-sample rate. More...

float	_gain_omega
	Gain of the sub-sample rate correction. More...

std::complex< float >	_p_0T
	Phase at T = 0 (samples). More...

std::complex< float >	_p_1T
	Phase at T=-1 (samples). More...

std::complex< float >	_p_2T
	Phase at T=-2 (samples). More...

std::complex< float >	_c_0T
	Constellation at T=0 (samples). More...

std::complex< float >	_c_1T
	Constellation at T=-1 (samples). More...

std::complex< float >	_c_2T
	Constellation at T=-2 (samples). More...

Buffer< float >	_hist
	The last `_superSample` phases. More...

size_t	_hist_idx
	Current phase history index. More...

int	_last_constellation
	The last output constellation. 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

template<class Scalar>
class sdr::BPSK31< Scalar >

A simple BPSK31 "demodulator".

This node consumes a complex input stream with a sample rate of at least 2000Hz and produces a bitstream with 31.25 Hz "sample rate". Use the Varicode node to decode this bitstream to ASCII chars. The BPSK31 signal should be centered around 0Hz. This node uses a simple PLL to adjust for small detunings.

Constructor & Destructor Documentation

template<class Scalar >

sdr::BPSK31< Scalar >::BPSK31 ( double dF = 0.1 )

inline

Constructs a new BPSK31 demodulator.

This node first subsamples the input signal to a multiple of 31.25 Hz (by default to 2000Hz = 64*31.25) using an interpolating sub-sampler. Therefore, the input signal must be filtered sufficiently well to avoid artifacts of the interpolating sub-sampler. Then, the phase-constellation of the signal is determined as either -pi or pi while the frequency of the carrier is tracked using a simple PLL. Finally, the BPSK31 bit stream is decoded by detecting a phase-change (0) or not (1).

Note: This node uses floating point arithmetic, hence it should not be used on streams with a high sample rate! Which is not neccessary as it only decodes a BPSK signal with approx. 31 baud.

Parameters

dF	Specfies the (relative anglular) frequency range of the PLL to adjust for small deviations of the BPSK31 signal from 0Hz.

template<class Scalar >

virtual sdr::BPSK31< Scalar >::~BPSK31 ( )

inlinevirtual

Destructor.

Member Function Documentation

template<class Scalar >

int sdr::BPSK31< Scalar >::_currentContellation ( ) const

inlineprotected

Returns the current constellation.

template<class Scalar >

void sdr::BPSK31< Scalar >::_errorTracking ( const std::complex< float > & sample )

inlineprotected

Updates the PPL state (_mu and _omega).

template<class Scalar >

bool sdr::BPSK31< Scalar >::_hasTransition ( ) const

inlineprotected

Returns true if there is a phase transition at the current sample.

template<class Scalar >

float sdr::BPSK31< Scalar >::_phaseError ( const std::complex< float > & value ) const

inlineprotected

Computes the phase error.

template<class Scalar >

void sdr::BPSK31< Scalar >::_updatePLL ( const std::complex< float > & sample )

inlineprotected

Updates the PLL (_F and _P).

template<class Scalar >

void sdr::BPSK31< Scalar >::_updateSampler ( const std::complex< Scalar > & value )

inlineprotected

Updates the sub-sampler.

template<class Scalar >

virtual void sdr::BPSK31< Scalar >::config ( const Config & src_cfg )

inlinevirtual

Needs to be implemented by any sub-type to check and perform the configuration of the node.

Implements sdr::SinkBase.

template<class Scalar >

virtual void sdr::BPSK31< Scalar >::process	(	const Buffer< std::complex< Scalar > > &	buffer,
		bool	allow_overwrite
	)

inlinevirtual

Needs to be implemented by any sub-type to process the received data.

Implements sdr::Sink< std::complex< Scalar > >.

Member Data Documentation

template<class Scalar >

float sdr::BPSK31< Scalar >::_alpha

protected

Gain factor of the carrier PLL.

template<class Scalar >

float sdr::BPSK31< Scalar >::_beta

protected

Gain factor of the carrier PLL.

template<class Scalar >

Buffer<uint8_t> sdr::BPSK31< Scalar >::_buffer

protected

Output buffer.

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_c_0T

protected

Constellation at T=0 (samples).

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_c_1T

protected

Constellation at T=-1 (samples).

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_c_2T

protected

Constellation at T=-2 (samples).

template<class Scalar >

Buffer< std::complex<float> > sdr::BPSK31< Scalar >::_dl

protected

The delay line for the interpolating sub-sampler.

template<class Scalar >

size_t sdr::BPSK31< Scalar >::_dl_idx

protected

The current index of the delay line.

template<class Scalar >

float sdr::BPSK31< Scalar >::_F

protected

Frequency of the carrier PLL.

template<class Scalar >

float sdr::BPSK31< Scalar >::_Fmax

protected

Upper frequency limit of the carrier PLL.

template<class Scalar >

float sdr::BPSK31< Scalar >::_Fmin

protected

Lower frequency limit of the carrier PLL.

template<class Scalar >

float sdr::BPSK31< Scalar >::_gain_mu

protected

Gain factor of the sub-sampler.

template<class Scalar >

float sdr::BPSK31< Scalar >::_gain_omega

protected

Gain of the sub-sample rate correction.

template<class Scalar >

Buffer<float> sdr::BPSK31< Scalar >::_hist

protected

The last _superSample phases.

template<class Scalar >

size_t sdr::BPSK31< Scalar >::_hist_idx

protected

Current phase history index.

template<class Scalar >

int sdr::BPSK31< Scalar >::_last_constellation

protected

The last output constellation.

template<class Scalar >

float sdr::BPSK31< Scalar >::_max_omega

protected

Maximum of the sub-sample rate.

template<class Scalar >

float sdr::BPSK31< Scalar >::_min_omega

protected

Minimum of the sub-sample rate.

template<class Scalar >

float sdr::BPSK31< Scalar >::_mu

protected

Holds the fractional sub-sampling counter.

template<class Scalar >

float sdr::BPSK31< Scalar >::_omega

protected

Current sub-sample rate.

template<class Scalar >

float sdr::BPSK31< Scalar >::_omega_rel

protected

Relative error of the subsample rate.

template<class Scalar >

float sdr::BPSK31< Scalar >::_P

protected

Phase of the carrier PLL.

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_p_0T

protected

Phase at T = 0 (samples).

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_p_1T

protected

Phase at T=-1 (samples).

template<class Scalar >

std::complex<float> sdr::BPSK31< Scalar >::_p_2T

protected

Phase at T=-2 (samples).

template<class Scalar >

size_t sdr::BPSK31< Scalar >::_superSample

protected

Holds the number of phase constellations per bit.

template<class Scalar >

float sdr::BPSK31< Scalar >::_theta

protected

Constant phase shift between real axis and first constellation.

(Currently unused).

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

/Users/hannes/Uni/Elektronik/sdr/libsdr/src/psk31.hh

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

template<class Scalar> class sdr::BPSK31< Scalar >

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

template<class Scalar>
class sdr::BPSK31< Scalar >