METHOD OF AND APPARATUS FOR LOCATING A DISCRETE INGROUND BORING DEVICE

摘要

A method of and apparatus for locating the position of a boring device (40) within the ground with respect to a particular reference location along an above ground path (37) directly over the intended course to be taken by the boring device (40) utilize an electromagnetic field which is emitted from the boring device (40) and an above-ground apparatus for simultaneously sensing the strength of the field at a plurality of distinct sensing points (5a and 5e). The sensing points are selected so that the apparatus never has to leave the path directly above the boring device's intended course to locate the boring device, even if the latter deviates laterally from the path.