Survey of excitation signals with respect to scanning vibrometer measurements

The quality of a vibration measurement depends strongly on the choice of the excitation signal. Common excitation signals were compared for measurements with a scanning vibrometer. It is shown that the best signal can be different as for measurements with accelerometers. While many points are acquired simultaneously with accelerometers, all points are measured sequentially with a scanning vibrometer. Therefore the measurement time is a more critical factor for the scanning vibrometer. As a further difference, a scanning vibrometer changes the position of the sensor without turning off the excitation. In this paper common excitation techniques are described. They show differences in signal-to-noise ratio, generation of leakage effects and measurement time. Not all of them are suitable for measuring non-linear structures. The described excitation signals are compared for typical scanning vibrometer applications.