Apparatus and method for detecting magnetically detectable plastic pipe

Abstract

An apparatus is disclosed for manipulation by an operator or user for detecting magnetically detectable plastic pipe and other sources of magnetic fields from a distance having a horizontally oriented support member with a handle extending at an acute angle therefrom. A magnetic field gradiometer comprising a hollow non-magnetic tube with two flux-gate magnetometers therein is supported at the distal end of the support member a substantial distance ahead of the operator in a substantially vertical position. A microprocessor is supported on the support member operatively connected through a differential amplifier to the gradiometer for processing signals therefrom. An electronic read-out module is supported on the handle spaced from the gradiometer and operable to receive signals from the microprocessor and convert them into an audible or visual display to be sensed by the operator or user. The size and weight distribution of the apparatus and the angles at which the components are assembled assure that when the apparatus is hand held by the handle the gradiometer is balanced in a vertical position at a substantial distance ahead of the operator or user. An alternate embodiment, i.e., a magnetic field mapper, is shown having a plurality of gradiometers supported in parallel on supporting wheels and having the visual and audio display in the form of a laptop or notebook type computer supported on the handle for the wheeled apparatus. A hand held embodiment of the mapper is also disclosed.