New performance function for the comparison of different sampling strategies in non-linear conversion instruments

A method for the performance evaluation of digital measurement instruments based on asynchronous sampling and nonlinear signal conversion is proposed. The authors propose a performance index for the comparison of different asynchronous strategies and develop the analytical form of that index for two sampling techniques, equally spaced and random. The idea is to interpret the instantaneous output of the instrument as a discrete random variable with a uniform distribution over the successive occasions of measurement. Thus, the asymptotic variance of the reading can be a sum of contributions, each of which is obtained by weighting the contributions relative to each spectral component of the signal according to a frequency-dependent coefficient which is assumed to the performance index