Roll-independent magneto meter system
AssigneeThe Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorBrian W. Daniels
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Abstract
A roll-independent magnetometer which may be used for example in a towed array magnetometer system comprises a first magnetic field sensor having iso-angular flux sensitivity about a roll axis and a second magnetic field sensor having sensitivity along the roll axis, the arrangement being such that a component of a magnetic field along the roll axis is measured by the second unidirectional sensor and the component of the field lateral to the roll axis is measured by the first sensor. Corrections may be applied for the inclination of the sensor and the angle of dip of the Earth's field. The angle of dip may be measured either in the towing vessel, in the towed body, or provided in look-up tabulated form.
Claims13
A roll-independent magnetometer system comprising two magnetic field sensors, said system comprising:
- a first magnetic field sensor mountable on a moveable object and arranged to have iso-angular flux sensitivity about a roll axis;
- and
- a second magnetic field sensor mountable on the object and arranged to have sensitivity along the roll axis wherein said second sensor is an elongate toroidal magnetic body having a large length to width ration, arrangeable lengthwise of the roll axis of the object and dimensioned to permit accurate spatial colocation with the first sensor, said second sensor is provided with a primary coil for connection to a source of an energizing alternating signal and a secondary pick-off coil encircling the magnetic body and having an axis parallel to the roll axis;
- the arrangement being such that a component of a magnetic field along the roll axis is measured by the second unidirectional sensor and the component of the magnetic field lateral to the roll axis is measured by the first sensor.
A roll-independent magnetometer system comprising two magnetic field sensors, said system comprising:
- a first magnetic field sensor mountable on a moveable object and arranged to have iso-angular flux sensitivity about a roll axis;
- and
- a second magnetic field sensor mountable on the object and arranged to have sensitivity along the roll axis;
- the arrangement being such that a component of a magnetic field along the roll axis is measured by the second unidirectional sensor and the component of the magnetic field lateral to the roll axis is measured by the first sensor, wherein the longitudinal component of the external field is measured by providing one of a mumetal wire and other material, parallel to the roll axis and transmitting an alternating current, a pick-off winding provided around the mumetal wire, a DC bias source connected to the mumetal wire and an AC detector connected to the pick-off coil, the arrangement being such that the field is determined from the DC bias required to cancel the effect of the field.
Dependencies are inferred from the claim text.