摘要:

AbstractJustesen presented the asymptotically good block codes, and then the asymptotically good convolutional codesRjin a constructive way. The latter are the concatenated codes, where the outer code is the convolutional code generated by the generator polynomial of Reed‐Solomon code, and the inner code is Wozencraft's randomly shifted code. The performance of Justesen's convolutional code is not necessarily high for low code rates. Sugiyama, Kasahara, Hirasawa and Namekawa presented new asymptotically good convolutional codesRcby applying the second order concatenation to Justesen's convolutional codesRj, which gave an improvement for the low code rates.This paper presents constructively new asymptotically good convolutional codesR(J), by comgining the second‐order concatenation of the forementioned improved convolutional codesRcand the generalized concatenated codes. It is shown that the new codesR(J)always have a higher performance than that of the convolutional codesRc, and have the best performance for the low code rates 0

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740301

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper describes a design approach for constructing activeRfilters to simulate the doubly resistively terminatedLCcircuit and its compensation techniques. Using this approach, the necessary compensation resistance values can be obtained from only one measurement of the filter response.The approach in this paper is applied to an all‐pole lowpass filter. However, it is shown that it can also be applied to a low‐pass filter having transmission zer

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740302

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe demand for the mobile communications is increasing every year, and TV and automobile telephone by satellite communication are expected to find wider applications. If individuals are to carry communication equipment, then the equipment must be small size, lightweight and highly efficient. To realize antennas which must also be of small size, lightweight and highly efficient. For such equipment it is desirable to employ the adaptive array with phase control.Conventionally, the LMS algorithm has been applied frequently in the design of the adaptive array. However, the authors believe that the learning algorithm is better suited to the adaptive array because of its higher convergence speed and the clear specification of the convergence condition.This paper extends the real‐type learning algorithm to the complex‐type learning algorithm. The convergence condition for the algorithm is derived, and the result of the application of the method to the adaptive array is shown. A method of deriving the reference wave also is presented which is less affected by the input signal variation and is suited to the adaptive array with only the phase control. Using the proposed complex learning algorithm and the new reference wave, the phase‐controlled adaptive array is designed. A satisfactory result is obtained by simul

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740303

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe computer today is a tool that can be used by everyone. On the other hand, it is important for the student of information sciences to correctly understand the operational principle of the computer as a basic knowledge required in understanding or solving the problems concerning the computer.To answer questions concerning the internal operation of the computer, it is necessary to understand the behavior of the actual circuit at the IC level. With the widespread use of the personal computer, it now seems possible to construct an efficient simulator for educational purposes. However, few reports have been presented concerning the approach at such a level.From such a viewpoint, the author developed a computer simulator aiming at the understanding of the operation of the registers and gates based on the machine language program. Two modes, i.e., the hardwired logic and microprogram, are executed by the control unit of the system. The operation can be switched to the set‐up constructed by a student. Several elaborations are made so that the operation actually is felt. For example, the operation is represented by a time‐chart so that the time‐relations among signals can be understood.A scheme is adopted whereby the generation program for the control signals is constructed directly from the time‐chart. It is expected that an efficient training for the operational principle over a wide range can be realized on a personal computer using the proposed system, relating the system behavior to the detailed circuit operations from the viewpoints of both software and h

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740304

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe unbiased estimation of the log spectrum is a method which is a stricter formulation of the cepstral method from the viewpoint of the spectral estimation. In the unbiased estimation of the log spectrum, the model spectrum is represented by cepstral coefficients and a spectral criterion is minimized with respect to the cepstral coefficients. By introducing an instantaneous gradient estimate of the criterion in a manner similar to the LMS algorithm, we develop an adaptive cepstral analysis algorithm. The properties and the features of the algorithm are discussed. In the analysis system, an IIR adaptive filter whose coefficients are given by the cepstral coefficients is realized by the LMA (log amplitude approximation) filter. The filter has an exponential transfer function and its stability is guaranteed.In contrast to the conventional LMS algorithm, where the coefficients are updated based on the input vector and the output of the filter, the feature of the proposed filter is that the coefficients are updated based only on the output vector. The computational complexity in the update of coefficients and LMA filtering is of the order of0(M), whereMis the order of the analysis. The convergence property of the proposed algorithm is shown through the analysis of synthesized signals, and the usefulness of the method is demonstrated through an application example to the analysis of the natural speech.

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740305

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn analytical method has been applied to a charge redistribution A‐D converter. In this method, the element values of each constituent element in a circuit are treated as statistical probability variables. Hence, the probability distribution of the circuit characteristics of design objectives is derived analytically from the probability distribution of the element values. If the circuit characteristics are described in terms of the circuit element values, the probability distribution of the circuit characteristics is derived from the sensitivity analysis of the analytical expression.In the case where the probability distribution of the circuit characteristics cannot be determined by the sensitivity analysis alone such as in the case of the error characteristics of binary weighted capacitor array, the characteristics are shown to be derivable as the probability distribution by combining the combinatory logic error analysis.By means of the Monte Carlo simulation, the accuracy of the derived circuit characteristics is verified. By means of the probability distribution formula of the derived circuit characteristics, a formulation is carried out for design of the A‐D converter including the yield. A guideline for design by the nonlinear optimization is presented for the A‐D converter including the yield equ

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740306

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

年代:1991

数据来源: WILEY

摘要:

AbstractA neural network model for solving optimization problems proposed by J. J. Hopfield et al. has yielded good solutions of the traveling salesman problem. The present paper describes a method of solving module placement problems in automatic LSI device layout, in which a neural network model is used to optimize a set quadrisection procedure by minimizing its objective function. The solutions obtained for this method are comparable to or better than those obtained by the GFDR method, an iterative‐improvement method of solving the module placement proble

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740307

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper proposes a method of speech analysis using a new stochastic model. This model represents two different kinds of MA parts associated with pseudo‐periodical pulse train input and Gaussian process input. Therefore, the new model describes individually two different production models for voiced and unvoiced sound in the frequency domain and can precisely realize speech production models in comparison with an ARMA model. It has been shown from experimental results that the proposed stochastic model can extract more accurate characteristics of real speech than an ARMA mode

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740308

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe advent of the present‐day low‐cost personal computer and work station has seen widespread applications. These personal computers and work stations often are used as a system including the hard computer disk (called the hard disk). Various files are constructed and stored in the hard disks. Often, those files are lost due to the mis‐operation of the user or the failure of the hard disk itself.The usual means to cope with such a situation is to back up the content of the hard disk at specified intervals by the floppy disk and other devices. However, time to backup usually is left to the intuition and the experience of each user. This paper considers this situation, and proposes a backup policy where the backup is executed when a certain number of jobs are completed. Then a formulation is presented to determine the optimal number of jobs, in the sense that the expected cost per unit time is minimized.In this paper, it is assumed that only those parts which are modified or updated after the previous backup are backed up at each time. Based on the formulated expression, the existence condition for the optimal solution is de

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740309

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper presents a method to estimate the optimal pairing and ordering method for cascade‐type state‐space digital filters, each having a second‐order section realized in 2D form or optimal form.The optimality criterion is based on minimizing the normalized round‐off noise. The scaling method used is theL2norm orL∞norm. To show the effectiveness of the proposed method, this method is compared with four conventional methods. As numerical examples, the estimation method is shown for three filters having different orders.The result of these examples allows a more optimal filter to be selected in terms of the optimality criterion of normalized round‐off noise when compared to the other conventional methods. Further, the proposed method also is capable of providing an estimation method for filters having section optimal form, of which the conventional methods are not capable. Finally, if the coefficient matrix is transformed using an equivalent transformation, it is also possible to extend the method to realizations other than 2D or the section o

ISSN:1042-0967    

DOI:10.1002/ecjc.4430740310

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

年代:1991

数据来源: WILEY