US3775674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flux gate gradiometer using a pulse generator to drive the energizing windings as well as actuate the detector
Assignee: United States Department of the Air Force
•
Filing: 1972-01-27
•
Granted: 1973-11-27
•
Expires: 1992-01-27
Abstract
Abstract A gradiometer is provided utilizing two flux gate magnetometers to detect magnetic field strength. The signal is sensed only during the magnetic core saturation drive pulse portion of the cycle, the core driver circuitry acting to control sense windings and drive windings simultaneously. There is provided unidirectional drive of the core, a low duty cycle drive, and interrogation of the sense winding only during the drive pulse. The unidirectional drive of the core and low duty cycle conserve power.
Inventors
- 👤 Sloun P Van
- 👤 B Pearlstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:15
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/04; G01R33/022
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
291 words
A gradiometer to detect magnetic fields comprising first and second flux gate magnetometers serving as a sensor for magnetic fields, each of said flux gate magnetometers including a magnetic core, a drive winding, and a sense winding, said drive being connected in a series arrangement, pulse generating means providing pulses having a preselected time duration at a predetermined pulse repetition rate, said pulses driving said series arrangement, a differential amplifier having first and second inputs, said first input receiving the output signal of one sense winding, and the second input the output signal from the other sense winding, a first switch, normally off, in the output path of said differential amplifier, said first switch connected to said pulse generator and upon receipt of pulses from the generator means being turned on for the duration of each received pulse to permit output signals from said differential amplifier to pass therethrough, means connected to said sense windings to generate a bucking field in either direction for said two flux gate magnetometers to cancel out the earth''s ambient field, means connected to said first switch to amplify the difference signal from said differential amplifier to provide an output signal representative of the detected magnetic field, and means connected to said means to amplify to establish the voltage level which said second sense winding operates from thus permitting the establishment of a zero output in the quiescent condition, said means Establishing said voltage level including a resistor and capacitor network receiving said signal representative of said detected magnetic fields, said network having a long time constant, an amplifier, transistor impedance matching means interconnecting said network and said amplifier, the output signal from said amplifier being received by one of the inputs to said differential amplifier.
Claim 2
Dependent Claim
291 words
A gradiometer to detect magnetic fields comprising first and second flux gate magnetometers serving as a sensor for magnetic fields, each of said flux gate magnetometers including a magnetic core, a drive winding, and a sense winding, said drive being connected in a series arrangement, pulse generating means providing pulses having a preselected time duration at a predetermined pulse repetition rate, said pulses driving said series arrangement, a differential amplifier having first and second inputs, said first input receiving the output signal of one sense winding, and the second input the output signal from the other sense winding, a first switch, normally off, in the output path of said differential amplifier, said first switch connected to said pulse generator and upon receipt of pulses from the generator means being turned on for the duration of each received pulse to permit output signals from said differential amplifier to pass therethrough, means connected to said sense windings to generate a bucking field in either direction for said two flux gate magnetometers to cancel out the earth''s ambient field, means connected to said first switch to amplify the difference signal from said differential amplifier to provide an output signal representative of the detected magnetic field, and means connected to said means to amplify to establish the voltage level which said second sense winding operates from thus permitting the establishment of a zero output in the quiescent condition, said means Establishing said voltage level including a resistor and capacitor network receiving said signal representative of said detected magnetic fields, said network having a long time constant, an amplifier, transistor impedance matching means interconnecting said network and said amplifier, the output signal from said amplifier being received by one of the inputs to said differential amplifier.
Claim 3
Dependent Claim
86 words
A gradiometer as described in claim 1 wherein the means to generate a bucking field is comprised of means to average the signals from said sense windings, switch means connected to said pulse generator and said means to average and actuated by said pulses from said pulse generating means to switch on the average signal during said preselected time duration, an amplifier receiving the average signal, a pair of feedback windings associated with said two flux gage megnetometers, said feedback windings receiving the amplified average signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |