I would like to detect the change of the frequency content through a real signal using sliding window as shown in following figure.
However, applying fourier transform is costly for windowing operations. For example, at the above case assume window size is 50 samples; I need to calculate fourier transform 950 times. I wonder is there any mathematical workaround to shorten the calculation time.
I would really be happy if I gain some calculation time. Thanks in advance!