DOI:10.1049/piee.1967.0001

出版商:IEE    

年代:1967

数据来源: IET

DOI:10.1049/piee.1967.0002

出版商:IEE    

年代:1967

数据来源: IET

摘要:

The problems associated with the international exchange of colour-television programmes are discussed. The interchange of programmes between Europe and America would be possible, without conversion between the scanning standards, if dual standards were adopted in Europe, and an experiment is described in which the feasibility of dual-standard colour television is assessed from the point of view of the subcarrier frequency-changing or translating process. It now seems certain that different colour systems, operating on a common 625-line scanning standard, will be used within Europe, and investigations have been carried out into methods of transcoding between the proposed systems. These investigations show that both translating and transcoding operations between one colour system and another on the same scanning standard can be accomplished without serious impairment of the picture quality.

DOI:10.1049/piee.1967.0003

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Transmissions from v.h.f. and u.h.f. aerials may be distorted by reradiated signals if tall obstacles such as masts or towers are situated in the service area. The amplitudes of these reradiated signals are governed by factors discussed in the paper.

DOI:10.1049/piee.1967.0004

出版商:IEE    

年代:1967

数据来源: IET

摘要:

A widely used approximate technique for treating radiation problems involving a source-excited interface is derived from a saddle-point evaluation of the inverse transform-integral representation of the solution. The total solution is approximated to by the first saddle-point term plus residue terms in their respective wedges of contribution, i.e. space wave plus complex waves. The paper considers the well known approximation of space wave plus complex waves in the light of the modified saddle-point technique. The condition for validity of this approximation is shown to be that the numerical distance, a quantity involving both the distance from pole to saddle point and the distance from origin to observation point, should be greater in magnitude than ten. The discussion is numerically illustrated using the example of unidirectional travelling-leaky-wave and surface-wave aperture distributions. For these examples, graphs are compared of the approximate solutions and of solutions including the correction terms. Diagrams which show where in space the complex wave is a valid and significant part of the total solution are also constructed. The leaky-wave case is particularly interesting, since the correction terms are required in a rather large region of space.

DOI:10.1049/piee.1967.0005

出版商:IEE    

年代:1967

数据来源: IET

摘要:

The paper is concerned with calculation of the small-signal admittance parameters of field-effect transistors in general. For this purpose, it is first shown that field-effect transistors can be effectively treated as a special class of analogueRCtransmission lines, in which the resistance is uniformly distributed but the capacitance is nonuniformly distributed. The difficulty of analysing this type of transmission line is resolved by assuming piecewise uniformity as a good first-order approximation. The matrix method of analysis is employed. This has been found to be a simple and rapid means of calculating admittance parameters of field-effect transistors in a closed analytical form, which is particularly suitable for practical circuit analyses. These parameters lead naturally to the appropriate representation of device characteristics by equivalent circuits, valid over their entire useful frequency range. Calculation of both the forward- and reverse-transmission parameters under saturated-drain-current conditions has been the main object of the analysis, which is, however, in general terms throughout.

DOI:10.1049/piee.1967.0006

出版商:IEE    

年代:1967

数据来源: IET

摘要:

The performance of a particularRC-active circuit, using a modified parallel T with unity-gain amplifier, is analysed on the assumption that the amplifier is ideal. Approximate expressions are then derived which enable the effects of finite input impedance, nonzero output impedance and nonzero source impedance to be calculated. It is shown that some of these effects can be reduced in magnitude by the use of an infinite-gain, instead of a unity-gain, amplifier, and that a further improvement is possible by using the two types of amplifier together in one circuit. The analysis is extended to cover these two arrangements.

DOI:10.1049/piee.1967.0007

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Lyapunov's second method is used to show that circuits composed of a finite connection of linear, passive, time-variable elements are necessarily stable. Such connections may involve transformers and gyrators as circuit elements, as well as the conventional resistors, inductors and capacitors. An equivalent structure is determined, using only time-variable gyrators to interconnect constant elements consisting of unit capacitors and unit resistors. Using this model, asymptotic stability and uniform asymptotic stability of the original circuit may be investigated. Examples are given to illustrate the methods and concepts.

DOI:10.1049/piee.1967.0008

出版商:IEE    

年代:1967

数据来源: IET

摘要:

A technique is proposed by which all paths of exactlyqbranches interconnecting a given source-sink node pair can be obtained. Using the proposed technique, paths of increasing length can be found sequentially. The method is based on a symbolic noncommutative multiplication among the entries of anNmatrix which is a modified version of the vertex adjacency matrix.

DOI:10.1049/piee.1967.0009

出版商:IEE    

年代:1967

数据来源: IET

摘要:

A simple method is described for the design of tapped-potentiometer circuits to produce an output voltage which is any specified function of the shaft rotation. Functions of any complexity may be synthetised, the circuits requiring only one source of e.m.f. The design procedure may be carried out on a digital computer or alternatively a simple graphical method is presented.

DOI:10.1049/piee.1967.0010

出版商:IEE    

年代:1967

数据来源: IET