EXPONENTIAL WINDOW FUNCTION EFFECTS ON FREQUENCY RESPONSE FUNCTION ESTIMATION

摘要

Impulse excitation is a widely adopted method for frequency response functions measurements. When the measured data are processed digitally, the application of exponential window functions can reduce leakage phenomenon. However, it introduces bias errors on the estimated frequency response functions, natural frequencies, and damping ratios. This paper discuss the influence of exponential weighting function. After applying rectangular windows, the effects of exponential window function is obtained. Most of the work is carried out in time domain, the remaining is investigated in frequency domain these effects on a second order system is studied. The range of time constant in exponential window functions is found such that the induced bias errors are negligible. This result can be applied to higher order systems without loss of generality. A brief discussion on the combination of force window and exponential window is also given.