Practical choices in the FRF measurement in presence of nonlinear distortions

The frequency response function (FRF) of the best linear approximation to a nonlinear system is usually measured by averaging system responses to a normally distributed, filtered, and clipped random excitation (Gaussian noise). This signal is compared to the multisine signal with random phases. It is shown that a random phase multisine signal defined over an even-odd frequency grid is superior to the Gaussian signal in terms of the variance and the bias of the measured FRF of the approximated nonlinear system.