Research On Amplification Technology Of Wideband Inductive Magnetism Transducer

The inductive magnetism transducer is most widely used in the frequency domain electromagneticexploration, as the magnetic field receiver. It has many characteristics like light and flexible, wideexploration range, high efficiency, low cost, high resolution. It can be used to monitor the waterquality of the geological surface, also can be used to detect the mineral resources of geologicaldeep. So it has a very broad application prospects. According to the principle of skin effect, andthe skin depth is directly related to the frequency, different frequencies corresponding to differentexploration depth. So, in order to have a exploration depth as wide as possible, the inductivemagnetism transducer should have a frequency band as wide as possible. The inductivemagnetism transducer developed by domestic has a limited probing depth, because of it’s narrowfrequency bands, low sensitivity and low resolution. We mainly rely on imports of foreignhigh-performance magnetism transducer, which has a expensive price, and some of them exportrestrict to us. This seriously hampered the progress of electromagnetic exploration work.The inductive magnetism transducer is composed of induction coil and amplifier. The inductioncoil output signal has the following characteristics: wide frequency bandwidth,large dynamicrange, weak signal,phase at the resonant frequency of mutation.This article from the compensationof the inductive magnetic sensor amplification circuit point of view analysis, suitable for theinduction coil output signal characteristics of the amplifier circuit design, in order to let theinduction coil measured useful signal acquisition system to collect and to get the measuredmagnetic field information.The main contents of this article are as follows1,Studied the magnetic measuring principle of the induction type magnetic sensor, and thephysical structure of the induction coil model analysis and simulation, and the induction coiloutput signal is measured to verify the correctness of the analysis and policy. Through the analysisof the induction coil, the simulated and measured, a clear induction coil output signalcharacteristics and post-stage amplifier circuit design requirements.2, According to the characteristics of the induction coil of the output signal, designed after level compensation amplifier circuit, after level compensation amplifier into a low-frequency amplifiercircuit and the high-frequency amplifier. The low-frequency amplifier circuit is used to improvethe sensitivity and resolution of low frequency magnetic sensors, high-frequency amplifier circuitused to extend the high frequency band of the magnetic sensor. PC control, the low frequencyamplifying circuit switching.3, High-frequency amplifier circuit used magnetic feedback structure, magnetic feedbackmechanism is studied theoretically, and its simulation and experimental verification; the choice ofthe feedback depth study proposed a feedback too deep, resulting in a self-excited oscillation ofthe critical conditionsthrough experiments; designed magnetic feedback circuit, reducing thedynamic range of the magnetic sensor output to solve the problem of coil output frequencycharacteristics at the resonant frequency of mutations, and extends the width of the magneticsensors are used for high frequency band; designed lownoise preamplifier circuit is used toimprove the high frequency resolution of the magnetic sensor4, Low-frequency amplifier used the chopper amplification structure, chopper amplificationprinciple, the time domain and frequency analysis; a theoretical analysis of the chopper amplifiernoise and residual offset; by repeated experiments, to determine the optimal structure and deviceparameters,amplifier circuit to bring1/f noise is effectively suppressed, and extends thelow-frequency band width of the magnetic sensors can be used to improve the low frequencyresolution5, Putted the high-frequency amplifier circuit and the low-frequency amplifier circuit together forjoint commissioning, so that the output characteristics of the magnetic sensor has a betterconvergence in the high and low band. And complete the overall test of the induction typemagnetic sensor, calibration of the sensitivity of magnetic sensors and magnetic sensorsamplitude-frequency characteristics, and phase frequency characteristics and noise levels weretested through field trials to test the design the success of the induction type magnetic sensorsFinally, we succeed in the develop of the inductive magnetism transducer, with wide frecquencyband, high sensitivity, low noise, high resolution. Through numerous field tests, it is verified thesuccess of the inductive magnetism transducer developed by us. We contrast our inductivemagnetism transducer to MFS06inductive magnetism transducer developed by German，theperformance of us is approaching to the German’s. It illustrates that we have achieve international level.