How to acquire time-frequency response from simulink example 'Simulating a Bistatic Radar with Two Targets'

Hello,

I am trying to change the simulink example 'Simulating a Bistatic Radar with Two Targets' so that instead of showing Doppler-Range response I would have time-frequency response, a spectrogram with visible Doppler signature on it.

I believe that the answer is simple but for some reasons I can't figure it out, I am new to simulink.

I appreciate your guidance. Piotr