摘要:

AbstractIn a speech signal transmission by means of the pause of speech such as the DSI, the speech detection capability is significant and accurate detection of it is indispensable. This paper proposes a detector for operations in each block with improved detection characteristic realizing a shortened hangover time and a high sensitivity. These results are obtained based on the sign bit sequence matrix processing in terms of the short‐time energy, the zero crossing rate and the sign bit sequence of the input signal. Especially in processing the sign bit sequence matrix, a degree of the speech spectrum concentration is investigated by processing the sign bit sequence of the original signal as well as the obtained signal through the pre‐emphasis filter, and the sign bit sequence matrix composed of the sign bit sequence of the fundamental frequency and its harmonic sine and cosine waves. A computer simulation has indicated that a speech level of above ‐51 dB m is detected effectively without any degradation of speech quality. The average activity of speech in an international long‐distance line is reduced remarkably to 36% compared with the conventional one of 40%, and the average talkspurt is shortened to 436 ms which is half that of the conventional ones. Furthermore, it is shown that the detector has an excellent discrimination characteristic for therma

ISSN:8756-6621    

DOI:10.1002/ecja.4400630702

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe numerical integration method is proposed to derive the group delay characteristics and impulse reponse of the reactance low‐pass filter for a given characteristic function of the filter. The approximate values of coefficients in the group delay characteristics τ(ω) are derived from given characteristic function by applying the numerical integration method to the integral formula using Hilbert transform. A simple method is proposed to evaluate the error due to the numerical integration. The coefficient of the transfer function is derived from the coefficient of (ω). Further, the impulse response is calculated from the transfer function by applying the numerical integration method to the integral formula of Laplace inverse transform in which the Bromwitch integral path is replaced by a special path. Finally, the transfer function of the low‐pass filter with sufficiently flat attenuation characteristics in the passband is derived by the minimization method for given group delay characteristics and step re

ISSN:8756-6621    

DOI:10.1002/ecja.4400630703

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

年代:1980

数据来源: WILEY

摘要:

AbstractLumped‐element representations are derived for lossy multiwire lines using simple circuit matrix with the assumptions that (1) phase constants of all transmission modes are identical, and (2) their attenuation constants are independent of frequencies. Since these assumptions are valid in the limited frequency range, simplified representations of lossy multiwire lines are derived in the vicinity of a quarter‐wavelength frequency. As an application of narrowband equivalent representations, analysis and design of lossy interdigital‐line filters of narrow‐band are inves

ISSN:8756-6621    

DOI:10.1002/ecja.4400630704

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe communication FIR filters are used in a cascade configuration of several ten degrees to several hundred degrees which require the solution of very‐high‐degree algebraic equations for the analysis. The conventional algorithms enable algebraic equations of about 200 degrees to be solved. This paper proposes a novel algorithm which solves accurately and effectively very‐high‐degree algebraic equations. This algorithm utilizes the finite bit method and is not subject to overflow and underflow. This algorithm is independent of the initial values and can solve algebraic equations of as high as 1000 degrees. The computation time is proportional to the square of the

ISSN:8756-6621    

DOI:10.1002/ecja.4400630705

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

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper describes the optimization of linear interpolation of picture elements in terms of least mean square error for pictures of a square array of elements. Two kinds of models are assumed for autocorrelation functionm, nwhich is defined as the correlation of two elements separatedmpicture elements in a horizontal direction andnpicture elements in a vertical direction. One is a homogeneous model in whichm,nis given by the equationm, nIn the interpolation of the picture element at the point not sampled, the optimum interpolation can be achieved by the linear combination of the four picture elements nearest to the point to be interpolated. This is strictly true in the case of an inhomogeneous correlation function and approximately true in the case of a homogeneous correlation function. On the other hand, in the interpolation of the picture element at the sampling point, the interpolation can be optimized by the linear combination of eight picture elements around the point to be interpolated. This is strictly true in the case of an inhomogeneous correlation function and approximately true in the case of a homogeneous correlation function.Using the above results, interpolation techniques in “standard conversion in broadcasting television signals” and “system conversion from video phone signal to broadcasting television signal” are reviewed, and the pictures processed with the interpolation techniques are ev

ISSN:8756-6621    

DOI:10.1002/ecja.4400630706

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

年代:1980

数据来源: WILEY

摘要:

AbstractSystematic investigation is made on the noise generated in an FM transmission system for the simultaneous transmission of wideband picture signals and narrowband voice and data facsimile signals. In thermal noise analysis, tradeoffs are carried out between the noise characteristics resulting due to the methods of modulation and multiplexing of narrowband signals. Methods of handling the cross noise and distortion noise, caused by narrowband signals are described. As far as the methods of modulation of the subcarrier wave which corresponds to the narrowband signal are concerned, AM, FM and PSK are considered. The FM and PSK are taken as the focus of present discussion. As far as the distorition noise is concerned, besides the noise of narrowband signal, it is necessary to account for the noise that drops into the picture signal band. The reason for the former is considered mainly to be the differential gain (DG), and the reason for the latter varies depending on the dropping frequency of the noise. The computed values agree very well with the experimental characteristics.For the medium of transmission of multiple signals that include wideband picture signals, the frequency modulation formula has an advantage and the probability of its future development is large.

ISSN:8756-6621    

DOI:10.1002/ecja.4400630707

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

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper presents formulas for calculation of the distortion noise in picture and subcarrier FM transmission. The distortion is calculated from the transmission channel characteristics at the sideband of the FM wave which is expanded in Bessel function. FM and PSK are considered as the subcarrier modulation. The spectral models for the picture brightness signals and color signals are approximated by e‐aΔat frequency Δ.The main results include: (1) the calculation of the distortion due to the differential gain (DG); (2) the calculation of 16 different kinds of distortions; and (3) the application to TV‐speech multibroadcasting, two‐picture simultaneous transmission, and picture‐telephone simultaneous tra

ISSN:8756-6621    

DOI:10.1002/ecja.4400630708

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

年代:1980

数据来源: WILEY

摘要:

AbstractOwing to their economy and flexibility, much attention is devoted to single‐channel encoders based on LSI technologies. Various circuit configurations have been proposed. This paper presents a systematic discussion of the types of circuit configuratious with a view to applying a counting encoder with lower element accuracy to a single‐channel encoder. Initially, we propose various circuit configurations types for companding encoding by controlling the pulse width of the counting clock at the power of two. We then classify the counting encoder with regard to the processing pattern of encoding, clarify the relationship between the element accuracy and performance deterioration and describe the circuit type adopted for using LSI. The application conditions for digital networks are examined and a simple method is proposed which permits synchronization of the PCM output signal to the zeroth group even if the counting clock and the zeroth group are functioning asynchronously. In addition, we propose a method of adjusting the levels of analog input signals as appropriate for the counting encoder. It is expected that the above discussions will provide the optimum composition of the single‐channel counting en

ISSN:8756-6621    

DOI:10.1002/ecja.4400630709

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

年代:1980

数据来源: WILEY

摘要:

AbstractIt is important for the 16QAM carrier recovery circuit to have low phase jitter as well as only four stable phase points. In this paper, a novel carrier recovery with selective gated phase‐locked loop (PLL) is proposed which uses only the error information of the 4PSK signal and an identical phase signal; its construction and noise characteristics are also described. First, a concrete construction based on a working priciple and digitalized circuitry is given. Next, the phase jitter due to additive white Gaussian noise in a carrier tracking loop with binary phase comparator (PC) characteristic is analyzed using an equivalent linearization technique; also, it is shown that the carrier recovery loop can be described in a linear model of the past by introducing equivalent linear gain, equivalent input noise and the degradation factor caused by the symbol error. From this study, we conclude that with the selective gated PLL, the phase jitter performance of the carrier recovery can be improved by about 6 dB over that of the carrier recovery without the selective gated PLL. This has enabled us to improve the phase noise, power density, locking characteristic, tracking characteristic, etc., by about 100%. The noise characteristics are almost the same as that of 4PSK carrier recovery. The numerical calculations have been done for the equivalent PC. This recovery system does not have false lock point

ISSN:8756-6621    

DOI:10.1002/ecja.4400630710

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

年代:1980

数据来源: WILEY

摘要:

AbstractA new transmission system is proposed in which the television signal is used as the modulation signal and the wideband FM signal with low modulation index is transmitted through a multichannel narrow‐bandwidth transmission path. The signal processing of this system is as follows:1Carrier frequency of broadband FM signal is made equivalent to the sum of the maximum carrier frequency of the modulation signal and half the frequency deviation by using a frequency converter.2Frequency is divided byNby flip‐flop and the signal is transmitted asNchannels narrow bandwidth FM signal. The phase difference between each of the channel carrier frequencies is π/Nradian.3In the receiver, the broadband FM signal is reformed by an exclusive‐OR circuit after the wave is shaped by the limiter.This paper analyzes the above‐proposed FM signal and estimates the change of frequency spectrum. Furthermore, it has been confirmed experimentally using the television signal that the output of the 30 MHz and FM modulator having 14 MHz bandwidth (base band of modulation signal is about 5 MHz) can be transmitted through the 4 channels having 3.6 MHz b

ISSN:8756-6621    

DOI:10.1002/ecja.4400630711

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

年代:1980

数据来源: WILEY