On the use of signals with a constant signal-to-noise ratio in the frequency domain

Most parametric frequency-domain estimation methods, applied to linear time-invariant systems, do not take into account the disturbing input noise. It is shown that these estimators can still be used to obtain unbiased estimates from noisy input-output measurements if an input signal with a constant signal-to-noise ratio is used. By means of an experiment in the field of modal analysis, it is demonstrated that a multisine excitation can be used to create an input signal with a constant signal-to-noise ratio, even when the disturbing noise at the input is strongly colored. It is shown that multisines allow a very efficient (low crest factor and time factor) and fast synthesis of the wanted input signal