×

Enhanced precise location

  • US 8,515,689 B2
  • Filed: 09/12/2008
  • Issued: 08/20/2013
  • Est. Priority Date: 05/18/2007
  • Status: Active Grant
First Claim
Patent Images

1. A method for determining a location of underground cables and pipes, comprising:

  • measuring a set of complex electromagnetic field magnitudes and phases at a plurality of positions while traversing a target line in a substantially parallel direction using a plurality of 3-dimensional electromagnetic coil sensors, the plurality of 3-dimensional electromagnetic coil sensors being mounted on opposite sides of a cart frame within wheel wells of a cart-based location receiver such that there is a horizontal separation between the plurality of 3-dimensional electromagnetic coil sensors, and such that the plurality of 3-dimensional electromagnetic coil sensors are oriented substantially orthogonal to the target line;

    modeling a set of expected complex electromagnetic field magnitudes of a single underground conductor at each of the plurality of positions to form a set of hypothesized values corresponding to a set of individual models for the target line, the modeling including using 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 individuals models is a best model;

    determining confidence information at each of the plurality of positions based on a comparison between the measured set of complex electromagnetic magnitudes and phases and the best model; and

    determining parameters at each of the plurality of positions related to the target line from the best model.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×