Autonomous magnetic measurement system

• US 8,321,161 B1
• Filed: 09/17/2010
• Issued: 11/27/2012
• Est. Priority Date: 09/17/2010
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Bruno, Anthony B., Kasper, Rolf G.
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US12/884,769
• Time in Patent Office: 802 Days
• Field of Search: 702/57, 702/92, 702/150, 333/35.R, 333/56, 333/61, 333/16, 333/19, 333/57, 333/26, 701/530, 701/213, 701/518, 324/338, 324/347, 324/345, 324/226, 324/202, 324/244
• US Class Current: 702/57
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

Abstract

The invention as disclosed is an autonomous magnetic measurement system for monitoring the background magnetic fields associated with power lines, electronic devices, electronic vehicles and the Earth'"'"'s background magnetic field. The components of the autonomous magnetic measurement system include a series of three axis analog magnetic sensors, a fluxgate compass, and a programmable micro-controller. The micro-controller receives data from the sensor and compass and is programmed to autonomously detect magnetic signals having particular characteristics of interest.

Claims

1. An autonomous magnetic field measurement system comprising:

a tetrahedral structure constructed of a non-magnetic, dielectric material;

a plurality of three axis magnetic sensors joined to the vertices of the tetrahedral structure, wherein each three axis magnetic sensor generates a plurality of data signals pertaining to a proximate surrounding magnetic field in three orthogonal directions and a total magnetic field according to (B_x²+B_y²+B_z²)^1/2;

a flux gate compass that generates a plurality of data signals pertaining to the spatial orientation of the autonomous magnetic field measurement system;

a micro-controller connected to the flux gate compass and the plurality of three axis magnetic sensors that receives and processes the plurality of data signals generated by the flux gate compass and the plurality of three axis magnetic sensors to derive a plurality of magnetic field data for at least one frequency of interest over a specified period of time;

a memory unit, connected to the micro-controller, containing an analysis software that instructs the micro-controller in the method of processing the plurality of data signals generated by the flux gate compass and the plurality of three axis magnetic sensors;

a non-volatile digital memory storage device connected to the micro-controller that stores the plurality of magnetic field data derived by the micro-controller; and

an electric power source electrically connected to the flux gate compass, the plurality of three axis magnetic sensors, the micro-controller, the memory unit and the non-volatile digital memory storage device to provide direct current power to the autonomous magnetic field measurement system.

2. The autonomous magnetic field measurement system of claim 1 wherein the flux gate compass and the micro-controller are electrically connected across a universal asynchronous receiver transmitter.

3. The autonomous magnetic field measurement system of claim 1 wherein the plurality of three axis magnetic sensors and the micro-controller are electrically connected across a parallel port interface port such that the micro-controller can receive both direct current and alternating current digital magnetic field data from the plurality of three axis magnetic sensors.

4. The autonomous magnetic field measurement system of claim 1 wherein the plurality of three axis magnetic sensors are aligned such that the x axis of each sensor is parallel to the other sensor and the z axis of each sensor points in the positive up direction.

5. The autonomous magnetic field measurement system of claim 1 wherein all but one of the plurality of three axis magnetic sensors as arranged on the tetrahedral structure function as a gradiometer while the remaining one of the three axis magnetic sensors functions as a reference sensor.

6. The autonomous magnetic field measurement system of claim 1 wherein the analysis software is capable of being tailored to measurements of specific types of magnetic fields by removing the memory unit and reprogramming the analysis software.

7. The autonomous magnetic field measurement system of claim 1 wherein each of the plurality of three axis magnetic sensors uses three identical circuits each comprised of a 1 mm amorphous ferromagnetic fibers composed primarily of nickel (Ni), cobalt (Co), and Iron (Fe) in a micro-fiber that is approximately thirty microns in diameter and a preamplifier assembled into a three orthogonal axis probe, wherein the micro-fiber exhibits giant magneto impedance such that the voltage output of the three axis analog magnetic sensor is directly proportional to the magnetic field in all directions.

8. The autonomous magnetic field measurement system of claim 1 wherein the plurality of three axis magnetic sensors, the flux gate compass and the micro-controller are fabricated on a single integrated circuit chip having a plurality of interfaces to allow a standard computer to read a plurality of data directly from the micro-controller and display the plurality of data in a plot or spreadsheet.

9. A method for measuring dynamic magnetic fields through an autonomous magnetic field measurement system comprising:

arranging a plurality of three axis magnetic sensors on a tetrahedral structure with a flux gate compass, and electrically connecting the sensors and compass to a micro-controller at a specified distance from an electrical source of magnetic fields;

receiving a continuous plurality of magnetic field data generated from the plurality of three axis magnetic sensors, with the micro-controller;

receiving a continuous plurality of spatial orientation data from the flux gate compass with the micro-controller;

measuring a plurality of dynamic magnetic fields having a predetermined specified frequency of interest at a predetermined specified sample rate for a predetermined specified period of time, including a natural variability of said plurality of dynamic magnetic fields and a maximum magnetic field value with the micro-controller using the continuous plurality of magnetic data and plurality of spatial orientation data;

contrasting the plurality of dynamic magnetic fields at predetermined specified frequencies of interest relative to the Earth'"'"'s magnetic field with the micro-controller; and

storing the direct measurements and relative measurements in a non-volatile digital memory storage device connected to the micro-controller.