Patent ID: 6510106
Filing Date: 2003-01-21
Classification: G01S,G01V

Abstract:
Subsurface object location apparatus for determining the position of an object located below a surface, comprising:a subsurface unit having a transmitter and being arranged to be mounted on an object the location of which is to be monitored; a plurality of surface units disposed at spaced locations at the surface and each having a receiver; and a processing unit arranged for determining at least one of, the times of reception and relative times of reception at the plurality of receivers, of a signal transmitted from the transmitter and determining the location of the object on the basis of at least one of, the times and the relative times of reception, wherein the transmitter and receiver are arranged respectively to transmit and receive inductive signals and wherein said processing unit is arranged for performing a cyclic correlation to determine one of the times of reception and relative times of reception of the signal at each surface unit, said cyclic correlation being performed between the received signal and a synthesized signal.