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列车车载分布式监测系统的时间同步方法研究 被引量:1
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作者 张冰 王志良 +1 位作者 曹熙 田亮 《铁道机车车辆》 北大核心 2024年第6期97-102,共6页
针对车载分布式监测系统内各子节点系统时钟不一致的情况,提出了一种基于软件实现的、不依赖额外时钟同步设备且精度高于NTP协议的系统同步方法。计算各子节点与中心节点的时间偏差,此时间偏差不用于调节子节点的本地时钟,而是与子节点... 针对车载分布式监测系统内各子节点系统时钟不一致的情况,提出了一种基于软件实现的、不依赖额外时钟同步设备且精度高于NTP协议的系统同步方法。计算各子节点与中心节点的时间偏差,此时间偏差不用于调节子节点的本地时钟,而是与子节点采集的数据及对应时间戳一起发送至中心节点。中心节点可根据时间偏差对各设备上报数据的时间戳进行修正,以此达到分布式系统同步的目的。而在计算子节点与中心节点的时间偏差中,相较于传统的NTP网络时间协议,还需考虑报文在软件应用层到网卡之间的传输时延。为计算此时延,引入比NTP精确度更高的PTP参考主机预先对该时延进行估计,由此得到分布式系统的时偏精度高于传统的NTP协议。 展开更多
关键词 车载 分布式系统 同步 系统时钟偏差 网络时间协议
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Clock-based RAIM method and its application in GPS receiver positioning 被引量:4
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作者 滕云龙 师奕兵 《Journal of Central South University》 SCIE EI CAS 2012年第6期1558-1563,共6页
Because the signals of global positioning system (GPS) satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. I... Because the signals of global positioning system (GPS) satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring (RAIM) method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias (RCB) is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites. 展开更多
关键词 positioning precision receiver autonomous integrity monitoring (RAIM) receiver clock bias (RCB) grey theory Markov chain
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