Patent ID: 8209136

Claim:
A line locator, comprising: a plurality of coil detectors, each of the plurality of coil detectors oriented to measure a component of an electromagnetic field, wherein the plurality of coil detectors comprise a first coil detector and a top coil detector; circuitry coupled to receive signals from the plurality of coil detectors and provide quadrature signals indicating a complex electromagnetic field strength; a position locator for indicating a position of the line locator; a processor coupled to receive the complex electromagnetic field strength and the position and calculate values related to a target line; a memory configured to store instructions; and a display coupled to the processor, the display indicating to a user the values related to the target line, wherein the processor executes the instructions for performing the following: modeling an expected complex field strength corresponding to complex field strengths and a phase error measured at the plurality of coil detectors at each of a plurality of positions determined by the position locator with the target line and a hypothesized number of bleedover cables to form a set of hypothesized values corresponding to a set of individual models for the target line for each of the hypothesized number of bleedover cables, wherein modeling uses a phase error function of locations, current and phase of each line including the target line and the bleedover cables, and an estimation of a current attenuation at two nearest side tones to update a fit factor, the side tones defined by a carrier frequency and a modulation frequency; determining which of the set of individual models is a best model; and determining parameters related to the target line from the best model.