Apparatus and method for measuring buried ferromagnetic objects with a high accuracy of position and in synchronization with a sync pulse provided by a global positioning system

An apparatus for detecting at an earth's surface anomalies in an earth's magnetic field caused by buried ferromagnetic objects, an improvement comprising:

• a plurality of magnetometers in a predetermined array on a mobile platform movable on the earth's surface;
• a fixed station on the earth's surface;
• means, disposed on the mobile platform, for collecting pseudo range data and range correction data from a global positioning system (GPS) and the fixed station in synchronization with and in a first time period centered around a sync pulse signal provided by the GPS;
• and
• collecting means for collecting magnetic field strength data while the mobile platform traverses an area on the earth's surface, during a second time period initiated upon receipt of the sync signal to provide synchronized pseudo range data, range correction data and magnetic field strength data.

A method for detecting buried ferromagnetic objects, comprising:

• receiving on a mobile system moving on an earth's surface, global positioning system (GPS) range correction data from a fixed reference point on the earth's surface;
• receiving GPS pseudo range data on the mobile system moving on the earth's surface;
• measuring magnetic field strength data with an array of total field magnetometers on the mobile system while it is moving on the earth's surface, wherein the collection of the magnetic field strength data is synchronized to and in a second time period initiated upon receipt of a sync pulse signal provided by the GPS and the collection of the pseudo range data and the range correction data is in a first time period centered around the sync pulse;
• and
• combining the pseudo range data, the range correction data and the magnetic field strength data in order to determine a location of anomalies in an earth's magnetic field caused by buried ferromagnetic objects.

A mobile system for detection of buried ferromagnetic objects, comprising:

• an all-terrain vehicle and towed sensor platform including a plurality of magnetometers, a global positioning navigation system, and a data acquisition hardware and software system;
• the navigation system including antenna and receiver means, on the towed platform, for receiving range correction data from a stationary global positioning system (GPS) antenna located on an earth's surface, and for receiving pseudo range data from a plurality of GPS satellites;
• the magnetometers being disposed in a predetermined array about the antenna and receiver means and a predetermined distance above the earth's surface for detecting magnetic anomalies caused by a presence of buried ferromagnetic objects;
• and
• the data acquisition hardware and software system including means for initiating collection of magnetic field strength data, the range correction data and the pseudo range data, in synchronization with a sync pulse signal provided by the GPS to provide synchronized pseudo range data, range correction data and magnetic field strength data;
• and
• means for storing the synchronized pseudo range data, the range correction data and the magnetic field strength data.

A portable system for detecting buried ferromagnetic objects comprising a wheeled assembly or a harness assembly worn by an operator including:

• a navigation antenna for receiving global positioning system (GPS) range data in synchronization with a synchronization pulse;
• a power supply;
• a magnetometer for detecting anomalies in an earth's magnetic field caused by buried ferromagnetic objects;
• an interface for receiving magnetic field strength data from the magnetometer and the range data from the navigation antenna and for providing digital signals representative thereof;
• a computer for receiving the digital signals and processing the same to create synchronized range data and magnetic field strength data;
• and
• means for storing the synchronized range data and magnetic field strength data.