摘要:

A novel radar system is proposed which effectively and simply combines the respective merits of pulsed a.m. and f.m. c.w. Doppler radar, by the use of a combined a.m. and f.m. waveform. Simple waveform changes permit the radar to be adapted to suit a wide range of operational requirements. This type of radar would require computer control for its full exploitation, and it is assumed that its principal application will be in fully automatic track-while-scan radars. The operation of the system in its various modes is described, and some technical aspects of the implementation of the system are discussed.

DOI:10.1049/piee.1970.0098

出版商:IEE    

年代:1970

数据来源: IET

摘要:

A general identification-friend-foe/selective-identification-feature code-validation scheme is described. This general class of schemes contains, as a subset, particular schemes which are in present use in military and commercial applications. For the general validation scheme, an expression for the cumulative probability of code validation on or withinNinterrogations (2 ≤N< ∞) is derived and plotted.

DOI:10.1049/piee.1970.0099

出版商:IEE    

年代:1970

数据来源: IET

摘要:

The paper examines a well known, frequently occuring and tedious problem in radio engineering. An algorithm is devised and a computer program based on it implemented to give a complete and rapid solution.

DOI:10.1049/piee.1970.0100

出版商:IEE    

年代:1970

数据来源: IET

摘要:

Several features of the diffraction of electromagnetic waves by large obstacles are examined both theoretically and by optical experiments using a laser source and idealised models. The underlying purpose of the work was to establish and verify, where possible, working methods of estimating the field strength in the shadows of rounded hills. The emphasis throughout is largely on the propagation conditions which arise in u.h.f. broadcasting, where ordinary terrain has a near-dielectric behaviour and its surface becomes effectively rough. Guided by the results of the simulation experiments, an attempt is made to deal with hill crests whose surfaces are randomly rough and with those of irregular shape.

DOI:10.1049/piee.1970.0101

出版商:IEE    

年代:1970

数据来源: IET

摘要:

‘Adaptation’ is known to affect the results of television quality-grading tests, in the sense that observers become more critical when the average picture quality is high and vice versa. The magnitude of the effect of adaptation for a particular type of impairment is dependent on the value of an ‘adaptation coefficient’ ; for the two types of impairment tested, flat random noise and a single echo of 8 μs delay, the adaptation coefficient was found to be larger in the former case. A method of adjusting test results for a standard ‘conditioning situation’, defined by a grand mean score of 0.5, is described. The magnitudes of the adjustments required are given for values of the grand mean typical of those that might occur in practice.

DOI:10.1049/piee.1970.0102

出版商:IEE    

年代:1970

数据来源: IET

摘要:

In the paper, the features of some possible systems for direct domestic reception of 12GHz television signals broadcast from satellites are discussed. Estimates of transmitter powers are derived from reasonable assumptions about the required picture quality and receiver noise figure. It is conclued that the most likely arrangement for a.m., f.m. or p.c.m. signals will consist of a 12GHz to u.h.f.(or v.h.f.) convertor suitable for feeding the aerial socket of a standard receiver. Appropriate microwave components and the overall economics are briefly considered.

DOI:10.1049/piee.1970.0103

出版商:IEE    

年代:1970

数据来源: IET

摘要:

Recent developments in the UK telephone system have jointly resulted in a requirement for faster signalling between telephone exchanges. In a network using ‘Channel-associated’ signalling, ‘line’ signalling is usually effected on a link-by-link basis, and it is important to ensure that supervisory signals are repeated as quickly as possible. Fast ‘interregister’ signalling commonly takes the form of multifrequency (m.f.) pulsing, using a ‘two out of six’ code. In a wholly integrated digital network, direct coding of the channel bits to provide fast interregister signalling could offer an attractive alternative arrangement. A different signalling principle, applicable to both analogue and digital networks, uses separate data channels to convey both line and interregister signals. The method of signalling is more compatible with processor-controlled switching systems than other types of switching system, but may present cost problems on the smaller sized routes. The economic application of new fast-signalling techniques to register-controlled exchanges in a network composed predominantly of step-by-step exchanges presents serious interworking problems which may possibly be minimised by the provision of an ‘overlay’ network. Because of the time required to establish the economic implications of such a solution, it may well be desirable at the present time to proceed independently with the introduction of m.f. signalling between registor-controlled exchanges over the existing junction network, using a system which is compatible with that already developed for the trunk network.

DOI:10.1049/piee.1970.0105

出版商:IEE    

年代:1970

数据来源: IET

摘要:

New methods employing an edge-numbering convention are proposed for listing all circuits and cutsets of an arbitrary graph, which are an improvement over the ones recently given by Maxwell and Reed. Storage of a master path matrix, whereby the all-path matrix between any two nodes of a given graph can be derived by simple modification, is discussed. A technique for generation of all trees, including a given set of edges and some significant properties of master path matrices, are also discussed. The algorithms proposed are all suitable for computer adoption.

DOI:10.1049/piee.1970.0106

出版商:IEE    

年代:1970

数据来源: IET

摘要:

A new synthesis procedure employing only unity-gain controlled sources is introduced, by which the denominator polynomial of a voltage transfer function can be decomposed in two ways. One of these gives a prescribed pole sensitivity, the modulus and argument of which can easily be controlled. The other gives a pole sensitivity that can be optimised by Calahan'sRC-RLdecomposition. A modification of the basic configuration gives a very stable, simple and insensitive circuit for realising lowpass or bandpass transfer functions. Synthesis of positive-real-axis transmission zeros is possible if an additional voltage invertor is used. The new method is compared with Hakim's circuit and with theRC-gyrator cascade circuit. The paper includes three design examples.

DOI:10.1049/piee.1970.0107

出版商:IEE    

年代:1970

数据来源: IET

摘要:

The principles and design method of a new type of reluctance motor are described. The rotor of the new machine has one system of flux barriers per pole pair and is nonsegmented. The machine combines the advantage of simplicity of manufacture with a performance which is satisfactory by any present standard.

DOI:10.1049/piee.1970.0108

出版商:IEE    

年代:1970

数据来源: IET