bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of temperature characteristics for rectangular GT‐cut quartz crystal resonators
Authors: Kawashima Hirofumi 
Published: July 2007

AbstractThis paper describes the frequency temperature characteristics of a rectangular GT‐cut quartz crystal resonator. First a secular equation is derived from a stress distribution obtained by a thin plate equation and a probe method. From the secular equation, a relationship between resonant frequency, frequency temperature coefficients and cut angle is shown, a dimensional ratio is calculated, and frequency temperature characteristics of the rectangular GT‐cut quartz crystal resonator are clarified. Finally, it is confirmed that the obtained results agree well with the experimental results obtained by Mason and Nakazawa.
A placement of circuit modules
Authors: Fukunaga Kunio , Yamada Shoichiro , Kasai Tamotsu 
Published: July 2007

AbstractThis paper gives a suboptimal layout for minimizing the virtual wiring length of a given circuit which is one of the design problems in the circuit module placement. The connective relations among circuit modules are represented by a circuit hypergraph and then by a circuit graph. A graph space method is proposed in which the modules are placed so that the pair with strong affinity is close and the pair with weak affinity is distant. Based on such a graph, the modules are assigned to the two‐dimensional slots. It is shown that even when there is a restriction that some of the module placements are already specified, the placements of other modules can be performed without affecting the overall connective relationships. The effectiveness of the method is verified by a computer simulation.
Analysis of lamb wave propagation characteristics in rotated Y‐cut X‐propagation LiNbO3 plates
Authors: Mizutaui Koichi , Toda Kohji 
Published: July 2007

AbstractLamb wave propagation characteristics in rotated Y‐cut X‐propagation LiNbO3 plates are analyzed theoretically as a parameter of the rotation angle of the crystal to elucidate velocity dispersion characteristics, mechanical displacement and electric potential, and electromechanical coupling constants. Calculation results show Lamb wave propagation characteristics in the 90° rotated Z‐cut plate and the 128° rotated Y‐cut plate. The zero‐order symmetrical mode at a 0° rotation angle (Y‐cut) has a high coupling constant over 20 percent. The zero‐order symmetrical and antisymmetrical modes degenerate with a plate thickness more than three wavelengths and become the Rayleigh wave range in substance. In measurement of the central frequency of the Lamb wave filter, the experimental results agree well with the theoretical analysis and the analytical results by this method are useful in constructing Lamb wave devices using interdigital transducers.
Effects of random multiplication gain of photodetectors on signal‐to‐noise ratios and error rates of noise‐like optical signal
Authors: Takahashi Nobuo , Morinaga Norihiko , Namekawa Toshihiko 
Published: July 2007

AbstractThe effects of random multiplication gain of the photodetector on signal‐to‐noise ratios (SN) and error rates of noise‐like optical signal which obeys Gaussian distribution have been analyzed. By assuming the avalanche photodiode as the photodetector and adopting McIntyre's equation in the probable multiplication, the clearly special feature of the probability distribution of the detected output photoelectron counts of the noise‐like optical signal has been demanded. Next, considering the additional noise of background radiation and thermal noise, SNR and error rates have been analyzed for the avalanche photodiode. In these analyses, the optimum gain which gives the maximum SNR or the minimum error rate, is also derived with some physical meanings.
An LC simulation by active RC low‐pass filter with reduced number of operational amplifiers
Authors: Ishibashi Yukio 
Published: July 2007

AbstractAn active RC filter which simulates an LC ladder filter is known to be of lower sensitivity than a cascade filter. A number of filters of this type have been proposed in recent years. This paper describes a synthesis method for LC simulation by an active RC low‐pass filter with reduced number of operational amplifiers by using a Sallen‐Key circuit for the 2nd‐order circuit encountered in the conventional leapfrog composition and by eliminating some of the variables of the input and output sides. First we discuss a sign decision method for the node voltage and loop current of a prototype LC filter and the elimination of variables. Then we derive relations for the variables which should be realized in the circuit and introduce a circuit which can realize them. Next we study the element sensitivities. We then compose a 5th‐order Chebyshev low‐pass filter and perform an experiment with it. By computer calculation we show that the sensitivity of this circuit is slightly higher than that of the conventional leapfrog circuit near the cutoff frequency, but at low frequency it is 1/2 ‐ 2/3.
Effect of sound field on attenuation coefficient measurement and its correlation
Authors: Itoh Takashi , Kasai Chihiro 
Published: July 2007

AbstractIn the conventional method, where the ultrasound attenuation coefficient is determined from the echo signal reflected from inside of the subject, it is assumed that the incident and the reflected waves propagate as plane waves. This paper regards the subject as a set of scatterers and shows that the attenuation coefficient determined by the plane wave assumption contains an error. The method considered is the determination of the attenuation coefficient from the difference of power spectra of the echo signals reflected from different depth, and the effect of the sound field produced by the transducer is also included. The error can be evaluated by the shape function determined by the geometry of the transducer. Consequently, the error can be corrected by subtracting the error term from the attenuation coefficient obtained by the plane wave approximation. To verify the effectiveness of the proposed correction method, an experiment was made using a phantom which is a mixture of agar gel and graphite powder. The result indicates that the attenuation coefficient of the phantom determined by the plane wave approximation does not agree with the value obtained by the transmission method, but there is good agreement if the correction is made by subtracting the error calculated from the geometry of the transducer. Thus, the effectiveness of the proposed method was verified.
New models of compound channels and their modeling methods
Authors: Suematsu Toshinari 
Published: July 2007

AbstractStatistical models of communication channels are used to evaluate the performance of error correcting and error detecting codes. The most important problem is how to get a reasonable communication channel model which represents actual channels. This paper presents three compound channel models, i.e., models which generate both random and burst errors. These models represent actual channels better than the channel models proposed previously. The parameters of these models can be determined from probability distribution of the lengths of error‐free runs and solid burst errors, which are relatively easy to measure from actual channel outputs. Characteristics of these models and their modeling methods are discussed.
New dual digital phase‐locked loop
Authors: Yamasaki Shoichiro , Nakagawa Masao , Tsunogae Toshio 
Published: July 2007

AbstractIn the phase‐locked loop (PLL), the following mehods are used to eliminate the steady‐state phase error produced by the input signal with frequency off‐set: (1) the perfect integrator is used as the loop filter, realizing the perfect second‐order PLL; (2) the dual phase‐locked loop (DuLL) is constructed by combining two first‐order PLL's, realizing a perfect second‐order PL, L. Method (1) has the problem of VCO drift, and method (2) has the problem that the choice of the loop constant (damping factor) is limited. Furthermore, both methods have the problem of unsatisfactory performance for the interfacing signal. This paper proposes a new DuLL which is constructed by adding a feedback circuit from the second PLL to the first PLL in the conventional DuLL. By theoretical analysis, it is shown that the new DuLL can remedy the problems in conventional circuits. Then the circuit is constructed by a digital signal processing technique. The pull‐in and interference characteristics are examined by computer simulation, indicating that the new DuLL has excellent characteristics.
Experimental design of millimeter‐wave nonradiative dielectric waveguide filters
Authors: Yoneyama Tsukasa , Nishida Shigeo , Kuroki Futoshi 
Published: July 2007

AbstractA nonradiative dielectric waveguide has no radiation from the bends or discontinuities, it has low loss, and is suited for millimeter‐wave integrated circuits. This paper studies the bandpass and band‐rejection filters built by using such waveguides at the 50‐GHz frequency band. In general, the filters are designed by the coupling coefficients of resonators and loaded Q‐factors, but theoretical evaluation of these values is not necessarily easy. Here, an experimental design tecnnique is discussed which can also be applied to the filter structure that is difficult to solve analytically. As an example, we designed and fabricated 3‐pole bandpass and bandstop filters having center frequency of 49.5 GHz built from circular post resonators of Teflon. Excellent characteristics were realized.The measured value of the insertion loss of the bandpass filter is 0.3 dB and the transmission loss of the bandstop filter is 30 dB. These are good practical values.
An analysis of meandering lines
Authors: Nakamura Takashi , Sekine Toshikazu , Yokokawa Senji 
Published: July 2007

AbstractMicrowave IC circuits are compact and light, and have planar structure with high reliability. Analyses have been made assuming that the basic transmission line has a uniform structure in its transmission direction. Due to the recent progress in print technology, meandering lines which make circuits compact are being used. In this paper, a new analysis of general meander lines is given. The theory is based on the generalized transmission‐line equations which are equivalently transformed from the integro‐differential equations for arbitrary wire conductors. Nonuniform distributed quantities can be expressed by integrals for the traveling‐wave mode current along the meander line. Using these quantities, the transmission characteristics are derived by two‐port network analysis. Transmission characteristics of periodic meandering lines are obtained from the iterative parameter expression and when their unit cell has a symmetric structure, they are equivalent to uniform lines. Next, examples are given for triangular and rectangular periodic meander lines and their dependency on frequency and line structure is studied. Finally, experiments are made on triangular meander lines and their results are in good agreement with experimental data.
Parallel‐running of two ladder‐type microwave multiple‐device oscillators
Authors: Fukui Kiyoshi , Nogi Shigeji , Wang Ming 
Published: July 2007

AbstractThe steady‐state operation and the stability of the parallel operation of two multiple‐device oscillators are studied when the coupling is small. The oscillators are of the form made of device mounts arranged along the propagation direction in the waveguide cavity or, in general, the form with the equivalent circuit expressed in terms of an active ladder network. The phase reference planes of both oscillators are chosen at their final stages. The section between these stages is considered as the coupling circuit. Formulas for the system response (locking frequency, phase difference between the element oscillators and amplitude response) are derived for the degree and phase of coupling and degree of mutual detuning. As the number of stages increases in a multiple‐device oscillator with more than two stages, the phase reference planes effectively move toward the interior of the cavity. However, if the effective coupling phase is used, the response can be represented by the theoretical equation identical to the case of parallel running of single‐device oscillators. In the case of the multiple‐device oscillator in which the device mounts are placed near the side walls of the cavity, the external Q decreases with an increasing number of stages and the increase of the locking range is derived from a theory. In the experiment, two multiple‐device oscillators of this type with up to eight stages (16 devices) are used and the theoretical results are confirmed. The output combining efficiency is more than 98 percent.
Constraints of the output‐power‐minimization adaptive array for a broadbanded desired signal
Authors: Takao Kazuaki , Ishizaki Toshio 
Published: July 2007

AbstractWhen a broadband desired signal is incident on an adaptive array under output‐power‐minimization with constraints, the sideband components of the desired signal away from the constraints are regarded as the unwanted signal and the frequency characteristics are degraded. The following three constraint methods for broadband desired signals are compared in terms of their output distortion and signal‐to‐interference‐plus‐noise ratio under various conditions. In the higher‐order derivative constraint method, good characteristics are exhibited even if little preliminary knowledge is available on the desired signal. However, too much of its degrees of freedom are spent. In the double‐frequency constraint and the conventional correlation constraint methods, the output distortion increases when the anticipated value of the bandwidth of the desired wave and that of the actually incident wave are different. On the other hand, in the improved correlation constraint method in which the amount of feedback is modified in software, good performance is observed regardless of the bandwidth of the incident wave, and hence is the most desirable choice.
64‐kb/s wideband speech coding algorithm based on bandsplitting and adaptive prediction
Authors: Suzuki Junji , Taka Masahiro 
Published: July 2007

AbstractThe wideband speech signal spectrum is mainly distributed within the low‐frequency band. Subband coding and adaptive predictive coding have been proposed as low‐bit rate speech coding algorithms to take advantage of this property. This paper theoretically clarifies the improvement in signal‐to‐quantization noise ratio when these two bit‐rate reduction techniques are used at the same time and quantitatively analyzes the speech signal spectrum distribution. It also proposes a wideband speech coding algorithm which encodes 7‐kHz‐band speech signals at 64 kb/s, the same encoding bit rate as that of the conventional companding PCM. Through computer simulation the subjective quality is evaluated and the effectiveness of the algorithm is shown.
Steady‐state analysis of nonlinear oscillatory circuits by iterative decomposition method
Authors: Yamamura Kiyotaka , Horiuchi Kazuo 
Published: July 2007

AbstractNewton's method is well known for finding the fixed point of the Poincaré mapping for steady‐state analysis of nonlinear oscillatory circuits. However, in practice, quadratic convergence of this method is not ensured due to the discretization error of the numrical integration and the errors of the approximate solutions for nonlinear equations which are solved at each time‐step of the numerical integration. This paper proposes a new method for the steady‐state analysis of nonlinear nonautonomous and autonomous systems which takes account of the numerical integration error stated above. In this method, the system of equations which includes a Poincaré mapping is discretized and reexpressed is a system of finite difference equations to which an iterative decomposition method is applied. Although this approach is essentially equivalent to the conventional Newton method based on the Poincaré mapping, it has the advantages that the Jacobian matrix can always be computed exactly for an arbitrary time‐steplength and that the local quadratic convergence of the algorithm is guaranteed. Considering these advantages, this paper also proposes a strategy to improve the computational efficiency of the algorithm in which initially, a large time step is used to find a rough solution which is then used as the starting value in the subsequent Newton iteration. Numerical examples are given to verify the relevant theorems and to show the effectiveness of the proposed algorithm.
Secret sharing system using (k, L, n) threshold scheme
Authors: Yamamoto Hirosuke 
Published: July 2007

AbstractIn the (k, n) threshold scheme, the information X is partitioned and coded into subinformation. If any k subinformation is obtained among n subinformation, the original information X can be recovered completely. However, no information can be obtained at all concerning X from any (k – 1) subinformation. Thus, the (k, n) threshold scheme is suited to the distributed storage or transmission of information. On the other hand, each subinformation requires the same number of bits as the original information X, which is very inefficient from the viewpoint of the coding efficiency. This paper extends the (k, n) threshold scheme and proposes the (k, L, n) threshold scheme. In the proposed scheme, the original information can be recovered completely from any k subinformation, but no information concerning X is obtained at all from any (k – L) subinformation. From any (k – t) subinformation (1 ≤ t ≤ L – 1), the information obtained for X contains the ambiguity of (t/L) H(X). In (k, L, n) scheme, the bit‐length of each subinformation is 1/L of the information X, which is a coding with very high efficiency. This paper presents a construction method for (k, L, n) threshold scheme, together with the discussion of its characteristics.
Broadband power inversion adaptive array
Authors: Inagaki Oki 
Published: July 2007

AbstractThe power inversion adaptive array proposed by Compton differs from other adaptive arrays in that it does not require any information on the desired signal. However, there is a sudden reduction in the ratio of signal to interference and noise (SINR) at the output terminal when the relative bandwidth of the interference signal exceeds 5%. In this paper the elements are arranged in a circular arc and a formula is proposed for microprocessor determination of the element weight from the covariance between the element inputs. It is shown that the decrease in SINR is kept below 3 dB even when the relative bandwidth of the interference is as large as 50%. In Method 1 of the circular arc arrangement an element is placed at the center of the circle and in Type 2 no element is placed at the center. Wideband elimination of the interference can be achieved with the arrival angle orthogonal to the line connecting two arbitrary elements. The element arrangements are studied with a low level of redundancy for this ideal angle of arrival. It is shown that a system without redundancy can be realized with a 4‐element array of Method 2.
A method for overload handling in synchronized multiplex system
Authors: Takase Juhro 
Published: July 2007

AbstractThis paper presents theoretical relations between transmission characteristic and increase of effective binary access channels in existing synchronized digital multiplex communication systems such as FDM and TDM to absorb traffic burst when connected to digital channels whose capacity is larger than their traffic capacity. At BER = 103 in noise‐free transmission and without off‐set of the demodulator, a 10 percent increase of digital channels is obtained by using a discrete amplitude level of 4 (2‐bit alternating binary encoding) and 14 percent increase by the amplitude level of 8 (3‐bit alternating binary encoding). At BER = 10‐4 with transmission S/N of 30 dB and demodulator off‐set of ‐23 dB, the increase of channels is 5 percent both by the amplitude levels of 4 and 8. The case of amplitude level of 4 is most preferable considering the relation between BER and the increase of access channels.
Outer conductor shields and electromagnetic fields around delay–type inductive communication cables
Authors: Okamoto Kunihiko 
Published: July 2007

AbstractTwo kinds of delay‐type inductive communication cables in actual use for mobile communication are shown theoretically and experimentally. They are characterized by two different types of outer electromagnetic fields, that is, convergence type and induction type, according to the shield construction of the outer conductors. The convergence type aims at limiting the communication region by using the wavelength reduction rate in a cable; the induction type aims at generating a relatively strong outer electromagnetic field. Despite the similarity of their appearances, these two kinds of cables are shown to have entirely different usages, characteristics, and mechanisms of generating electromagnetic field. This paper studies the shield effect of the delay‐type line outer conductor, especially the phenomenon of outer electromagnetic field generated by earth return circuit as a result of the imperfect shield effect of outer conductor for longitudinal electric field. This field interferes with the main wave in the case of the convergence‐type cable, and is a dominant main wave in case of the induction‐type cable. These two kinds of cables have already been developed and are now in use.
Properties of the second‐order digital bandpass functions obtained by bilinear transformation
Authors: Matsumoto Naoki 
Published: July 2007

AbstractThis paper describes the properties of the second‐order digital bandpass filter functions which are obtained from the secondorder analog bandpass functions by the bilinear z‐transformation. Taking note of the magnitude and the argument of the poles of the bilinear‐transformed transfer function, we can express the center frequency, the bandwidth and the variable range of the center frequency of the bandpass filter as simple functions of these parameters. In particular, when the poles are complex conjugate, it can be shown that the bandwidth does not change with the argument of the poles if the magnitude of the poles is constant. It seems that in the past the quality factor Q of digital filters has not been investigated fully. In this paper we introduce two definitions of Q from the time and frequency domains, and show that they are numerically equivalent if the ratio of the product of the center frequency and sampling rate to Q is less than a certain value. Finally, we discuss the relation between the pole argument and the filter dynamic range when the second‐order digital bandpass function is realized in direct form.
A traffic forecasting method taking account of outliers
Authors: Saito Hiroshi , Abe Takeo 
Published: July 2007

AbstractTraffic forecasting is used for circuit dimensioning and income prediction. Traffic forecasting in Japan has been carried out mainly by multiple regression models. However, recently, a traffic forecasting method using the Kalman filter for a state space model was proposed by David and Pack. When such a forecasting method is used, it is necessary to cope with outliers caused by various factors, such as social and/or economic factors, and observation errors. In this paper, because outliers correspond to the outliers of noises in the state space model, an algorithm for detecting and discriminating outliers by considering the noise distributions is developed. A new traffic forecasting method with a state space model including this algorithm is proposed. This method detects and discriminates changes in traffic patterns, and applies the necessary dispositions. The validity of this method is confirmed by applying it to field data.