MATLAB: I want to plot PSD for the input data(meters)

@dsp @psd @matlab

I want to plot PSD for my input data (meters) if the input in volts the the PSD in dB/Hz what if the input in meters then what are the units of PSD please some body help me Ts=30; Fs =1/Ts; y=MP1; %input data(meters) h = spectrum.welch; Hpsd=psd(h,y,'Fs',Fs); what are units of y axis after the plot

Best Answer

If you are measuring displacement in meters in the time domain, then your frequency domain amplitudes (after performing the FFT) should be in units of meters / Hz. Squaring those amplitudes should give you meters-squared / Hertz-squared. However... since Matlab generates their power spectra by normalizing their FFT result by the number of samples (N) instead of the sampling frequency (Fs), their output might have PSD units associated with meters-squared / samples-squared (which is completely meaningless to me).
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