How can I get a two-dimensional contour line graph from Wavelet Time-Frequency analysis?

Hi, How can I obtain a visualizing scalogram similar to that shown in Figure 1 using Wavelet Time-Frequency analysis?

Figure 1:

Answer 1

[William Rose]

@Navid,

Here is an example:

fs=1000;        % sampling rate (Hz)
t=(0:1000)/fs;  % time vector for x (s)
x=chirp(t,50,1,300)+chirp(t,350,1,75); % x= sum of up-chirp and down-chirp
% next: compute STFT
[s,f,t1]=stft(x,fs,'FrequencyRange','onesided','FFTLength',64,'Window',hann(64));
contour(t1,f,abs(s))        % plot contours of STFT
colorbar

Good luck.

[Navid]

Dear William Rose,

I want to express my gratitude for the guidance you provided. I followed your example and extended it to wavelet transform, as shown below:

[cfs,f] = cwt(x,fs);

contour(t,f,abs(cfs).^2);

colorbar

Thank you for your time and consideration.

Sincerely,

Navid

[William Rose]

@ Navid, YOu are welcome. Good job on the wavelet transform. Best wishes for success in your work.