基于"北斗"卫星通信系统的测试

"北斗"卫星通信系统是"十一五"国家863计划重点项目,在该系统展开应用之前,必须对系统各方面指标进行测试与实验.利用信号源、频谱仪、功率分配器、定向耦合器、衰减器、误码率测试软件、PC机搭建卫星通信测试平台,对卫星通信链路性能进行测试,主要通过短信业务、误码率、移动终端语音时延这3个重要指标对系统的性能进行评估.测试...     

基于"北斗"卫星通信系统的测试

"北斗"卫星通信系统是"十一五"国家863计划重点项目,在该系统展开应用之前,必须对系统各方面指标进行测试与实验.利用信号源、频谱仪、功率分配器、定向耦合器、衰减器、误码率测试软件、PC机搭建卫星通信测试平台,对卫星通信链路性能进行测试,主要通过短信业务、误码率、移动终端语音时延这3个重要指标对系统的性能进行评估.测试结果分析证明:该系统的关键性能指标均达到军方要求,体现了系统的优越性与实用价值.     

基于ADS半物理平台的声表面波标签测试

提出了一种基于ADS半物理平台的声表面波标签测试方法。采用矢量网络分析仪实际测试声表面波标签实物的S参数,在ADS软件中构建标签的物理抽象模型,并虚拟构建标签激励信号,利用ADS瞬态仿真功能获得标签回波信号,再采用MATLAB对回波进行数字正交解调,从而客观准确地测量标签各反射栅的时延、相位。最后通过搭建的半物理平台对声表面波标签进行了测试,表明了ADS半物理平台的有效性。     

光纤链路测试诊断快速入门（二）链路安装特性测试

数据中心等短距离高速光纤通信中时常遇到的问题是：光纤链路工作不稳定,误码率较高,检测链路损耗却是合格的,部分链路甚至无法实现连接。这种情况在多模高速光纤链路中较为常见,单模光纤则偶见之。数据中心普遍使用的万兆多模光纤链路,有可能因为误码率较高造成服务器资源的过载和低效,也会使登录访问服务器的远程用户数据帧传输的延迟超差。光纤＂二级测试＂是现场评价高速光纤链路安装质量最实用的方法,可以在较大程度上帮助解决＂低损耗、高误码率＂的问题。光纤二级测试的内容是在一级测试的基础上结合OTDR曲线测试,并给出评估结果,以期确认是否存在可能引起链路性能下降的＂事件＂点。本文所述的链路安装特性检测主要是指如何利用＂OTDR＂曲线和＂事件＂列表来判断高速链路的安装质量,帮助快速诊断链路问题。     

非同轴射频器件校准件参数仿真技术的研究

随着射频器件的快速发展,要求对射频器件S参数测试技术越来越严苛,一般设计相应的测试夹具,而非同轴射频测试夹具引入的误差较大,不容忽视,有必要对非同轴射频测试夹具引入的误差进行消除。文章通过Synthesize综合,算出微带线的宽度为1. 6mm,拟设计覆盖100MHz～12. 5GHz的频率,确定SOLT校准件和TRL校准件物理尺寸。采用ADS软件分别对SOLT校准件的直通校准件仿真、短路校准件仿真、开路校准件仿真、负载校准件仿真,得出设计的SOLT校准件性能良好。类似的采用ADS软件对TRL校准件进行仿真,得出设计的TRL校准件能覆盖100MHz～12. 5GHz的频率,且传输性能良好。     

基于ADS的射频通信系统教学研究

针对目前的射频通信系统教学中出现的系统概念不易理解和建立,分析介绍了ADS软件图形化的各类仿真分析方法,指出基于通信系统EDA软件ADS进行射频系统分析设计的教学是解决问题的有效方案。通过在Ptolemy环境中,代入DSP算法并建立收发射频系统进行BER（误比特率）仿真,展示了基于ADS进行射频数字通信系统的全系统仿真过程。     

卫星通信系统级联编码方式及其Labview仿真

文章通过卫星通信系统中不同级联编码在Ka频段信道模型的基础上，对几种级联编码方式进行了分析研究和Labview仿真。仿真结果表明：采用足够深度的内交织级联码系统在高频段上可以获得更低的误码率和更高带宽效率。     

卫星通信链路计算中干扰因素分析

本文通过讨论卫星通信链路计算方法，发现卫星通信链路计算当中的一些干扰因素，并对这些干扰因素进行分析，以找到解决这些问题的方法，从而使卫星通信链路的计算更加精确。     

一种功率节省的协作传感器网络伙伴选择方法

针对无线传感器网络的传统协作伙伴选择方法不允许链路复用中继,致使产生中继节点抢占的问题,建立了允许协作链路间复用中继节点的系统模型,运用拉格朗日乘子法优化中继节点上功率分配最大化协作增益,分析复用中继能获得误码率增益和功率增益的条件和功率分配,提出一种中继复用的分布式协作伙伴选择方法。理论分析和仿真结果表明,允许中继通过功率分配进行复用的新伙伴选择方案能降低无线传感器网络的系统总功耗,并使更多链路的误码率需求得到满足。     

卫星移动通信系统星间链路几何参数分析

对现有卫星移动通信系统星间链路的分析发现，随着卫星通信系统轨道高度的增加，卫星通信系统星间链路指向的动态调节范围不断扩大，星间链路的相对距离也不能增大，据此进行了对最优化极轨道卫星通信系统星间链路与主要参数的模拟与分析，并得到了一些规律性的结论，为星间链路的设计与建立闰定了理论基础，同时，卫星通信系统星间链路指向性能的周期性规律变化也为星间链路连接过程中最优化搜索算法的建立提供了探索方向和理论依据     

Power versus stabilization for laser satellite communication.

To establish optical communication between any two satellites, the lines of sight of their optics must be aligned for the duration of the communication. The satellite pointing and tracking systems perform the alignment. The satellite pointing systems vibrate because of tracking noise and mechanical impacts (such as thruster operation, the antenna pointing mechanism, the solar array driver, navigation noise, tracking noise). These vibrations increase the bit error rate (BER) of the communication system. An expression is derived for adaptive transmitter power that compensates for vibration effects in heterodyne laser satellite links. This compensation makes it possible to keep the link BER performance constant for changes in vibration amplitudes. The motivation for constant BER is derived from the requirement for future satellite communication networks with high quality of service. A practical situation of a two-low-Earth-orbit satellite communication link is given. From the results of the example it is seen that the required power for a given BER increases almost exponentially for linear increase in vibration amplitude.     

一种基于HLA/RTI的卫星组网仿真系统

设计了一种基于HLA/RTI的卫星组网仿真系统,在该系统中卫星节点、星间链路、卫星轨道和通信节点路由被划分为功能独立的联邦成员.这种结构具有良好的可扩展性,可适用于不同的卫星星座结构,同时可以适应不同的路由策略和各类空间通信链路模型.最后通过统计卫星组网网管报文响应时间验证了该仿真系统的可行性.卫星组网仿真系统为卫星组网的其他研究提供了仿真验证平台.     

Optimization of a laser satellite communication system with an optical preamplifier

We derive a model that optimizes the performance of a laser satellite communication link with an optical preamplifier in the presence of random jitter in the transmitter-receiver line of sight. The system utilizes a transceiver containing a single telescope with a circulator. The telescope is used for both transmitting and receiving and thus reduces communication terminal dimensions and weight. The optimization model was derived under the assumption that the dominant noise source was amplifier spontaneous-emission noise. It is shown that, given the required bit-error rate (BER) and the rms random pointing jitter, an optimal transceiver gain exists that minimizes transmitted power. We investigate the effect of the amplifier spontaneous-emission noise on the optimal transmitted power and gain by performing an optimization procedure for various combinations of amplifier gain and noise figure. We demonstrate that the amplifier noise figure determines the optimal transmitted power needed to achieve the desired BER but does not affect the optimal transceiver telescope gain. Our numerical example shows that for a BER of 10(-9), doubling the amplifier noise figure results in an 80% increase in minimal transmitted power for a rms pointing jitter of 0.44 microrad.     

传输斜移对同步并行光传输系统性能的影响

针对一个具体的链路模型,通过计算机仿真分析了传输斜移对同步并行光传输系统性能的影响.光纤中的信号分析在频域中通过快速傅立叶变换(fast fourier transform,FFT)进行.分别计算了单信道误码率以及没有传输斜移和有传输斜移时并行信道总的误码率.计算结果表明,在噪声不是影响系统性能的主要因素时,传输斜移是决定并行光传输系统最大同步传输速率和传输距离的一个重要因素.     

Measuring radiation induced changes in the error rate of fiber optic data links

The purpose of this work is to investigate the effects of ionizing (gamma) radiation exposure on the bit error rate (BER) of an optical fiber data communication link. While it is known that exposure to high radiation dose rates will darken optical fiber permanently, comparatively little work has been done to evaluate moderate dose rates. The resulting increase in fiber attenuation over time represents an additional penalty in the link optical power budget, which can degrade the BER if it is not accounted for in the link design. Modeling the link to predict this penalty is difficult, and it requires detailed information about the fiber composition that may not be available to the link designer. We describe a laboratory method for evaluating the effects of moderate dose rates on both single-mode and multimode fiber. Once a sample of fiber has been measured, the data can be fit to a simple model for predicting (at least to first order) BER as a function of radiation dose for fibers of similar composition.     

故障安全消息传输的故障安全性测试

本文介绍了故障安全现场总线物理层＝数据链路层界面上消化传输的故障安全性测试方法。首先，引入故障安全消息传输系统的基本概念，并对传输信道进行模拟，建立消息传输模型，然后用计算机实现模拟测试。为了提高采样效率采用了重要性采样法。     

Optimum divergence angle of a Gaussian beam wave in the presence of random jitter in free-space laser communication systems

The average bit error rate (BER) of optical communication systems is considered in the presence of random angular jitter. First, the received power and the BER in the absence of jitter are reviewed. Then the average BER is obtained in the presence of circularly symmetric, normally distributed jitter by using the probability density function of the optical signal. By minimizing the power penalty for average BER, the optimum ratio of the divergence angle of the laser beam to the random angular jitter at the desired BER is obtained. An analytic approximation of the optimum ratio is derived as a function of the desired average BER. The results can be used for designing the link budget of optical communication and tracking channels in the presence of jitter.     

Time jitter influence on the performance of gamma–gamma turbulence FSO links with various modulation schemes

ABSTRACT

The research area of optical wireless communication links has attracted significant interest over the last years due to the significant advantages offered by this kind of technology. However, the performance of FSO communication systems depends strongly on the effects, which are related to the atmosphere along the propagation path such FSO links are using. More specifically, the weather conditions and atmospheric turbulence effects can deteriorate considerably the performance characteristics. In this work, we are studying the joint influence of atmospheric turbulence and time jitter effects on the average BER of an FSO link by presenting a new approach for various modulation schemes. Thus new closed-form mathematical expressions are derived for accurate estimation of the BER performance of the optical wireless communication systems. Finally, using the obtained expressions and typical parameter values for FSO links, the numerical results are presented and then verified through Monte Carlo simulations.     

基于GNSS/INS联合仿真的组合导航终端测试方法研究

为解决GNSS/INS组合导航终端动态定位性能的实验室测试问题,本文在转台惯性仿真测试和卫星导航仿真测试技术的基础上,提出了GNSS/INS联合仿真两步法,即先通过惯性传感器实物测试获得其特征误差模型,再使用测试场景中载体初始条件和轨迹数据驱动该误差模型产生惯性传感器的模拟输出数据流,最后同步GNSS信号仿真的方法实现GNSS/INS联合仿真的过程。仿真测试结果与外场实测对比后,证明该方法获得的测试数据准确度满足预期指标、结果可靠,而且比其他传统测试方法的成本低、效率高。