摘要:

The rapid development of television as an entertainment medium has resulted in considerable engineering effort being directed at perfecting the performance and reliability of the analysis of a picture into an electrical waveform, the undistorted transmission of this waveform over a radio or cable link and its synthesis back to the reconstituted picture. This complete chain of transmission and reception and many of the subsidiary techniques have uses outside the broadcast entertainment field, and development has been devoted to their application to improve the efficiency of industrial processes and professional techniques.The paper attempts to survey the field of application of television technique to the industrial and professional fields, and to present in perspective the British contribution to television outside domestic broadcasting. Following some historical notes is an analysis of the various basic application principles involved, with some deductions on their resulting scope and limitations. These applications are then collated into three groups, namely those associated with a broadcast link, specific industrial and professional applications of a closed television chain, and applications of techniques which are either subsidiary to television or have been intensively developed as a result of its growth. Each of these groups is then subdivided into the practical applications concerned, which are described, and some assessment is made of their present and potential value. A concluding review points to those techniques and their applications which appear to hold most promise for future development.

DOI:10.1049/pi-3a.1952.0082

出版商:IEE    

年代:1952

数据来源: IET

摘要:

Television distribution by wire networks, mainly for densely populated urban areas, is described. The subject is treated by considering the various types of network and transmitting and receiving systems. Attention is mainly focused on screened quad cable and coaxial cable.Transmitting and receiving systems are considered under two main subdivisions—those distributing unmodified waveform and those distributing modified waveform.System layouts illustrated by simple calculations on subscribers' feeders are included.

DOI:10.1049/pi-3a.1952.0083

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper considers the cinematograph camera and assesses its inherent limitations. The advantages of multiple-camera working are discussed, with special reference to the electronic camera; the recording of an electronic image is shown to be the culminating development.The paper discusses picture quality, contrast range and tonal fidelity, and the objective and subjective evaluation of definition. The reconciliation of the electronic and photographic viewpoints is shown to be possible, and the standards of the motion-picture and television industries are compared.The paper concludes with a survey of the performance requirements of the electronic camera, the mechanics of motion-picture recording of electronic images and factors governing the choice of film stock.

DOI:10.1049/pi-3a.1952.0084

出版商:IEE    

年代:1952

数据来源: IET

摘要:

In view of the continued growth of the wire broadcasting of sound programmes, attention has been given to the possibilities of the wire broadcasting of television programmes since the television service first commenced in 1936. The first licence for commercial operation of a television wire-broadcasting system was issued by the Post Office in the autumn of 1950 and four systems were in operation before the summer of 1951. These licences are issued subject to certain technical conditions and are accompanied by recommended standards of performance similar in scope to those which have for some years been associated with the licence agreements for the wire broadcasting of sound programmes.The main purpose of the paper is to describe and discuss the technical conditions and recommended standards of performance specified for television wire-broadcasting systems, and the methods of testing used to check whether the systems conform to the conditions and standards.Mention is made (with reference to more detailed accounts which have been published elsewhere) of some aspects of the history and development of wire broadcasting, to show the extent of its present and possible future use and to introduce the considerations which have been taken into account in drafting the conditions and the performance specification.The main features of a number of experimental or working systems are tabulated. Special features of these are discussed and results are given of tests made on four systems.

DOI:10.1049/pi-3a.1952.0085

出版商:IEE    

年代:1952

数据来源: IET

摘要:

High-grade television receiving equipments, such as will be needed in large-screen installations, require a considerably more satisfactory synchronizing system than is provided in commercially-manufactured home receivers. A description is given of a complete circuit system of original conception, developed for incorporation into an experimental cinema equipment. It provides, under precise local control, line- and frame-trigger and black-level-clamp switching-pulse waveforms, all of which are derived from an advanced form of automatic phase follower and thereby rendered substantially immune from received interference and all but the most severe degradation of the signal. A significant technical advance is the introduction of automatic interlace, with fine manual control of interframe spacing to allow the removal of interlace error. Since the method adopted is tantamount to regeneration of the synchronizing signal, it would appear to be adaptable to other problems, particularly in network repeater stations.

DOI:10.1049/pi-3a.1952.0086

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper deals with the development of a large-screen cathode-ray-tube projector employing the Schmidt optical system and a back-aluminized projector tube, and is concerned mainly with the design of the optical system, the tube and the associated electron-optical components. A brief description is given of developments which took place prior to the advent of the back-aluminized tube.The performance of the Schmidt optical system and the factors influencing the choice of aperture ratio are discussed; in the present application a 17.5-inf/1 system is used in conjunction with a 9-in projection tube.Some aspects of the projection tube are described, reference being made to the electron gun, spot-size measurement, gas-focusing effect and problems associated with the fluorescent screen. Particular attention is given to the reduction of aberrations introduced by the magnetic focusing and deflection systems. The application of the 8-pole pincushion convertor is investigated.

DOI:10.1049/pi-3a.1952.0087

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper discusses the provision of television equipment for viewing surgical operations in teaching hospitals. After considering the specific conditions which prevail in an operating theatre, the description of a particular television equipment demonstrates an approach to these problems.Electrically this design follows closely that used in a standard 405-line camera channel employed with the C.P.S. Emitron. The novelty of the unit lies chiefly in the mechanical and optical features of the camera and lighting apparatus, and these are treated in greater detail.The paper concludes with a critical review of the value of television as a teaching aid and of the possibilities for its future development, based on extensive experience of the equipment in the Department of Surgery, Guy's Hospital, London.

DOI:10.1049/pi-3a.1952.0088

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The purpose of this instrument is to facilitate the observation and recording of objects moving at very high speeds and events taking place in extremely short times. In particular, it is intended to enable very fast repetitive motion to be observed stroboscopically, and such transient phenomena as burning high explosives to be recorded photographically.The equipment described has been designed in conjunction with an experimental image convertor tube (a development of type ME1201), and is intended as part of a comprehensive unit to exploit inherent capabilities.The static conditions necessary for focusing are discussed. Using the method desciibed, a resolution of 20 television lines/mm can be obtained at the image on the screen, with an electronic magnification variable between ×4and ×3/4. The focusing system used enables an erect image to be formed at certain magnifications.The arrangements for controlling the photographic exposure are described. Two alternative arrangements are available. The first is aimed at providing the shortest possible exposure for transient events; an effective shutter opening time of 1/20 microsec has been reached. In the second system, for stroboscopic observation, exposures down to one microsec are available at repetition rates up to 100 kc/s.In some applications a time-scale is desirable. This can be provided by moving the image across the screen at a known velocity. Three methods of producing a time scale in this manner are described. By these means writing speeds on the screen varying between 10 mm/sec and 90 km/sec can be obtained. The slower deflections, up to 500 m/sec, are virtually linear with time, while the faster speeds are obtained by using portions of either a continuous or damped-train sinusoidal deflection.Finally, some of the further developments of the equipment are reviewed, which preliminary experiments have suggested as being both possible and desirable.

DOI:10.1049/pi-3a.1952.0089

出版商:IEE    

年代:1952

数据来源: IET

摘要:

A cathode-ray tube providing a television raster of high brilliance and short time-constant is placed in front of the eyepiece of a microscope. The objective produces a minute spot of light that scans the preparation under examination. The amount of light transmitted is determined by the density of the specimen, and the transmitted light is picked up by a multiplier photocell, the output of which is used to modulate a display cathode-ray tube, the raster of which is locked to the scanning raster. The output of the photo-multiplier is also fed via amplitude and time-discriminating circuits to a high-speed counter. Pictures superior to those of a normal optical microscope in size, brightness, contrast and resolution of low contrast materials are obtained. In the case of a field containing discrete particles such as dust, blood, chemical particles, etc., the particles are automatically counted and sized. Applications to such diverse fields as clinical medicine, computers, nuclear physics, and chemical engineering are described.

DOI:10.1049/pi-3a.1952.0090

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The title of the paper is one more indication of a gradual awakening to the necessity for conserving natural resources—in this case ether spectrum-space. It is becoming increasingly important to achieve maximum efficiency in the transmission of television signals, and this is discussed under two main headings: Broadcast Television, where the choice of system is limited by the cost and maintenance of receiving equipment; and Television Relay, where the cost and complication of the equipment are relatively unimportant so long as a specified service can be established, e.g. transatlantic television. In broadcast television, the terminal equipment, especially the receiver, is likely to exert a decisive influence on the type of system to be adopted; in this country it will particularly affect the choice of colour-television standards. In television relaying, novel, but probably expensive, methods of compressing television signals may find application.In both cases the maximum enjoyment of the programme is an important criterion, and it should be stressed that enjoyment must not be confused with intelligibility. The characteristics of normal vision must be fully exploited, i.e. the television system must be matched to the eye-brain mechanism to give maximum overall economy. In appraising a standard the full theoretical performance must be closely approached in practice; only if that is done will defects such as spurious patterns be revealed and become an annoyance. The system musthave all necessary corrections incorporated (e.g. aperture, amplitude, phase and gamma), and must also have an adequate signal/noise ratio.

DOI:10.1049/pi-3a.1952.0093

出版商:IEE    

年代:1952

数据来源: IET