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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 wavelet time scattering network, 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 network, 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 wavelet time scattering network 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
          OptimizePath: 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')

Figure contains an axes. The axes with title Wavelet Bandpass Center Frequencies contains 2 objects of type line. These objects represent Filter Bank 1, Filter Bank 2.

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')

Figure contains an axes. The axes with title Wavelet Filters with Q = 1 contains 8 objects of type line. This object represents Center Frequencies.

.

Input Arguments

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Wavelet time scattering network, 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

Output Arguments

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Wavelet bandpass center frequencies for filter banks of the scattering network sf, returned as a vector or cell array of vectors. If there is only one filter bank in sf, or if filterbanks is a scalar, then F is a real-valued vector. Otherwise, F is a cell array, where each element is a real-valued vector.

Data Types: double

Extended Capabilities

Introduced in R2018b