摘要:

AbstractThis paper analyzes the single‐mode and nonresonant multimode oscillations in the ladder‐type oscillator, using the averaged potential method we introduced previously. In particular, physical description of the phenomenon is presented. The averaged potential represents the time‐average of the loss in the oscillator, and the stable oscillation is produced so that its value is minimized. Based on the fact that the averaged potential is of a quadratic form when the characteristics of the active element are represented by a third‐order polynomial, an algorithm is constructed to determine all minimum points of the averaged potential. Then the condition for stable single‐ or multimode oscillation is derived as the condition for the mode configuration. By this discussion, the physical significance of the stable oscillation mode is clarified, indicating the relation between the property of an active element and the behavior of the ladder oscillator. Finally, the oscillation mode of the ladder oscillator in which active elements are fully or partially included can be described from the viewpoints of the averaged potential method. Examples are shown for the latter case where triple‐ and quadruple‐modes of oscillations ca

ISSN:8756-6621    

DOI:10.1002/ecja.4400670501

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

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper considers the problem of designing an observer for the Roesser state‐space model with unknown disturbance. After showing the minimal order for the existence of an observer, a necessary and sufficient condition for a minimal‐order potential observer to decouple unknown disturbance is given. Furthermore, a sufficient condition for a minimal‐order potential observer to be stabilizable is examined. Finally, an algorithm is presented for designing a disturbance decoupled observer. This algorithm is applicable to 2‐D systems without unknown disturbance as the speci

ISSN:8756-6621    

DOI:10.1002/ecja.4400670502

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe LMS algorithm and learning identification, which presently are typical adaptive algorithms, have a problem in that the speed of convergence may decrease greatly depending on the property of the input signal. To avoid this problem, this paper presents a geometrical discussion as to the origin of that defect, and proposes a new adaptive algorithm based on the result of the investigation. Comparing the convergence speeds of the proposed algorithm and the learning identification by numerical experiment by computer, great improvement was verified. The algorithm is extended to a group of algorithms which includes the original algorithm and the learning identification, which are called APA (affine projection algorithm). It is shown that APA has some desirable properties, such as, the coefficient vector approaches the true value monotonically and the convergence speed is independent of the amplitude of the input signal. Clear conclusions are also obtained for the problem as to what noise is included in the output signal when an external disturbance is impressed or the degree of the adaptive filter is not sufficient.

ISSN:8756-6621    

DOI:10.1002/ecja.4400670503

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

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper describes a construction method for the pole‐deviation tracking filter, which is a computing system to follow the variation‐in‐time of the poles of the signal waveform. Until now, the methods such as filter‐bank, FFT and LPC, are used to track the deviation of poles, assuming the stationarity within the frame. There are some methods in nonstationary speech analysis that assume the variation within the frame. However, they have a problem in that the error may accumulate since the locations of poles are calculated after correcting the LPC coefficients. The method proposed in this paper, on the other hand, is an extension of the idea of POLPEC I, which we have proposed as a means of speech recognition. It assumes the variation within the frame, and the pole deviation is calculated directly from the waveform. By this scheme, the location of the pole is not averaged within the frame and the error does not accumulate. Neither is it necessary to solve an algebraic equation of higher order to determine the pole location. The result of simulation using synthesized waveform and the analysis of C‐V type speech also are

ISSN:8756-6621    

DOI:10.1002/ecja.4400670504

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

年代:1984

数据来源: WILEY

摘要:

AbstractTo realize analog and digital ADM (Amplitude Domain Multiplex) signal transmission systems which transmit analog and digital signals in the baseband domain by amplitude domain multiplexing, intersymbol interference caused by the low‐frequency cutoff of the transmission line is a serious problem and dc‐balancing of the signals becomes necessary. This problem has not yet been discussed. This paper describes a new ADM technique for dc‐balancing of the signals within a word by using dc‐balance mB‐nB codes for the digital signal and dc‐balance signal processing within a word for the analog signal; a practicable system design is also proposed. Moreover, dc‐balance mB‐nB codes with a small clock rate increase and RDS (running digital sum) are proposed and dc‐balance mB‐nB codes suitable for this system are specified. A method for defining the optimum amplitude ratio of the analog and digital signals, and simple word synchronization and line‐error detection by checking the digital word sum are illustrated. Finally, an example of the application to subscriber loop‐transmission systems is presented and the system e

ISSN:8756-6621    

DOI:10.1002/ecja.4400670505

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe demodulation of phase‐modulated signals is performed primarily by synchronous detection which has excellent characteristics. Thus, to regenerate a reference carrier wave that is identical with the transmitted one, a pure carrier should be received for a fixed time as a preamble before the data. Therefore, in digital radio terminals which are expected to appear, if a single extremely short information data burst has to be transmitted, it would possibly require the addition of a long preamble. If the relative carrier frequency offset is large in a low‐speed transmission system, then a longer preamble is necessary.This paper proposes a demodulation system for phase‐modulated signals which allows a shorter preamble or eliminates the need for it completely. The proposed system is based on the recent rapid progress in the speed, capability, and price of the microprocessors which obviates immediate demodulation, but makes it practical to store a data sequence of a fixed length without any demodulation. In addition, it is possible to realize the demodulation with batch processing by a block demodulation system. In such a system the complete transmitted burst signal containing no preamble can be demodulated with the optimum carrier phase. If this system is used merely as a frequency offset detector, it can complete the detection more than 5 times faster than a phase‐locked system under the same noise con

ISSN:8756-6621    

DOI:10.1002/ecja.4400670506

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe authors previously proposed a complex power‐series representation for input‐output nonlinearities and, on the basis of analysis of a predistortion (PD) compensation algorithm using this representation, developed a complex synthesizing PD algorithm which can compensate simultaneously for phase and amplitude nonlinearities in the TWT amplifier [1]. The algorithm is applied in this paper to compensating the nonlinearity of a TWTA operating in a high‐capacity SSB‐AM microwave system and describes the realization of a nonlinear distortion compensator which gives excellent distortion reduction with high stability. First the PD circuit required to achieve the prescribed distortion reduction and the nonlinear characteristics and degradation factors of the TWTA are analyzed and the design method for the complex synthesizing PD circuit is clarified. Second, in order to achieve easy adjustment and long‐term stability in the counterbalancing compensation, an automatic self‐adjusting stabilization method using microprocessors is proposed. Application of the self‐adjusting system to this circuit has achieved a long‐term stable reduction of more than 30 dB per 30 MHz in the nonlinear distortion noise of TWTA. This reduction is sufficient to develop a practical rad

ISSN:8756-6621    

DOI:10.1002/ecja.4400670507

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe distribution of prediction error at DPCM coding of audio or video signals can be approximated closely by Laplace distribution which, therefore, has been used widely for the determination of the quantization characteristics. The procedure for the practical determination of the quantizing characteristics for a given number of quantization levels, however, relies basically on the approximation methods chosen. Thus, considerable inconvenience is experienced during the theoretical analysis of the various characteristics corresponding to the different coding systems. In this paper, the optimum (Lloyd‐Max) quantization of Laplace density signals is considered and a recursive formula for the determination of the optimum quantization interval has been derived to show that the optimum quantization noise power is given as smin2/4(sminis the minimum quantization interval length) when the number of the quantization levels is sufficiently large. Furthermore, the optimum quantization intervals (steps) have been determined by a digital computer with an accuracy of 8 digits and compared with the results of known approximation

ISSN:8756-6621    

DOI:10.1002/ecja.4400670508

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

年代:1984

数据来源: WILEY

摘要:

AbstractHyperthermia is presently drawing attention in the field of cancer therapy. This paper describes the results of a heating experiment at 40 MHz using the dipole array applicator proposed by the authors as a means to realize deep heating in the human body. As the first step, numerical calculations are made of the electric field distribution in the object phantom (simulating human body), indicating that the electric field and consequently the heat generation is almost uniform in the phantom. Then a phantom is constructed in which the circulation of a saline solution can be varied depending on the location, and the heating experiment was performed. When the saline solution is not circulated, the temperature rise is almost uniform within the phantom, as is expected from the calculation of electric field distribution. When the saline solution is circulated, the temperature rise is high in the area of smaller circulation, which simulates the cancer. As an example, for 30‐minute heating by 1.6 kW, the temperature‐rise is

ISSN:8756-6621    

DOI:10.1002/ecja.4400670509

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

年代:1984

数据来源: WILEY

摘要:

AbstractWhen a dielectric resonator is used for a filter or for frequency stabilization of an oscillator, often it is necessary to know its external Q. This paper studies theoretically the external Q values under the assumption that the dielectric resonator is installed in a cylindrical metal case and a loop is used for coupling between the resonator and the external circuit. In the analysis, instead of using the electromagnetic field in the dielectric resonator, the resonator is replaced with a polarization current from which the vector potential is derived. From the vector potential, the magnetic field distribution is calculated. The power is supplied to the external circuit by the loop coupling of this magnetic field. From the energy stored in the dielectric resonator and the power delivered to the circuit, the external Q is derived. To study the effect of the metal case on the external Q value, cases with various heights have been considered at 3.5 GHz and the effectiveness of the method is confirmed by comparison with experiments.

ISSN:8756-6621    

DOI:10.1002/ecja.4400670510

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

年代:1984

数据来源: WILEY