Patent ID: 7304479

Claim:
In a system in which a transmitter is moved through the ground within a given region along a path while transmitting a locating signal having a transmit axis such that the locating signal exhibits locate points at the surface of the ground, one of said locate points being ahead of the transmitter and the other one of said locate points being to the rear of the transmitter so as define a vertical plane including the transmit axis and a locate line that is accessible at the surface of the ground and included in a locate plane which extends through the transmitter in a direction normal to the transmit axis, a method comprising: a) establishing an above ground point that is within a side locating region defined between a pair of planes one of which extends through each locate point normal to said transmit axis; b) measuring a local flux intensity of the locating signal at the above ground point using a portable locator in a particular orientation; and c) using the local flux intensity to establish a predicted locate line angular orientation which, at least to an approximation, limits possible directions to and orientations of a predicted locate line relative to the particular orientation of the portable locator at the above ground point.