Broadband Low-noise Fluxgate Sensor

The technology of the magnetic field measurement is an important method to research the magnetism and related physical phenomenon, which have gradually developed as an independent subject. At present, flux-gate technology with excellent performance is used more widely in the magnetic field measurement.A fluxgate sensor with the wide bandwidth and low noise is studied in thesis. First, the principle and the classification of fluxgate sensor are introduced. The principle of fluxgate sensor is analyzed by mathematics and graphic method. Basing on the numerical simulation model, the fluxgate probe, the excitation coil and the sense coil are also analyzed in thesis. By comparing the signal detection methods currently used in the flux-gate technique: second harmonic,pulse amplitude,pulse interval and pulse width, a type of fluxgate with wide bandwidth and low noise is designed.At present, the fluxgate sensor development tends to be simplistic, miniature, automatic and digital. Considered all those factors, the prototype of six fluxgate sensors with wide bandwidth and low noise, and the signal processing circuit is designed based on the method of second harmonic and pulse amplitude. The sensors are tested in the YiChang Magnetic Metrological Station of China Shipbuilding Industry. The result indicates that the various performance such as the bandwidth, the noise,the linearity and the sensitivity all meet or exceed its expectation parameters. The digital part is designed based on the microchip computer C8051F063 which include two channel 16-bit ADCs on-chip. The values of three axis sensor are displayed by LCD. The digital output is transmitted to the computer through RS-232, which facilitates the further processing.