This paper describes the determination of modal parameters directly from
the frequency and impulse response curves, and discusses the factors ef-fecting the accuracy of the measurements. It summarizes the effects of noise, weighting functions, resolution bias and excitation methods.
A new technique, based on the Hilbert transform of the impulse response is described. The technique is used to obtain a large dynamic range of time
, signals on a logarithmic axis and is shown used for determination of damp-. ing from the envelope of the impulse response and for separation of modes in the time domain.