TSignalFilter Class — Dew Signal

public class TSignalFilter : TSignal

Apply a digital filter to the input signal.

Use this component to filter a signal: select from a large range of digital filters (FIR window / Parks-McClellan, IIR Butterworth / Chebyshev / Elliptic, median, moving-average, Savitzky-Golay, integer / fractional delay, differentiator, Hilbert, wavelet) and maintain a list of predefined filters. TSignalFilterDialog is the component editor.

For a linear filter with impulse response h the output is the convolution of the input x with h: y[n] = sum_k h[k] x[n-k]. For an IIR filter realised as second-order sections the recursion is y[n] = 1/a_0(sum_(k=0)^M b_k x[n-k] - sum_(k=1)^N a_k y[n-k]).

Design vs. external taps. When ExternalTaps is False the filter
is designed from Response, the design method and the band specification in Filters; the design only runs when Filters holds at least one template (otherwise the component is an identity pass-through and Taps stays empty). When ExternalTaps is True the user-supplied Taps are used directly (FIR taps, or IIR second-order sections interleaved as B_0,A_0,B_1,A_1,...).

The unit impulse response of a designed FIR equals its taps: h[n]=Taps[n]. A moving-average filter of length L uses $h[k]=1/L$ (DC gain 1). Set FloatPrecision on the operand before filling; the output Data follows the input precision.

Properties

Name	Type	Description
Active	Boolean	Set active to false to suppress the propagation of the Pull request and the subsequent call to the Update method.
AutoFilterOrder	Boolean	If True, the Order/FirLength of the IIR/FIR filters will be automatically estimed.
BandWidth	Double	Return the bandwidth of the signal.
BandwidthH	Double	Returns the upper bandwidth edge of the signal.
BandwidthL	Double	Returns the lower bandwidth edge of the signal.
Beta	Double	Beta is the parameter for the Kaiser window.
BlockAssign	Boolean	Block streaming of specific properties when storing only a "template".
ChannelCount	Int32	Get or set the number of channels multiplexed in the data property.
Complex	Boolean	Set this property to true, to request computation using complex numbers.
Continuous	Boolean	If True, the component will pass on the udpate request to the connected component.
Data	TVec	Stores the result of the processing.
DownDelay	Int32	The phase delay (must be less then DownSample) used by the multi-rate FIR filter.
DownSample	Int32	The downsample factor used by the multi-rate FIR filter.
Dt	Double	Time between two consecutive samples.
EditorActive	Boolean	Returns True, if the component editor is displayed.
ExternalTaps	Boolean	Set this property to True, if you have defined your own filter response and have placed the taps in the Taps property.
Filters	TFilterList	Holds a list of defined filters.
FirLength	Int32	Defines the length of the FIR/Median filter, if the AutoFilterOrder property is false.
FirMethod	TFirFilterMethod	Specifies the FIR filter design method to be used.
FloatPrecision	TMtxFloatPrecision	Set this property to request computation in 32bit/64bit precision with real/complex numbers.
FloatPrecisionLock	Boolean	Set this property to true to lock changes to FloatPrecision property.
FractionalDelay	Double	Defines the combined fractional delay of the input signal (integer + fraction).
FractionalDesignSpec	TFractionalImpulse	Defines the FIR filter properties used for fractional delay filtering.
GridDensity	Int32	Grid density used by the remez exchange algorithm for optimal FIR filter design.
HzRes	Double	Frequency resolution obtained, if an FFT algorithm would be run on the data.
IgnoreAtt	Boolean	Set it to True, if you want to explicitelly define the Beta parameter for the Kaiser window, when designing a FIR filter windowed with a Kaiser window.
IIRFrequencyTransform	TIirFrequencyTransform	Specifies the IIR frequency transformation method to use.
IirMethod	TIirFilterMethod	Specifies the IIR filter design method to be used.
Input	TAnalysis	Connector property to obtain a pointer to the TSignal component holding the data to be processed.
IsDouble	Boolean	Set this property to false, to request computation in 32bit floating point precision, 64bit, if true.
Item	Double	Default property to access values of a real signal.
ItemNumber	Int32	Number to label the object when it is an item in the List.
Length	Int32	Get or set the length of the signal in samples.
Marks	TMarkList	Stores the time stamps and amplitude of selected samples.
MaxAmplt	Double	Stores the maximum amplitude of the signal found by the MinMax method.
MaxX	Double	Use the MaxX property to store the time stamp (in seconds) of the right most sample.
MinAmplt	Double	Stores the minimum amplitude of the signal found by the MinMax method.
MinX	Double	Use the MinX property to store the time stamp of the left-most sample.
NormalizedFrequency	Double	The value of the normalized frequency used when defining multiband filters.
OnAfterUpdate	TNotifyEvent	The event is triggered after the call to the Update method.
OnBeforeUpdate	TNotifyEvent	The event is triggered just before the call to the Update method.
OnDisplayUpdate	TNotifyEvent	The event is triggered after the OnAfterUpdate event. Use this event to update any associated charts or graphs or result tables.
OnGetInput	TNotifyEvent	If the Input property is not assigned, the component will call OnGetInput.
OnNotifyUpdate	TNotifyEvent	The event is called after a call to InternalUpdate, OnAfterUpdate and OnDisplayUpdate from within the Update method.
OnParameterUpdate	TNotifyEvent	The event is triggered when ParamUpdate method is called. The ParamUpdate method is usually called by component editors when a value was changed by the user and the editor was "Live".
Order	Int32	Defines the order of the IIR filters, if AutoFilterOrder is false.
PipeState	TPipeState	Returns the state of the pipe after the last update.
Prepared	Boolean	Returns true, if the filter has been succesfully initialized.
Reference	TReferenceList	Stores a list of components that have to be notified, when this component is destroyed.
Response	TResponseType	Specifies the type of the filter, to be designed.
SamplingFrequency	Double	Defines the sampling frequency of the signal.
SamplingTime	Double	The length of the signal in seconds.
ScaleFactor	Double	Defines the factor by which to multiply the input signal.
SuspendNotifyUpdate	Boolean	Set this property to True, to prevent calling OnNotifyUpdate from the Update Method.
Taps	TVec	Holds the taps for the filter.
UpDelay	Int32	The phase delay (must be less then UpSample) used by the multi-rate FIR filter.
UpSample	Int32	The upsample factor used by the multi-rate FIR filter.
UseNormalizedFrequency	Boolean	True, if you want to normalize the frequency of the defined bands.
UsesInputs	Boolean	Set it to True to indicate, that valid signals will be connected to the Input or Inputs properties.
Wavelet	TWaveletType	Set the wavelet to be used for wavelete decomposition.
WaveletDecomp	TWaveletDecomp	Selects the result of wavelet decomposition.
WaveletP1	Int32	Defines the first wavelet parameter (if required).
WaveletP2	Int32	Defines the second wavelet parameter (if required.)
Window	TSignalWindowType	Specifies the window type to be used when designing windowed FIR filters.

Methods

Name	Description
AllowStreaming	Returns the negatated value of BlockAssign.
Append	Appends Sample to the end of the signal.
Assign	Assign values of all published properties from Source.
AssignTemplate	Assign values of "template-like" published properties from Source.
Copy	Copies signal Data and sampling frequency information.
Crest	Compute the CREST parameter.
EditorClass	To be overriden in descendanr classses.
Init	Initialize streaming filter with Taps.
InputsDirty	If all Inputs[i] are dirty the function returns true.
InternalPull	When called, the method will pass Update requests recursively to all connected objects.
Invalidate	Notifies all connected components that this component has fresh data.
LoadFromStream	Load the component from stream.
LoadTemplateFromFile	Load a template from file.
LoadTemplateFromStream	Load a template from stream.
MarksToStrings	Convert marks to strings.
MinMax	Find minimum and maximum amplitude and store the result in the MinAmplt and MaxAmplt properties.
ParamUpdate	The method can be assigned to some other component even handler, as a notification that a parameter has changed and that Self should consider a recalculation.
Peak	Find the maximum deviation of the signal from its mean value.
PipeReset	Recursively processes all connected components backward and calls Reset method.
Prepare	Prepare the defined filter for streaming.
Process	Filter data in Src and place the result in Dst.
ProcessSample (2)	Filter a single sample.
Pull	Request recalculation of the entire chain of all connected components.
PullUntilEnd	Calls Pull until pipeEnd is returned.
Reset	Same as setting Prepared to false. Reinitializes the delay lines.
SaveTemplateToFile	Save template to file.
SaveTemplateToStream	Save template to stream.
SaveToStream	Save the component state to stream.
Size	Assign the size of the signal from Src.
StateSpaceIIR	Returns the currently designed IIR filter in state space form.
TransferFunIIR	Returns the currently designed IIR filter in zero pole form.
Update	Request recalculation of the data and place the result in Self.
UpdateNotify	Call this method only, if SuspendNotifyUpdate is True.
ValuesToStrings	Convert values to strings.
ZeroPoleIIR	Returns the currently designed IIR filter in zero pole form.

Events

Name	Description
OnAfterUpdateEvent	The event is triggered after the call to the Update method.
OnBeforeUpdateEvent	The event is triggered just before the call to the Update method.
OnDisplayUpdateEvent	The event is triggered after the OnAfterUpdate event. Use this event to update any associated charts or graphs or result tables.
OnGetInputEvent	If the Input property is not assigned, the component will call OnGetInput.
OnNotifyUpdateEvent	The event is called after a call to InternalUpdate, OnAfterUpdate and OnDisplayUpdate from within the Update method.
OnParameterUpdateEvent	The event is triggered when ParamUpdate method is called. The ParamUpdate method is usually called by component editors when a value was changed by the user and the editor was "Live".