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WA WP Decomposition VI

Owning Palette: Wavelet Packet VIs

Installed With: Advanced Signal Processing Toolkit

Computes the 1D wavelet packet (WP) decomposition and stores the resulting coefficients and wavelet packet tree information in the wavelet packet structure. Wire data to the signal input to determine the polymorphic instance to use or manually select the instance.

Details  Examples

Use the pull-down menu to select an instance of this VI.

WA WP Decomposition (waveform)

entropy specifies the method and the associated parameter to use to compute the entropy of the wavelet packet coefficients.
type specifies the method to use to compute the entropy of the wavelet packet coefficients.
0shannon (default)
1threshold
2sure
3norm
4energy
optional parameter specifies the associated parameter for the threshold, sure, and norm entropy. The VI ignores the settings in optional parameter when you select shannon or energy in type. For the threshold and sure methods, the reference value must be greater than 0. For the norm method, the reference value must be greater than 1.
extension specifies the method to use to pad data at the borders of the input signal. The default is symmetric. The extension length is equal to the length of the wavelet filters. When you select the extension method, make the transition between the input signal and the padded data as smooth as possible because a smooth transition generates fewer large detail coefficients and enhances the efficiency of the signal representation.
0zero padding—Uses zeroes to pad the input data. Watch for abrupt transitions between the padded zeroes and the input data, which causes large artifacts near the transition.
1symmetric—Uses replications of the input data to pad the data, except that the VI left-flips the block at the input and right-flips the block at the end.
2periodic—Adds a replication of the input data block before and another replication after the input data block to pad the data.
WP session is a reference to an existing wavelet packet structure.
signal specifies the input signal.
levels specifies the number of levels in the discrete wavelet analysis. levels must be a positive integer no greater than log2(Ls), where Ls is the length of the signal. The default is –1, which indicates that the VI sets levels as the largest integer no greater than log2(Ls).
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.
wavelet specifies the wavelet type to use for the discrete wavelet analysis. The default is db02. The options include two types: orthogonal (Haar, Daubechies (dbxx), Coiflets (coifx), Symmlets (symx)) and biorthogonal (FBI, Biorthogonal (biorx_x)), where x indicates the order of the wavelet. The higher the order, the smoother the wavelet. The orthogonal wavelets are not redundant and are suitable for signal or image denoising and compression. The biorthogonal wavelets usually have the linear phase property and are suitable for signal or image feature extraction. If you want to use other types of wavelets, do not wire this input. Instead, use the Wavelet Design Express VI to design the wavelet you want, bundle the resulting analysis and synthesis filters, and then wire them to the filter banks input.
filter banks specifies the analysis filter banks and the synthesis filter banks for the wavelet you specify. If you specify a value for filter banks, the VI ignores the settings in the wavelet input. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters.
analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters for the wavelet you specify.
lowpass specifies the coefficients of the lowpass analysis filter, which the VI uses to compute the approximation coefficients.
highpass specifies the coefficients of the highpass analysis filter, which the VI uses to compute the detail coefficients.
synthesis filters specifies the coefficients of the lowpass synthesis filters and the highpass synthesis filters for the wavelet you specify.
lowpass specifies the coefficients of the lowpass synthesis filter, which the VI uses to filter the interpolated approximation coefficients in the wavelet reconstruction.
highpass specifies the coefficients of the highpass synthesis filter, which the VI uses to filter the interpolated detail coefficients in the wavelet reconstruction.
WP session out contains a reference to an existing wavelet packet structure, which this VI can modify.
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 WP Decomposition (array)

entropy specifies the method and the associated parameter to use to compute the entropy of the wavelet packet coefficients.
type specifies the method to use to compute the entropy of the wavelet packet coefficients.

0shannon (default)
1threshold
2sure
3norm
4energy
optional parameter specifies the associated parameter for the threshold, sure, and norm entropy. The VI ignores the settings in optional parameter when you select shannon or energy in type. For the threshold and sure methods, the reference value must be greater than 0. For the norm method, the reference value must be greater than 1.
extension specifies the method to use to pad data at the borders of the input signal. The default is symmetric. The extension length is equal to the length of the wavelet filters. When you select the extension method, make the transition between the input signal and the padded data as smooth as possible because a smooth transition generates fewer large detail coefficients and enhances the efficiency of the signal representation.

0zero padding—Uses zeroes to pad the input data. Watch for abrupt transitions between the padded zeroes and the input data, which causes large artifacts near the transition.
1symmetric—Uses replications of the input data to pad the data, except that the VI left-flips the block at the input and right-flips the block at the end.
2periodic—Adds a replication of the input data block before and another replication after the input data block to pad the data.
WP session is a reference to an existing wavelet packet structure.
signal specifies the input signal.
levels specifies the number of levels in the discrete wavelet analysis. levels must be a positive integer no greater than log2(Ls), where Ls is the length of the signal. The default is –1, which indicates that the VI sets levels as the largest integer no greater than log2(Ls).
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.
wavelet specifies the wavelet type to use for the discrete wavelet analysis. The default is db02. The options include two types: orthogonal (Haar, Daubechies (dbxx), Coiflets (coifx), Symmlets (symx)) and biorthogonal (FBI, Biorthogonal (biorx_x)), where x indicates the order of the wavelet. The higher the order, the smoother the wavelet. The orthogonal wavelets are not redundant and are suitable for signal or image denoising and compression. The biorthogonal wavelets usually have the linear phase property and are suitable for signal or image feature extraction. If you want to use other types of wavelets, do not wire this input. Instead, use the Wavelet Design Express VI to design the wavelet you want, bundle the resulting analysis and synthesis filters, and then wire them to the filter banks input.
filter banks specifies the analysis filter banks and the synthesis filter banks for the wavelet you specify. If you specify a value for filter banks, the VI ignores the settings in the wavelet input. You can use the Wavelet Design Express VI to design the analysis filters and the corresponding synthesis filters.
analysis filters specifies the coefficients of the lowpass analysis filters and the highpass analysis filters for the wavelet you specify.
lowpass specifies the coefficients of the lowpass analysis filter, which the VI uses to compute the approximation coefficients.
highpass specifies the coefficients of the highpass analysis filter, which the VI uses to compute the detail coefficients.
synthesis filters specifies the coefficients of the lowpass synthesis filters and the highpass synthesis filters for the wavelet you specify.
lowpass specifies the coefficients of the lowpass synthesis filter, which the VI uses to filter the interpolated approximation coefficients in the wavelet reconstruction.
highpass specifies the coefficients of the highpass synthesis filter, which the VI uses to filter the interpolated detail coefficients in the wavelet reconstruction.
WP session out contains a reference to an existing wavelet packet structure, which this VI can modify.
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 WP Decomposition Details

The following illustration shows a full decomposition of the wavelet packet tree at level 3:

The black numbers indicate the path of each node, and the red numbers show the index of each node. The path is a combination of the characters 0 and 1, where 0 represents lowpass filtering, and 1 represents highpass filtering. For example, a value of 101 indicates that the VI passes the signal through a highpass filter, through a lowpass filter, and then through a highpass filter.

The discrete wavelet decomposition and the arbitrary path decomposition are two special cases of the wavelet packet decomposition. You can decompose the approximation coefficients and the detail coefficients in the wavelet packet decomposition. The discrete wavelet decomposition implements the analysis filtering only on the approximation coefficients. However, you can apply analysis filtering to the approximation or the detail in the arbitrary path decomposition.

Examples

Refer to the following VIs for examples of using the WA WP Decomposition VI:

  • Wavelet Packet - Plot Tree VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
  • Wavelet Packet - Read and Write Coefficients VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
  • Wavelet Packet - Read Entropy VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
  • Wavelet Packet - Join Node VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb
  • Wavelet Packet - Split Node VI: labview\examples\Wavelet Analysis\WAGettingStarted.llb

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