how can i lower the requested number of coefficient in gtcc?

i am trying to extract the feature using gtcc. Error is shown the in the command window. My fs is 1k, I need to lower the requested number of coefficients.

clear all close all clc

numfiles=1947;
Features=[];
fs=1000;

N   = 4;    % Order
Fc1 = 1;  % First Cutoff Frequency
Fc2 = 100;  % Second Cutoff Frequency

% Construct an FDESIGN object and call its BUTTER method.
h  = fdesign.bandpass('N,F3dB1,F3dB2', N, Fc1, Fc2, fs);
Hd = design(h, 'butter');

for i=1:numfiles
    
    % Data Loading
    filename=sprintf('B(%d).mat',i);
    ECG=importdata(filename);
    %preprocessing 
    EECG=filter(Hd,ECG);
    %Feature Extraction
    GTCC = rms(gtcc(EECG,fs,'numcoeffs',4));
    
    
    Feat=[GTCC];
    Features=[Features;Feat];
    
    disp(i)
end

Answer 1

[Vidhi Agarwal]

Hi @Muhammad,

When you're using the "gtcc" function for feature extraction and encounter an error related to the number of coefficients, it typically means that the requested number of coefficients ('numcoeffs') is too high for the given sampling frequency and signal length. Below are the ways you can follow that might help you out.

• Make sure that the length of your ECG signal is sufficient for the "gtcc" computation. If the signal is too short, it may not support the requested number of coefficients.
• Start with a smaller number and gradually increase it to find the maximum that your data can support.
• Verify that the sampling frequency (fs) is correctly set and appropriate for the ECG data. A mismatch in expected and actual sampling frequency can affect feature extraction.
• Ensure that the preprocessing step (bandpass filtering) does not excessively reduce the signal length or alter it in a way that affects the "gtcc" computation.

To understand more about "gtcc" function, refer to the following documentation:

• https://www.mathworks.com/help/audio/ref/gtcc.html

Hope that helps!