ISSN:0098-9886    

DOI:10.1002/cta.4490010102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractA drawback of all ladder digital filters discussed hitherto is the requirement for including unit elements to separate consecutive ladder arms. It is shown how this requirement can be circumvented. By means of the new method, any LC‐ladder filter can very simply be translated into a corresponding digital structure requiring only as many multipliers as corresponds to the number of degrees of freedom in the original LC‐fil

ISSN:0098-9886    

DOI:10.1002/cta.4490010103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractA simple technique for designing low‐pass recursive digital filters with nearly linear phase characteristic is presented. The linearity of phase is obtained by placing the poles in the neighbourhood of the passband at equal intervals on a circle of radiusr, inside the unit circle on thez‐plane. The zeros are placed in the stopband on another circle of radius 1/r. The phase characteristics of these filters are shown to be linear with a maximum periodic error ofrmradian, wheremis the sum of the number of poles and zeros of the filter. This error can be made small by suitably choosingmandr. Stop‐band transmission characteristics of these filters are also examined and an upper bound obtained for the asymptotic db

ISSN:0098-9886    

DOI:10.1002/cta.4490010104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractThe paper deals with the analysis and synthesis of passive reciprocal one‐ports composed of aninfinitenumber of conventional elements (positive R, L. C and ideal transformers), considered as equivalent circuits of physical distributed one‐ports. In the generalization from finite to infinite networks, several (generally overlooked) basic difficulties arise, which are discussed and partially clarified. Physically, a prescribed positive real functionz(p) is only specified in Rep>0, and alosslessinfinite realization always exists. Since the value of the function in Rep<0 is then deduced byz(p) +z(–p) = 0, the resistancer(α, ω) = Rez(α +jω) is such thatr(0, ω) = 0, but the limit ofr(α, ω) for α = +0 may be strictly positive, so that a lossless impedance may have a resistive behaviour in steady‐state. The classical Foster and Cauer synthesis procedures may consequently all fail for lossless non‐rational impedances, whereas the procedures of Darlington and Bott‐Duffin (and sometimes Brune) succeed. Since every point is a transmission zero for an odd function, a cascade synthesis with all zeros atp= 1 always works, and explicit expressions for the element values are obtained. Many examples are treated in detail, and their sometimes pathological behaviour in

ISSN:0098-9886    

DOI:10.1002/cta.4490010105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractIn this paper the theory of orthogonal polynomials is taken as the starting point for developing the theory of semi‐infinite inhomogeneous ladder networks of two element kinds. It is shown that the transfer impedance of the ladder network, suitably normalized, is just the Green's function of a self‐adjoint difference operator of ‘Sturm–Liouville’ type. An integral representation for this Green's function is given, and is evaluated in product form. The theory is illustrated with a number of examples based on classical orthogonal polynomials, the use of which enables all the calculations to be carried through e

ISSN:0098-9886    

DOI:10.1002/cta.4490010106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractThe most popular method of investigation of periodic oscillations in nonlinear systems is the describing function method. Two theorems on the existence of a free vibration in a given neighbourhood of the approximate vibration obtained by this method are presented in the paper. Moreover, for a typical transfer functionK(jω) of the linear part of the system and a typical describing function of the non‐linear element, the theorem on the estimation of frequency of the free vibration is giv

ISSN:0098-9886    

DOI:10.1002/cta.4490010107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractIn the light of several recent theoretical breakthroughs1,2it appears reasonably certain that the insertion‐loss synthesis of a broad class of practical lumped‐distributed filters will soon become a reality. In particular, the structure of filters composed of a finite cascade of lumped reactive 2‐ports and equidelay ideal TEM lines is now almost completely understood and the related approximation problem not only seems soluble but also amenable to digital computer implementation.The advances in References 1 and 2 were sparked by a remarkable counter‐example due to Rhodes and Marston3and it is the purpose of the present summary to give a complete discussion and account of the concrete gains made up to this point without, of course, entering into proofs of material already published. Briefly, the order of ideas is as follows. In Reference 1 a fundamental synthesis theorem is established with the aid of the 2‐variable positive‐real concept and in Reference 2 explicit formulae are derived for the various junction reflection coefficients. In addition, Reference 2 reformulates the synthesis theorem in Reference 1 and succeeds in removing the 2‐variable positive‐reality requirement but only at the expense of introducing two extra conditions of the 1‐variable type. Theorem 2 of the present note succeeds in eliminating the more complicated of these two conditions and has as consequence the final and definitive ‘Strong Theorem 1’. A full proof of theorem 3 is given in the Appendix and one illustrative example is

ISSN:0098-9886    

DOI:10.1002/cta.4490010108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractA frequency‐locked RC active ladder filter is described, which is frequency‐locked to a sinusoidal control tone. The tunable ladder filter is used as a frequency discriminator by using two of the filter branch voltages to generate a control voltage. The control voltage is then used to tune or frequency‐scale the ladder filter transfer function to lock the filter to the frequency of the control tone. A simple linear frequency‐signal control system is developed to describe the frequency‐locked performance of the adaptive filter. The frequency‐locked filter can be designed so that the sinusoidal control tone is rejected at the filter output, making it possible to adapt the filter transfer function during transmission of a message. A practical frequency‐locked filter is given in which a frequency‐locked third order elliptic lowpass filter is designed. The performance of the practical filter is analysed using a simple linear contr

ISSN:0098-9886    

DOI:10.1002/cta.4490010109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractIn this paper, a system ofNcoupled active infinite lines, excited by a set ofNseries impressed voltage sources and ofNparallel impressed current sources, is considered. The system is assumed to be described by both a Telegraphist's and a State‐space mathematical model. Conditions are given for the existence and the uniqueness of the response of the structure to the given excitation, within the framework of suitable distribution space

ISSN:0098-9886    

DOI:10.1002/cta.4490010110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractThe problem of realization of a given real symmetric matrixRof ordernas an open‐circuit resistance matrix of some resistiven‐port network having nullitynis considered in this paper. The solution presented is in the form of a realization technique which implies the necessary and sufficient conditions for this type of realization. Derived from fundamental topological considerations in the analysis of resistiven‐port networks, the realization technique presented here is found to be superior to the existing

ISSN:0098-9886    

DOI:10.1002/cta.4490010111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY