Patent ID: 7960973

Claim:
In a system including a boring tool that is movable underground using a drill string which extends from the boring tool to a drill rig that operates at the surface of the ground, a method comprising: configuring a transmitting device for producing at least one rotating dipole field which rotates about an axis in relation to the surface of the ground such that the transmitting device may emanate said rotating dipole field from a tilted orientation with respect to a vertical direction; measuring the tilted orientation using a tilt sensor forming part of the transmitting device to produce a tilt signal; sensing said rotating magnetic dipole field at a receiving position to produce a set of flux measurements responsive to the rotating dipole field when said transmitting device is in said tilted orientation; using the set of flux measurements, determining a position of the receiver relative to the transmitting device in a tilted coordinate system that is defined by the tilted orientation of the transmitting device; and determining the position of the receiver in a level coordinate system in relation to the transmitting device based on the position of the receiver, as determined in said tilted coordinate system, and said tilt signal.