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Owning Palette: Filter Banks VIs

Installed With: Advanced Signal Processing Toolkit

Computes the mother wavelet function and the scaling function from a filter bank.

Details  Example

	filters contains the coefficients of the lowpass filters and the highpass filters to compute the mother wavelet and scaling functions. lowpass specifies the lowpass filter coefficients. highpass specifies the highpass filter coefficients.
	refinements specifies how many levels of lowpass filters to use to calculate the mother wavelet and scaling functions. refinements must be greater than or equal to 1.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	scaling function info contains the scaling function information the VI computes from the filter bank. t0 contains the offset to use when plotting the mother wavelet or scaling function. dt contains the multiplier to use when plotting the mother wavelet or scaling function. The unit of dt is in samples. scaling function contains the scaling function the VI computes from the filter bank.
	mother wavelet function info contains the mother wavelet function information the VI computes from the filter bank. t0 contains the offset to use when plotting the mother wavelet or scaling function. dt contains the multiplier to use when plotting the mother wavelet or scaling function. The unit of dt is in samples. wavelet function contains the mother wavelet function the VI computes from the filter bank.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

WA Mother Wavelet and Scaling Function Details

You can relate the mother wavelet function and the scaling function to the filter banks with the following equations:

where is the Fourier transform of the scaling function , is the Fourier transform of the mother wavelet function , is the corresponding lowpass filter, is the corresponding highpass filter, and h is refinements.

You can recover a precise approximation of and when refinements is large enough. Refer to A Wavelet Tour of Signal Processing for more information about the mother wavelet function and the scaling function.

Example

Refer to the Mother Wavelet and Scaling Function VI in the labview\examples\Wavelet Analysis\WAGettingStarted.llb for an example of using the WA Mother Wavelet and Scaling Function VI.