摘要:

In 1963, details were published of a new method of teleprinter signalling for use on high-frequency radio circuits. This system (Piccolo) uses a different tone to represent each of the 32 characters of the teleprinter alphabet; the tones are orthogonally related and are detected at the receiver by quenched resonators. Piccolo has been further developed and refined, and has been adopted by the British Foreign & Commonwealth Office as the standard machine-telegraph method for diplomatic wireless communications; it is now in worldwide use. The paper describes the improvements made to the original models, a range of new ancillaries to improve compatibility, selective-calling facilities, and the s.s.b. radio equipment with synthetiser frequency control with which Piccolo is used. Operational techniques and performance figures are quoted. Other applications of the system are discussed, and possibilities for further development are mentioned.

DOI:10.1049/piee.1972.0239

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The problem considered is that of calculating the angles of arrival of the components of a multimoded signal from simultaneous measurements of the signal induced in each element of a linear array. A numerical method is described in which the arrival angles are obtained from the roots of a polynomial whose coefficients are solutions of a set of linear equations. This method has been applied to determination of elevation arrival angles for multimode signals in the h.f. band, using data from a vertical array of equally spaced horizontal loops. In this case, the ground is assumed to be perfectly conducting, but the method of analysis is not restricted to this condition.

DOI:10.1049/piee.1972.0240

出版商:IEE    

年代:1972

数据来源: IET

摘要:

An investigation has been carried out on the two radiated beam patterns of a coupled-waveguide antenna. In general, the shapes of the two beams differ because of propagation asymmetry about the coupling plane. Using the analysis of the coupled-mode theory, it has been shown that, for antennas where very little of the input energy is radiated, the two beams can be made almost similar by appropriate reduction of the phase velocity of the nonradiating waveguide. The same principle, when applied to an efficient antenna, causes deterioration of the sidelobe levels, although the peaks of the two beams can still be maintained equal. For the efficient antenna, the problem of beam-port coupling is also considered with respect to uniform and cosine plus pedestal radiating aperture distributions.

DOI:10.1049/piee.1972.0241

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The distortion performance of double-balanced switching-diode mixers and modulators may be optimised by suitable design of the local-oscillator circuit. The paper describes simple techniques for defining optimum drive conditions for ‘split-ring’, ‘hybrid’, and ‘star’ modulators.

DOI:10.1049/piee.1972.0242

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The two quantities which define the performance of the junction circulator are its shunt conductance and its susceptance-slope parameter. It is shown in this paper that these two quantities are related in a universal way by the difference between the two split frequencies of the junction resonant modes. For many junctions, the difference between these frequencies is connected in a standard way to the magnetic splitting of the device. It is therefore sufficient to calculate either one of them to characterise fully the junction circulator. In this paper, the susceptance-slope parameter is calculated by forming the input admittance of the constituent resonator. The constituent resonator for the stripline circulator is the one formed by the ferrite disc fed by a single TEM line. It contains all the physical variables of the device. This principle is applied to a number of different geometries. The paper also describes a new quarter-wave-mode circulator.

DOI:10.1049/piee.1972.0243

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The paper presents a detailed study of a computer-controlled queuing system with Poisson input, first-come-first-served queue discipline and multiple-exponential servers that are subject to breakdowns and repairs. A generating function for the state probabilities of the system and a necessary and sufficient condition for the existence of statistical equilibrium for the system are derived. Further, a formula for the determination of the first waiting-time distribution in the system is obtained by the use of the theory of Markov chains.

DOI:10.1049/piee.1972.0244

出版商:IEE    

年代:1972

数据来源: IET

摘要:

An algorithm for the minimisation of logic functions using XOR (exclusive-OR) gates in addition to AND, OR and INVERT gates is presented. It applies to functions with inherent symmetries, and the saving of hardware compared with that achieved by other minimisation methods is typically 40–60%. The algorithm could be included in the minimisation part of an automated-logic design program, or used as a logic designer's tool, either in the form of an on-call program or in the form of two templates for quick manual application.

DOI:10.1049/piee.1972.0245

出版商:IEE    

年代:1972

数据来源: IET

摘要:

Methods have been developed for the analysis of sophisticated electron-collection systems. The electron beam is treated either by representing it by a finite number of supersized charge carriers or (providing that the angle of divergence of the beam is small) by using a modification of the paraxial-ray equation. The results are employed to obtain a quantitative estimate of the collector efficiency and the heat dissipation on the collector walls.

DOI:10.1049/piee.1972.0246

出版商:IEE    

年代:1972

数据来源: IET

摘要:

A new algorithm for finding all trees, cotrees and 2-trees in a connected linear graph is given. The procedure will not generate any duplication, redundancies or cancellation of terms. The method given is based only on the definition of tree, so that no complexity arises. Further, it is shown that, if a certain condition is satisfied by the graph, the 2-trees can be obtained directly from the trees that have been generated. An illustrative example on the algorithm is also given.

DOI:10.1049/piee.1972.0247

出版商:IEE    

年代:1972

数据来源: IET

摘要:

The expression of the field pattern due to four squinted horns is deduced by using the Eulerian transformation and translation. This expression is solved by computer to optimise the slope of the difference-mode field pattern.

DOI:10.1049/piee.1972.0248

出版商:IEE    

年代:1972

数据来源: IET