An overview of MIMO-FRF excitation/averaging/processing techniques

The use of characterized excitation and choice of averaging techniques are fundamental to the estimation of multiple input, multiple output (MIMO) frequency response function (FRF) data. The characteristics of the excitation and averaging selected greatly influence the quality of the resulting MIMO-FRF measurements. Presented is an overview of the basic excitation methods, such as random, periodic random, pseudorandom, and burst random (random transient) as well as more advanced excitation methods, such as burst-cyclic random, slow random, MOOZ random, and periodic chirps. The application of these excitation and averaging methods is discussed relative to lightly or heavily damped systems, systems with small non-linearities, FRF models, and peak to RMS (crest factor) as well as signal-to-noise ratio (SNR) issues. Experimental examples are given to demonstrate the important issues.