计算机数据采集系统中的精度问题研究

Research on Precision of Computer-based Data Acquisition System

计算机数据采集系统中的误差主要来自三方面,即仪表误差、数据采集转换误差和计算机数据类型引起的误差。仪表误差中粗大误差可通过统计学的方法以剔除。通过对数据转换误差精度分析,在选取数据采集部件时,采用A/D采集卡和传感器两个部分误差的匹配的原则达到精度与价格的平衡。由计算机数据类型引起的误差,基本可以忽略。以计算机为基础构成的数据采集系统采用内部时钟方式完成采集和数据处理,虽给数据采集处理系统采集频率带来了一些限制,其事件驱动和软件计时可以从程序角度给予弥补。

The errors in a computer-based data acquisition system are mainly from three aspects: instrument error, data conversion error from analog data to digital data and some errors caused by conversion from digital data to its original data in computers. Some coarse errors belong to instrument error can be removed easily with the statistic method. The analysis of the data conversion error can help user to select the suitable sensors and A/D converters, and keep the balance between cost and procession. The data conversion error in computer caused by using some data type can be neglected. Usually, a computer-based data acquisition system completes its data acquisition and processing in its timer interval process program. Although this mechanism brought some restrictions to data acquisition frequency of the system, the event-driven method and software timer method can partly solve this problem.