精确时间同步协议在空间无线信道下的适应性研究

Research on the Adaptability of Precision Time Protocol to Space Wireless Channel

摘要:

IEEE1588协议定义的精确时间协议（Precision Time Protocol，PTP）能够实现地面以太网网络节点中的时钟同步，达到亚微秒级时间同步精度。相比于稳定的地面以太网环境，深空网络环境具有长时延、时延抖动及信道不对称等特点。对PTP协议在深空邻近空间无线信道下的时间同步性能进行了研究。首先，介绍了PTP协议的同步原理。其次，对深空邻近无线网络信道环境对于适用于地面以太网环境的PTP协议时间同步性能的影响进行了分析，并提出采用卡尔曼滤波算法和设定主从时钟钟差阈值相结合的方法，对PTP协议进行适应性改进。最后，采用损伤仪和测试仪模拟深空邻近无线网络信道环境，利用时钟分析仪对软件结合硬件实现的PTP协议进行了时间同步性能测试。测试结果表明，改进后的PTP协议提高了在深空邻近空间无线信道下时间同步的精度和稳定性。

Abstract:

IEEE 1588 defines the Precision Time Protocol, also known as PTP, which can synchronize the time of each Ethernet node within sub-microsecond precision. In this paper, we discuss the influence of long delay and jitter of the Space wireless channel as well as the load of the network on synchronization performance. First of all, we introduce the principle of PTP. Then the influence factors of deep Space proximity wireless channel is analyzed and the method of Kalman Filter and thresholds for the variation of offset is introduced. Finally, the Spirent TestCenter and Calnex Attero is used to simulate the channel to test the performance of PTP. eliminate effect of network load on synchronization performance. The test results show that the proposed method can eliminate the effect of network load and jitter in simulated deep Space proximity wireless channel and the improved PTP has a steady synchronization precision of sub-microseconds.