Method and apparatus to minimize gradient errors in buried utility depth measurements

摘要

A buried utility locator uses the “gradient method” to determine the depth of a buried, current-carrying utility. The method and corresponding apparatus used in said locator, to minimize field gradient measurement errors, includes first and second antennas. Both the first and second antennas are mounted along a common vertical axis inside the locator's housing. The first antenna is a gradiometer formed by two vertically spaced-apart magnetic field sensors connected in a differential configuration. The second antenna provides a secondary field measurement along the direction of the gradient sensor axes.