On line ultrasonic velocity gauge

摘要

A device which measures the velocity of ultrasonic waves in a moving web is provided. A pair of wheels is mounted for continuous surface contact with the paper and a transducer, which contacts the web on each revolution, is located in each wheel for relating electrical and mechanical signals. Timing means measures the time it takes a mechanical signal generated at the first wheel to reach the second wheel. Noise reducing and amplifying means are provided for effective operation.