| 摘要 |
<p>PURPOSE:To easily survey even a short branch tube from a ground surface. CONSTITUTION:Branch tubes 23, 29, 33, 37 are branched from a main tube 22 buried under soil 21. Locating wires (position surveying leads) 26, 27, 30, 31, 34, 35, 38, 39 are respectively laid in reciprocating directions at the tubes 23, 29, 33, 37. Locating wires 28, 32, 36, 40, 41 are laid along the tube 22. These wires are continuously connected in series, and a signal current is supplied from an oscillator 24. Magnetic fields generated from signal currents flowing to the wires are sensed by an oscillator 42. Although the tubes 29, 37 are short, the equivalent currents flow to the wires 30, 31 and 38, 39 to those flowing to the wires 28, 36 laid along the tube 22, magnetic fields which can be sensed are generated from a surface ground.</p> |
