DOI:10.1049/ecej:19890030

出版商:IEE    

年代:1989

数据来源: IET

摘要:

Open Systems Interconnection (OSI) is intended tofacilitate interworking between data terminal equipments(DTEs) of different designs and from multiple vendors, thus providing the user community with a broad level of independence in the procurement of IT equipment. Whilst OSI local area network (LAN) standards have aimed tofulfil this objective, actual variations in data rates, mediatypes and cabling topographies have hindered progress.The ‘tree and branch’ cabling architecture presented in the paper provides a powerful solution to these problems. Based on twisted-pair and optical-fibre media, it could support today's industry standard LANs, point-to-point communication links such as V24, and circuit-switched telephony within an elegant, integrated cabling system. Furthermore, the proposed combination of architecture and media provides an appropriate infrastructure for tomorrow's functionally integrated services networks. This natural evolutionary path would protect initial investment, and establish the cabling system as a long-term building utility.The proposed cabling architecture and choice of mediais presently being processed by the International Standards community as the basis for a ‘building communicationscabling system’. It seems that ‘open system cabling’ isindeed a technically feasible and practical possibility.

DOI:10.1049/ecej:19890032

出版商:IEE    

年代:1989

数据来源: IET

DOI:10.1049/ecej:19890033

出版商:IEE    

年代:1989

数据来源: IET

摘要:

In high-density recording, the performance of the conventional Viterbi decoder for FM recording code is degraded by the influence of the correlation between samples of the noise at the discrimination point. A decoding method is therefore proposed which uses a Viterbi decoder whose form assumes a simple Markov process for the noise at the discrimination point. The errorprobability of this method is obtained by computer simulation and the performance is compared with that of a conventional decoder. The results show that a large improvement in performance is achieved.

DOI:10.1049/ecej:19890034

出版商:IEE    

年代:1989

数据来源: IET

摘要:

In practical communication systems, spurious amplitudeand phase effects are normally mutually interrelated. Most semiconductor and thermionic amplifier devices, when driven from their quasilinear region into a saturated stateby large amplitude signal changes, impress phase and amplitude changes onto other signals operating within thenormally linear region. Practical digital modems are sensitive to varying levels of spurious amplitude and phase modulation, but the ability to quantify this for one type of interference without the presence of the other has proved difficult. The paper describes a method of generating test signals which contain one or other of these modulation modes with a high rejection of the other. Test results of measurements on a typical phase-reversed-keyed modemare included and show the effects of these two forms of interference.

DOI:10.1049/ecej:19890035

出版商:IEE    

年代:1989

数据来源: IET

摘要:

A simple ground clutter model has been analysed using nonlinear methods of power spectral estimation and the performance of these methods has been studied. The methods considered are the maximum entropy method (MEM), the maximum likelihood method (MLM), the leastsquares method (LSM), the autoregressive moving average(ARMA) method and Prony's energy spectral-density estimation (PESD). The performance of these powerspectral-estimation methods has been studied for different data lengths and different model orders.

DOI:10.1049/ecej:19890037

出版商:IEE    

年代:1989

数据来源: IET

摘要:

The impact of home automation on domestic lifestyles will be as far ranging as was that of factory automation on industry and its benefits will be available to all sectors of society. Home automation will be achieved not with the household robot but with embedded computing power and memory within dozens of pieces of domestic equipment, each of which will communicate with the user and with other equipments. Within the integrated home system the communication media will include infra-red, radio, mainswires, installed twisted wires and coaxial cable, and later perhaps optical fibre. Applications will include security, lighting, heating, cooking, washing appliances, audio and video systems, energy management as well as a number ofnew applications such as health monitoring, home publishing etc. A large standards activity is in place by the major manufacturers of domestic equipment throughout Europe to ensure that their equipments are reliable and compatible.

DOI:10.1049/ecej:19890038

出版商:IEE    

年代:1989

数据来源: IET