Patent ID: 6920943

Claim:
In a system in which a boring tool is moved through the ground in a region, an arrangement for tracking the position and/or guiding the boring tool as it moves through the ground, said arrangement comprising: (a) means located within said boring tool for transmitting an electromagnetic field; (b) one or more detector means for receiving said electromagnetic field, each detector means having an electromagnetic field receiving antenna assembly including at least one antenna for measuring at least one component of the intensity of said electromagnetic field, each detector being located at a fixed position with its antenna at a particular orientation within said region, but not necessarily along an intended path of movement of said boring tool; c) means for determining certain initial conditions prior to drilling which include the positions of said detectors in said region, the particular orientation of the antenna associated with each detector provided and an initial position and orientation of the boring tool; (d) processing means for using at least one measured component of the intensity of said electromagnetic field, which is obtained using said detector or detectors after the boring tool moves a distance along said path, in determining, at least to an approximation, the position of the boring tool after moving said distance; and (e) a mapping tool having means for transmitting an electromagnetic field and a tilt sensing mechanism, said mapping tool being used to determine the positions and orientations of all of said antennas for each detector within said region.