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Variable permeability magnetometer systems and methods for aerospace applications

  • US 10,036,784 B2
  • Filed: 04/01/2015
  • Issued: 07/31/2018
  • Est. Priority Date: 11/17/2014
  • Status: Active Grant
First Claim
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1. A magnetometer comprising:

  • a cylindrical coil assembly extending from a first end to an opposing second end, having a variable permeability core configured to measure low strength magnetic fields having a frequency response range between 0 and 700 hertz, the cylindrical coil assembly further comprising terminals, including at least a first terminal at the first end and a second terminal at the second end of the coil assembly, wherein the variable permeability core includes a plastic coil form and a foil strip constructed of a variable permeability magnetic material that is wrapped within the plastic coil form, the variable permeability core further including a search coil having a sense winding that is wound over the plastic coil form, the search coil further including a secondary winding configured for feedback control or calibration of the magnetometer, the secondary winding being disposed over the sense winding;

    a current source circuit operably connected to the terminals, and including a crystal oscillator configured to provide a high-frequency clock signal to drive the current source circuit and thereby apply a plurality of electric currents to the cylindrical coil assembly, including a voltage-controlled sense current across the terminals, a feedback current applied to the secondary winding to cancel out variation in the Earth'"'"'s field caused by a change in orientation of the cylindrical coil assembly, and a biasing current across the terminals; and

    a voltage readout circuit operably connected to the terminals and configured to measure a voltage across the terminals, with direct current offsets eliminated, due to the applied voltage-controlled currents from the current source circuit,wherein an inductance of the cylindrical coil assembly directly varies as an ambient magnetic field strength varies a permeability of the variable permeability core, and a voltage across the terminals varies directly with the inductance such that the measured voltage across the terminals is a direct measure of the ambient magnetic field strength.

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