Residence times difference fluxgate

Analytical and experimental results are presented on the fluxgate magnetometers that adopt a time readout technique. Our approach is based on the characterization of the times spent by the core magnetization in each of the two stable equilibrium states of the potential function, that underpins the dynamic of a typical ferromagnetic core, when a (carefully configured) periodic excitation signal is applied. This technique, which we have also generalized to allow a treatment in the presence of a noise-contaminated target signal, presents several interesting features and, in particular, it can be implemented by using bias signals having lower amplitude and frequency than those used in conventional fluxgate processing schemes, thus reducing the device power requirements. Results will be presented, for use during device design and realization, which enable us to propose guidelines for extracting the optimal response. Experiments, have been carried out on a miniaturized fluxgate prototype; this device admits of numerous desirable characteristics, including very good sensitivity, resolution, as well as ease of operation, and reduced onboard power requirements. We conclude with some previously developed theoretical results that characterize the system dynamics in the presence of noise. (C) 2005 Elsevier Ltd. All rights reserved.