Estimate cross-power spectra using Welch' method of spectral estimation. The exact amount of overlap in Welch' method is rounded up to a certain amount of samples. More...

#include <lasp_avpowerspectra.h>

Public Member Functions
	AvPowerSpectra (const us nfft=2048, const Window::WindowType w=Window::WindowType::Hann, const d overlap_percentage=50., const d fs_tau=-1)
	Initalize averaged power spectra computer. If a time constant is given > 0, it is used in a kind of exponential weighting.

	AvPowerSpectra (const AvPowerSpectra &)=delete

AvPowerSpectra &	operator= (const AvPowerSpectra &)=delete

void	reset ()
	Reset to empty state. Clears the time buffer and sets estimator to empty.

ccube	compute (const dmat &timedata)
	Compute an update of the power spectra based on given time data. Note that the number of channels is determined from the first time this function is called. If a later call has an incompatible number of channels, a runtime error is thrown.

ccube	get_est () const
	Returns the latest estimate of cps (cross-power spectra.

us	exactOverlapSamples () const
	The overlap is rounded to a certain amount of time samples. This function returns that value.

Detailed Description

Estimate cross-power spectra using Welch' method of spectral estimation. The exact amount of overlap in Welch' method is rounded up to a certain amount of samples.

Definition at line 76 of file lasp_avpowerspectra.h.

Constructor & Destructor Documentation

◆ AvPowerSpectra() [1/2]

AvPowerSpectra::AvPowerSpectra	(	const us	nfft = `2048`,
		const Window::WindowType	w = `Window::WindowType::Hann`,
		const d	overlap_percentage = `50.`,
		const d	fs_tau = `-1`
	)

Initalize averaged power spectra computer. If a time constant is given > 0, it is used in a kind of exponential weighting.

Parameters

nfft	The fft length
w	The window type.
overlap_percentage	A number 0 < overlap_percentage <= 100. It determines the amount of overlap used in Welch' method. A typical value is 50 %, i.e. 50.
fs_tau	Value should either be < 0, indicating that the estimate is averages over all time data. For a value = 0 the instantaneous power spectrum is returned, which can be interpreted as the spectrogram. For a value > 0 a exponential forgetting is used, where the value is used as the time constant such that the decay follows approximately the trend exp(-n/fs_tau), where n is the sample number in the power spectra. To choose 'fast' time weighting, set time_constant to the value of fs*0.125, where fs denotes the sampling frequency.

Definition at line 55 of file lasp_avpowerspectra.cpp.

◆ AvPowerSpectra() [2/2]

AvPowerSpectra::AvPowerSpectra ( const AvPowerSpectra & )

delete

Member Function Documentation

◆ compute()

ccube AvPowerSpectra::compute ( const dmat & timedata )

Compute an update of the power spectra based on given time data. Note that the number of channels is determined from the first time this function is called. If a later call has an incompatible number of channels, a runtime error is thrown.

Parameters

timedata

Returns: a copy of the latest estimate of the power spectra. an update is only given if the amount of new time data is enough to compute a new estimate. if no new estimate is available, it returns an empty ccube. Note that the latest available estimate can be obtained using get_est().

Return a copy of current estimator in case we have done one update. Othewise, we return an empty ccube.

Definition at line 88 of file lasp_avpowerspectra.cpp.

◆ exactOverlapSamples()

us AvPowerSpectra::exactOverlapSamples ( ) const

inline

The overlap is rounded to a certain amount of time samples. This function returns that value.

Returns: The amount of samples in overlapping.

Definition at line 167 of file lasp_avpowerspectra.h.

◆ get_est()

ccube AvPowerSpectra::get_est ( ) const

Returns the latest estimate of cps (cross-power spectra.

Returns: a copy of the latest estimate of the power spectra. an update is only given if the amount of new time data is enough to compute a new estimate. If no estimate is available, it returns an empty ccube.

Definition at line 134 of file lasp_avpowerspectra.cpp.

◆ operator=()

AvPowerSpectra & AvPowerSpectra::operator= ( const AvPowerSpectra & )

delete

◆ reset()

void AvPowerSpectra::reset ( )

Reset to empty state. Clears the time buffer and sets estimator to empty.

Definition at line 81 of file lasp_avpowerspectra.cpp.

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

src/lasp/dsp/lasp_avpowerspectra.h
src/lasp/dsp/lasp_avpowerspectra.cpp

Public Member Functions