Origin of l/f Noise-Active Degradation Generating Entropy

Abstract

Noise measurements analysis has been associated with degradation. In particular one type is called 1/f noise and is not fully understood. In the time domain, the signal has a random noise appearance. However, in the frequency domain, the spectrum goes as 1/f in intensity at low frequencies. Noise issues, of course occur at all frequencies. In reviewing the literature, we note that 1/f noise in particular seems to be strongly related to aspects in materials that can be interpreted in terms of degradation in materials (i.e. disorder). In this paper we describe some key aspects of 1/f noise found in the literature and discuss how observations relate to generated entropy. We conclude from the literature the 1/f noise region is of paramount importance to observing subtle degradation occurring in materials. In fact, we find that active degradation is the root cause of 1/f noise in materials. We then use a thermodynamic frame work to help interpret our view. We model the 1/f spectral region using an entropy model. We suggest two models. Results help to provide a broader understanding of 1/f noise, identify the region of the spectrum related to the onset of degradation, and show how it can be used to do prognostics. Experiments are suggested to demonstrate how 1/f noise measurements can be used as a prognostic tool for reliability testing to identify and predict degradation over time.