GPS assisted walkover locating system and method

An above-ground tracking system, comprising:

• a portable frame extending from a first end to a second end;
• a display disposed on the frame proximate the second end;
• a receiving antenna supported by the frame proximate the first end, wherein the receiving antenna is responsive to a magnetic dipole field;
• a global positioning system receiver supported by the frame;
• a processor coupled to the antenna and receiver;
• and
• a memory coupled to the processor having program instructions stored therein which, when executed by the processor, perform the steps of:
• in response to a first and single user request, obtaining a first set of measurements comprising:
• a location measurement from the global positioning receiver;
• and
• a magnetic field measurement from the receiving antenna;
• and
• thereafter, obtaining iterative sets of measurements, comprising:
• a location measurement from the global positioning receiver;
• and
• a magnetic field measurement from the receiving antenna;
• determining from the magnetic field measurements of the first set of measurements and iterative sets of measurements, as the location measurement and magnetic field measurement change, a relative position of a null location within the magnetic field at which the magnetic dipole field is vertical;
• and
• recording an absolute position of the null location within the magnetic dipole field using the location measurement of the first and iterative sets of measurements and the relative position.