摘要:

The title suggests both the benefits and the problems of communication and the relationships between communication systems and those who use them. The theme is the role that electrical engineering can play in improving communications and in the optimisation of relations between equipment and people. The profession has made major contributions to increasing man's abilities to communicate. Its technologies have given us a variety of methods of communication for differing purposes and will continue to offer increasing speed and greater quantity. In the future these should not be the only objectives. The ultimate object of communications is to connect people. The aim must be for systems matched to users which meet needs, at desired times, between places of people's choice and at a cost and use of resources which can be afforded. A number of recent advances are described, and ways suggested by which various modes of communication, and combinations of them, could offer increasing scope for a variety of versatile facilities in the future. Development of communication technology will and should continue, and advances will change ways of life. The challenge is to use them in the right way; to use them for personal development rather than becoming passive terminals; and to advance understanding of the possibilities, the dangers of misuse, and the way they can be used for the advancement of man.

DOI:10.1049/piee.1976.0001

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The paper traces the development of electronics applications to aviation (avionics). The rapid development of electronic equipment and systems is discussed, and the paper points out the mutual dependence of air frame and equipment in aerospace projects.

DOI:10.1049/piee.1976.0002

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The design, manufacture and commissioning of an airborne radar transmitter amplifier is described. The microwave valve employed is a crossed-field amplifier (c.f.a.), cathode modulated by a hard-valve shunt modulator. The peak output power is 15 kW, and pulse lengths up to 5 μs may be used. The e.h.t. supply is derived from a high frequency transistor invertor stabilised by a feedback loop.

DOI:10.1049/piee.1976.0003

出版商:IEE    

年代:1976

数据来源: IET

摘要:

Electrical transducing methods for use in rotating-vane anemometry and tachometry are discussed and the advantages to be gained from a capacitance-change pickoff are outlined. Both a theoretical and practical analysis for the capacitance variation in such systems is given, leading to the conclusion that the resulting change, when converted into a voltage-time signal is ideally suited to cable and telemetry transmission. A simple transducingcircuit technique is then presented with measured results indicating that changes of less than 0.01 pF can readily be resolved. In addition, the circuit performance with high residual-capacitance values is investigated, the results of which have led to the development of an insertion-type flowmeter. The paper is concluded by illustrating the application of the techniques in a respiratory-flow transducer.

DOI:10.1049/piee.1976.0004

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The performance of optimum linear block codes has been examined by computer simluation, and the error distribution at the decoder output, the block-error probability and the bit-error probability have been determined for the codes when they are used on a binary symmetric channel with random errors. A table showing the distribution of errors in the decoder output is presented, and it is shown how the table can be used to determine exact values for the bit-error probability and the block-error probability. The exact values of bit-error probability computed from the table are compared with values obtained using a known theoretical approximation to the bit-error probability, and some conclusions are drawn as to the general usefulness of the theoretical approximation. Also, block-error probabilities are computed from the information presented in the table and these values are compared with the estimates of block-error probability obtained from minimumdistance considerations.

DOI:10.1049/piee.1976.0005

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The recent published literature contains a description of a data-transmission system in which the data signal at the transmitter is fed through a channel equaliser that includes a device for holding the transmitted signal within a given range of values. The paper presents a theoretical analysis of the system, together with the results of computer simulation tests, and proposes a simple modification to the equaliser that maximises the tolerance of the data-transmission system to additive white Gaussian noise. It is shown that the original and modified equalisers are equivalent, both in their basic methods of operation and in their tolerances to noise, to the corresponding conventional nonlinear equalisers, used at the receiver. Finally, a simple error detector is described which operates on the received signal, with no need for any redundant data, and which gives extremely powerful protection against errors when used with the original nonlinear equaliser at the transmitter.

DOI:10.1049/piee.1976.0006

出版商:IEE    

年代:1976

数据来源: IET

摘要:

An analysis is developed for the prediction of intermodulation distortion effects in abrupt-junction current pumped varactor frequency convertors optimised to satisfy the requirements of communications-receiver front-end performance. The technique is extended to the prediction of gain compression effects, and is applied to a practical circuit. Excellent agreement with predictions is demonstrated for intermodulation performance; and a useful indication of gain compression is shown.

DOI:10.1049/piee.1976.0007

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The different roles of manufacturers, supply authorities and consultants in the British electrical-supply industry date from the very start of electrical power engineering at the end of the 19th century. The paper traces the role of the consulting-engineering profession in the development of the home supply industry through the men who founded practices at that time leading to the development of today's British consulting engineering firms which serve the power industry of the world. The development of these firms is shown throughout the years to have depended on engineering, economic and political factors. Consulting-engineering work is illustrated with reference to two projects: an unusual power station project in Mexico and the topical Hong Kong mass-transit system. The changing problems of the consulting-engineering profession are considered in the light of current economic pressures, energy patterns and the increase of nationalism overseas, and it is shown why the services of British consulting engineers have never been in greater demand throughout the world than at the present time.

DOI:10.1049/piee.1976.0008

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The paper describes, briefly, the background to the El Chocon 500 kV transmission system, indicating the size and location of the generating plant together with the atmospheric and natural conditions prevailing along the line route to the greater Buenos Aires load centre, some 1040 km to the north east of the generating sources. The electrical requirements of the two physically independent but parallel overhead lines are discussed in terms of the required phase-conductor arrangement. The optimum economic conductor size is shown to co-ordinate with the requirements of radio interference and line reactance. The expected fault performance of the lines is examined, and the earthwire and tower-foot earthing requirements to give satisfactory lightning performance are outlined. The mechanical design of fittings, including joints, clamps, spacers and dampers is described. A section is devoted to the electrical-performance requirements of the insulation, mainly in terms of the required switchingsurge performance and radio-interference characteristics. The tests necessary to prove the performance of the ‘V’ string insulators in satisfying the above requirements are described. The type of suspension tower finally chosen, of guyed construction, is justified, together with a description of tower foundations, guy anchors and tower tests. The paper concludes with a discussion of tower-assembly and erection techniques and the problems relating to conductor stringing.

DOI:10.1049/piee.1976.0009

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The paper summarises the findings of an extensive field investigation into the behaviour of soils affecting operation of buried power cables. Statistical treatment of the large volume of results available leads to the establishment of thermal-resistivity values for defined groups of soils and the main types of load encountered in practice.

DOI:10.1049/piee.1976.0010

出版商:IEE    

年代:1976

数据来源: IET