THE ANALYSIS OF NONSTATIONARY DYNAMIC SIGNALS

In most experimental noise and vibration studies, a problem is identified and analyzed in the frequency domain by applying a Fast Fourier Transform (FFT) to the measured signals. For most applications the FFT is perfectly acceptable - as long as the known limitations inherent in the technique are understood. However, one of the fundamental premises of the FFT is that the signal is stationary, in other words, docs not vary in spectral content over time. Clearly, the FFT model may not be the most appropriate one to choose for the analysis of nonstationary noise and vibration signals.