基于地面站的星间链路全网测试技术

星间链路是我国自主导航系统的重要技术支撑,基于相控阵天线的并发空分时分双工(CSTDD,concurrent spatial time division duplexing)组网体制为星间链路的实现提供了一种可行途径,该体制通过指向性天线形成窄波束切换指向来实现对整个空域的复用,通过单条链路半双工方式工作实现卫星之间的双向通信,从而实现整个星间链路采用同一频点。在全星座组网未完成的情况下如何对星间网络的全网性能进行有效测试是一个技术难题;星间链路全网测试技术旨在利用星间链路CSTDD体制的特点,利用单台地面站设备,对星间链路CSTDD体制的全网性能进行测试;详细介绍了星间链路CSTDD体制的特点,提炼出了星间链路的测试需求;并根据CSTDD体制特点,依托单台地面站设备,组成星间链路测试设备;产生指定数量的虚拟卫星,和空中的被测试卫星组成星间链路网络,完成了星间链路物理链路、测量数据、通信数据的测试,为组建我国自主导航系统提供了技术支撑。

An energy efficiency clustering routing protocol for WSNs in confined area

Wireless sensor networks (WSNs) are important application for safety monitoring in underground coal mines, which are difficult to monitor due to natural conditions. Based on the characteristic of limited energy for WSNs in confined underground area such as coal face and laneway, we presents an energy- efficient clustering routing protocol based on weight (ECRPW) to prolong the lifetime of networks. ECRPW takes into consideration the nodes' residual energy during the election process of cluster heads. The constraint of distance threshold is used to optimize cluster scheme. Furthermore, the protocol also sets up a routing tree based on cluster heads' weight. The results show that ECRPW had better perfor- mance in energy consumption, death ratio of node and network lifetime.

Energy optimal routing for long chain-type wireless sensor networks in underground mines

Wireless sensor networks are useful complements to existing monitoring systems in underground mines. They play an important role of enhancing and improving coverage and flexibility of safety monitoring systems.Regions prone to danger and environments after disasters in underground mines require saving and balancing energy consumption of nodes to prolong the lifespan of networks.Based on the structure of a tunnel,we present a Long Chain-type Wireless Sensor Network（LC-WSN）to monitor the safety of underground mine tunnels.We define the optimal transmission distance and the range of the key region and present an Energy Optimal Routing（EOR）algorithm for LC-WSN to balance the energy consumption of nodes and maximize the lifespan of networks.EOR constructs routing paths based on an optimal transmission distance and uses an energy balancing strategy in the key region.Simulation results show that the EOR algorithm extends the lifespan of a network,balances the energy consumption of nodes in the key region and effectively limits the length of routing paths,compared with similar algorithms.

A New Alternative Method for Checking Total Stations

Today, just by activating a button on the display panel of a total station, one can measure horizontal and vertical angles or calculate distances and coordinates of points. For this reason, it has become necessary to improve the check of a total station in order to respond to its contemporary way of use. The aim of this research is to create a new method for checking total stations using only one check--field, in a different way of the today＇s standards. The basic principle, of the comparison of an instrument＇s measurements to those of another instrument with higher accuracy, is implemented into a mathematical model such as the adjustment of an indoor geodetic network. Thus, the check of the proper function of a total station is applied. An a-priori calculation Of^o of the network＇s adjustment can be calculated by modeling the uncertainties using statistical methods as the random number generators by means of the Monte Carlo method. The prospective ao can then be compared to the a-posteriori ao provided by the adjustment of the measurements which are carried out by using the total station under check.