The Reasearch On Signal Acquisition System Of Three Dimensional Ocean Current Sensor Can Measure Upwelling

Marine observation technology as the basis of marine development and other marine activities, is one of the most intense competition field of marine power, and the sensor with high performance is a prerequisite for accurate measurement of marine elements. Up to now, the measurement of upwelling is lack of measuring sensor with high performance at home and abroad.The upwelling velocity is only1/1000to one percent of horizontal velocity, according to this characteristics, the research group designes a3D ocean current sensor which can measure upwelling, and the signal acquisition system designed in this paper is an important part of this sensor.Firstly, this paper analyzes the source of input signal of signal acquisition system, determines that the strain at the cross elastic beam and the end of the micro stress amplification device is the input signal, and puts forward the resolution is no less than1uε as the design requirement. Because the strain cannot be measured directly, using the Wheastone full bridge circuit will convert strain measurement to voltage measurement. Because the output voltage signal is very weak and essy to be "submerged" by noise, through the analyzing of noise sources in signal acquisition system, this paper proposes the design idea of reducting the pre circuit of analog digital conversion and using conversion chip with high integration. Based on the excellent characteristics of noise suppression of∑-Δ modulation type analog-to-digital converter,it chooses AD7195as the ADC.After the analysis of technology of ocean observation platform, this paper uses the submersible buoy system as the observation platform of current sensor, proposes the design requirements of self-contained and low-power. In order to reduce the volume of sensor sealing chamber, this paper uses polymer lithium battery,its nominal voltage is3.7V, and designs the voltage conversion circuit; in order to improve the precision of analog digital conversion, uses high precision reference voltage, ratio measurement technology and AC excitation technique, and designs the analog digital conversion circuit and program; to meet the requirement of data storage in self capacitance sensor, designs the storage circuit; in order to satisfy the needs of data processing and testing personnel setting the analog-to-digital converter according to the characteristics of ocean currents in different sea, designs the Labview program; through the analysis of coupling paths of noise in the system, uses ground shield and single point parallel grounding measures, improving the anti interference ability of signal acquisition system.Finally, the communication function is tested by experiments, and the error of signal acquisition system is±0.11uεThe signal acquisition system designed in this paper can meet the requirements of the3D ocean current sensor which can measure upwelling.