Ultrasonic test instrument

Claim 1

An ultrasonic test instrument for the nondestructive testing of workpieces including a pulse generator for producing ultrasonic transmit signals at predetermined time intervals and a receiver for receiving ultrasonic echo signals corresponding to the transmit signals and evaluating the amplitudes and the transit times of the ultrasonic echo signals appearing during an expected measurement range, the latter signals being supplied to an amplitude and a first time gate circuit and to a transit time measuring circuit and an amplitude measuring circuit for causing only one echo signal at a time to have its amplitude and transit time evaluated between the predetermined time intervals, the improvement comprising: a presettable counter coupled for receiving the output signal from said amplitude and time gate circuit and providing an output signal whenever the number of pulses received at the input of said counter is equal to the preset value of said counter; said output signal from said counter being coupled to said transit time measuring circuit as well as by means of a second time gate circuit to said amplitude measuring circuit, whereby to cause said amplitude measuring circuit to evaluate an echo signal only during the time interval defined by said second time gate circuit.