摘要:

Following a brief reference to progress in the application of carrier telephony to circuits in cables in this and other countries, an account is given of the carrier system operating between Bristol and Plymouth. This system affords 12 telephone channels per pair in the range 12 to 60 kc. Separate cables are provided for the two directions of transmission, and negative-feedback repeaters are provided at intervals of approximately 20 miles. When fully equipped the system will provide 228 circuits. The account of this system is followed by a description of the 4-tube underground coaxial cable which has been installed between London and Birmingham and of the modulating and repeater equipment that has been developed to operate 320 carrier telephone channels in the range 0.5–2.1 Mc. Repeaters are provided at intervals of approximately 7 miles, separate tubes being used for the two directions of transmission.Applications to television and the probable line of development of multi-channel and wide-band systems are discussed.

DOI:10.1049/jiee-1.1937.0179

出版商:IEE    

年代:1937

数据来源: IET

摘要:

The general problem of control of the grid is outlined. Reference is made to the location and layout of the control buildings. Details are given of the communication system rented from the Post Office and of the special requirements with regard to its use in conjunction with the Central Electricity Board's system. The equipment of the control rooms, consisting of telephones and automatic indicating equipment, control desks, system diagram, frequency and time control instruments, is described.Reference is made to the general features of the telephone system and automatic indicating gear. Particulars are given of the various systems of remote metering employed. Concentration of essential equipment in a convenient form on the control desk is explained, with special reference to the desk at Bristol. Types of system diagram and frequency-control equipment are discussed.

DOI:10.1049/jiee-1.1937.0181

出版商:IEE    

年代:1937

数据来源: IET

摘要:

In Part (1) the various types recently put forward to solve the high-voltage cable problem are discussed. The principle of the gas cable is stated, together with the advantages to be expected.Part (2) describes very briefly the experimental work on the basis of which the cables were made, and gives reasons for the choice of paper, gas, operating pressure, etc.Part (3) is devoted to the construction and performance of the actual cables. Examples are given which show their extreme stability, and also the accuracy with which their performance can be predicted. A series of typical designs are tabulated, and the advantages anticipated in Part (1) are shown to be realized.Part (4) deals with the design of gas-cable joints and sealing ends, and the methods used to maintain dryness during their making. The gas feeding arrangements and other accessory apparatus are also described.

DOI:10.1049/jiee-1.1937.0184

出版商:IEE    

年代:1937

数据来源: IET

摘要:

Interest in rural electrification is growing, and technical details of various schemes have appeared in theJournaland elsewhere. This paper contains what is believed to be the first complete survey of financial results attained on rural supply.After a review of the technical details and commercial progress of four schemes, the general financial results are divided into their components and referred to various bases. The economics of farm supplies is elucidated and then the analysis is developed to ascertain the return on capital, and the capital expenditure per consumer. An attempt to determine the economic limit of rural electrification is followed by an examination of the various items of expenditure and revenue. Following other statistical data, the conclusion is reached that technical proficiency is secondary to economic and financial control.The schemes referred to in this survey are those given prominence in the 16th Annual Report of the Electricity Commissioners.

DOI:10.1049/jiee-1.1937.0186

出版商:IEE    

年代:1937

数据来源: IET

摘要:

The results of the measurement at a frequency of 1 million cycles per sec. of the effective inter-electrode capacitances under working conditions of a variety of valves are tabulated, together with an estimate of the net capacitance residing between the active elements themselves.The grid-filament capacitance shows an increment which increases with anode current up to the point at which grid current flows. The increment diminishes at a given value of anode current as the anode voltage is increased. Experiment shows that. this increment in; capacitance is not a simple function of anode current, neither .of anode-filament nor of mutual conductance. It is augmented the higher the filament temperature and is probably fc. function of the initial velocity of the electrons.The effective grid-anode capacitance suffers a reduction as the anode current increases, but the reduction is much smaller, proportionately than the increase in grid-filament capacitance.Every type of valve examined displays the effect—even the small acorn trdodes and. pentodes, in which the increment represents a 50% augmentation of the “cold” value ofCfg.

DOI:10.1049/jiee-1.1937.0187

出版商:IEE    

年代:1937

数据来源: IET

摘要:

Various experiments have suggested that the effective capacitance of a diode is probably dependent on the magnitude of the anode current: this effect, however, is not disclosed by the classic analyses of Benham and of Llewellyn. This paper shows that an analysis which ignores the emission velocity of electrons is not competent to describe the capacitance effects in a diode. A steady-state solution is found for a planar diode in which the emission velocity is not ignored. Also it is calculated that the mean-square velocity of electrons crossing the potential barrier is the same as the mean-square velocity of emission from the cathode. By considering the inertia effect of the electrons in conjunction with the displacement current at the barrier, an expression is derived for the phase angle of an electrode system. This expression shows that the phase angle is markedly dependent on the anode current. It is therefore thought that the analysis describes the basic mechanism of certain capacitance effects which have been observed in triodes.An Appendix contains the steady-state solution of the temperature-saturated planar diode, and curves are given which show the force at the cathode and at the anode as a function of the anode current, expressed as a fraction of the space-charge limited current; also a curve which shows the transit time as a function of the anode current

DOI:10.1049/jiee-1.1937.0188

出版商:IEE    

年代:1937

数据来源: IET

摘要:

This paper describes a medium-wave Adcock direction-finder capable of working over the wavelength range 750 to 2000 metres (frequency 400 to 150 kc.) with a pick-up factor between 3 and 5 metres. Under favourable conditions a bearing can be taken on a field strength of 10 microvolts per metre with a swing of less than 1°. When the field strength is 1 microvolt per metre the corresponding swing is ± 10°.The standard wave error is less than 1° as measured on a wavelength of 1 760 metres (frequency 170 kc), and this may most probably be taken to be representative of its value over the whole range. The instrumental error after balancing is less than 1°, but no information is at present available as to how long the balance remains constant.The instrument may therefore be said to constitute a practical development of the balanced-coupled Adcock system, retaining all the advantages of that type as regards polarization error but with a greatly enhanced pick-up factor compared with that of the early experimental model, which makes the apparatus capable of taking bearings with field strengths as low as 1 microvolt per metre, and with an instrumentalaccuracy as good as that of a loop-type Bellini–Tosi direction-finder.

DOI:10.1049/jiee-1.1937.0189

出版商:IEE    

年代:1937

数据来源: IET

摘要:

This paper gives full details of the construction and performance of a short-wave aural Adcock direction-finder of the coupled type with a working wavelength range of from 35 to 70 metres (frequency 8.6 to 4.3 Mc.). It describes how the design of the instrument is based on the principles brought to light in an earlier investigation. It deals with its design in respect of polarization error, pick-up factor, and instrumental error, and describes experiments by which these properties were measured. The values obtained for these were as follows: standard-wave error, 3° to 8°; pick-up factor, 4.5 to 6 metres; instrumental error, 2° to 3° at maximum.The apparatus is considered to constitute a satisfactory direction-finder from a practical point of view, though it will be possible in future models, one of which is already under construction, to take advantage of the experience gained to obtain an instrument with lower instrumental and polarization errors and higher pick-up factor.

DOI:10.1049/jiee-1.1937.0190

出版商:IEE    

年代:1937

数据来源: IET

DOI:10.1049/jiee-1.1937.0191

出版商:IEE    

年代:1937

数据来源: IET