Reliability Efforts in Large European Programs for Military and Commercial Aircraft Development

Many large complex aerospace programs in Europe are carried out on an international basis, i.e., by multinational industrial consortia and based on multinational governmental support. The sophisticated program structures established for this reason create a new type of problem area which influences project performance and also extends on the reliability area. Whereas, generally, reliability is primarily directed towards overcoming technical risks by well-known engineering methods and control procedures, in multinational projects the aspect of overall risk management is becoming increasingly important and has to be adequately considered in the organizational structure. The above considerations are reflected in the reliability cooperation models of the Panavia 200 (MRCA) and the European Airbus A 300 Programs, which represent two of the largest current European multinational development programs. The experience gained through these programs can be applied to any other type of complex international development task. International cooperation in the reliability area can strongly increase the resources of technical information and know-how useable for the project. Although compromises between conflicting opinions and philosophies are unavoidable, reliability work may become more efficient overall because of more practical approaches.     

Communication Satellites for Public Television

Over the years, broadcasting in the United States, both radio and television, developed chiefly as a privately owned, commercial service. In that same period, however, some commercial television and radio stations emerged to meet various special needs, as for example, the requirements of schools and universities for educational programs. These stations were mainly local, set up by educational and other local public organizations. These groups had a number of common interests which resulted in the setting up of associations or other similar bodies which could act for groups of stations and organize the sharing of programs. The most familiar of these early organizations is probably National Educational Television (NET) which for many years operated a limited television distribution network.     

System Considerations for European Communication Satellites

A regional communication satellite system is being planned for Europe to satisfy the future needs of the European Conference of Post and Telecommunication Administration (CEPT) and the European Broadcasting Union (EBU). A model of the mission for the satellite system, based on the estimated future traffic requirements of the potential customers, has been defined to serve as a basis for system design. Starting with the postulated traffic model and with a review of the various system constraints, the present paper defines the parameters and the tradeoffs leading to the choice of the communication techniques fulfilling the requirements of the mission model. The resulting baseline communication system and its major characteristics are described. Alternate system design options are presented and commented upon. Some of these options would enhance the performance of the system but would generally involve more advanced techniques and would represent a larger technological risk. Finally, research and development topics in the field of communication technology are identified. Some of these topics are being investigated and some of the results are described in other papers.     

Rogue Commercial Geosynchronous Communications Satellites

The growth in numbers of commercial communications satellites in geosynchronous orbit raises the possibilities for radio frequency interference into space-earth transmission systems due to a malfunctioning satellite and of physical damage to an operating satellite due to collision with co-orbiting objects. These possibilities are addressed and recommendations are presented to minimize such occurrences.     

同步卫星移动通信系统的网络内部通信

本文论述了采用 Ｆ Ｄ Ｍ Ａ ／ Ｔ Ｄ Ｍ Ａ 体制的区域卫星移动通信系统的基本特点、组成以及网络内部通信。文中对网络内部通信划定了界线,明确了它的主要任务,并对内部通信链路和同步过程作了详细的描述。     

低轨卫星L频段中继通信载荷技术研究

针对深远海和陆基间高速率实时数据通信需求,完成了一种应用于低轨卫星的高集成度、低成本、低功耗L频段中继通信载荷的设计和实现。该中继通信载荷将通信天线、射频前端、信号处理单元、电源变换单元和接口单元等集成化设计。接收前端采用有源相控阵天线设计,发射前端设计了GaN功率放大器以提高接收单元獹/T值和发射单元等效全向辐射功率(Effective Isotropic Radiated Power,EIRP)。信号处理单元集成了零中频接收结构和直接射频调制结构,可完成反向链路8Mb/s载荷数据接收解调及前向链路数据处理转发的功能。载荷单机和装星后的环境模拟测试以及星地通信回路模拟测试结果表明,装星载荷可实现L频段卫星通信。整机质量为12.87 kg,在工作温度-25℃～+55℃范围内,发射端功率放大器输出大于30 W时,最大功耗为91.2 W(3.04 A/30 V)。     

卫星间通信技术研究动向

随着空间事业的发展，卫星间通信在各种空间活动中成为为越来越重要的技术，本文主要介绍利用微波，毫米波和光波进行卫星间捕捉、跟踪及通信技术研究的情况，同时概要说明世界发达国家研究卫星间通信的动向。     

Planning of Production Reliability Stress-Screening Programs

This paper describes qualitative and quantitative techniques for planning, monitoring, and evaluating stress screening programs. The techniques were developed under a recent study for the Rome Air Development Center. A model for use by reliability managers to aid in planning and evaluating stress-screening programs is presented. Guidelines are outlined for determining the applicability of screens to different equipment types and for selecting the proper level of assembly at which to apply the screens. An example of how the techniques are applied to a production screening program is provided. While stress screening is now widely employed throughout the defense industry and many experiments and studies on the subject have been conducted, the precise information needed to plan an optimum production stress screening program is still unavailable. Planning must rely on sound judgment and available data from experience. With the proper selection and placement of screens the stress-screening model is a useful tool in screen parameter selection and in providing a quantitative anticipation of screen results. A comparison of actual and anticipated results allows an evaluation of initial assumptions regarding the initial quantity of defective parts, the number of induced defects, and the true screening strength. Consistent differences between actual and anticipated results serve as the basis for altering the screening parameters and maintaining the most effective screening for the resources invested.     

Commercial Radio as Communication

Most communication and culture producing institutions in the United States operate more for commercial than for any other motives. This essay examines commercial radio by comparing the day-to-day work routines in that institutional setting with the principles of a theoretical communication model. Commercial radio, of course, does not meet the standards of such a model. By this thought experiment, however, we can illuminate many peculiarities of the conduct of communication by commercial radio, learn more about the application of theoretical models to the evaluation of practicing institutions, and offer assessments of commercial radio that derive from communication theory, rather than from economics, law, politics, or business concerns.     

Cutset Manipulations for Communication Network Reliability Estimation

The problem of calculating the reliability of a communication network of given topology is discussed. The definition of failure is generalized from simple disconnection to the event that terminal capacity falls below some threshold, and simple methods are developed for bounding the probability of such failures and for approximating the mean time between failures (MTBF). It is shown that the cumulative distribution function of terminal capacity is readily calculated, and that the dependence of network reliability on individual link reliability is substantially different when the generalized (and more realistic) definition of failure is used.     

通信产品系统可靠性预计和分配

本文主要介绍系统可靠性建模、可靠性分配和预计的一种思路，便于在今后的产品设计过程中加强可靠性系统设计。     

Joint Optimization Communication and Computing Resource for LEO Satellites with Edge Computing

Low earth orbit(LEO) satellites with wide coverage can carry mobile edge computing(MEC)servers with computing power to form the LEO satellite edge computing system, providing computing services for ground users that cannot access the core network. This paper studies the joint optimization problem of communication and computing resource in the LEO satellite edge computing system to minimize the utility function value of the system. Due to the fact that, general optimization tools cannot effective...     

卫星量子通信的光子偏振误差影响与补偿研究

针对采用偏振编码的卫星量子通信中的偏振保持问题,研究了大气散射和卫星与地面站间相对运动对量子偏振态相位和对准的具体影响。仿真分析了量子偏振态相位延迟和对准误差对系统量子误码率影响,提出了一种新的BB84协议与半波片旋转相结合的偏振补偿方案。该方案通过对准提前量补偿的加入弥补原有补偿方案补偿过程中不能进行通信的缺陷,可基本实现零角度偏振误差,保证卫星量子通信的安全可靠性,且因该方案仅需在原有系统上添加一个半波片,易于实现。     

Analyzing the Interface of Reliability and Economics of Unmanned Satellites

This paper deals primarily with the reliability of unmanned scientific or commercial satellites. In the course of reliability analysis an hierarchy of reliability predictions is generated, reaching from preliminary apportionment by subsystems: to figures of merit, usually obtained by Boolean algebra; to results based on failure modes, effects and criticality analysis (FMECA); to data from an elaborate, though still static, fault tree; and eventually to data depicting the dynamics of mission time line and contingency analyses. The outlined routine has been developed, mainly in the US, to quite some perfection, but it still leaves unanswered the customer's most natural concern: how much reliability, within what time, at what price? Therefore, an attempt is made to schedule the above work elements, so that the amount of reliability as well as its allocation become subject to the classical criterion of marginal utility. It is fully realized that there are considerations, such as design freeze partly due to long-lead items, that put a limit to this endeavor. The postulated analysis consists, in essence, of two models in sequence: first, the fault tree, which exhibits the technical failure modes, their probability of occurence, and their interdependence. Second, the mission failure model, referring to total and partial deficiences in performing utility functions, and to their interactions as regards the degree of performance.     

通信监测设备的可靠性分析与设计

仔细分析了信监测设备的结构特点和稳定运行的可靠性要求。在此基础上，系统的研究给出并实现了系统可靠性设计方案。理论分析和系统运行测试结果表明：设计分析了正确可靠。     

提高通信对抗装备的可靠性

分析了通信对抗装备的可靠性现状，对影响可靠性的因素进行了初步的探讨，并针对如何提高装备的可靠性提出了几点建议。     

Evolution of Space Traveling-Wave Tube Amplifier Requirements and Specifications for Modern Communication Satellites

Complex nonconstant envelope high-order digital modulation schemes used in modern communication satellites bring new requirements for the linearity and power efficiency of the on-board traveling-wave tubes (TWTs). As a result, a reassessment of typical TWT specifications is required. A digital system-level figure-of-merit, the total degradation, is proposed. It accounts for the characteristics of any coded signaling scheme, as well as for the performance of the overall communications link, including cochannel and adjacent channel interference. This figure-of-merit allows for reoptimizing the operating point of currently used TWTs, comparing the end-to-end performance of different tubes, and revising the standard TWT linearity-versus-efficiency requirements based on carrier-to-third-order-intermodulation (IM) ratio (C/IM3), noise power ratio, and carrier-to-noise-plus-IM ratio [C/(N + I)].