Sample Class Reference

Transform discrete time series. More...

#include <Sample.h>

Inheritance diagram for Sample:

Collaboration diagram for Sample:

Public Member Functions
double	GetHighPassFrequency (void)
	Returns the current highpass frequency. More...
unsigned int	GetNativeFrequency (void)
	Returns the current native sampling frequency [Hz]. More...
unsigned int	GetWindowSize (void)
	Returns the window size (=0 if no windowing). More...
unsigned int	GetWorkingFrequency (void)
	Returns the current working sampling frequency [Hz]. More...
void	SetDCRemoval (const bool aDCremove=true)
	Activates/Deactivates the DC removal. More...
bool	SetFrequencies (const unsigned int aNativeFrequency, const unsigned int aWorkingFrequency, const double aHighPassFrequency=0.0)
	Defines frequencies for the transformation. More...
bool	SetHighPassFrequency (const double aHighPassFrequency)
	Defines a highpass frequency. More...
bool	SetNativeFrequency (const int aNativeFrequency)
	Sets a new native sampling frequency. More...
void	SetWindow (const unsigned int aWindowSize, double *aWindow)
	Defines the window. More...
bool	SetWorkingFrequency (const unsigned int aWorkingFrequency)
	Sets a new working sampling frequency. More...
bool	Transform (const unsigned int aInSize, double *aInData, const unsigned int aOutSize, double *aOutData)
	Transforms data. More...
Constructors and destructors
	Sample (const unsigned int aVerbosity=0)
	Constructor of the Sample class. More...
virtual	~Sample (void)
	Destructor of the Sample class. More...

Protected Attributes
double	fHighPassFrequency
	Cutoff frequency. More...
unsigned int	fNativeFrequency
	Native sampling frequency. More...
bool	fRemoveDC
	DC removal flag. More...
unsigned int	fVerbosity
	Verbosity level. More...
double *	fWindow
	Window. More...
unsigned int	fWindowSize
	Window size. More...
unsigned int	fWorkingFrequency
	Working sampling frequency. More...

Private Member Functions
void	HighPass (const unsigned int aSize, double *aData)
	Highpasses the data. More...
void	MakeHighPassFilters (void)
	Constructs the highpass filters. More...
void	MakeSamplingFilters (void)
	Constructs the re-sampling filters. More...
void	PreSample (unsigned int &aSize, double *aData)
	Pre-samples the data. More...
void	RemoveDC (const unsigned int aSize, double *aData)
	Removes the DC component. More...
void	Resample (unsigned int aSize, double *aInData, double *aOutData)
	Re-samples the data. More...

Private Attributes
unsigned int	fIntermediateFrequency
	Intermediate sampling frequency. More...
unsigned int	fResampleFactor
	Resampling factor (>=1). More...
IIRFilter *	iirFilter [NORDER]
	Downsampling filters. More...
IIRFilter *	iirFilterHP [NORDERHP]
	Highpass filters. More...
bool	presample
	Pre-sample flag. More...

Detailed Description

Transform discrete time series.

A timeseries, sampled at a native frequency is transformed in the time domain. Supported transformations (in this order):

• Remove DC frequency
• High-pass filter (order=12)
• Window the data
• Resample to a working frequency

Once the transformations are configured, call Transform() to transform your timeseries.

Author

Florent Robinet

Constructor & Destructor Documentation

Sample()

Sample::Sample

(

const unsigned int

aVerbosity = 0

)

Constructor of the Sample class.

Parameters

[in]

aVerbosity

Verbosity level.

~Sample()

Sample::~Sample ( void  )

virtual

Destructor of the Sample class.

Member Function Documentation

GetHighPassFrequency()

double Sample::GetHighPassFrequency ( void  )

inline

Returns the current highpass frequency.

GetNativeFrequency()

unsigned int Sample::GetNativeFrequency ( void  )

inline

Returns the current native sampling frequency [Hz].

GetWindowSize()

unsigned int Sample::GetWindowSize ( void  )

inline

Returns the window size (=0 if no windowing).

GetWorkingFrequency()

unsigned int Sample::GetWorkingFrequency ( void  )

inline

Returns the current working sampling frequency [Hz].

HighPass()

void Sample::HighPass ( const unsigned int  aSize, double *  aData  )

private

Highpasses the data.

The data vector, sampled at the native frequency, is highpassed.

Parameters

[in]	aSize	Data vector size.
[in,out]	aData	Pointer to the data vector.

MakeHighPassFilters()

void Sample::MakeHighPassFilters ( void  )

private

Constructs the highpass filters.

Using Highpass frequency and Native frequency.

MakeSamplingFilters()

void Sample::MakeSamplingFilters ( void  )

private

Constructs the re-sampling filters.

Using Native frequency and Working frequency.

PreSample()

void Sample::PreSample ( unsigned int &  aSize, double *  aData  )

private

Pre-samples the data.

The input data vector is resampled to the power-of-two just below.

Note

The output vector size does not change. However, the returned size gets smaller!

Parameters

[in,out]	aSize	Data vector size.
[in,out]	aData	Pointer to the data vector.

RemoveDC()

void Sample::RemoveDC ( const unsigned int  aSize, double *  aData  )

private

Removes the DC component.

Parameters

[in]	aSize	Data vector size.
[in,out]	aData	Pointer to the data vector.

Resample()

void Sample::Resample ( unsigned int  aSize, double *  aInData, double *  aOutData  )

private

Re-samples the data.

The input data vector, sampled at the native frequency, is resampled to the working frequency.

Warning

The output vector must be the right size (fWorkingFrequency)!

Parameters

[in]	aSize	Input data vector size.
[in]	aInData	Pointer to the input data vector.
[out]	aOutData	Pointer to the output data vector.

SetDCRemoval()

void Sample::SetDCRemoval ( const bool  aDCremove = true )

inline

Activates/Deactivates the DC removal.

The DC component is computed and is subtracted from all data samples. The final vector has a DC component equal to 0.

Parameters

[in]

aDCremove

Activate/deactivate the DC removal.

SetFrequencies()

bool Sample::SetFrequencies	(	const unsigned int	aNativeFrequency,
		const unsigned int	aWorkingFrequency,
		const double	aHighPassFrequency = 0.0
	)

Defines frequencies for the transformation.

It is possible to work with a sampling frequency smaller than the native frequency, often for performance reasons. It must be an integer value and a power of 2. When transformed (see Transform()), the input data are first downsampled to the working frequency with an anti-aliasing filter.

It is also possible to highpass the data before downsampling.

Parameters

[in]	aNativeFrequency	Native sampling frequency [Hz].
[in]	aWorkingFrequency	Working sampling frequency [Hz].
[in]	aHighPassFrequency	Highpass frequency [Hz].

Returns

true if the frequencies were successfuly changed, false otherwise.

SetHighPassFrequency()

bool Sample::SetHighPassFrequency ( const double  aHighPassFrequency )

inline

Defines a highpass frequency.

It is possible to highpass the data. This function sets a new highpass frequency. When transformed (see Transform()), the input data are filtered.

Parameters

[in]

aHighPassFrequency

Highpass frequency [Hz].

Returns

true if the frequency was successfuly changed, false otherwise.

SetNativeFrequency()

bool Sample::SetNativeFrequency ( const int  aNativeFrequency )

inline

Sets a new native sampling frequency.

Parameters

[in]

aNativeFrequency

New native sampling frequency [Hz].

Returns

true if the frequency was successfuly changed, false otherwise.

SetWindow()

void Sample::SetWindow ( const unsigned int  aWindowSize, double *  aWindow  )

inline

Defines the window.

Parameters

[in]	aWindowSize	Window size: it must match the size of input data when calling Transform().
[in]	aWindow	Array of window values.

SetWorkingFrequency()

bool Sample::SetWorkingFrequency ( const unsigned int  aWorkingFrequency )

inline

Sets a new working sampling frequency.

It is possible to work with a sampling frequency smaller than the native frequency, often for performance reasons. This function sets a new working frequency. It must be an integer value and a power of 2. When transformed (see Transform()), the input data are first downsampled to the working frequency with an anti-aliasing filter.

Parameters

[in]

aWorkingFrequency

New working sampling frequency [Hz].

Returns

true if the frequency was successfuly changed, false otherwise.

Transform()

bool Sample::Transform	(	const unsigned int	aInSize,
		double *	aInData,
		const unsigned int	aOutSize,
		double *	aOutData
	)

Transforms data.

The input data vector (time-domain) is transformed in this order:

• DC removal: RemoveDC()
• Highpass: HighPass()
• Window the data.
• Resampling: Resample()

The input and output vectors must have an integer duration.

Warning

The window is set with SetWindow(). The window size must match the input data size.

The memory for the output vector must be allocated with the right size before calling this function. No size check will be performed and the data size provided by the user will be trusted.

The input vector can be altered in case of presampling. Do not use after calling this function.

Parameters

[in]	aInSize	Input vector size.
[in]	aInData	Input vector.
[in]	aOutSize	Output vector size.
[in]	aOutData	Output vector.

Member Data Documentation

fHighPassFrequency

double Sample::fHighPassFrequency

protected

Cutoff frequency.

fIntermediateFrequency

unsigned int Sample::fIntermediateFrequency

private

Intermediate sampling frequency.

fNativeFrequency

unsigned int Sample::fNativeFrequency

protected

Native sampling frequency.

fRemoveDC

bool Sample::fRemoveDC

protected

DC removal flag.

fResampleFactor

unsigned int Sample::fResampleFactor

private

Resampling factor (>=1).

fVerbosity

unsigned int Sample::fVerbosity

protected

Verbosity level.

fWindow

double* Sample::fWindow

protected

Window.

fWindowSize

unsigned int Sample::fWindowSize

protected

Window size.

fWorkingFrequency

unsigned int Sample::fWorkingFrequency

protected

Working sampling frequency.

iirFilter

IIRFilter* Sample::iirFilter[NORDER]

private

Downsampling filters.

iirFilterHP

IIRFilter* Sample::iirFilterHP[NORDERHP]

private

Highpass filters.

presample

bool Sample::presample

private

Pre-sample flag.

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

• src/Streams/Sample.h
• src/Streams/Sample.cc