I am trying to apply a window function to smooth my signal and finally obtain the peaks of the signal. Yet, for spectral leakage I apply window function in time domain. After taking the Fourier amplitude spectrum ı want to further smooth the signal. Yet I do not know how to apply smoothing windows for frequency domain. Should I use convolution for the Fourier amplitude spectrum of the window and Fourier amplitude spectrum of the data?
What is the meaning of smoothing window length with 0.1 Hz or 0.2 Hz?