bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission loss planning for digital networks
Authors: Sawakuri Tatsuya , Yamamoto Yutaka , Satoh Naoshi
Published: July 2007

This paper describes the transmission loss plan for a digital network on the basis of transmission quality evaluation data for telephone, modern and facsimile services. First, reference equivalent distribution of a subscriber loop and terminal return loss distribution at 2‐wire/4‐wire conversion circuit of digital local exchange subscriber circuit, which are network parameters for transmission loss planning, are estimated based on investigations of the actual conditions. Next, with respect to the telephone, the relation between transmission loss and opinion is clarified both for a short length of connection where degradation due to echo is negligible and for medium and long length of connections where the echo performance is taken into account. With respect to modem and facsimile, the relation between openloop loss and quality degradation is evaluated experimentally. As a result of total evaluation of network parameters and evaluation data with respect to telephone, modem and facsimile, it is revealed that the transmission loss in EO‐EO all‐digital network should be set at 4 dB for intra‐office connecnection. Here, degradation due to echo is negligible and 8 dB for medium and long length of connections where echo performance is taken into account to maintain good telephone and modem‐facsimile transmission quality. Finally, the transmission loss plan from existing analog network to EO‐EO all digital network is shown.
Access time analysis of dynamic MOS RAM
Authors: Nagayama Yasuji , Works Kitaitami , Mashiko Koichiro , Yoshihara Tsutomu , Nakano Takao
Published: July 2007

Among the high‐performance factors of dynamic MOS RAM's, high speed is the most important and its research and development has been carried out actively. However, a model for access time analysis which serves as a guide for the realization of high‐speed access time has not been proposed extensively nor is its quantitative analysis sufficient. It is shown in this paper from the factor analysis of 64K dynamic MOS RAM access time that approximately 50% of the access time is spent on the sense time to read a small signal. Further, an analytical relation for the delay time of basic clock circuits is derived. Also, a model for the access time analysis is proposed which represents the access time as a sum of word line delay, bit line delay, sense time, and signal delay in the peripheral circuits. It is shown that the calculated value and the measured value of the access time of the fabricated 64K dynamic RAM agree to within 15% error. This confirms the effectiveness of the model. Further, from the access time sensitivity analysis using the access time analysis model, the simplicity of the peripheral circuits, the increase of the conductance value, and the reduction of the threshold voltage are shown to be effective for high speed.
A packet transfer control method using circuit switching function
Authors: Hiramatsu Yukio , Mase Kenichi , Kajiwara Masaichi
Published: July 2007

As the scale of the packet switching network and the number of pac̀ket transit nodes increases, the packet switching load and packet delay in the network increase in general. Technologies to suppress these tendencies and to construct the packet network economically are becoming more and more important. This paper assumes transit switches (TS) with both circuit and packet switching functions in a packet switched network. Then a packet transfer method is proposed in which the transit switches set up the direct channel between a pair of source and destination nodes if the traffic between the node pair increases beyond a threshold. First, newly introduced controls for setting up and releasing the direct channels and their desired realization methods are clarified. Next, direct channel set‐up/release characteristics and packet delay characteristics are clarified through numerical calculations of the source switch model and simulation. From these results it is shown that this control method reduces the transit switching load and shortens the packet delay in the transit network. Furthermore, an approximate formula is derived to determine the threshold value of traffic between source and destination switches.
Bifurcations and chaos in sampled data systems with dead zone
Authors: Ushio Toshimitsu , Hirai Kazumasa , Hirayama Hiroshi
Published: July 2007

Depending on the parameter values various kinds of bifurcations can be produced in a nonlinear system. Although there have been many studies made on the bifurcations of fixed points, many problems remain unsolved for bifurcations of invariant closed curves. On the other hand, it has recently been noted that deterministic systems sometimes exhibit chaotic solutions. This phenomenon is called chaos, which is becoming one of the important problems in engineering. However, little attenuation has been devoted to bifurcation and chaos in sampled data systems. This paper discusses the relation between the bifurcation, chaos and sampling period in a sampled data system with dead zone. As the first step, the fold bifurcation set and the range of existence for chaos are determined for a one‐dimensional sampled data system. Then the fold bifurcation set and the Hopf bifurcation set are determined for a two‐dimensional sampled data system. It is verified by numerical experiment that transition of the invariant closed curve to chaos by Hopf bifurcation is closely related to the stable and unstable manifolds of saddle‐type fixed point.
Characterization of Si MIS solar cell
Authors: Okuno Tetsuhiro , Osaka Yukio , Hirose Masataka
Published: July 2007

The MIS solar cell has an advantage in that its open‐circuit voltage is high. However, its operation has not been understood fully as yet. We have investigated the effects of an Si02 thin layer and of an Si/Si02 interface on the quality of the MIS solar cell. We found that suppression of majority carrier currents by the Si02 layer caused a high open‐circuit voltage. Furthermore, a means is discussed to determine whether the conduction mechanism which determines the open‐circuit voltage is due to tunneling currents of majority carriers or to diffusion currents due to minority carriers.
Delayed random access schemes ‐an improvement method of delay distributions for packet broadcasting systems ‐
Authors: Mukumoto Kaiji , Fukuda Akira
Published: July 2007

In many cases, the characteristics of random access schemes have been evaluated using average quantities such as average transmission delay, throughput, etc. Random access systems usually have packet delay distributions with long exponential (geometrical) tails. This may be a serious drawback when the suitable criterion is not the average delay but some high percentile (90%) value of delay. We propose delayed random access schemes which improve delay characteristics. In this modified system, a terminal which has just generated a packet does not enter the random access state immediately but enters the state after a delayed time determined by some procedure. Hence, queueing discipline tends to be like FIFO and distribution for transmission delay is improved. For three typical delayed time determination procedures, the extensive effect of this modification is demonstrated using the O‐ALOHA. the three procedures are shown to be effective for improving transmission delay distributions. Some practical studies showing a practical implementation example of a delayed random access scheme are included.
Analysis of broadside‐coupled strip lines with anisotropic substrate
Authors: Kitazawa Toshihide , Hayashi Yoshio , Fujita Kenji , Mukaihara Hiroshi
Published: July 2007

Two analytical approaches are presented for broadside‐coupled strip lines with anisotropic substrates. One is based on the quasi‐static approximation which uses the Fourier transformation and the Ritz procedure. the other is based on the rigorous hybrid‐mode formulation, and the frequency dependent solutions are obtained by using the network analytical methods of electromagnetic fields and Galerkin's procedure. Some numerical results are presented for sapphire and Epsilam‐10 substrates. the effect of the inclination of the optical axis is not so large, and the effect of the shift of central axes of strip lines S/W in the odd modes is larger than that in the even modes. the rigorous frequency dependent solutions converge to quasi‐static values at lower frequencies, and the dispersion of the even modes, which cannot be neglected at higher frequencies.
Numerical technique of perturbation method for computing periodic solution of piecewise‐linear autonomous system
Authors: Okumura Kohshi , Kishima Akira
Published: July 2007

This paper discusses the numerical method of computation in the perturbation for periodic solution of piecewise‐linear autonomous system, which we can calculate up to higher‐order approximations. In many cases of autonomous equations for electrical and electronic circuits, linear and nonlinear terms can be separated leading to the equation of the form × = Ax + f(x) where = d/dt, is a small parameter. This paper considers the case where the coefficient matrix A is of the simple structure and f(x) can be represented by a practically effective piecewise‐linear function. the differential equation is transformed by the mode matrix of A, and using the discrete Fourier transform, an algorithm is constructed which determines the periodic solution up to higher‐order approximations. As the first step, a discussion is made on the relation between Jacobian matrix for Newton's method to solve the determining equation for the amplitude and phase of the zeroth‐order approximation and Jacobian matrix for the piecewise‐linear function. Then it is shown that the first‐ and the higher‐order approximation can be determined by solving the linear equation with Jacobian matrix of Newton's method in determining the zeroth‐order approximation as the coefficient matrix. It is shown also that to improve the computation time for determining the solution, a faster search of the simplex for the periodic solution is necessary, resulting in a proposal for the search method. In the proposed solution method, Newton's method does not converge when the value of the periodic solution at a time point matches a corner of the simplex. A remedy for such a situation is shown.
Synthesis of minimum quantization error digital filters using floating‐point arithmetic
Authors: Akamine Masami , Higuchi Tatsuo
Published: July 2007

Quantization error arising from roundoff and coefficient quantization presents a serious problem in realizing a digital filter with finite‐word length arithmetic. This paper proposes floating‐point realizations of digital filters that minimize quantization error. A filter synthesis problem is formulated with the relationship between round‐off error and coefficient quantization error that has recently been investigated by the authors. the formulation reveals that a combination of the minimum‐ coefficient‐sensitivity structure and the optimum order of additions leads to a realization of a digital filter with the minimum quantization noise. the proposed synthesis consists of transformations in a state space. the optimum ordering of additions is found with the assumption of the use of the successive addition that is amiable to hardware implementation. Finally, the effectiveness of the proposed method is illustrated by an example.
An interferometer direct‐coupled Josephson logic gate
Authors: Hohkawa Kohji , Ishida Akira
Published: July 2007

New interferometer direct‐coupled Josephson logic gates are proposed which have good input‐output signal separation and stable, high‐gain, wide‐margin operation. Formulas for evaluating the threshold characteristics and conditions for high gain and high sensitivity are derived. Dynamic properties such as switching times and waveforms are obtained by computer simulation. These gates were tested‐fabricated with a lead alloy whose properties agreed with the results of computer simulation: sensitivity was 2.5 over a bias range of more than 50%. Thus, they can be used as basic logic elements in buffers and OR gates.
Stability of switched capacitor filter possessing periodic parameter
Authors: Sato Chikara , Fujisaka Hisato
Published: July 2007

Generally, the switched capacitor filter (SCF) is composed of capacitors and switches which operate with constant period T and sometimes contain operational amplifiers. This paper considers an SCF having an extra switch which operates by the period 2MT (M; integer). the stability of the circuit is investigated when two SCF characteristics are switched alternately in the time domain by the newly added switch. Zeroinput response of the second‐order SCF with an additional switch is expressed by the linear difference equation with periodic coefficient. the stability of the solution of this difference equation is investigated. As a result it is shown that even if each characteristic of the SCF is stable individually, the system may become unstable when the two characteristics are switched in the time domain by the newly added switch. the stability conditions and the boundary curves from stability to instability are obtained. Further, corresponding instability phenomena are confirmed by experiment.
An expression of equivalent circuit in active RC filters
Authors: Okine Mitsuo
Published: July 2007

Many second‐order active filters with operational amplifiers have been proposed. Modeling the operational amplifier with nullators and norators, or else with an equivalent circuit with controlled sources, the transfer function is determined and matched with the desired filter function.

In this paper, a new equivalent circuit is given for these filters. This is done by selecting three terminals in the circuit—the input and output terminals, together with another arbitrary terminal within the circuit—yielding a structure formed by a fundamental inverse‐L circuit and a controlled source. the voltage transfer function is then given as the product of the inverse‐L voltage ratio and the amplifier gain.

Using this equivalent circuit, any filter may be represented by an inverse‐L structure with any of the following two sets of elements: (1) inductance or FDNR, or (2) negative RC elements. Since the operation of the inverse‐L filter can be analyzed easily merely by comparison with the operation of LC filters, the properties and operation of the active RC filters can be explained.
Design and characteristics of optical power meter high‐density fiber unit
Authors: Maekawa Eiji , Yoshida Koji , Nihei Fumihiro
Published: July 2007

Properties of a power meter for a fivefiber cable unit are investigated. Light sources which are amplitude modulated are connected to the fibers and separated after being detected by a single photodetector; this system requires a photosensor, a current‐voltage converter, and bandpass filters for separating amplitude‐modulated signals. A test fabricated system has been used to confirm that the photodetecting system meets the design requirements and that errors caused by the bandpass filters are less than 0.01 dB; the temperature characteristics and reproducibility of the measurement are equivalent to the conventional power meter for a single fiber.
A hierarchical neural network model for associative memory
Authors: Fukushima Kunihiko
Published: July 2007

The author has previously proposed (neo) cognitron, which is a multi‐layered neural network model with hierarchical structure, and has shown that the model can acquire a higher‐order pattern recognition ability by self‐organization. This paper reports on a new neural network model which has a junction of associative memory as well as an ability of pattern recognition. the new model is realized by adding positive feedback efferent connections to the cognitron‐type multi‐layered neural network model. Even if a fragment of a training pattern is given to the network after completing its self‐organization, the positive feedback signal acts to produce the correct entire pattern gradually with the course of time in the first cell layer. When more than one training patterns are presented together, a competition arises among the patterns, but one of them survives with the course of time, with the others vanishing. At the same time, one cell, corresponding to the pattern ultimately recalled in the initial layer, responds in the deepest layer, indicating the result of recognition. When the positive feedback is interrupted for a moment at this stage, the response for the suppressed pattern appears. By repeating such a procedure, patterns simultaneously presented can be separately and successively recalled.
Error performance improvement of QDPSK in the presence of cochannel or multipath interference using diversity
Authors: Horikoshi Jun
Published: July 2007

The quadriphase PSK system is thought to show the highest spectrum efficiency among M‐ary PSK systems for mobile communication purposes and is a noted digital radio system. the diversity effect of the QDPSK system using differential detection has been analyzed approximately. However, since no exact analysis has been done, approximation accuracy has not been clarified. This paper first compares the exact analytical value under cochannel interference and the approximate formula. As a result, it is shown by the method of least squares that the error rate is approximated very closely in precision with a simple formula. Analysis of multipath interference, which simulates frequency selective fading, is carried and the performance difference from that under cochannel interference is discussed. the diversity effect for multipath interference is lessened slightly compared with cochannel interference. It is also indicated that when the average power of a first‐coming wave is nearly equal to that of a delaying wave (often the case in multipath interference) and the error rate is degraded, the diversity effect cannot be expected practically. Finally, the need for a technique to alleviate degradation caused by this difficult‐to‐control propagation characteristic is mentioned.
Coupling of electromagnetic waves to transmission lines
Authors: Kami Yoshio , Sato Risaburo
Published: July 2007

The problem of coupling between the transmission line and the external electromagnetic waves is analyzed more easily and more effectively if it is treated via transmission line theory rather than scattering theory if the cross section of the transmission line is much smaller than the wavelength and the principal mode of the induced current is TEM. This paper derives the transmission line equations by which the induced current is excited by the electric field components in the transmission direction and between the lines among the electromagnetic field components. the relation with the conventional theory, physical meanings and the equivalent circuits are discussed. In the experiment in which a plane wave is used as the external electromagnetic field, the results agree well with the present theory and the validity of the theory is confirmed if the transmission line cross section is extremely small. Further, a compensation method is discussed for the transmission line height for which the principal mode is considered TEM. the theoretical accuracy is shown and the fact that the line width restricts the range of applicability of this theory is confirmed experimentally.
Synthesis of voltage transfer function matrix with active RC network
Authors: Hisanaga Kiminori , Takahashi Shin‐Ichi
Published: July 2007

This paper proposes a method of constructing an RC active network to realize a voltage transfer function matrix without using an integrator. the method is based on the fact that an m‐input system of multivariable controllable canonical form can be decomposed into m subsystems of controllable canonical form using state feedback and input transformation. the required m‐input p‐output voltage transfer function matrix is constructed using m passive RC networks and (m + p) summers. the network has the following structure. the capacitor edge voltage of the passive RC network is taken out as the state variable, and the state differential equation is realized by the feedback through the input‐side summers. the output equation is realized by the feedforward through the output‐side summers. the feature of the proposed method is that it is applicable to any proper rational transfer function matrix of any size, not only of the square form. Another feature is that the transfer function matrix can be realized with a fewer number of active elements.
An approximation for the auto‐covariance function of the virtual waiting time in an M/G/1 and its applications
Authors: Matsuda Jun
Published: July 2007

This paper proposes R(t), an approximation for the auto‐covariance function of virtual waiting time in an M/G/1. Calculation by R(t) is much easier and faster than the exact formula R(t). By the use of this approximation, not only the computation for arbitrary model becomes possible, but also the computation time can be reduced below 10‐3 time even for the model which can be calculated by the exact formula, such as M/M/1. Comparisons between R(t) and R(t) for several models show that R(t) approximates R(t) closely enough for practical use. We have applied R(t) to the accuracy estimation of waiting time measurement by test calls (test call method) and obtained several important results for waiting time measurement. They are: i) the accuracy is improved as the interval of test calls is set shorter, but is hardly improved even if the interval is set shorter than ten times the mean waiting time (saturation characteristic); ii) better measurement accuracy is obtained by the test call method if the interval of test calls is properly set than by the real call method; and iii) the coefficient of variation of service time distribution greatly affects the measurement accuracy.
X‐ray CCD image sensor with a thick depletion region
Authors: Saito Hirobumi , Watabe Hiroshi
Published: July 2007

In order to obtain an image sensor for X‐rays with long absorption length and energies greater than 1 ± 2 keV, a CCD with a thick depletion region has been investigated. A thick depletion region can be obtained by using a semiconductor substrate having high purity (high resistivity) and by applying a high gate voltage. However, it is not easy to apply a high voltage since the gate voltage in a CCD is a high‐speed clock pulse for charge transfer. This paper proposes a mode (dc bias‐voltage mode) in which a DC bias voltage is superimposed, keeping the charge‐transfer clock pulse voltage low. the conditions of SCCD and BCCD device parameters are investigated in order to determine useful ranges of these parameters for normal operation and for preventing dielectric breakdown. It is shown that when a substrate with usual purity (doping density 1020 m3) has an applied dc bias voltage of about 300 V, a depletion region with thickness of about 60m can be obtained. the effectiveness of the dc bias voltage mode is confirmed. When CCD characteristics other than depletion region thickness and simplicity of device structure are considered, a BCCD with the frame transfer system is suitable for X‐ray image sensors.
A new fourier descriptor applicable to open curves
Authors: Uesaka Yoshinori
Published: July 2007

Fourier descriptors are known to be used for describing planner curves in frequency domain. the traditional Fourier descriptors proposed by Zahn and Roskies, and Granlund have the following disadvantages: 1° it is difficult to apply them to open curves; and 2° the end‐points of a reproduced curve from the low‐frequency part of the descriptors do not necessarily coincide with the end‐points of an original curve. the present paper proposes a new Fourier descriptor that does not have these disadvantages and is obtained by expanding in Fourier series the complex‐valued exponential function of the total curvature function of a curve. the proposed descriptor is applicable not only to closed curves but also to open curves, and the end‐points of its reproduced curve always coincide with those of the original curve. the descriptor is invariant under the translation and dilation of a curve. the descriptor of a rotated or reflected curve has simple relations to that of the original curve. Furthermore, the reproduced curve from the low‐frequency part is a good approximation to the original curve in visual sense, and so the information of pattern classes concentrates in its low‐frequency part. In this sense, the proposed descriptor may be used to good advantage in pattern recognition. the abovementioned was verified theoretically and/or experimentally.
Performances of switched diversity for mobile radio systems in rayleigh fading environment
Authors: Imamura Kenji , Hattori Takeshi
Published: July 2007

In the signal transmission of land mobile communication, the received electric field is affected by multipath fading due to multipath propagation, and the transmission quality is degraded. A diversity reception of some type can be an effective technique against this fading. This paper analyzes theoretically the improvement possible using two‐branch switched diversity against the cochannel interference and thermal noise when voice signals are processed by compander and are transmitted by PM. When the baseband SNR (signal‐to‐noise ratio) under fading is 15 dB, the improvement effects against thermal noise and cochannel interference are 9 dB and 4.5 dB, respectively. When the SNR is 10 dB, they are 7 dB and 3 dB. Furthermore, we show that the optimum switching level maximizing the baseband SNR exists and depends on CNR (average carrier‐to‐noise ratio), CIR (average carrier‐to‐interference ratio), and the modulation level.
Reflection characteristics of twisted component in rectangular waveguides
Authors: Yabe Hatsuo , Nishio Kazunori , Mushiake Yasuto
Published: July 2007

To develop a design theory for rectangular twisted waveguide components, the reflection characteristics at the junction to a straight waveguide are studied theoretically. First, a perturbation method and a modal analysis are applied to the hybrid mode field inside the twisted waveguide. In addition to the terms of the second perturbation for the twist constant, we derived analytical expressions for the reflection coefficient and the normalized admittance at the junction. It was found that the reflected wave caused by the higher‐order mode components generated at the junction is equivalent to that caused by the capacitive susceptance inserted in parallel in the transmission line. Also, the difference in the phase constant between the straight and twisted waveguides is due to discontinuity in the characteristic impedance. Next, a theoretical formula containing the effect of multiple reflection has been derived for the overall VSWR of the twisted component inserted in a straight waveguide. the validity of this formula has been confirmed by experiments in the 10‐ GHz band with specially manufactured twisted waveguides. Further, a design chart for a practical 90‐degree twist has been presented and a design method has been given for a broadband transmission characteristic with restricted maximum VSWR values.
Modelling of hot‐carrier effects in small‐geometry MOSFETs
Authors: Wada Masashi , Iizuka Hisakazu , Shibata Tadashi , Dang Ryo
Published: July 2007

The generation of hot carriers in MOS transistors greatly obstructs their microminiaturization, since this effect becomes more serious in a smaller geometry which creates higher internal electric fields. A two‐dimensional simulator of MOSFET has been developed by the authors which includes the generation of hot carriers. the model used takes account of the motion of electrons injected in the gate oxide film. By using this simulator, the device characteristics with an applied voltage stress can be predicted. the simulator has made possible the accurate calculation of the dependency of the gate current on the gate voltage, which could not be solved by conventional simple models. By using this simulator, it is also possible to obtain directly the change of the device characteristics due to the capturing of electrons in the oxide film which is the cause of the channel current, since their distribution now can be obtained. the calculated values of the prediction of the channel current are in good agreement with values obtained experimentally. This simulator is considered to be a useful tool for solving hot‐carrier problems in small‐geometry MOSFETs.
Spread spectrum synchronizing loop for spreading code modulated by code shift keying
Authors: Yoshida Tadayoshi , Nakagawa Masao
Published: July 2007

Sequence Inversion Keying (SIK) which inverts the signs of the spreading codes, has been used mainly for conventional Spread Spectrum (SS) modulation. Since SIK modulation is essentially not suited to multilevel transmission which enables us to decrease inter‐channel interference, the inter‐channel interference begins increasing significantly if we try to improve the interference characteristic or the multiplexing capability. to improve the performance of the SS, code shift keying (CSK), which is a kind of multilevel modulation, of the spreading code has been proposed recently. However, there have been no reports of a synchronous technique for CSK at the receiver. This paper proposes two types of new synchronizing loops for CSK of SS and their performances are evaluated through experiments. the loops for a 2‐phase and 4‐phase CSKs are treated in the experiments. Both show good synchronizing characteristics and the synchronizing loops which show little performance deterioration despite the increase in the number of phases, are obtained. the proposed schemes compare favorably with the conventional SIK synchronizing loops and give practically sufficient results.
Improving the accuracy and error analysis in floating‐point FFT computation
Authors: Honma Hitoshi , Sagawa Masahiko
Published: July 2007

The cause of the error in the FFT is due mostly to the quantization error of the input data, the round‐off error in arithmetic operation, and the computation error of Wnk= exp (‐j 2nk /N). of these, the error of Wnk is complex, and this error is approximated in the reported error analysis by the truncation error by finite bits. This paper examines the actual computation error of Wnk and its effect. As a result, it is shown that the computation error of Wnk is much larger than the truncation error by the finite bits, and can produce instability in the algorithm. Then to solve the problem, this paper proposes a method to improve the computation accuracy of Wnk. the proposed method can be executed without increasing greatly the processing time and the memory, compared with the direct FFT computation. By using the proposed processing, the error analysis is made more reliable than in the past and the error accompanying the FFT is reduced. Finally, the effectiveness of the proposed method is verified by several examples.
Measurement of contact resistance of electric contacts using SQUID galvanometer
Authors: Minowa Isao , Kanno Makoto
Published: July 2007

SQUID (Superconducting Quantum Interference Device) is a very powerful tool in the measurement of very small current, voltage, and resistance because it can be used as a high‐sensitivity galvanometer with zero internal resistance. Since the contact resistance of electric contacts of good quality switches or connectors is low in the milliohm range, it cannot be measured without flowing a current in the range of more than milliamperes in the conventional measuring method. Accordingly, so far, no measured data exist in the very small current region below these values and it is not known whether or not the contact resistance will change in the very small current region in the switches or connectors used in the circuits used for very small signals. In this research, the very small current region of nanoamperes and very small voltage region of picovolts can be measured by using a SQUID galvanometer. In the typical examples of measured results obtained so far the contact resistance of new connectors showed a constant resistance independent of the magnitude and direction of the current in almost all cases.
Generation of musical tones in PARCOR speech synthesizer
Authors: Hibino Masahiro
Published: July 2007

This paper discusses a method in which the impulse response of the digital filter in PARCOR speech synthesizer is used as a musical tone. the following items are discussed. (1) Creation of musical tone‐scale by pole frequency of digital filter. (2) the effect of operational accuracy on the quality of a musical tone, which is an important factor in determining the size of the circuit. (3) Improvement of the quality of the musical tone. For the present circuit size where the word length of k‐parameters is 10 bits and the operational bit length is 14, the sinusoidal wave above C4 has the sufficiently accurate pitch frequency, and there is no problem in creating the musical tone scale. However, it was seen that the impulse response is attenuated in a short period, and a musical tone with practicable envelope characteristics cannot be obtained. As a method to solve this difficulty, a method is proposed whereby the lower bits are rounded‐up in the multiplier output of the filter circuit. the effectiveness of the proposed method has been verified. By this scheme, a PARCOR speech synthesis LSI has been realized which can generate sinusoidal waves of various kinds of envelopes as well as musical tones.
Noise suppression signal processing using 2‐point received signals
Authors: Kaneda Yutaka , Tohyama Mikio
Published: July 2007

A number of research reports has been presented on the noise suppression signal processings as one of the important technical problems. Although a reduction feeling of the noise level can be obtained by the conventional method using the one‐point received signal, it has been pointed out that the program of improving the articulation is not sufficient. to solve this problem, we propose a noise suppression signal processing method using two‐point received signals. As the first step, the noise suppression method is discussed assuming that the desired signal is uncorrelated to the noise. It is shown that the noise suppression filter, which is the optimum in the sense of least‐mean‐square error, is obtained from the correlation coefficients between the frequency components of the two‐point received signals. Then a method is shown in which the two‐point receiving noise suppression system can be constructed using FET based on the proposed principle. Finally, to verify the effectiveness of the proposed processing, the method is applied to the two‐point received speech under room noise. the articulation tests were performed for the processed and unprocessed speeches. As a result, it was seen that the syllable articulation score could be improved by 4 to 10 percent when the correlation coefficient between the two‐point received signals of the noise is 0.1 or less and that of the speech is 0.9 or more.
High‐rate preparation of Co‐Cr films on continuous tape substrates via a targets‐facing type sputtering method (TFTS‐method)
Authors: Matsuoka Morito , Hoshi Yoichi , Naoe Masahiko , Yamanaka Shun'Ichi
Published: July 2007

A target‐facing type sputtering apparatus which can deposit three‐layer films on a long film base continuously, is constructed. Using this apparatus, a Co‐Cr perpendicular magnetic recording medium is formed continuously to obtain the following results.

A Co‐Cr film with deposition rate of more than 0.4 μm/min is obtained with fine structure and good C‐axis orientation.

When the tape substrate is advanced and the Co‐Cr film is deposited continuously, deterioration of the film C‐axis orientation results from oblique incidence of the sputtered particles at the time of initial deposition.

the properties (such as C‐axis orientation and the magnetic characteristics) of initially deposited film dominates the characteristics of film as a whole.

the (111) oriented permalloy film is used as base soft magnetic layer, and the Co‐Cr film is deposited on this film. Orientation of Co‐Cr film is decided by (111) orientation of the permalloy film.

the temperature of the substrate surface during deposition changes greatly according to the substrate thickness and the applied tensile force on the substrate, thereby changing the film magnetic characteristics. the Co‐Cr perpendicular magnetic recording medium with desired magnetic characteristics and good C‐axis orientation can be formed continuously at high speed by controlling the substrate temperature and by suppressing the oblique incidence of the sputtered particles.
Cyclic sequences generated by neuron model
Authors: Wada Mitsuo
Published: July 2007

A neuron can be considered as a threshold element with refractory period. In order to arrive at a generalized treatment of several neuron models proposed in the past, this paper considers a certain type of threshold element network model which has, in addition to exponential decay of refractoriness with time, the effect of past excitations included in the exponent. The periodic behavior of such a network is analyzed and the existence condition for arbitrarily assumed periodic sequence and its generation rule are derived. The procedure is closely related to the continued fraction expansion of a rational number and the sequence is uniquely determined from the network dynamics. The entire set of periodic sequences produced by a network can be derived by the proposed procedure. Lastly, the relation between the proposed network model and the analog neuron model is discussed.
Crosstalk attenuation characteristics between shielded balanced pairs
Authors: Tomita Nobuo , Ohmura Makoto , Koga Hiroaki , Kojima Nobuya
Published: July 2007

Future telecommunication networks will be digitalized and widebanded. The crosstalk between telecommunication lines will be a problem when bilateral signals are transmitted concurrently through a balanced pair cable. A study to suppress this crosstalk is being conducted on a balanced multipair cable with internal shielding for proper units, hereinafter referred to as a shielded balanced pair cable. Theoretical equations are needed to represent the crosstalk attenuation characteristics between shielded balanced pairs for the purpose of designing shield structures for such cable. Hitherto, no equation has been derived pertaining to the amount of crosstalk attenuation between shielded pairs applicable to the design of shield structures.

In this paper, shielded balanced pair cables are divided largely into unit‐shielded types and screen‐shielded types. Theoretical equations are derived pertaining to the amount of crosstalk between shielded balanced pairs with consideration of both direct and indirect crosstalk paths. The correspondence to measurements permits design of shield structures by confirming the adequacy of the theoretical equations.

In addition, it is established that both direct and indirect crosstalk have dominant frequency ranges considering these frequency characteristics. The electrostatic unbalanced capacitance is also presented for wire shielding within a required amount of crosstalk attenuation.
ϵ‐separating nonlinear digital filter and its applications
Authors: Harashima Hiroshi , Odajima Kaoru , Shishikui Yoshiaki , Miyakawa Hiroshi
Published: July 2007

This paper proposes an ϵ‐separating nonlinear digital filter (called an ϵ‐filter). This filter is intended for effective filtering of low‐amplitude noise superposed on the signal with sharp discontinuities and can be realized by combining a simple nonlinear element with a conventional linear filter. In this paper, the basic ϵ‐filter and its modifications to a trend‐adaptive filter and a two‐dimensional filter are described. The effectiveness of the new filter is demonstrated by computer simulation. Some of its application to EEG analysis, image processing and coding are also presented.
Complementary Schottky transistor logic
Authors: Kaneko Kenji , Okada Yutaka , Okabe Takahiro , Ogura Setsuo , Kudoh Satoshi
Published: July 2007

A high‐speed logic circuit, which is compatible on a single chip with I2L (integrated injection logic) and high‐voltage analog circuits is proposed. It is well known that the I2L features low power consumption and high packing density, but that its speed is lower than that of other bipolar circuits. On the other hand, high‐speed bipolar logic circuits consume a lot of power and occupy large area on a silicon chip. This paper proposes a new logic circuit which fills the gap in speed and density between the high‐speed bipolar and I2L circuits and reports the results of experiment. The new logic circuit uses a pnp transistor as a load device and a Schottky‐clamped npn transistor as a driver. An experimental circuit fabricated using an analog‐compatible technology showed a minimum delay time of 1.5 ns and a power‐delay product of 0.5 pJ. A counter circuit was operated at a frequency of 52 MHz.
Characteristics of pitch period and amplitude perturbations in speech of patients with laryngeal cancer
Authors: Kasuya Hideki , Ebihara Satoshi , Chiba Takashi , Konno Tadao
Published: July 2007

As the first step to detect laryngeal cancer by acoustic means (especially cancer of the vocal chords), this paper analyzes the pitch period perturbation quotient (PPQ), pitch amplitude perturbation quotient (APQ) and pitch correlation amplitude (PA) measure, from the outer‐tracheal waves. The results are compared with the result of TNM classification, which is widely used as a clinical classification. The 49 samples were examinees, in which normals were 16 and patients with laryngeal cancer were 15. Among the 15 patients with laryngeal cancer, 14 had cancer of the vocal chords. As the result of analysis, the following conclusions were made. (1) Both PPQ and APQ exhibit correlations with TNM classification, but APQ will be more effective in the detection of cancer of the vocal chords. (2) PA is not very effective in detection at an early stage (T1). (3) Pathologically developed vocal chord cancer (T2) can completely be detected. (4) If allowance is made for 37.5% (6/16) of false positive for the normal, 92.9% (13/14) of the vocal chord cancer can correctly be detected.
Evaluation of SnO2/SiOx/n‐Si solar cells
Authors: Nagatomo Takao , Amano Yuji , Omoto Osamu
Published: July 2007

The insulator interface plays a key role in solar cells with MIS and SIS structures. However, the mechanism of its effect has not been well studied. A simple method of making SnO2/SiOx/n‐Si solar cells by using the spraying method is reported herein. Diode properties of the cells are studied for different values of saturation current density and diffusion potential. Optoelectronic properties of the cells are also investigated as functions of photocurrent density, open‐circuit voltage and fill factor. It is found that SnO2/SiOx/n‐Si solar cells prepared by the spraying method are not diodes of minority‐carrier type and that an increment in open‐circuit voltage has considerable effect on the diode parameters. The diode parameters, device characteristics and open‐circuit voltage vary considerably with the thickness and surface state density of the insulator interface.
Study on IDT for acoustic imaging uses
Authors: Kikuchi Tsuneo , Moriizumi Toyosaka , Yasuda Tsutomu , Members Regular , Nomura Toru , Toda Kohji
Published: July 2007

A piezoelectric interdigital transducer (IDT) normally used for SAW devices can emit high frequency ultrasonic waves into water. To make use of this phenomenon in an acoustic imaging system, characteristics of longitudinal waves radiated from the IDT into water and the radiation mechanisms using the ASPW method were investigated. It was found that two types of longitudinal waves are radiated from the IDT and one of them can be beam‐scanned by changing the frequency. Finally, a focussed ultrasonic wave was obtained from an arched IDT in water and the surfaces of several objects were observed with good resolution.
Spatial‐domain design of separable‐denominator two‐dimensional digital filters
Authors: Hinamoto Takao , Makita Yoshihiro , Maekawa Sadao
Published: July 2007

This paper describes a method for determining the coefficients of a transfer function. In this description when the ideal two‐dimensional Markov parameters and the orders of the separable‐denominator two‐dimensional transfer function are given, the two‐dimensional Markov parameters generated from this transfer function will give the best approximation to the ideal two‐dimensional Markov parameters over a designated finite interval. To minimize the performance measures in this paper, the optimization technique proposed by Evans and Fischl for the time‐domain design of one‐dimensional digital filters is extended to this two‐dimensional case. Their technique has the merit of easy judgement of stability because the two‐dimensional digital filters are designed using a separable‐denominator two‐dimensional transfer function.
Theoretical treatment of arbitrarily shaped cut‐ends of dielectric optical waveguide
Authors: Nishimura Eiichi , Morita Nagayoshi , Kumagai Nobuaki
Published: July 2007

A theoretical analysis is presented for the problem of reflection, transmission and radiation at an arbitrarily shaped discontinuity in a dielectric slab waveguide. An integral equation is derived for the electromagnetic field at the discontinuity and is solved by successive approximation. Of the Green's functions for this procedure, the one on the waveguide side is not the complicated form taking into account the exact boundary condition on the waveguide but an approximate form derived from geometrical optics approximations and mirror images. It is shown that the scattered wave is readily obtained once the electromagnetic field at the discontinuity is found. After discussing the numerical accuracy, numerical results are obtained for the reflected and transmitted waves and the scattering patterns for several shapes of discontinuity.
A study of twin‐waveguide systems for efficient surface wave excitation
Authors: Kitajima Hiroe
Published: July 2007

In general the transmitted wave in a twin‐film waveguide exists as even and odd modes when the higher order modes are absent. In this paper we consider the bandwidth of the propagation constant determined by the Gaussian beam diffraction angle and show the possibility of efficient surface wave excitation by means of a prism under the condition that the propagation constant difference between the even and odd modes can be suitably specified. When the transmitted wave passes through the gap and leaks into the side of the prism, the phase velocities of the even and odd modes become degenerate. When the coupling mode with degenerate velocity is excited by a Gaussian beam, the phase angle shift of the plane reflection constant with respect to the incidence angle is linear over the greatest range of incidence angles, so that the reflected beam will be very little distorted from the Gaussian type and a large beam shift can be obtained. Consequently the parameter accuracy required for high coupling efficiency can be relaxed. For simplicity, the two‐dimension problem is solved, the thicknesses of the gap and buffer film between the two guides for efficient surface wave excitation are obtained, and the amplitude of the reflected beam and the beam coupling efficiency for a Gaussian incident beam are found and investigated. For the optimum case the coupling efficiency can be as high as 94.7%.