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centerFrequencies

Wavelet scattering bandpass center frequencies

Description

example

F = centerFrequencies(sf) returns the wavelet bandpass center frequencies for all filter banks of the scattering decomposition framework, sf. The output F is a cell array with Nfb elements, where Nfb is the number of scattering filter banks. Each element of F is a real-valued vector. If you specify a sampling frequency in sf, F is in hertz. If you do not specify a sampling frequency, F is in cycles/sample.

If there is only one filter bank in the scattering framework, F is a real-valued vector containing the wavelet bandpass center frequencies.

F = centerFrequencies(sf,filterbanks) returns the wavelet bandpass center frequencies for the specified filterbanks. The argument filterbanks is a scalar or vector with all the elements between 1 and Nfb inclusive, where Nfb is the number of scattering filter banks.

Examples

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Create a scattering decomposition framework with a sampling frequency of 50 Hz.

sf = waveletScattering('SamplingFrequency',50)
sf = 
  waveletScattering with properties:

          SignalLength: 1024
       InvarianceScale: 10.2400
        QualityFactors: [8 1]
              Boundary: "periodic"
     SamplingFrequency: 50
             Precision: "double"
    OversamplingFactor: 0

Plot the wavelet bandpass center frequencies for all the filter banks.

bpcf = centerFrequencies(sf);
plot(bpcf{1},'rx-')
hold on
plot(bpcf{2},'bo-')
grid on
title('Wavelet Bandpass Center Frequencies')
legend('Filter Bank 1','Filter Bank 2')
ylabel('Hz')

Plot the wavelets filters used in computing the second-order scattering coefficients.

orderCoef = 2;
[filters,f] = filterbank(sf);
figure
plot(f,filters{orderCoef+1}.psift)
grid on
title('Wavelet Filters with Q = 1')
xlabel('Hz')
ylabel('Magnitude')
hold on
pl = plot(bpcf{orderCoef},max(filters{orderCoef+1}.psift),'bo');
legend(pl,'Center Frequencies')

.

Input Arguments

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Scattering decomposition framework, specified as a waveletScattering object.

Filter bank indices, specified as a positive integer or vector of integers. Elements of filterbanks are integers between 1 and Nfb inclusive, where Nfb is the number of scattering filter banks.

Example: F = centerFrequencies(sf,[1 2]) returns the wavelet bandpass center frequencies for the first two filter banks in sf.

Data Types: double

Introduced in R2018b