Research Of Intelligent Amorphous Wire Weak Magnetic Field Measuring Instrument

As the development of science and technology, the measure of weak magnetic field has been more and more used in the filed of Military, Aviation, Ocean, Geology and Medical science etc. The constantly development of these field call higher and higher request on the parameter of the weak magnetic field measuring instrument, such as sensitivity. The basic and key technology of the instrument is sensor whose performance has quite effect on the sensitivity and precision of the instrument. In this paper, an intelligent weak magnetic field measuring instrument is designed. The magnetic field sensor uses Co-based amorphous wire which has very excellent soft magnetic characteristic as sense organ. This instrument can meet the need both on sensitivity and precision. As the development of Single Chip Microcomputer, at present, the measuring and control instrument almost all use microprocessor to make them intelligent, and the most used is Single Chip Microcomputer. The intelligent instrument can manage many problems which are impossible or difficult for the traditional instrument. They can also make the circuit more predigest, the instrument more reliable, and the cost lower.In this paper, the following works are developed based on the thought mentioned above. The research of the amorphous alloy and sensors are presented. The characteristic of the Co-based amorphous wire is presented. The circuit of the sensor is designed and the theory why it can measure the magnetic field is analyzed. The magnetic field sensor is made and it's performance, such as sensitivity, linearity, is tested at room temperature. The result show that the linearity is 0．0786%FS and the precision can reach to 0．1091%FS. The signal processing circuit and the Single Chip Microcomputer and interface circuit is designed and made. The software of this system is designed and the program is carried out according to the characteristic and function of this instrument. At last, the instrument is made and the performance of it is tested. It can measure the static and alternating magnetic field whose frequency is below 1KHz. The measuring range is-4 Oe～+4 Oe. It can used to measure the geomagnetic field and the magnetic field distributing in the room. It can also used to inspect the disfigurement of the steel wire and steel tube, and so on. It can revise nonlinearity error and temperature effect automatically, check itself when startup, and storage and show the value of the magnetic field. It has serial communication port and can communicate with PC, so the measured value can be transmitted to PC to make further process. The operation is under the control of the keyboard and the result is shown on the LCD. The test results at room temperature show that the precision of this instrument is no less than 1%.