Patent ID: 6549011
Filing Date: 2003-04-15
Classification: G01V

Abstract:
A method of tracing a conductor, comprising the following:applying an alternating signal to the conductor at a first point, the alternating signal having first and second continuously present sinusoidal components with frequencies F1 and F2 respectively; detecting at a second point and at a third point the field produced by the alternating signal on the conductor, the field having first and second continuously present sinusoidal field components with frequencies corresponding to the frequencies of the first and second sinusoidal components of the alternating signal; and determining any change in phase difference of the first and second sinusoidal field components between the second and third points, the determination of a predetermined phase relationship tracing the conductor from the second point to the third point and the determination of a change in said phase relationship indicating a different conductor is being traced from said second point; and, wherein the frequencies F1 and F2 are phase-locked and related by NÃ—F1=MÃ—F2, where N and M are non-adjacent integers greater than 1, one of which is odd and one of which is even, having no common factors.