| 摘要 |
PURPOSE:Searching the position just above underground metallic route and detecting outputs from two receiving coils are used in minimum method to facilitate measurement. CONSTITUTION:Transmission coil TC is used to provide high frequency current to underground metallic route 1 such as pipe route, in the indirect method. Receiving coil C0 is used in the minimum method to search the position vertically above the underground metallic route 1. The receiving coil C0 is located in the position at right angle to the axis of the transmission coil TC and free from magnetic force generated from the transmission coil TC. Minimum-method-use receiving coils C1, C2 are located on a straight line at right angle to the transmission and receiving coils TC-C0 connecting line, and spaced from the receiving coil C0 by distances d1 and d2. The transmission coil TC, given by high frequency output from oscillator 3, outputs to cause the underground metallic route 1 to generate magnetic field, which is received by the receiving coil C0 to generate output e0. If e0 becomes zero, it indicates the receiving coil C0 is just above the underground metallic route 1. Outputs e1, e2 from the receiving coils C1 and C2 are inputted in devider 11, the output of which provides the depth of the underground metallic route 1. |
