can i use Wavelet transform to extract frequency of voltage and current signals?

I want to extract coefficients of voltage and current signals to give inputs to my Neural Network.or is there anyeasy way to extract the frequency components?i tried this code though:

   numcsvfiles = 2; % Number of csv files

   a4_matrix_Concatenated = [];
  for z = 1:numcsvfiles

filename= strcat(int2str(z),'.csv'); % Suppose the csv files are named: 1.csv, 2.csv, ...
name = strcat('a4_matrix_csv',int2str(z),'.mat');
clear a4_matrix
for k = 1:6
  display(['CSV file number ' num2str(z) ' , Column number ' num2str(k)])
  % Read the z-th csf file

    aux_var = csv(:,(k));
    %figure(1);
    %plot(aux_var);
    N=4;

    % Calculate the wavelet decomposition
    [C,L] = wavedec(aux_var,N,'db1'); % Daubechies 1 Wavelet

    %tam_a4=L(1);
    %a4 = C(1:tam_a4,1);
    %cA4 = appcoef(C,L,'db1',4);

    % Reconstruct the level 4 approximation from the wavelet
    A4 = wrcoef('a',C,L,'db1',N);

    a4_matrix(:,k)=A4;
    %figure(2);
    %plot(A4);

end
a4_matrix_Concatenated = [a4_matrix_Concatenated;a4_matrix];
   % save(name,'a4_matrix'); % Save the matrix with a4 coefficients to each csv file

end

save('a4_matrix_Concatenated.mat','a4_matrix_Concatenated')
%%Test plot

     % 2.csv - current_3 - graph and a4 graph
  figure(1);
  plot(aux_var);
   figure(2);
   plot(A4);