DOI:10.1049/ree.1966.0059

出版商:IERE    

年代:1966

数据来源: IET

摘要:

Summary: During the summer and autumn of 1964 the British Radio Equipment Manufacturers Association (B.R.E.M.A.) carried out extensive tests of N.T.S.C. colour television receivers, to assess their performance under typical domestic operating conditions. This paper describes the organization of these tests and records the results obtained. It was found, somewhat unexpectedly, that the viewers found the (u.h.f.) tuning controls easy to use and this may be regarded as very satisfactory since the quality of the picture obtained was good.

DOI:10.1049/ree.1966.0060

出版商:IERE    

年代:1966

数据来源: IET

摘要:

The detection performance for four typical cases of multiplicative radar signal processing is determined and a comparison is made with similar cases using linear addition.Both i.f. multiplication as it might be used in multiplicative arrays and video multiplication as used in radar diversity combiners are considered for non-fading and Rayleigh-fading signal amplitudes.In most of the cases considered the losses introduced by the use of multiplicative processing are quite small. Exceptions are when signals of significantly different signal/noise ratios, or equal-frequency i.f. signals of random relative phase are multiplied together.

DOI:10.1049/ree.1966.0061

出版商:IERE    

年代:1966

数据来源: IET

摘要:

In communications and control practice increasing use is being made of active-RCnetworks instead of the conventional passiveRLCtypes. The network theory literature contains a number of different procedures for the synthesis of such networks but so far there has been very little correlation of these procedures either with each other or with the well-known methods of passive synthesis, which are generally based on the lattice. The object of this paper is to show that such correlation may be achieved. The treatment is comprehensive and is believed to have some tutorial value in the earlier sections but there are also some original features.As a preliminary step an original development is made of the structure of the lattice in order to bring out the distinction between the restricted (i.e. convertible to bridged-T form) and the general cases of the lattice. The unbalanced equivalents of the latter case generally contain an ideal unity-ratio inverting transformer and, as a transition to active form, it is shown that this may be realized formally by a (+R, −R) network. Hence, the general lattice may be realized as an active bridged-T consisting of two negative impedance converters (NIC's) and the usual inverse pair of passive impedances. Then, when the latter are realized in active −RC form using the standard procedure employed in the literature the same pair of NIC's may be employed. However, there are two special cases of the active transformer replacement, for which one or other of the inverse impedance arms are nullified and the active bridged-T reduces to active T or π form. Then, when the three impedances of the T or π are separated into + and −RCparts, the three negative ones may be brought together and realized by the corresponding network placed in cascade between a pair of NIC'S. When the networks so obtained are operated between ideal terminations, for example an ideal voltage source and an open-circuit load, certain simplifications may be made. One of these is identified as the form of realization used (without derivation) by T. Yanagisawa in his wellknown paper. The principal conclusion of the paper is that one can develop from the classical lattice a broad class of active-RCnetworks that includes useful forms, not all of which appear yet to have been employed in the literature.

DOI:10.1049/ree.1966.0062

出版商:IERE    

年代:1966

数据来源: IET

摘要:

A univibrator circuit using a tunnel diode and a transmission line is analysed. A graphical method is presented to calculate the width and the magnitude of the univibrator pulse. Conditions for the univibrator action to take place are derived. The effects of variation of the tunnel diode bias and the characteristic impedance of the line on the pulse width are also studied. The modifications to be made in the graphical analysis for the case of a line with small losses are discussed in detail.

DOI:10.1049/ree.1966.0063

出版商:IERE    

年代:1966

数据来源: IET

摘要:

Third-order unity numerator control systems arise from the use of feedback compensation in order to meet the system specification. The normalization technique described in the paper permits the complete analysis and synthesis of third-order unity numerator linear or quasi-linear control systems by reference to the coefficient plane. Attention is concentrated on systems with a pair of complex roots plus a real root so orientated in thesplane that all three poles significantly affect the system response. Thus compared with certain existing design techniques, no approximations arise from the neglect of the third system pole when such criteria as bandwidth, maximum percentage overshoot, and velocity constant are determined.Conventional synthesis involves the determination of the system transfer function given the system performance specification. Provided that three independent adjustable parameters are available, three independent performance criteria can be met at one and the same time. It is shown that the coefficient plane yields the appropriate transfer function coefficients directly from a simply constructed coefficient plane contour. For systems with only two adjustable parameters, a performance compromise is necessary. The coefficient plane is ideal for the rapid determination of the best possible compromise between, say, peak amplitude ratio and bandwidth which can be achieved with such a restricted system. An alternative, and even simpler synthesis proposition based on standard forms of transfer function is also illustrated.

DOI:10.1049/ree.1966.0064

出版商:IERE    

年代:1966

数据来源: IET