Introduction of a general user excitation source signal for modal testing

The use of controlled excitation is fundamental to the estimation of multiple-input multiple-output frequency response function data and the characteristics of the excitation greatly influences the quality of the resulting measurements. In recent years there has been some renewed interest in the use of arbitrary excitation signals, such as pseudo random and periodic random. A general user excitation source signal (GUESS) is a natural extension of these techniques. While these signals have a predefined frequency spectrum, GUESS allows an arbitrary frequency spectrum to be defined for the excitation signal. One application of GUESS would be to shape the excitation spectrum with a 1/omega(2) characteristic in order to better excited low frequency modes when measuring the response with accelerometers. Another application would be to shape the excitation spectrum based on the measured frequency response of the system to improve the dynamic range of the response measurements.