Digital compass and magnetometer having a sensor coil wound on a high permeability isotropic core
DCFirst Claim
1. A magnetometer comprising:
- an oscillator circuit comprising;
oscillator driver means having first and second terminals for providing an oscillating current; and
sensor means having a first coil wound on a first high permeability isotropic core for controlling the frequency of said oscillator circuit, said first coil coupled between said first and second terminals, said first coil having a magnetic axis;
said oscillator driver means for providing a DC bias current through said first coil, such that when said sensor means experiences a change in an externally applied magnetic field, the frequency of the oscillating current changes monotonically with the change in magnitude of the applied external magnetic field in the direction of the magnetic axis of said first coil; and
measurement means for measuring the frequency of the oscillating current and providing a measurement signal in response thereto.
2 Assignments
Litigations
0 Petitions
Accused Products
Abstract
A digital compass (20) has a sensing coil (60) wound on an elongated strip of high direct current permeability magnetic material. The sensing coil (60) is connected to a sensing circuit (56). The sensing coil and sensing circuit are responsive to the Earth'"'"'s magnetic field to provide an oscillating signal at an output (28) of the sensing circuit (56) which varies in frequency with orientation of the at least one sensing coil (60) with respect to the Earth'"'"'s magnetic field. A microprocessor (36) is connected to receive information inputs from the oscillating signal. The microprocessor converts the information inputs to an indication of orientation of the sensing coil with respect to the Earth'"'"'s magnetic field based on the frequency of the oscillating signal. A display (52) receives the orientation indication from the microprocessor.
91 Citations
17 Claims
-
1. A magnetometer comprising:
-
an oscillator circuit comprising; oscillator driver means having first and second terminals for providing an oscillating current; and sensor means having a first coil wound on a first high permeability isotropic core for controlling the frequency of said oscillator circuit, said first coil coupled between said first and second terminals, said first coil having a magnetic axis; said oscillator driver means for providing a DC bias current through said first coil, such that when said sensor means experiences a change in an externally applied magnetic field, the frequency of the oscillating current changes monotonically with the change in magnitude of the applied external magnetic field in the direction of the magnetic axis of said first coil; and measurement means for measuring the frequency of the oscillating current and providing a measurement signal in response thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 14)
-
-
9. A digital compass comprising:
-
a first voltage comparator circuit having first and second input terminals, and a output terminal, said output terminal being coupled back to said second input terminal and said second input terminal being coupled to a first reference potential; a first sensing coil wound on a high permeability isotropic core having a magnetic axis and being connected between said first input terminal and said output terminal of said first voltage comparator circuit so as to form a first relaxation oscillator, said first relaxation oscillator providing a first oscillating signal having a frequency that is a monotonic function of the magnitude of the earth'"'"'s local magnetic field in the direction of the magnetic axis of the first sensing coil; and processor means coupled to receive said oscillating signal from said first relaxation oscillator for providing an indicator signal representative of the orientation of the magnetic axis of said first sensing coil with respect to the direction of the earth'"'"'s local magnetic field. - View Dependent Claims (10, 11, 12, 13, 15, 16, 17)
-
Specification