Free nuclear precession gradiometer system

Patent · Tue Oct 08 04:00:00 EDT 1985

OSTI ID:5846158

Hinton, G F

A free nuclear precession gradiometer uses a fluid sample surrounded by a coil the fluid sample containing one or more nuclear species which display a magnetic moment. Current in the coil polarizes the nucleii, which when the current is abruptly terminated precess coherently about the earth's magnetic field. The exact frequency generated is a precise measure of the absolute value of the earth's magnetic field. The signal is in the form of a damped sinusoid with the rate of decay being a function of gradients in the ambient magnetic field. Two vector magnetometers are mounted rigidly on the sensor at the right angles to each other and to the earth's magnetic field. A servo system continuously orients the sensor in a two-axis gimbal system to reduce the output of the vector magnetometers to zero. The instrument is polarized, a counter is triggered to make the frequency measurement, and the signal is analyzed by determining the average amplitude of the signal over a precise interval of time. The result is simultaneous measurement of total intensity and total gradient.

• Assignee: The United States of America as represented by the Secretary of the Navy
• Patent Number(s): US 4546317
• OSTI ID: 5846158
• Country of Publication: United States
• Language: English

Related Subjects

440300* -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
ANALOG-TO-DIGITAL CONVERTERS
COMPUTER CALCULATIONS
COMPUTERS
COUNTING CIRCUITS
CRYOGENICS
DESIGN
ELECTRONIC CIRCUITS
ELECTRONIC EQUIPMENT
EQUIPMENT
FREQUENCY MEASUREMENT
IMPACT FUSION DRIVERS
MAGNETIC FIELDS
MAGNETIC GRADIENT ACCELERATORS
MAGNETIC MOMENTS
MAGNETOMETERS
MEASURING INSTRUMENTS
MEASURING METHODS
MICROELECTRONIC CIRCUITS
MICROPROCESSORS
OPERATION
POLARIZATION
PROTON PRECESSION MAGNETOMETERS