Reserch On The Detection Of Magnetic Field Based On Magnetoresistive

The Earth is like a giant magnet. Its magnetic field is very weak and exists on the surface of the earth and the space near earth. As a kind of natural magnetic field, it plays an important role in many fields, such as military navigation, communications, geological exploration, earthquake prediction and so on. Based on this, a high efficient and accurate measurement of magnetic field is extremely important. This paper takes AMR sensor as the earth magnetic field sensing probe to build the weak magnetic signal extraction and amplification integrated circuit controlled by MCU and conclude the software design. The study designs a magnetic field detection system with low power, portable, low cost advantages based on the sensing anisotropic magnetoresistance effect.Finally realized the detecting system which can effectively measure the magnetic field. The main research contents include the following aspects.Firstly, this paper introduce the working principle of anisotropic magnetoresistance effect and Wheatstone bridge. Exploring the working principle of magnetic field detection to use the AMR sensor unit(HMC1021Z and HMC1022). Discussing and verifying the feasibility of magnetic field measurement and the related solutions. Secondly, do the detection system circuit design, the system mainly comprises a magnetic field detection unit, set / reset unit, signal processing unit, microcomputer control and display unit and power supply module. In view of the influence of signal noise, the system taken software and hardware combined filter which can effectively eliminate the noise of the mV level. For the signal amplification circuit design, making a variety of different schemes from the chip and the method of power supply to make a comparative analysis, the final choice is use AD623 with single supply as the chip for the amplification circuit design. In the power supply design, the paper designed battery power supply and 220 V AC power supply which can make the test flexibility. Choosing LCD liquid crystal display as the output display which can significantly reduce the power consumption. In order to effectively carry out the measurement of the geomagnetic field, first of all, the sensors were calibrated which can get the characteristic curve about the voltage changing with the magnetic field. This can overcome the problems for the sensor itseif’s bias which maybe caused error. The measurement results of the magnetic field is 0.520 gauss which is consistent with the actual. Finally, carried on a preliminary research and complete the design of two-dimensional electronic compass based on the realization of the detection of the magnetic field. Drawing the curve of the changing magnetic field with angle. Based on the detection data, the electronic compass can effectively identify angle which can provide technical support for geomagnetic navigation.