# How to calculate FMCW Radar Chirp STFT?

I have received signal from FMCW Radar which is of the shape [128x64] = [Number of samples per chirp x Number of chirps per cycle] and i want to calculate the stft i am calculating it with stft command and for that using vectorized data.[1x8192]

fs = 1000e3;
win = blackman(64,'periodic');
[S,F,T] = stft(data,fs,'Window',win,'OverlapLength',60,'FFTLength',256);
S = abs(S);
imagesc(T,F,S);
colorbar;
xlabel('Time');
ylabel('Frequency');
zlabel('Amplitude');
title('Spectrogram');


From this i am getting the same plot for every cycle. Is this approach correct or do i have to calculate the stft separetely for every chirp? If my approach appraoch is correct what does this stft tells me? Data

• that image is inaccessible to the public. Please edit your question and use the "image" button in the editor to upload your picture. – Marcus Müller May 29 '20 at 9:51
• @MarcusMüller please see – A R. May 29 '20 at 10:27
• very nice, thank you! – Marcus Müller May 29 '20 at 10:29
• so, it's hard to say whether this is correct. Is it what you expect? – Marcus Müller May 29 '20 at 10:29
• i can't make any judgement. That is the question, i uploaded the data – A R. May 29 '20 at 10:31