Integrated threshold arming method and apparatus

摘要

An intervalometer for determining the arrival time of a bandwidth limited energy pulse employs an integrated threshold arming apparatus and method for conditioning an event recognition circuit. The event recognition circuit, which is typically a zero crossing detector, responds to the conditioning signal for detecting a predetermined event after occurrence of said conditioning signal. The integrated threshold arming circuit employs a signal integration circuit responsive preferably to a rectified signal input, and comparison means for determining when the integrated value crosses a predetermined threshold. A dual threshold implementation can also be employed to further discriminate against false noise signals. The apparatus and method are preferably employed in connection with volumetric flow measurements of turbulent and time-varying fluids by ultrasonic pulse interrogation.