摘要:

AbstractA complex basis can be defined for a set × of variables such as element currents and voltages (excluding the exciting current and voltage), of a linear lumped‐con‐stant network in the sinusoidal steady state. If a subset Xβof × is a minimal set that satisfies the condition that any variable in × ‐ Xβcan be expressed as a linear combination of variables in Xβwith constant (not including frequency) coefficients, then Xβis called a complex basis of X, and the number of variables in, Xβis called the complex degree of freedom. This paper derives one of the complex bases of the set × of all the element currents and voltages excluding the exciting currents and voltages of the LCR network. Let G be the graph of the network, and consider trees Tiand Tv, together with their cotrees Kiand Kvin G, satisfying the following conditions C1 and C2:Ti∩ Kvis a union edge set of current sources and voltage sources;Under the condition C1, Tiand Tvcontain as many capacitors as possible and Kiand Kvcontain as many inductors as possible. Let Tscbe a tree of the graph obtained from G by shorting all the edges other than capacitor edges and let K0zbe a cotree of the graph obtained by opening all the edges other than inductor edges. Let Ti, Tv⊇ Tscand Ki, Kv⊇ K0z. Then, capacitor voltages of Tv‐ Tsc, inductor currents of Ki‐ K0z, capacitor currents of Tv∩ Kiand inductor voltages and resistor voltages

ISSN:8756-6621    

DOI:10.1002/ecja.4400660702

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

年代:1983

数据来源: WILEY

摘要:

AbstractMaximum likelihood decoding of convolutional codes by Viterbi decoding method is an effective error correcting technique. However, little study on Viterbi decoding of high rate codes has been done since the number of paths entering each trellis state increases as the code rate increases. This paper presents a new maximum likelihood decoding of convolutional codes of rate (n ‐ 1)/n using a trellis. the trellis is drawn according to the state transitions of the syndrome former of the code, and has only one or two paths entering each state rather than 2n‐1paths as in the case of conventional trellises. Thus, we can replace the 2n‐1‐ary comparisons at each state needed in the conventional Viterbi decoding for the code of rate (n ‐ 1)/n by binary comparisons. the implementation of maximum likelihood decoders for high rate convolutional codes is simplified greatly by this approach. Moreover, this decoding method shows the same performance as that of conventional Viterbi decoding method from the viewpoint of selecting the maximum likelihood code

ISSN:8756-6621    

DOI:10.1002/ecja.4400660703

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis paper describes the realization of real‐time PARCOR analysis of speech by digital signal processors. to achieve low bit‐rate transmission of speech a real‐time PARCOR analyzer is developed which can be used as an adjunct to the PARCOR speech synthesis LSI. Especially, new methods are proposed for the detection of speech intervals, determination of voiced/unvoiced sounds, extraction of pitch and automatic correction of the result, which are essential in securing the quality of synthesized speech under the restriction of real‐time analysis. the usefulness of the proposed method is shown by experiment. In order to realize the proposed methods by the newly developed signal processor, the required memory capacity and the effect of computational accuracy are discussed. A means is presented to overcome the restriction. As a result, a single‐board real‐time PARCOR speech analysis‐synthesis system

ISSN:8756-6621    

DOI:10.1002/ecja.4400660704

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe sampling theorem established by Someya and Shannon is presntly finding wide applications in various fields. However, it often happens in actual application that the assumption of band‐limitation which is a prerequisite of the theorem is difficult to verify. From such a viewpoint, this paper generalizes the sampling theorem to remedy the problem. the blurring operation originally has the function of positively suppressing the higher‐order harmonic components. It is a regular linear operation for which the inverse operation exists. Utilizing this property and combining the operation with the traditional sampling theorem, a new sampling theorem is derived, by which only those components of the object function in the limited band can be extracted. the generalized sampling function derived first in this paper is a natural extension of the traditional sampling function. With its analytical structure as well as the clearly stated method of computation, the generalized sampling theorem derived in this paper is applicable widely to actual probl

ISSN:8756-6621    

DOI:10.1002/ecja.4400660705

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn a nonlinear resistive network composed of nonlinear resistors, of which the v‐i characteristics can be represented by a strictly monotone increasing function, linear resistors, dc sources and dependent sources, the number of solutions for the network equation depends generally on the network parameters including nonlinear characteristics, resistances, source values, and transmittances of dependent sources. For a certain class of networks, however, the solution is unique for all network parameters. For example, Nielsen and Willson gave the topological necessary and sufficient condition for the network consisting of transistors represented by the Ebers‐Moll model, the nonlinear resistors mentioned above and dc sources to have a unique solution. It is important from a theoretical viewpoint to examine the condition for the uniqueness of the solution for more general types of networks. This paper gives the topological necessary and sufficient condition for the network consisting of nonlinear resistors, linear resistors, dc sources and current‐controlled current sources with transmittance α in the range 0<α

ISSN:8756-6621    

DOI:10.1002/ecja.4400660706

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

年代:1983

数据来源: WILEY

摘要:

AbstractAs the scale of the packet switching network and the number of pac̀ket transit nodes increases, the packet switching load and packet delay in the network increase in general. Technologies to suppress these tendencies and to construct the packet network economically are becoming more and more important. This paper assumes transit switches (TS) with both circuit and packet switching functions in a packet switched network. Then a packet transfer method is proposed in which the transit switches set up the direct channel between a pair of source and destination nodes if the traffic between the node pair increases beyond a threshold. First, newly introduced controls for setting up and releasing the direct channels and their desired realization methods are clarified. Next, direct channel set‐up/release characteristics and packet delay characteristics are clarified through numerical calculations of the source switch model and simulation. From these results it is shown that this control method reduces the transit switching load and shortens the packet delay in the transit network. Furthermore, an approximate formula is derived to determine the threshold value of traffic between source and destination switch

ISSN:8756-6621    

DOI:10.1002/ecja.4400660707

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis paper discusses pattern synthesis to obtain a fan beam with slot array antennas created on the narrow wall of a waveguide. Traditional pattern synthesis methods of this kind of antenna include the sampling technique of a continuous source distribution over the antenna aperture and the approach in which each slot is treated as a discrete source. In this paper, the locations of slots derived by the sampling method are used as the initial values. the current amplitude and the location of each slot are corrected by linear programming so that the antenna efficiency is improved.Although the problem of finding the correct amplitude in each slot is a linear problem, that of correcting the slot location is nonlinear. Hence, linear programming is applied to the latter by linear approximation. A successive method is studied in which the amplitude and location of the slot are alternately and repeatedly modified. the antenna efficiency of ‐3 dB has been improved to ‐1 dB. the effect of fabrication inaccuracy on the optimally designed antenna is compared to that based on the traditional des

ISSN:8756-6621    

DOI:10.1002/ecja.4400660708

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

年代:1983

数据来源: WILEY

摘要:

AbstractPyramidal absorbers widely used today often exhibit complicated scattering phenomena. From the point of view of measurement equipment and operation, it is not easy to measure these phenomena over wide ranges in frequency and incident angle by the traditional method. In this paper, the direct spatial standing‐wave measurement method for the oblique incident case is studied and extended to the method for measuring the scattering characteristics of the absorber. This method has been used for measurement of the reflection coefficient from an absorber with an oblique incident wave. In the new method, the standing‐wave ratio (or the scattering coefficient) and the scattering angle of the wave with the maximum intensity of all the waves are measured at the front surface of the sample. the measurement error of the standing‐wave ratio around 1.1 (scattering coefficient 0.04762) is less than ±20% in terms of scattering coefficient for the incident angle ranging from 0° to 80°. the error in the scattering angle is less than 6° for the 0° scattered wave and less than ±3° for all other scattering angles. the new method requires only simple equipment and the operation is easy. Therefore, measurement of the scattering characteristics of a pyramidal absorber can be done quickly over wide ranges of frequency and in

ISSN:8756-6621    

DOI:10.1002/ecja.4400660709

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

年代:1983

数据来源: WILEY

摘要:

AbstractAs a means of information compression in speech communication, the pause‐in‐speech deletion technique has been applied to digital speech interpolation, etc. This paper examines a pause‐in‐speech technique, which, after detection of a voice segment, goes backward some tens of milliseconds before the voice segment and can turn a voice switch on. Used in a delay‐allowable communication system, this permits efficient compression of the pause in speech while maintaining minimum quality degradation and can be a cost‐effective economization method. the possibility of a backward hangover process with pause deletion and rewriting of voice segments in pause segments in the buffering process using addressing control is discussed. Experimental results reveal that the backward hangover process (hangover time of 32 ∼ 64 ms) permits less voice deletion (especially at word fronts, which are essential to quality reproduction) than the ordinary hangover process. the total cost effectiveness is discussed with respect to a voice storage system and it is shown that the cost of the system can be reduced without speech quality degradation by applying the backward hangover process and addressing control

ISSN:8756-6621    

DOI:10.1002/ecja.4400660710

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

年代:1983

数据来源: WILEY

摘要:

AbstractWe calculated the Allan variance (the frequency stability measure in the time domain) of a rain‐attenuated 34.5 GHz beacon signal transmitted from a geostationary satellite. the obtained results showed that the rain‐attenuated signals basically had random‐process characteristics with fα (α<0) types of power spectral densities‐typically with α = ‐2, i.e., a random walk process. Also calculated were the Allan variances of bit error rates (BER's) of time division multiple access (TDMA) signals which were attenuated by rain. Occasionally, the measurements showed that the variances were reduced to only a few seconds. We applied these results to sitediversity switching experiments and tried to determine optimum times to measure and compare the BER's of the TDMA signals to be switched (they came from both routes of the main and substations). Simulation experiment results showed that the measuring times to minimize the variances coincided almost with those to minimize switching errors. This was also proved by theoreti

ISSN:8756-6621    

DOI:10.1002/ecja.4400660711

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

年代:1983

数据来源: WILEY