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Owning Palette: Discrete Wavelet VIs

Installed With: Advanced Signal Processing Toolkit

Designs customized analysis filters and synthesis filters for discrete wavelet analysis and reconstruction, respectively.

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Dialog Box Options

Parameter	Description
Wavelet Type	Specifies the type of wavelet this Express VI uses to design a customized wavelet for discrete wavelet analysis and reconstruction. You can select the Orthogonal or Biorthogonal option.
Product of Lowpass (P0=G0*H0)	Specifies P0, which is the product of the lowpass analysis filter G0 and the lowpass synthesis filter H0. Contains the following options: P0 type—Specifies the type of P0. The default is Maxflat. You can choose from the following options: Maxflat Positive Equiripple General Equiripple Note  This option is available only if you select the Biorthogonal option in the Wavelet Type section. Zero pairs at pi (P0)—Specifies the value of p in the Maxflat filter P0(z), where P0(z) = (1+1/z)^(2p)*Q(z). This option is available only if you select the Maxflat option in the P0 type section. # of taps—Specifies the number of coefficients of P0(z). The length of P0(z) must be 4p–1, where p = 2, 3, …. This option is available only if you select the Positive Equiripple or General Equiripple option in the P0 type section. Passband—Specifies the normalized cutoff frequency of P0(z). The value of Passband must be less than 0.5. Passband is available only if you select the Positive Equiripple or General Equiripple option in the P0 type section.
Factorization (Type of G0)	Contains the following options: Filter type—Specifies how this Express VI factors P0 to G0 and H0. Contains the following options: Arbitrary—Specifies that no restriction exists on the placement of zeroes. Minimum Phase—Specifies that the zeroes of G0 are located inside the unit circle, except for the zeroes at pi. Linear Phase—Specifies that if one zero belongs to G0(H0), the reciprocal of that zero must belong to G0(H0). B-Spline—Specifies that except for some zeroes at pi, all the zeroes of P0 belong to H0. Zeroes at pi (G0)—Controls how many zeroes at z=–1 belong to G0(z). This option is available only if you select the Maxflat option in the P0 type section. The maximum value of this option is 2p, where p = the value of the Zero pairs at pi (P0) option.
Zeroes of G0 and H0	Shows the distribution of the zeroes of P0(z), G0(z) and H0(z). This Express VI uses this distribution to factor the zeroes of P0(z) into the zeroes of G0(z) and H0(z). Because the filter coefficients of P0(z) are real, all the zeroes of P0(z) are symmetrical with respect to the x-axis. Consequently, this Express VI displays only the upper half of the plane.The blue crosses represent the zeroes of G0(z), and the red circles represent the zeroes of H0(z).Click on the zero you want to select to switch the zero from that of G0(z) to that of H0(z) and vice versa. All the zeroes belong to G0(z) or H0(z). Selecting different values for Filter type puts different constraints on the selections of zeroes. For example, if you select Linear Phase for Filter type and select a zero for one filter, the filter automatically contains the reciprocal of the zero. Refer to the Wavelet Analysis Tools User Manual for more information about the different types of factorization.
Wavelet and Filter Banks	Displays the following graphs: Analysis scaling—Displays the scaling function of the analysis filter bank. Analysis wavelet—Displays the mother wavelet of the analysis filter bank. Analysis lowpass (G0)—Displays the coefficients of the lowpass analysis filter G0(z). Analysis highpass (G1)—Displays the coefficients of the highpass analysis filter G1(z). Synthesis scaling—Displays the scaling function of the synthesis filter bank. Synthesis wavelet—Displays the mother wavelet of the synthesis filter bank. Synthesis lowpass (H0)—Displays the coefficients of the lowpass synthesis filter H0(z). Synthesis highpass (H1)—Displays the coefficients of the highpass synthesis filter H1(z).
Frequency response	Displays the magnitude of the frequency responses of the designed filters G0(z) and G1(z). G1(z) is the sign-alternated version of H0(z). In other words, G1(z) is a highpass filter if H0(z) is a lowpass filter. The VI shows the frequency response of G0(z) in blue and shows the frequency response of G1(z) in green. The units of the y-axis are in dB, and the units of the x-axis are in terms of the normalized frequency. The full scale ranges from 0.0 to 1.0 pi.

Block Diagram Inputs

Parameter	Description
error in (no error)	Describes error conditions that occur before this VI or function runs.

Block Diagram Outputs

Parameter	Description
Analysis filters	Returns the coefficients of the analysis filters. lowpass—Contains the coefficients of the analysis lowpass filter G0(z). highpass—Contains the coefficients of the analysis highpass filter G1(z).
Analysis scaling	Returns the scaling function of the analysis filter bank.
Analysis wavelet	Returns the mother wavelet of the analysis 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.
Synthesis filters	Returns the coefficients of the synthesis filters. lowpass—Contains the coefficients of the synthesis lowpass filter H0(z). highpass—Contains the coefficients of the synthesis highpass filter H1(z).
Synthesis scaling	Returns the scaling function of the synthesis filter bank.
Synthesis wavelet	Returns the mother wavelet of the synthesis filter bank.