摘要:

This paper describes a television broadcasting station recently built by the British Broadcasting Corporation in a part of the Alexandra Palace, London, N. The development of the television service in this country is traced from the early attempts to promote an experimental service of transmissions on low standards of definition to the establishment of a highdefinitionpublic service.The paper is divided into six parts.Part 1 touches briefly upon the history of television development in this country, and describes in some detail the transmission of low-definition pictures from B. B. C. stations during the years 1929 to 1935.Part 2 deals with the recommendation of the Television Committee that a station for transmitting high-definition television should be established, and it discusses various factors upon which the subsequently appointed Television AdvisoryCommittee based its decisions regarding the choice of the Alexandra Palace site, the operating wavelengths, and standards of definition.Part 3 describes the arrangement of studios and apparatus rooms at the Alexandra Palace station. The problems of studio acoustics, production lighting, and the provision of essential supplies, are also dealt with.Part 4 describes the layout and arrangement of the control room and transmitter equipment installed for the vision and accompanying sound transmissions.Part 5 is concerned with the plant developed to enable current events and other programme items taking place at some distance from the Alexandra Palace to be televised. Some account is given of the use of land lines to carry television signals.Part 6 is a brief consideration of the reception results of signals from the Alexandra Palace since the beginning of the service, and embodies the result of signal-strength surveys made in the vicinity of, and at distances from, the station. Finally, the various types of television receivers and aerials are discussed.

DOI:10.1049/jiee-1.1938.0200

出版商:IEE    

年代:1938

数据来源: IET

摘要:

This part of the paper describes the technical considerations leading to the choice of the particular wave-form now standardized by the B.B.C. for radiation from the London Television Station. The various characteristics of the system are described, together with the considerations that led to their adoption. A slight modification of the published wave-form specification is suggested. Finally, automatic volume control is briefly discussed. An appendix gives the modified wave-form specification.

DOI:10.1049/jiee-1.1938.0201

出版商:IEE    

年代:1938

数据来源: IET

摘要:

Television equipment, in particular that supplied to the B.B.C. for the London Television Station, is described, and the technical considerations which led to its development are outlined. A description is given of the purpose and practical design of the apparatus handling modulation frequencies, which comprises studio equipment, camera control equipment, modulation amplifiers for the radio transmitter, and associated apparatus.Owing to the large amount of equipment covered by these headings, little more than cursory descriptions can be included, making it imperative to omit many details of design. References are therefore made to the relevant patent specifications, from which more detailed information may be gathered.

DOI:10.1049/jiee-1.1938.0202

出版商:IEE    

年代:1938

数据来源: IET

摘要:

This part of the paper sets out the agreed specification of the vision transmitter of the London Television Station. Details of the valves available for meeting the requirements are given, and their calculated performance in the balanced bridge circuit of the final modulated amplifier is outlined. This is followed by an examination of:(1) The mechanical assembly, with particular reference to the essential features governing the design of the variou s. components.(2) The control of the amplifier by the television signal, and the conditions relating grid input-volts and outputpower to the aerial feeder.(3) Special requirements of the system.The appendix includes a note on the determination of the compensating capacitance for grid-lead reactance, and general data regarding the transmitter.

DOI:10.1049/jiee-1.1938.0203

出版商:IEE    

年代:1938

数据来源: IET

DOI:10.1049/jiee-1.1938.0206

出版商:IEE    

年代:1938

数据来源: IET

摘要:

It is the author's purpose in this paper to discuss the problems of collective control on modern supply networks, to examine various alternative methods, and to explain how, by the aid of superimposed high-frequency signals, any distribution network may be used as a signalling system which will enable a supply undertaking to exercise remote control of consumer circuits from its own power station.He concludes that recent developments in this field have placed in the hands of the supply industry a powerful weapon with which to attack the economical development of heating loads, as well as providing an elegant solution to commonplace difficulties of street-lighting control, to which the supply industry has become accustomed but not reconciled.The special application of superimposed control in war time for the extinction of public lighting and for the dissemination of warning signals is not discussed in great detail, as such problems are of political rather than technical interest.As to terminology, control systems using superimposed signals are variously referred to as “carrier control,” “phantom circuit control,” and “ripple control” systems. Of the three, the author prefers “ripple control,” since it' avoids confusion with terms more properly applicable inother fields, yet gives a correct picture of the method itself.

DOI:10.1049/jiee-1.1938.0210

出版商:IEE    

年代:1938

数据来源: IET

摘要:

In this paper the authors investigate the problem in salient-pole dynamo-electric machines of flux passing from field pole-tip to pole-tip without linking the armature winding. This flux, designated “pole-tip leakage,” is of broad interest in determining both transient and steady-state performance characteristics of salient-pole dynamo-electric machines.The problem is treated as one of two' dimensions and the method of conformal transformation is used to obtain results in the form of elliptic functions. Numerical results are obtained by a method of cross-plotting and given in curve form for the usual range of variables. The curves have been used in the design of machines for 5 years, and the great number of test-results obtained have been found to be in very satisfactory agreement with the calculations.

DOI:10.1049/jiee-1.1938.0212

出版商:IEE    

年代:1938

数据来源: IET

DOI:10.1049/jiee-1.1938.0214

出版商:IEE    

年代:1938

数据来源: IET

摘要:

The taxation of electricity undertakings broadly resolves itself into two components, viz. local rates and income tax. The main principles given in Acts and legal decisions are explained, together with their application and incidence. The conclusion is reached that strict comparison of incidence is impossible, although a simpler method of valuation and assessment would be valuable.

DOI:10.1049/jiee-1.1938.0215

出版商:IEE    

年代:1938

数据来源: IET