Low Noise Design For Small Ground Vibration Detection System

With the continuous improvement of the Internet of things system,the perimeter intrusion prevention system,as an important part of the Internet of things,has become more and more common.As an important part of the circumferential intrusion prevention system,the micro ground motion detection system has become an important part of the security system in some special places.The magnitude of vibration signals generated by people walking on the ground is too small(Generally below10^-6V),so restraining the internal noise and external radiation interference of the system is particularly important.In order to accurately identify the moving situation of the personnel,the noise of the whole system should be reduced to very low.The low noise design of the small ground motion detection system has become the most important part of the whole system design,and it is the foundation of the actual application of the whole system.In this paper,the electromagnetic low-frequency vibration sensor is used as a sensor unit to perceive the small vibration signals of people walking on the ground.The signal is de-noised by the design circuit.It is the basis of the follow-up data analysis.The specific research content is divided into the following parts:1,The characteristics of the background noise of the sensor and the characteristics of the vibration signal produced by the personnel are studied.The amplitude and frequency energy distribution in the time domain are analyzed,and the amplitude and frequency characteristics of the vibration signal are determined.The output characteristic of the power supply is determined by testing the output curve of the power supply.2,In view of the vibration signal produced by the personnel walking and the background noise signal of the sensor,the sensor modulation circuit is designed,including the reverse voltage circuit,the reference voltage circuit,the filter circuit and the amplifying circuit,and the data simulation is carried out to the part of the circuit,and the schematic diagram of the part of the circuit is completed.3,According to the output characteristics of the power noise,the power depressurization module is designed,including the anti reverse circuit of the power supply,the DC-DC switching power supply circuit,the LDO linear power circuit,and the data simulation of this part of the circuit,and the schematic design of this part of the circuit is completed.4,According to the schematic diagram,carry out the layout design of each part.After the layout design is completed,the experiment is carried out at different seasons and temperatures,and the experimental conclusion is obtained,which meets the project requirements.