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step

System object: dsp.DyadicAnalysisFilterBank
Package: dsp

Decompose input with dyadic filter bank

Syntax

Y = step(dydan,X)

Description

Note

Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Y = step(dydan,X) computes the subband decomposition of the input X and outputs the dyadic subband decomposition in Y as a single concatenated column vector or matrix of coefficients. Each column of X is treated as an independent input, and the number of rows of X must be a multiple of 2N, where N is the value of the NumLevels property. The elements of Y are ordered with the highest frequency subband first followed by subbands in decreasing frequency

Examples

expand all

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

Sampling frequency 1 kHz input length 1024

t = 0:.001:1.023; 
x = square(2*pi*30*t);
xn = x' + 0.08*randn(length(x),1);

Default asymmetric structure with Daubechies order 3 extremal phase wavelet

dydan = dsp.DyadicAnalysisFilterBank;
Y = dydan(xn);

Level 2 yields 3 subbands (two detail-one approximation) Nyquist frequency is 500 Hz

D1 = Y(1:512); % subband approx. [250, 500] Hz 
D2 = Y(513:768); % subband approx. [125, 250] Hz
Approx = Y(769:1024); % subband approx. [0,125] Hz

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

Sampling frequency 1 kHz input length 1024.

t = 0:.001:1.023; 
x = square(2*pi*30*t);
xn = x' + 0.08*randn(length(x),1);

symmetric structure with Daubechies order 3 extremal phase wavelets.

dydan = dsp.DyadicAnalysisFilterBank('TreeStructure',...
'Symmetric');
Y = dydan(xn);
D1 = Y(1:256); % subband approx. [375,500] Hz
D2 = Y(257:512); % subband approx. [250,375] Hz
D3 = Y(513:768); % subband approx. [125,250] Hz
Approx = Y(769:1024); % subband approx. [0, 125] Hz
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