摘要:

AbstractAn approximation method is proposed for a class of band‐limited waveforms whose Fourier spectra F(ω) are confined in the interval ‐ω1 ≦ ω ≦ ω1. The side lobes of such waveforms are also small in the range of 0<ω0<∥ω∥<ω1. First, the approximation waveform is obtained from summation of the product of an interpolating function and the sampling value f(tk) at the sampling point tk(k = 0 ∼ K). One objective of the proposed method is to find an interpolating function that will minimize the envelope of a family of approximation waveforms, which is used as a measure of error associated with the approximation. The optimum interpolating function, also satisfies the condition of discrete orthogonality. The proposed approximation technique also piovides convergence to the actual waveform with respect to a set of sampling points determined by the conventional sampling theorem. The approximation error is evaluated and weighted in the frequency domain using Fourier series expansion. The lower and upper bounds of approximation error in the frequency domain are derived and their relationships to the original wave

ISSN:8756-6621    

DOI:10.1002/ecja.4410690301

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

年代:1986

数据来源: WILEY

摘要:

AbstractWhen an analog waveform is digitized and transmitted over a digital channel, a combination of an error‐correction technique and a concealment method is often employed to improve the quality of the communication system. New concealment methods based on the Kalman filter are Kalman filtering concealment (KFC), scalar‐approximation concealment (SAC) and symbol states estimating concealment (SSEC). It is shown by simulation that these three methods provide better performance than conventional methods. The use of redundancy in the error‐correcting codes and the statistics of the analog information source is the core concept of the new concealment methods. In particular, the SSEC method is shown to be superior to other methods in its effective realization of this co

ISSN:8756-6621    

DOI:10.1002/ecja.4410690302

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper proposes the uniform structure threshold logic network which can extract various kinds of features from the multidimensional time‐series pattern. First, the basic characteristics of the proposed network are described and discussions are made on what kinds of features the network can extract from the time‐series pattern. As a result it is seen that the network has many interesting aspects in feature extraction, e.g., flexibility in the range of patterns to be extracted and determination of the center of a pattern. Based on these results, the network is applied to the feature extraction of the character pattern and the speech spectrum pattern. The results indicate that the network can extract the line‐segment components in various directions composing the character and also the location of formant in the speech spectrum pattern. The property of the network to extract these features which are important in the recognition, will be utilized in highspeed recognition and in the LSI recognition s

ISSN:8756-6621    

DOI:10.1002/ecja.4410690303

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

年代:1986

数据来源: WILEY

摘要:

AbstractA method has been proposed in the spoken word recognition, which utilizes the frequency‐time pattern inherent to the word. However, in the application of the method for speech by unspecified speakers, normalization is required, in contrast to the case of specified speakers, since the formant in the pattern may be shifted along the frequency‐axis due to the individual difference of harmonization organs of the speakers. The method including the formant normalization or nonlinear conversion of the frequency‐axis contains a larger computational complexity, and is not suited to a large vocabulary of words. From such a viewpoint, this paper proposes a method, in which a common weighted average dictionary is constructed by superposing the binary local‐peak patterns of speakers, absorbing their individual differences into a dictionary. The individual differences of speakers are also overcome by matching with the dictionary the binary pattern with an allowable width along the frequency‐axis centered around the local peak of the input speech. The weighted average dictionary is only a pattern set representing the frequency of the local peaks inherent in the word, and the storage of data requires less memory capacity. Since the input pattern is matched based on the binary pattern set, the computational complexity is also reduced. With 110 words of 0A command as the sample speech, both male and female speech is used as the inputs. When the input speakers are restricted, a recognition rate of 97 percent was obtained for restricted speakers and nearly 92 percent was obtained for unrestricted

ISSN:8756-6621    

DOI:10.1002/ecja.4410690304

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

年代:1986

数据来源: WILEY

摘要:

AbstractA11‐pole models have been used in speech signal analysis to represent speech‐producing systems [1]. This paper introduces a new method for analysis of the group delay characteristics derived from spectral envelopes. The method derives the complex cepstrum from the spectral envelope connecting peaks of fine structure of the power spectrum.The effectiveness of the method is shown by application to synthesized and actual nas

ISSN:8756-6621    

DOI:10.1002/ecja.4410690305

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe discrete cosine transform (DCT) is one of the discrete orthogonal transformations, for which fast computation algorithms are known. It has the property that the transformed sequence has most of the energy in the lower‐order components, and is utilized widely in feature extraction and high‐efficiency coding. The following methods have been known as the fast‐cosine transform (FCT): (1) Computation is performed through the fast‐Fourier transform (FFT) with real sequence; (2) Computation is made by decomposing the matrix representing DCT into sparse factors. In those methods, approximately N log2N real multiplications and (3/2)N log2N real additions are required for computation of DCT for N = 2vpoints. The FCT proposed in this paper differs from those methods in the following points. The DCT is represented by a finite series of Chebyshev polynomials. The order of the series is successively halved utilizing the successive factorization of Chebyshev polynomial, finally arriving at DCT values. By this method, (1/2) N log2N real multiplications and (3/2) N log2N real additions suffice to calculate the DCT for N points: the number of multiplications is halved, compared with the previous methods. The method is similar, in its structure, to FFT with radix 2, which leads to the feature that the programming is

ISSN:8756-6621    

DOI:10.1002/ecja.4410690306

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

年代:1986

数据来源: WILEY

摘要:

AbstractIt is well known that wave digital filters (WDF's) imitating the behavior of doubly terminated reactance circuits have low coefficient sensitivity properties. Based on the Darlington synthesis procedure, a cascade synthesis of WDF's realizing arbitrary transfer functions has been shown. They are constituted with cascading basic WDF sections corresponding to basic reactance sections. The cascade synthesis procedure, however, is rather complicated in that transmission zeros have to be found by calculating the roots of an algebraic equation.

ISSN:8756-6621    

DOI:10.1002/ecja.4410690307

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

年代:1986

数据来源: WILEY

摘要:

AbstractElectric or sound field problems associated with an open boundary governed by a Poisson or Helmholtz equation, are analyzed via the finite element method in conjunction with a hybrid‐type infinite element. The original size and bandwidth of the system matrix of the finite region do not increase after connection of the infinite element matrices for expressing the outer infinite region. In this paper, errors associated with numerical calculations are examined for 3‐D fields in consideration of the infinite region. First, an infinite element matrix for 3‐D infinite acoustic field is derived. The formulations are easily applicable to the 3‐D electric field problems. Next, the numerical calculations are demonstrated for the acoustic field caused by a point driving source and the results are compared with the analytical solutions. Another numerical example is the calculation of electric field caused by a pair of electric charges. Reasonable accuracy is confirmed in the finite region, but the accuracy in the infinite region is not always satisfactory. The decay function used for the infinite element plays an important role in accuracy. The decay parameter can be determined by the aid of the minimum condition of the functional and it is found that the use of this condition promises reasonable

ISSN:8756-6621    

DOI:10.1002/ecja.4410690308

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn recent years physical design has played a major role in the development of digital and LST techniques. This paper describes the profiles and several requirements of communication office terminals with consideration of physical design technology and presents an evaluation method for equipment practice. New equipment practice with multipurpose both‐side ducts inside a. cabinet, used for exhausting air and/or cable wiring, is proposed. The relationship between physical structure and natural air‐cooling characteristics is empirically examined and it is shown that good results are obtainable relative to the packaging properties of the proposed equipment practice compared with conventional ty

ISSN:8756-6621    

DOI:10.1002/ecja.4410690309

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn the conventional SSMA (Spread Spectrum Multiple Access) system, the number of co‐channel users is unexpectedly small and the increase in the number of co‐channel users is one of the subjects of SSMA. Introduction of error correcting codes, improvement on primary modulation, etc., have previously been proposed. Especially in direct‐sequence SSMA, primary modulation using modified M‐ary FSK has been reported to provide a remarkable improvement. A primary modulation scheme using modified M‐ary FSK, named “unpacked MFSK/DS,” is presented here for improving the multiple access capability on direct‐sequence SSMA by flattening the power spectrum of transmitted SS signals. It is shown that the number of co‐channel users in SSMA can be increased to twice as many as that of the conventional MFSK/DS systems only by modifying the frequency allocation of MFSK symbols and without modifying the conventional MFSK transmitter/recei

ISSN:8756-6621    

DOI:10.1002/ecja.4410690310

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

年代:1986

数据来源: WILEY