| In science and technology,an instrument can measure the strength of Magnetic field and monitor the changes of magnetic field over time.Besides,it can also find the abnormal of magnetic field and its magnetic features.We call the instrument Magnetometer.There are many kinds of magnetometer applying in the magnetic exploration.According to different working methods,magnetometer can be divided into several types,air magnetometer,ground magnetometer,sea magnetometer and Well Logging magnetometer and so on.According to the working principle,magnetometer can be divided into the following types,mechanical magnetometer,Magnetic Resistance magnetometer,fluxgate magnetometer,proton—precession magnetometer,optical pumping magnetometer and super conducting magnetometer.According to the variety of magnetic field being measured,magnetometer can be divided into the other types,vertical magnetometer,level magnetometer,tri-axis magnetometer and magnetic gradiometer.The measurement of Magnetic field is important in the military,industry,scientific research.In this paper,new type of magnetoresistive sensor is used to develop a three-component magnetometer,the magnetometer will not be affected magnetoresistive sensor chip sensitivity and accuracy of the basic properties of the premise,can measure the level and vertical geomagnetic field strength.Magnetoresistive sensor as a result of small size,high sensitivity,easy installation,has a broad application prospect in the weak magnetic field measurements.The magnetometer developed by the author belongs to the ground magnetometer, which works based on the anisotropy of magnetic resistance FE-NI.These sensors HMC1001,1002 are products made by HONEYWELL Company.They are one-dimensional magnetometer and two-dimensional magnetometer respectively.Because the three magnetic axes are placed vertically,the magnetometer can be used to measure the three-dimensional magnetic field.The first chapter of this paper described the importance of developing of MR magnetometer.And the element of magnetic field is also explained in detail.So we can establish the mention of measuring.The second chapter firstly introduced the fundamental principle of the apply sensor and then introduced the method of using the sensor in detail.The third chapter designed the whole system,including the design of sensor probe system and control system.In the section of probe,there are the circuits of measuring magnetic field and measuring the angle of body.The MR sensor HMC1001,1002 produced by HONEYWELL company are used to measure the magnetic field,and the sensor SCA100T made by VTI is used to measure the angle of body.Because the Real-time data should be displayed,storied and processed.The control system should include the source block,key block,display block,counting block and communication block.Among these blocks,the single-chip system MSP430F1611 is due to control the transmission of the signal.In the power supply section,there are two LM7805 supplying the power of +5V,one is supplied for LED,and the other is supplied for the other circuit using +5V.AMS1117 is used to supply the power of +3.3V.MAX761,765 supplied the positive and negative 12V.Four keys are used to select the menu.They mean up,down, enter and exit respectively.The LED is JM 12864 produced by Nanjing Juemiao Company. Clock chip is DS1302 made by DALLAS.FT245 is used to accomplish the communication between microchip and PC.The fourth chapter described the accomplished experiment about the magnetometer, including the demarcating of the magnetometer,the calibrating of offset voltage at Zero point,and measuring of every index,including linear equation,stability,repeatability, temperature coefficient.Besides,temperature compensation was also accomplished in order to improve the precision.The fifth chapter summarized the design of this system,and described the existing problems of this system.
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