摘要:

This paper is divided into two parts. The first, part deals with the broad aspects of modern telephone transmission maintenance, the economic justification for good maintenance, and the general lines upon which it should be carried out. The second part gives the theoretical considerations leading up to the development of a series of testing instruments, by means of which transmission losses in any part of the telephone system can easily be measured. This part also contains brief descriptions of the instruments and their use.

DOI:10.1049/jiee-1.1924.0092

出版商:IEE    

年代:1924

数据来源: IET

摘要:

An account is given of the history of the dull-emitting thoriated tungsten filament and of the development of thermionic valves containing these filaments. Intrinsic properties are described and discussed.

DOI:10.1049/jiee-1.1924.0095

出版商:IEE    

年代:1924

数据来源: IET

摘要:

An account is given of some experiments conducted with two direction-finding receiving stations taking observations on ship transmitters located at various positions in the North Sea between England and the Continent. Damped waves of length 450 m were employed, as given by the ordinary spark transmitting sets with which the ships were fitted. The results obtained are analysed in detail and the various errors encountered are described. The effect of the various local errors to which a direction-finder is subject is not, however, studied in any detail, the object being rather to examine conditions prevailing across the sea, as compared with those across land. By careful attention to certain details various sources of error present in the earlier experiments were eliminated, with a resultant improvement in the overall accuracy. The general conclusion drawn from the experiments is that when the path of transmission is entirely over sea and in a direction making an appreciable angle with the coast line so as to be free from coastal refraction effects, the accuracy of radio direction-finding is sufficient for many navigation purposes up to ranges approaching 100 miles. Observations taken on various land stations with spark transmitters on wave-lengths of 450 and 600 m show that for greater distances over sea the variable “night” errors encountered are of a much higher order. When the propagation of the waves is entirely over land the corresponding variations are encountered at shorter distances.

DOI:10.1049/jiee-1.1924.0097

出版商:IEE    

年代:1924

数据来源: IET

摘要:

The paper is intended to show how the working costs per unit of electricity are influenced by various factors, viz. type of engine, nature and magnitude of load, price and calorific value of fuels.Internal-combustion engines only have been considered, as these are practically the only types in use for small modern plants.

DOI:10.1049/jiee-1.1924.0099

出版商:IEE    

年代:1924

数据来源: IET

摘要:

The following notes are the result of experiments made by research students, under the direction of the author, on a 25-period single-phase Atkinson-type repulsion motor in the Laboratories of Applied Electricity, Liverpool University. The work involved in preparing Part I was carried out by O. J. Crompton, C. G. Ramsay and E. W. Young. That entailed in the preparation of Part II was performed by T. W. Dann.In the first place a vector diagram for the motor, in line with the standard diagram for a single-phase series commutator motor, has been developed. It is then shown how, by means of bruoh shifting, the motor may be made to operate as a generator.It is obvious that regenration by means of brush shifting has limitations in its practical application. To obviate these limitations regeneration with a fixed brush-position and a reversed field coil was investigated. This was found to be a function of the speed and could not be varied independently. Finally, by injecting an E.M.F. into the armature short-circuit, with fixed brush-position and reversed field, it has been found possible to control the amount of power regenerated at any given speed.

DOI:10.1049/jiee-1.1924.0100

出版商:IEE    

年代:1924

数据来源: IET