微弱直流电压信号的采集与测量系统

发布时间：2018-04-15 20:13

本文选题：微弱信号检测 + 信号调理　；参考：《南京信息工程大学》2017年硕士论文

【摘要】：微弱信号检测技术快速发展,尤其在气象传感器方面得到了广泛应用。在需要微弱信号检测的领域中,各种微弱的物理量信号都需要先转成电信号再进行放大处理。因此,对微弱直流信号检测的研究具有重要的应用价值和理论意义。本文针对微弱直流电压信号测量过程中易受噪声干扰、测量精度不高、抗干扰能力差的问题,分析了微弱直流电压检测系统噪声干扰,提出了抑制噪声干扰的方法和措施,以MSP430F149为核心,设计了微弱直流电压信号采集与测量系统,实现了对10uv～45uv直流电压测量。具体研究和设计内容如下:采用高精度放大器,低通滤波和陷波技术,设计了信号调理电路,降低了内部噪声与外部干扰对微弱信号测量的影响。采用线性稳压芯片进行电源设计,减少了电源噪声对测量精度的影响,降低了功耗。采用隔离技术,隔离了前端对模数转换采集电路的影响。同时,设计了相关的信号显示和存储电路,实现了微弱直流电压信号的采集与测量。在IAR开发环境中,采用模块化思想,设计了系统下位机软件。主要包括主程序、A/D转换、显示程序、数据存储及通信程序等,通过主程序调用各模块的子函数完成系统功能,各个模块间采用全局变量和函数的参数进行信息传递。上位机监控软件采用Delphi和Access数据库开发。主要由数据采集、数据查询与显示、下位机校准等功能模块构成。下位机采集数据通过串口将数据发送到上位机保存、显示和处理。系统通过校准电路、软件数字滤波和基于最小二乘法的曲线拟合对测量结果进行补偿。校准电路中,将压值偏差写入存储器,系统开机后读取存储器校准值以修正输出。采用防脉冲干扰平均滤波法对随机噪声进行滤波处理,兼顾了中值滤波和算术平均值滤波的优点。基于最小二乘法拟合误差曲线,对测试电压值进行补偿输出。通过系统仿真和硬件测试,表明系统可以实现对10uv～45uv直流电压测量,并能将采集的数据进行自动存储和显示。在连接PC机的情况下,能通过串口实时将电压数据发送至上位机保存、显示和处理。
[Abstract]:Weak signal detection technology has developed rapidly, especially in meteorological sensors.In the field of weak signal detection, all kinds of weak physical signals need to be transformed into electrical signals and then amplified.Therefore, the research of weak DC signal detection has important application value and theoretical significance.In this paper, the noise interference of weak DC voltage detection system is analyzed, and the methods and measures to suppress the noise interference are put forward in order to solve the problem that the weak DC voltage signal is easy to be disturbed by noise, the measurement accuracy is not high and the anti-interference ability is poor.Taking MSP430F149 as the core, the acquisition and measurement system of weak DC voltage signal is designed, and the DC voltage measurement of 10uv~45uv is realized.The specific research and design contents are as follows: using high precision amplifier, low pass filter and notch technology, the signal conditioning circuit is designed to reduce the influence of internal noise and external interference on weak signal measurement.The linear voltage stabilizer chip is used to design the power supply, which reduces the influence of the power noise on the measurement accuracy and reduces the power consumption.Isolation technology is used to isolate the effect of front end on A-D conversion acquisition circuit.At the same time, the related signal display and storage circuit are designed to realize the acquisition and measurement of weak DC voltage signal.In the development environment of IAR, the software of the lower computer is designed with the idea of modularization.It mainly includes the main program called A / D conversion, display program, data storage and communication program, etc. The system functions are completed by calling the sub-functions of each module by the main program, and the global variables and the parameters of the function are used to transfer information among the modules.The host computer monitoring software is developed by Delphi and Access database.Mainly composed of data acquisition, data query and display, lower computer calibration and other functional modules.The data collected by the lower computer is sent to the upper computer through serial port to save, display and process.The system compensates the measurement result by calibrating circuit, software digital filter and curve fitting based on least square method.In the calibration circuit, the bias of the voltage value is written to the memory, and the system reads the calibration value of the memory to correct the output after the system is turned on.The average filtering method against impulse interference is used to filter random noise, which takes into account the advantages of median filter and arithmetic average filter.Based on the least square fitting error curve, the test voltage value is compensated and outputted.The system simulation and hardware test show that the system can measure the DC voltage of 10uv~45uv and can automatically store and display the collected data.In the case of connecting PC, the voltage data can be sent to the host computer to save, display and process through serial port in real time.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911.23

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