ULTRASONIC MEASUREMENT APPARATUS

摘要

An apparatus for measuring the time taken for a signal to be transmitted through a medium such as a bolt. An ultrasonic signal is transmitted into the bolt and reflections of the transmitted signal are detected after transmission through the bolt. After a first transmission is initiated, each of a series of further transmissions is initiated in response to detection of a second reflection of the transmitted signal resulting from the preceding transmission. The total elapsed time between initiation of the first transmission and detection of the second reflection of the transmitted signal resulting from the last transmission is measured, and the sum of time delays elapsing between initiation of each signal and detection of a first reflection of the resulting transmitted signal is measured. The time taken for transmission of the signal through the bolt is calculated from the difference between the total elapsed time and said sum.