Noise sources in a Schonstedt spinner magnetometer, the primary laboratory instrument used in paleomagnetic research, and various methods for dealing with them are investigated theoretically and experimentally. Based on the results, an instrument is designed and constructed which replaces the Schonstedt sensor and magnetometer with the recently developed University of British Columbia ring core sensor and magnetometer, and the Schonstedt analyzer with an adaptive filter. A 10dB improvement in the signal to noise ratio was achieved in the magnetometer, and a superior method for measuring this signal, using software, is suggested. A technique for faster noise reduction using a time-varying filter is developed analytically. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

An investigation made concerning the characteristics of a sensor coil for an induction magnetometer shows that it is feasible to make the first stage 60 Hertz rejection filter of the Butterworth type. This is an improvement in design over the Twin-T filter which is sometimes used as a first stage filter as the number of electrical components is reduced and there is no possibility of ringing between the coil inductor and the filter capacitors. Two methods of relative calibration for the induction magnetometer system give reliable response curves. One method uses a Wheatstone bridge. The sensor is one arm of the bridge and it is shown that the effect of the signal generator is the same as if the coil was excited by a natural event. The second method involves exciting the sensor by a field created by a small secondary coil. The agreement between the two methods is good. An experimental approach to the absolute calibration is successfully carried out by comparing the output from the uncalibrated system to an air core system which has been previously calibrated. A theoretical approach is used to give a good indication of the sensitivity of the sensor coil. The sensitivity is dependent primarily upon the turn number and the length of the coil. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (Masters) -- California Institute of Technology, 1936. / Title from home page (viewed 04/20/10). Includes bibliographic references.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Gonzalo Arce, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: Gonzalo Arce, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 66-67). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. Includes bibliographical references.

A recent theory describes the fluxgate magnetometer as a modulated inductor. In that theory, hysteresis and demagnetization are implicitly incorporated in the sense-coil inductance, an easily measured quantity. In this thesis, the principle equation of that theory is experimentally tested. Expressions relating the open-circuit and short-circuit output from a fluxgate magnetometer to the magnetic field are derived from the principle equation. In order to test the proposed relations, the writer assembled a ring-core fluxgate a computer-controlled current source to drive the fluxgate, and circuits required to monitor the open-circuit and short-circuit output signals, initial tests showed that the integrated open-circuit output voltage from the fluxgate is proportional to the magnetic field. The constant of proportionality is simply the product of the length-to-turns ratio of the sense-coil and the maximum change in the sense-coil inductance caused the drive current. This result was correctly predicted by the aforementioned fluxgate equation. Test results from the short-circuit experiment were also correctly predicted by the fluxgate equation. Therefore, experimental data is provided that supports the validity of the fluxgate equation. The same fluxgate theory is used to predict specific values of drive current parameters that maximize the fluxgate output signal. The computer-controlled current source was used to generate a bipolar square-pulse waveform with an adjustable amplitude, frequency, and duty cycle. A sinusoidal drive waveform was also used. Experimental data confirm the validity of all the predicted relations, and thus, provide substantial support for theoretical work that has been recently published. As a final application, the fluxgate theory was used to quantify the behavior of a ring-core fluxgate immersed in a magnetic fluid. A fluxgate was put in magnetic fluid in an attempt to discover if the fluxgate responds primarily to the ambient flux density, and consequently, to determine whether the output signal could be enhanced by simply placing the sensor in a container filled with magnetic fluid, The experiment was terminated when inductance measurements taken on the immersed sensor showed that stray flux from the toroidal drive-coil significantly altered the permeability of the magnetic fluid, and thus altered the calculated values of flux density in the magnetic fluid. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (M. Sc.)--University of Hong Kong, 2002.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 57-59). Also available via the Internet.