Neural network technique for the joint time-frequency analysis of distorted signal

Nonstationary distorted signals need to be analyzed in both the time and frequency domains to determine their characteristics. In this paper, a technique based on a neural network (NN) is presented which has the merit of providing such an analysis in real time. After arranging a suitable NN, the algorithm utilized to carry out the analysis is illustrated. Then, expressions assessing the dynamic behavior and the steady-state accuracy of the technique are derived. From the expressions, the influence of the NN parameters on the technique performance is readily recognized. As an example, the technique is applied to the analysis of the time evolution of the current harmonics absorbed by a diode rectifier and the results are compared with those obtained by the short-time Fourier transform.