Power Spectral Density
This calculation determines the Power Spectral Density of the selected Data Series using the Welch method. The specified Data Series is first divided into overlapping sections with specified by Window Length and Window Overlap and then windowed by the specified Window Type. The result is then zero-padded to specified FFT Length. The magnitude squared of the FFT of each of the sections is then averaged to determine the Power Spectral Density (PSD).
In the script, the calculation is performed by first creating the windowing function by calling the function makeWindow(type, length), using user specified parameter Window Type, as type, and user specified parameter Window Length, as length. The script then iterates through the data using windows. Each window is pair-wise multiplied with the windowing function. This step is illustrated in the diagram below:
Once the data in Figure 3 is acquired, the built in function .spectrum() is called, which determines the power spectrum. This data is then scaled. This result is summed with the result of the same process performed on every window, and then averaged to obtain an average window. This result is the Power Spectrum Density of the input data.
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