Acquisition And Measurement System Of Weak DC Voltage Signal

Weak signal detection technology has been developed rapidly, especially in the field of meteorological sensor,it has been used widely. In the field of weak signal detection, a variety of weak physical signals need to be converted into electrical signals and then amplified. Therefore, the study of weak DC signal detection has important application value and theoretical significance.Aiming at solving problems of the low DC voltage signal is susceptible to noise, low measurement accuracy and poor anti-interference ability during the process of measuring,the interference weak DC signal detection system are analyzed,and the methods and measures to suppress noise interference are put forward. With MSP430F149 as the core, a weak DC voltage signal acquisition and measurement system is designed to realize the 10uv?45uv DC voltage measurement. Specific studies and designs of content are as follows:The signal conditioning circuit is designed by using high precision amplifier,low-pass filter and notch technology, which reduces the influence of internal noise and external disturbance on weak signal measurement. Using a linear regulator chip for power supply design, to reduce the impact of power supply noise on measurement accuracy and reduce power consumption. Using isolation technology,isolated the adverse effects of front-end to analog-digital conversion acquisition circuit. At the same time, the design of the relevant signal display and storage circuit,to achieve a weak DC voltage signal measurement and acquisition.In the IAR development environment, use the modular thinking to design the software of lower level computer.Including the main program, A /D conversion,display procedures, data storage and communication procedures, etc. Through the main program to call the sub-function of the module to complete the system functions, the various modules using global variables and functions of the parameters of information transmission. Using Delphi and Access database to design PC monitoring software. Mainly by the data collection, data query and display, the next bit machine calibration and other functional modules. Through the serial port the lower level computer sends collected data to the host computer to save, display and processing. The use of monitoring software and other measuring instruments, it can achieve measurement accuracy calibration and compensation for the lower level computer.The system compensates the measurement results by calibrating the circuit,software digital filtering and curve fitting based on the least squares method. In the calibration circuit, the voltage deviation is written to the memory. After the system is turned on, the memory calibration value is read to correct the output. The random noise is filtered by the anti-pulse interference averaging method, and the advantages of median filtering and arithmetic mean filtering are taken into account. Based on the least squares fitting error curve, the test voltage is compensated for the output.Through the system simulation and hardware test, it shows that the system can realize the accurate amplification measurement of 10uv ?45uv DC voltage,and can automatically collect and display the collected data. In the case of connecting the PC,through the serial port real-time voltage data sent to the host computer to save,display and processing.