The Circuit Design Of The 3-Components Magnetometer And The Measure Method Research Of Underground Magnetic Field

In the development of industry, mineral is important and can't be replaced. But the superficial mineral was limited, after some years'excavation, they can't satisfy the need any more, so we must search the deep-seated mineral. However, the instrument we used now can't complete this new task, so the more powerful instruments should be designed and produced. The 3-components flux-gates magnetometer is one of these kinds of instruments, which can research the weak magnetic field which 500 to 1000 meters underground.According to the method of"the second harmonic wave", the circuit of the 3- components flux-gates magnetometer is composed of two main parts---sensor drive part and signal survey part. The drive part is constructed of a crystal oscillator, two decimals frequency dividers, a quarter divider, a filter and a pulse amplifier. 2 MHz sine wave from crystal oscillator, divided by frequency dividers 3 times; the output becomes 5 kHz square wave signal, then be filtrated and amplified, so the drive part provides the signal stable in frequency and magnitude to sensors. In the same time, the drive part also supplies 10 kHz to magnitude detection of survey part circuit, as reference signal of"the second harmonic waves".The survey part is constructed of an advance amplifier, a band-pass filter, a main amplifier, a phase shifter and phase detection. The filter filtrate the main harmonic wave and third harmonic waves. The amplifier amplifies the signal and the magnitude detection estimates the poles of the magnetic field from sensors. So, the whole function of survey part is filtrating noise, extracting the second harmonic waves signal, and making the signal easy for reading and recording.According to the precision limitations of the circuit, the 3-components flux-gates magnetometer uses gravity acceleration sensors and software to correct the signal data. Designer improved the underground magnetic field measure method. A lot of experimentations about sensors underground rotation were made and proved the way are workable.The 3-components flux-gates magnetometer is effective in underground magnetic field measure.