Research On Optimization Design Method Of Low Noise For MET Seismometer

Seismic exploration technology is still the most effective technical means in geophysical exploration at present.For seismic exploration,seismological observation as the most important part of seismic exploration plays an irreplaceable role in exploration.Seismometer is a sensor that converts vibration signals on the ground into digital signals through data acquisition.Different from conventional electromechanical seismometers,MET(Molecular Electronic Transducer)seismometer is a new type of seismometer.The principle of MET is that the vibration signal drives the electrolyte in the redox reaction chamber to create relative movement with sensitive components,and then causes the redox reaction around the cathode and anode electrodes in the chamber.After the process of external adjusting circuit,differential voltage output signal is obtained.MET seismometer uses the redox reaction of electrolyte in the chamber.The chamber structure makes it unnecessary to consider the gravity field effect of the mass block of conventional seismometer.Therefore,it is small in size and light in weight.It is more convenient to carry and use for users in field experiments.The low noise optimization design method of MET seismometer will be studied in the article.We will develop MET seismometer from two aspects: the low noise optimization design of the redox reaction chamber and the low noise optimization design of the external adjusting circuit of MET seismometer.Therefore,the core content of this paper is as follows:(1)The structure and self-noise type of MET seismometer.On the basis of a large number of related papers,the author summed up and summarized the structure and selfnoise types of MET seismometer,and analyzed the preparation scheme and self-noise optimization scheme of MET seismometer theoretically.(2)Low noise optimization design of the redox reaction chamber of MET seismometer.Research began from the core sensitive element of the redox reaction chamber and established the mathematical model and multi-physical field model of the sensitive element.Through the analysis of the sensitive element to determine the processing mode of the sensitive element by comparing the current density and the flow velocity of the solution in the single channel,then manufactured sensitive element with the low temperature co-fired ceramic technology.Seven-hole honeycomb tube structure was used to reduce the instability of electrolyte's flow rate in the reaction chamber,and the self-noise of the reaction chamber was optimized from the structure of the redox reaction chamber.Then the author solved the transfer function of the redox reaction chamber.(3)Low noise optimization design of the external adjusting circuit of MET seismometer.MET seismometer adjusting circuit consists of two parts,power supply circuit and signal processing circuit.The power supply circuit includes op-amp power supply circuit and anode power supply circuit.The signal processing circuit includes differential current-to-voltage circuit,signal amplification,filtering and feedback circuit.Finally a self-noise test system of adjusting circuit is constructed,and the noise test of adjusting circuit is carried out.(4)Performance test of MET seismometer.Through establishing self-noise detection system of MET seismometer,the time-domain waveform and power spectral density of the self-noise of MET seismometer are obtained.To provide vibration signal for MET seismometer by using of ultra-low frequency shaking table and to measure the sensitivity of MET seismometer.And to test the influence of temperature for MET seismometer by experiment.Later,the actual field test was used to verify the practicality of MET seismometer which has been optimized with low noise.