I have a recorded signal which contains several frequency components with stochastic phase and amplitude changes and want to extract the true signal with the other frequency components and noise removed. I have performed several filtering techniques to attempt to achieve this. However I need a robust measure of how correct my filtered signal is and I do not have a method of measuring the signal on it's own, without the noise and other frequency components, in order to validate it that way. One method I have applied is minusing the filtered signal from the raw signal in time space and then taking the fft/psd (power spectral density) of the remaining signal and I see that the peak is gone, is this a robust measure of checking the signal I am tracking is correct? Is there any other methods for analysing this without having a way of measuring the true signal?
Some examples of the raw and differences signals for a couple of different filtering methods are shown below: (blue is the PSD of the original raw signal, and green is the PSD of [raw - filtered])