摘要:

A mathematical analysis of linear anticodes is given in which a lower bound on the minimum of maximum- Hamming distance δ is obtained by the application of a systematic procedure for the generation of such anticodes. For the binary anticodes, the asymptotic form of this bound is established.

DOI:10.1049/piee.1976.0043

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The paper considers the optimum method of combining radar data from multiple sensors to provide estimates of and aircraft's position and velocity. This optimum, multi radar tracker is then compared with systems which form mono radar tracks and select or combine these to produce a single common track. The theoretical performance of each approach is discussed together with the practical difficulties of each implementation.

DOI:10.1049/piee.1976.0044

出版商:IEE    

年代:1976

数据来源: IET

摘要:

A moving-target-indication (m.t.i.) radar is used to reject signals from fixed, unwanted targets whilst retaining the Doppler shifted signals from moving targets. For a radar with a constant p.r.f., nulls in the m.t.i. response (‘blind speeds’) occur at multiples of the p.r.f. in addition to the desired null at zero frequency. The frequency at which the first blind speed occurs may be extended by the use of a nonuniform pulse-repetition interval, or staggered p.r.f. This paper presents the results of an investigation into methods of selecting these stagger periods to achieve acceptable passband performance.

DOI:10.1049/piee.1976.0045

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The optical theory of electromagnetism leads to a quite simple determination of the general features of the radiation pattern of an antenna in the presence of cylindrical reflector.

DOI:10.1049/piee.1976.0046

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The boundary value problem of diffraction of parallel and perpendicular polarised waves from gratings of conducting rectangular cylinders is solved by a rigorous mode-expansion formulation and numerical solution. Comparison of computed results with the limited theoretical and experimental results available in the literature demonstrates the accuracy of the numerical method. Further numerical results inducate the usefulness of these gratings for a variety of applications, and provide additional information on the physical phenomena which cause the unexpected transmission and reflection properties. Such results are also of considerable value in serving as standards to which various approximate solutions may be compared for accuracy and interpretation.

DOI:10.1049/piee.1976.0047

出版商:IEE    

年代:1976

数据来源: IET

摘要:

One of the most important criteria for comparing digital filters is based on the effects of finite word lengths. Although the errors originated by multipliers have been discussed in detail in the technical literature, very few contributions concern the adders in the floating-point implementation. In the paper, the use of the sensitivity of the the transfer function of the digital filter, with respect to the multiplier coefficients for characterising the effects in floating-point implementation, is extended to the adders by introducing the concept of the ‘equivalent multiplier’ The validity of this extension is illustrated by examples.

DOI:10.1049/piee.1976.0048

出版商:IEE    

年代:1976

数据来源: IET

摘要:

A theoretical method, described in detail in an earlier contribution, is extended to predict the dynamic response of a multistator, variable-reluctance stepping motor operating with multiphase excitation. Comparisons between experimental and predicted responses are made in terms of the settling time and pull-in-rate characteristics. The importance of allowing for core eddy currents in the theory is demonstrated. Consideration is also given to the feasibility of using closely coupled secondary coils on the stator to provide built-in electromagnetic damping for the motor. This too is considered regarding the effect produced on the settling time and pull-in rate.

DOI:10.1049/piee.1976.0052

出版商:IEE    

年代:1976

数据来源: IET

摘要:

The paper proposes a new theory for d.c. linear brakes with solid-iron secondary. Such brakes may be used to supplement the action of standard braking systems on conventional trains. The theory is based on 2-dimensional Fourier-series decomposition of the primary m.m.f., while the solid-iron secondary is notionally split into thin sheets of constant permeability, determined by an underrelaxed iterative procedure. The theoretical and test plots of braking force against speed show a fairly good agreement.

DOI:10.1049/piee.1976.0053

出版商:IEE    

年代:1976

数据来源: IET

摘要:

Systems incorporating long, compensated transmission lines operating in conjunction with salient-pole hydro-generators, necessary in the full utilisation of hydropower in remote regions, may operate in particular modes that do not occur with the more conventional power systems. When series-capacitor compensation is used, the line natural frequencies are modified and an extra oscillatory mode is introduced at a frequency which may interact with the machines in the system and cause instability. The paper reports on a study of transmission-system initiated oscillations at subsynchronous frequency, brought about by the introduction of series compensation, and self-induced oscillations at a frequency coinciding with the electromechanical natural frequency of the individual machines. A mathematical model of the complete system is developed that is suitable for use in computer studies. Representative results, from the numerous studies based on this model, are collected together in the paper, and are used to show the conditions which give rise to the two categories of instability.

DOI:10.1049/piee.1976.0054

出版商:IEE    

年代:1976

数据来源: IET

摘要:

Since the publication of a progress paper on oil-filled cables in 1961, continuous intensive research and developments have been carried out covering all the elements forming the cable, accessory design, technology. and system design as well as the new fields of application to d.c. land and both a.c. and d.c. long submarine connections. For each of these items the paper gives the highlights and concludes with an estimate of the limit of power which it may be possible to transmit with this type of cable.

DOI:10.1049/piee.1976.0055

出版商:IEE    

年代:1976

数据来源: IET