m beginner to matlab, sorry if my question sounds you simple,
my collected EMG signal contains 200000 samples it is in .txt format,

1, to extract the signal features in time and frequency domain do i want to normalise my signal?

2, what is the difference between fft plot and psd(power spectral density plot)?

3, Which method is best to find psd (ex: periodogram, pwelch) of signal with 200000 samples?