| 摘要 |
PURPOSE:To inspect the deterioration state of a wood pole with high precision by attenuating an ultrasonic wave to a constant value when transmitting and re- ceiving the ultrasonic wave to and from the wood pole and measuring the propagation time of the ultrasonic wave. CONSTITUTION:The ultrasonic wave signal is transmitted from a transmission terminal 2a to a reception terminal 2b in a sectional direction of the wood pole 1. At this time, if there is a deteriorating part H, the ultrasonic wave signal passes through paths R1, R2, and R3, etc. Further, the ultrasonic wave signal is attenuated to the constant value and transmitted and its propagation time is measured and compared with the normal propagation time. At this time, a standard piece is used to calculate the frequency attenuation and propagation time of the ultrasonic wave previously, and a threshold value is so determined the propagation time is long. Then, the ultrasonic wave increases in propagation time above the threshold value regardless of the paths R1, R2, and R3 if there is the deteriorating part H. Therefore, the deterioration of the wood pole is inspected precisely because the ultrasonic wave signal is attenuated to the constant value. |
