An accurate pipe length measurement under noisy environment using stationary waves

The authors previously developed an accurate pipe length measurement system using stationary waves in pipes. For pipes with open ends in manufacturing fields, however, the system cannot always be directly applied, because noises from outside the pipes enter them at their open ends and disturb the stationary waves inside the pipes and cause successive phase shifts in the stationary waves. The paper proposes a measurement system which realizes an accurate pipe length measurement under such a noisy environment by selecting the optimal data window and the optimal modes.