摘要:

An ‘intelligent’ telecommunications network is a network that is capable of providing flexible control of its services and capabilities to both network operator and network user. The evolution to intelligent telecomunications networks began some thirty years ago with the introduction of stored programme control exchanges into the public switched network. Since then the introduction of digital switching techology, common channel signalling and network databases have advanced the concept. The evolutionary path now being followed by many network operators will lead from the universal voice telephone service we have today to a universal information service of tomorrow in which the public switched network will be able to provide any combination of voice, data and image with maximum convenience and economy.— Truly the ultimate intelligent network?

DOI:10.1049/ecej:19900025

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Since the first television pictures were received fromTelstarby aerial 1 at Goonhilly Down in Cornwall, commercial operation of satellite systems has dictated that the earth-space link must be maintained as consistently as possible. Any break in transmission or lowering of quality results in huge losses for the operator and as a result the performance of the antenna tracking system has received a great deal of attention. Recently a new technique, termed ‘electronic beam-squinting’, has been developed to solve this problem both elegantly and economically. It is capable of a performance approaching that of the most expensive systems currently available for fixed earth stations and is also applicable to mobile terminals.

DOI:10.1049/ecej:19900026

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A significant national programme on the development of advanced software for VLSI system design is reported. The Silicon Architectures Research Initiative (SARI) is supported by selected UK electronics companies as well as the UK Department of Trade & Industry (DTI). It has resulted in the design and development of an interactive software suite for optimising a system implementation in VLSI circuit form. The new software permits a specific system design to be optimised in terms of chip speed or area prior to interfacing with one of the available commercial silicon layout tools.

DOI:10.1049/ecej:19900027

出版商:IEE    

年代:1990

数据来源: IET

摘要:

In multifrequency communications environments, such as land mobile radio sites, satellite earth stations, ships and surveillance aircraft, passive intermodulation products (PIMP) generated by nonlinear materials and metallic contacts can cause serious radio interference. This problem is well known and a wide range of coaxial cables, connectors and materials have been investigated. The paper gives an overview of passive intermodulation interference in communication systems. It describes briefly the theory of intermodulation, types of passive nonlinearities, mechanisms responsible for the generation of PIMP, guidelines for minimising PIMP generation and techniques for locating PIMP sources. Previous investigations of PIMP are summarised and the design of PIMP measurement systems is discussed. An example of PIMP measurement is also included.

DOI:10.1049/ecej:19900029

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The growth of a conversational audio-visual service such as videoconferencing depends on an ability to provide a complete system at a price the customer can afford. Video compression technology can play a significant role by drastically reducing transmission costs. The paper outlines progress in establishing a new standard, H.261, for video coding bit rates between 64 kbit/s and 2 Mbit/s.

DOI:10.1049/ecej:19900030

出版商:IEE    

年代:1990

数据来源: IET