Ultrasonic testing method for locating material defects - driving ultrasonic transducer with FM chirp signal with instantaneous frequency variation matched to transmission path transfer function

摘要

An ultrasonic transducer arranged in a transmission path is driven by a frequency modulated chirp signal whose instantaneous frequency is non-linearly modulated with time. The time variation of the instantaneous frequency of the chirp signal is matched to the transfer function of the transmission path. The chirp signal frequency variation is correlated with the corresp. frequency of the transmission path transfer function so that the rate of frequency change is lower for frequencies with a lower corresp. value of the transfer function than for frequencies with a higher corresp. value. USE/ADVANTAGE - E.g. for locating material defects. High time resolution over large range.