兴山县有线数字电视系统技术方案的实施

主要介绍制定兴山县有线数字电视系统设计方案的依据、系统的功能、频道规划、系统配置、技术指标、设备选型、工程概算、质量保证措施等方面的经验。     

基于HFC网智能小区的系统设计

信息技术在建筑行业的高速发展使得智能住宅和智能小区迅速崛起并成长为巨大的新兴产业,提出一个基于有线电视HFC网构建的数字智能小区系统,省去了综合布线的重复投资,该方案依托成熟的有线电视网技术,可实现智能小区建设所需的安全防范、管理自动化和信息自动化的功能。     

典型电缆连接器的装配质量控制措施

电缆连接器广泛应用于航空航天、军工、电子产品等领域,为了保证产品的质量,提高产品的可靠性,有必要对其进行研究.主要介绍了XKE型和SCSI型及J30J型电缆连接器的特性、用途和装配工艺控制措施.通过实际应用,取得了较好的效果.     

Optical amplifiers for video distribution

The promise of a broadband fibre communications network has attracted the interest of CATV and Telco concerns. Various networks and topologies have been discussed. Cost is a drawback in some of the proposed networks, particularly those networks which require switching. This paper discusses a low cost broadcast tree and branch network which uses optical amplifiers to extend the network penetration. Recent work in the development of optical amplifiers suggests that the Erbium fibre amplifier may be compatible with VSB-AM. The characteristics of such an amplifier will be discussed. This scenario allows an orderly transition from the present-day AM backbone system to the tree and branch fibre architecture. Once the broadband fibre plant is in place new services can be implemented that exploit the broadband nature of fibre.     

Israel's cable TV and pay TV — on the way to becoming a reality

Israel's cable TV plans are among the most comprehensive of any country. This paper reviews the progress to date, and details the technical specifications and administrative co-ordination involved in such a major enterprise.     

Realization of a 450 mhz cable tv system compatible with existing networks

This paper describes the realization in West Germany of a 450 MHz cable TV system, which matches into the infrastructure already formed by the existing 300 MHz systems. The studies and developments done to achieve this are described, and the results of a field trial detailed. Finally the impact of the new MAC standard is discussed.     

A continuous vibration analysis model for cables with sag and bending stiffness

The paper reports an investigation on a continuous model for dynamics of large-diameter sagged cables, taking bending stiffness and sag extensibility into account. Following the classical guidelines of cable dynamics, and by making some simplifications, a continuous model is found in this work; frequency and mode shape equations have been obtained in non-dimensional form. Comparison with Finite Element (FE) and Finite Difference (FD) models has been made to validate the proposed method. Moreover, it allows us to represent local effects at the end zones of cable correctly, if clamped boundary conditions are assumed. To obtain comparable results, the FE model would require a large subdivision, with consequently, a large number of elements. The proposed eigenfunctions allow us to solve the dynamic problem without a large computational effort compared to FE or FD approaches. Finally, in order to show the usefulness of the developed continuous model, an application on the main cables of the designed Messina Strait Bridge has been made.     

国家天文台FAST工程索网安装施工技术

国家天文台FAST工程索网安装共包括2225个主索节点、6670根主索和2225根下拉索,所有安装工作均需在空中完成,要求精度高,施工难度大。为了避免索网在安装过程中应力过大,并满足圈梁受力要求,施工过程中将整个索网对称等分为5个施工区域,每个区域都同步施工。施工时,需要采用大量悬空索道进行拼装,其中,施工通道为固定索道,需要承载较大受力,施工索道则随安装进度不断转移。     

微型计算机在瞬态电波波形测试中的应用

介绍了微型计算机在对瞬态电波波形进行自动采集，存贮，处理及显示中的应用，且提出了一种典型的测试系统的总体方案及其硬，软件设计，该系统具有良好的人机界面，操作方便灵活，测试的准确度，可靠性较高。