THD and SNR tests using the simplified Volterra series with adaptive algorithms

Abstract

A test technique for the total harmonic distortion (THD) and signal to noise ratio (SNR) is proposed. A mod$ed Volterra series using harmonics in place of powers of the sinusoidal input is used to model the nonlinear characteristic of the device under test (DUT). The leastmean square (LMS) adaptive algorithm is used to identify the DUT model. While maintaining comparable accuracy this technique provides a more flexible test procedure than conventional methods, in terms of the frequency resolution, the number of samples, and the sampling rate. It outperforms conventional methods when there is a bin energy leakage, which occurs in a non-coherent system. It requires a lower number of data points, as a result, less data acquisition time is needed and test time is reduced. In addition, it is real-time computing while other conventional methods post-process blocks of data.