Key Technoligies On Distributed Network Data Collection

Along with the computer technology and internet technology rapid development, networked test system of data acquisition and processing technology are widely used in many fields. Data acquisition system is an important means and tool for obtaining information which consists of sensors, signal acquisition and conversion, computer technology composition. Its quilaty of performance depends primarily on its accuracy and speed. Subject to a distributed network of data collection for the purpose of research, design a network test system structure to solve the distributed network under the multi-joint testing device interface design, clock synchronization, real-time data collection and analysis in the standardization of key problems. Real-time data synchronization in the network of high speed acquisition, clock synchronization, precision remote control theory of key technologies in a certain theoretical significance, solving some practical problems in the test and enhancing the ability of network data synchronization acquisition.Network test system is composed of real-time and non-real-time different test equipments, in order to meet the requirements of integrity and expansibility, put forward a distributed network as the platform, network-based middleware architecture. The entire distribution type network system is divided into low-layer (test equipment interface layer), the middle layer (middleware layer) and top-layer (data collection application layer) of the three-tier network architecture.Along with LXI instrument networks widely used in the test system, the reliability of data transmission and real-time requirements are high. In this paper, the reliability and real-time communication LXI, we present four kinds of methods to improve reliability and precision through the IEEE1588 clock synchronization protocol to improve communication performance. Analyzed IEEE 1588 synchronization mechanism, the synchronization process, the best master clock algorithm and the LXI trigger based on time-based approach.Deviation of transmission delay and the uncertainty of a serious impact on the precision time synchronization, so the delay and deviation measurement, analysis, and compensation to achieve high-precision time synchronization protocol. Firstly, analysed time synchronization method of the boundary of the model. Secondly, based on maximum entropy principle to the measurement of network delay data obtained to meet the most unbiased probability density function of the objective. Then, built a mathematical model of time synchronization errors and gave the random- process model of synchronization and its mean and standard deviation. At last, presented top-bottom curve of muti-hop time synchronization errors.This results are correct testified by emulational experiment.