fft – Normalizing Spectrograms – Signal Processing Stack Exchange

I am presently engaged in mm-wave radar research, and I utilize an SDK that supplies me with an FFT spectrum at intervals of 0.1 milliseconds. I use this data to create a spectrogram where the colour represents magnitude, and the x and y axes represent time and corresponding frequency respectively.

The attached image displays a spectrogram I generated when there was no object in front of the radar. The higher magnitudes at the initial frequencies are a result of coupling between the transmitter and receiver. How can I enhance the spectrogram to remove the elevated magnitudes at the starting frequencies?

(Note: In this context, the x-axis denotes time, and the y-axis represents FFT frequencies.)”