因此，必须建立一套良好的测量体系以及精确的无砟轨道控制网。
So, we should found a suit of favorable survey system and the precise control networks.
其中半实物仿真节点是自行设计的。仿真节点根据卫星运行轨道通过控制以太网接口模拟卫星网络星际链路切换，改变网络拓扑结构。
The semi-physical node controls the interface of Ethernet according to the satellite orbit and simulates the handoff of ISL, and so changes the topology of satellite network.
针对城市轨道交通GPS施工控制网，在施工期间提出了控制网检测的必要性。
Under the control of net being under construction specifically for city orbit traffic GPS, necessity having suggested that under the control of net checks in the period being under construction.
针对城市轨道交通GPS施工控制网，在施工期间提出了控制网检测的必要性。
Under the control of net being under construction specifically for city orbit traffic GPS, necessity having suggested that under the control of net checks in the period being under construction.
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