In this article we will look at why we need to consider energy correction when producing frequency spectra and how we go about it. We will use a perfect, ’special case’ signal to keep the explanation as simple as possible. The signal we will use is periodic within the time record used to calculate the [...]
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Before we discuss the use of data windows, we should first remind ourselves of three basic properties of the FFT (Fast Fourier Transform) process. First, energy information in signal must be preserved during transformation. That is, the energy measured on time signal must equal the energy measured on the frequency representation of that signal. Share:
By combining a speed signal with a data signal and using the Short Time FFT algorithm (Hopping FFT), it is possible to extract order data directly as a function of time (Orders from Hopping FFT) rather than as a function of speed (Waterfall). This is very useful when analyzing a complete operational cycle which includes [...] Share:
One would expect that averaging waterfalls and then extracting orders would give the same result as extracting orders from individual waterfalls and then averaging them. This [...] |
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