bluuebunny/crossref_metadata_2025 huggingface dataset:
Deflector for a deflection‐modulated EBS amplifier
Authors: Makishima Hideo , Shimokawa Kiyoshi , Mita Nagahisa
Published: July 2007

The deflection‐modulated EBS amplifier operating at microwave frequencies requires a deflector working effectively in the frequency band. the relation between the structure of a meander line and its deflection sensitivity, frequency response, and a new type of the support were investigated; thus a deflector for a 4‐GHz deflection‐modulated EBS amplifier was manufactured. A formula has been derived for the deflection, and it is found that the deflection sensitivity is maximized at a certain ratio of the finger gap to the finger pitch of the meander line. When this ratio is increased, the variation of the deflection sensitivity over a given frequency band is reduced. We proposed a quarter‐wave strip line to support the meander line; it is confirmed experimentally that its quality is almost equivalent to the conventional ceramic spacer.
Nb‐diffused LiTaO3 waveguides and light modulators by use of guided‐to‐radiation mode coupling
Authors: Onodera Hidetoshi , Okuda Masahiro , Awai Ikuo , Nakajima Masamitsu , Ikenoue Jun‐Ichi
Published: July 2007

An analysis and fabrication have been done on a guided‐to‐radiation mode‐coupled light intensity modulator made of a diffused waveguide, and a high modulation efficiency has been achieved. First, it has been shown theoretically that in a waveguide made of Nb‐diffused Z‐cut LiTao3 a modulation efficiency more than 50 dB/cm is obtained at the modulation electric field of 3 V/μm by choosing appropriate amounts of diffusion volume and depth of Nb. Next, before fabrication of the device, a number of waveguides was constructed with the Nb film thickness of 200 – 1000 Å, temperature of 1100 – 1200°c and time period of 3 – 9 hrs. the relation between the diffusion condition and the waveguide parameters were obtained. In the fabricated waveguides, Li2O out‐diffusion exists and an increase of the extraordinary index of refraction is observed. However, by means of a thermal process over 6 hrs at 900°C in LiNbO3 powder, the Li2O out‐ diffusion in the guided layer can be compensated. the modulator has been fabricated with the LiNbO3 powder process and repoling after diffusion for 3 hrs at 1200°C. In a slab‐type modulator with Nb film thickness of 610 Å (electrode spacing of 50 μm and length of 5 mm), the modulation depth was 23 dB at modulation voltage of 250V whereas in a channel structure of width 4 μm and Nb film thickness of 760 Å (electrode spacing of 10 μm and length of 5 mm) it was 19 dB at 70 V.
An extended fisher criterion for feature extraction ‐ Malina's method and its problems
Authors: Okada Toshihiko , Tomita Shingo
Published: July 2007

In the discussion of the two‐class feature extraction problem in pattern recognition, Malina [7] proposed recently a new criterion for overcoming the defects of Fisher's criterion. the discussion in this paper focuses on the effectiveness of Malina's criterion and at the same time points out the problem in his feature extraction method, indicating how to avoid the difficulties. First, no clear definition is made in Malina's method for the coordinate system in the feature space, and the coordinate system used is not optimal. Second, the eigenvalue problem must be solved including the solution of inverse matrix in order to determine the feature axis. For the first problem, this paper points out tha the coordinate axis di and dj in the coordinate system in Malina's method satisfies diTdj = 0, where is the sum of covariance matrices in the class. Then the optimal coordinate system from that viewpoint is given. For the second problem, the inverse matrix is eliminated by performing a certain transformation (A‐1 transformation) to the coordinate system of the original pattern space. the validity of A‐1 transformation is shown by the invariance of the distances among classes, and it is shown that the above optimal coordinate system under A‐1 transformation is the optimal orthogonal coordinate system satisfying diTdj = 0, i j. Finally, Malina's criterion is extended to the multiclass case and the problems are discussed.
Equivalent RC circuit representation of switched‐capacitor networks and its applications
Authors: Hayahara Etsuro
Published: July 2007

In the usual switched‐capacitor filter (SCF), all the switches connected to a node are simultaneously on or off. Thus, every node voltage in the SC circuit changes in synchronization only to in‐phase or out‐phase clock, and has a very simple representation by RC equivalent circuit. This paper derives first the RC equivalent circuits for the basic SC circuits, and presents a method of simulation for active or passive RC circuit using an SC circuit, based on the obtained result. Finally, it is verified by several experiments that the SC circuit constructed by the proposed method operates as the theory predicts.
Analysis of electromagnetic fields in inhomogeneous media by fourier series expansion methods
Authors: Yamasaki Tsuneki , Hinata Takashi , Hosono Toshio
Published: July 2007

This paper presents a new method of analysis with numerical results for planewave scattering by a layer with inhomogeneous permittivity μ(x) and permeability (x). the analysis is based on the following idea: (1) we construct a periodic structure, an iteration of the given layer and apply Maxwell's equation to derive a differential equation for this structure; (2) the electromagnetic fields in this periodic structure are expanded into Fourier series, and the obtained characteristic equation is transformed into an eigenvalue equation; (3) the electromagnetic field in the original inhomogeneous layer is expanded by the solutions of the eigenvalue equation, and the reflected and the transmitted waves are computed by using the boundary conditions. We call this method the Fourier series expansion method (FEM). When the differential equation obtained in the first step of FEM contains dϵp (x)/dx (or dμp(x)/dx), Hill's matrix method cannot be applied for the profile for which d2μp(x)/dx2 (or d2ϵp(x)/dx2) is discontinuous. By contrast, FEM in this paper can be applied even if ϵp(x) (or μp(x) is continuous. dϵp(x)/dx (or dϵp (x)/dx) is discontinuous. Even if ϵ(x) (or μ(x)) of the original inhomogeneous layer is discontinuous we can always construct a periodic structure with continuous ϵ(x) (or μ(x)), so that FEM can be applied. By numerical analysis, the usefulness of the method is evaluated from the viewpoints of the accuracy of the solution vs. the number of terms in the expansion of the comparison with already reported results. As an example of application, reflectivity is computed for the concrete layer with inhomogeneous permittivity and permeability containing magnetic particles.
Design of the pregroove‐shape on an optical disc based on the light diffraction analysis
Authors: Murakami Teruo
Published: July 2007

Scalar diffraction theory was used in computer simulation analysis of the tracking pregroove fabricated on optical discs: the groove shape relation to the read out (sum) and tracking push‐pull (difference) signals and to detector location; as well as pregroove manufacturing tolerances. As a result it was found that the maximum groove modulation on the sum signal both in the far field and the image plane occurs with a groove phase (depth) of λ/4. In the far field the tracking difference signal is insensitive to changes in groove width and the largest modulation output occurs for a groove phase of λ/8. In the image plane the beam diameter, groove width relation gives 2 points of stable tracking, and modulation is greatest for a phase of λ/4. For rectangular pregrooves, the edge slope has little effect on the readout or tracking signals and difficult control is not necessary. Finally, the formulas for the relationships between the main optical system design parameters (wavelength, beam size, and objective lens numerical aperture) and the groove parameters have been derived in order to generalize the results of the analysis.
Analysis of the tap weight fluctuation in zero forcing automatic equalizer
Authors: Sakurai Masaru , Murakami Junzo
Published: July 2007

Long‐term instability is one of many serious problems in Zero‐Forcing (ZF) automatic equalizers for television signals. This paper analyses this problem by solving the tap weight covariance matrix. the result is that the tap weight fluctuation (variance) increases significantly as the input signal bandwidth becomes narrow and/or the number of taps increases. the leakage algorithm which is very effective in reducing the tap weight variance is examined also. In addition, the timing adjustment which is another problem in the ZF algorithm, is examined and it is proved that the leakage algorithm does not improve the instability caused by timing misadjustment.
1/f frequency fluctuations of a quartz oscillator and temperature fluctuations
Authors: Noguchi Yasuaki , Teramachi Yasuaki , Musha Toshimitsu
Published: July 2007

We have investigated correlations between an ambient temperature and a frequency of a 5‐MHz, 5th overtone IC‐cut plano‐convex quartz oscillator. We found that the spectral density of frequency fluctuations is composed of three parts over a fluctuation frequency from 10−6 to 10−2 Hz; in the lowest frequency part it is proportional to 1/f2, which continues to 1/f and eventually to f0. the 1/f2 and f0 spectra are caused by ambient temperature fluctuations. Thus we have found that the 1/f spectrum has nothing to do with temperature fluctuations, which, therefore, provides a limit for frequency stability of a quartz oscillator.
A new way of generating the nyquist spectral‐shaped high‐speed and multilevel digital signals
Authors: Saito Yoichi , Matsue Hideaki , Komaki Shozo
Published: July 2007

High‐speed waveform transmission is of great importance in the realization of digital radio systems with high spectrum utilization efficiency. the binary transversal filter (BTF) offers an effective technique for achieving high‐precision waveform generation because it is a means of producing the desired waveform directly in the time domain. This paper presents a new technique for design of the BTF and discusses the authors' experimental results. the new BTF can be applied quite easily to high‐speed multilevel signals and is composed of a shift register, a programmable ROM (PROM) and a D/A converter which are driven by a multiphase clock. A was used to design the basic parameters of the BTF: sampling frequency, number of taps and tap coefficients, quantization levels for the D/A converter and allowable phase error for the clock signal. an analysis was conducted to determine the effect that each factor has the spectral characteristics and intersymbol interference characteristics. Further it was shown that based on this configuration and design method, a 12.5‐MB 4‐level Nyquist waveform can be realized without adjustment.
Nonlinear interaction of surface acoustic waves in waveguide
Authors: Nakagawa Yasuhiko , Ono Mitsuhiro
Published: July 2007

A theoretical and experimental study has been conducted on the nonlinear interaction of a surface acoustic wave (SAW) on a surface acoustic waveguide. It is shown theoretically and experimentally that from the parametric mixing phenomenon of two SAW's traveling in the opposite directions, a SAW with the sum frequency is generated which propagates with a certain angle from the waveguide. By changing the frequency difference, the propagation direction of the sum frequency SAW can be controlled freely. the excitation efficiency is such that: (1) it is higher for a narrow waveguide and for a larger velocity variation; and (2) it is periodic with respect to the waveguide width and the period is one wavelength of the sum frequency SAW. Such a generation of the sum frequency SAW and the SAW beam scanning in a plane are possible only with the SAW guided mode. Since the control of the SAW propagation direction in a plane is possible, an application to a two‐dimensional signal processing is conceivable.
Carry time of magnetically coupled Josephson adder circuits
Authors: Yamada Hajime , Ichimiya Yoshichika , Ishida Akira
Published: July 2007

A carry circuit for Josephson adder has been studied and tested experimentally. For carry calculation, a ripple carry process by asymmetrical interferometric majority gates is employed because it can reduce the gate number‐add time products compared with carry look ahead process by conventional OR‐AND gates. Add time measurement has been performed with these carry circuits connected to dummy sum circuits. Operation speed as fast as 740 ps was obtained for 16‐bit calculation, which shows excellent agreement with computer simulation. By the analysis, it has been clarified that the operation speed is limited by impedance mismatched input lines.
A synthesis method for the wideband variable equalizers
Authors: Kawakami Atsushi , Matsuda Tsukasa , Takahashi Shin‐Ichi
Published: July 2007

Approximated transfer functions are developed for variable equalizers to compensate for wideband signal attenuation distortion or for large attenuation distortion in the relative variation width of amplitude characteristics in communication systems. A method is presented for approximately expressing a variable transmission characteristic in the form of a 2‐variable minimum realizable rational transfer function which contains only variable parameters in the denominator. Next, actual approximated transfer functions are given for several specified equalization bands, equalization variable bands for variable parameters and various network orders. Analysis is made of the equalization errors of those variable transfer functions, verifying the effectiveness of this technique.
Design of plant expansion in subscriber optical fiber cable network
Authors: Yamamoto Hideo , Yamamoto Yoshikazu
Published: July 2007

This paper considers the low‐cost trends of optical fiber cables and the measures for coping with the widely scattered demands thatare regarded as special features in the initial stage of the formation of a subscriber optical fiber cable network. A method for economical construction of an optical cable network is discussed. First, the low‐cost trends of the optical fiber cables are dynamically grasped and a method is clarified for designing installation intervals and the sizes of the cables which will make the present annual expense worth a minimum by using dynamic programming. Next, for cable construction systems connecting the local office and the plural distribution areas, three systems, the fiber‐reduction system, fiber‐nonreduction system, and independent cable system, are considered and the applicable domains of these systems are clarified from the economical viewpoint with the installation cable size and distribution area as parameters. Moreover, a method is obtained for simultaneous design of the cable construction system which will minimize the total cost, and the distribution area size is shown for a given installation cable size. It is clarified from these results that it is more economical to use a shorter installation interval in the initial stage of the formation of the subscriber optical cable network than the present subscriber cable network using the symmetrical pair cables. Also, it is desirable to set a wide distribution area consolidating two to four present fixed distribution areas.
A decomposition method and acceleration techniques for a fixed point algorithm
Authors: Yamamura Kiyotaka , Oishi Shin'Ichi , Horiuchi Kazuo
Published: July 2007

Recently, extensive studies have been carried out on the algorithms which constructively determine the solution of nonlinear equations. These algorithms are in general called fixed‐point algorithms, and their attraction lies in the global convergence. However, fixed‐point algorithms have been a problem in that the execution speed is decreased greatly with the increase of the size of the system of equations to consider. This paper proposes a decomposition method and acceleration techniques as a means to improve the computational efficiency of the fixedpoint algorithms. Kevorkian's method is used in this paper as decomposition. Since the method includes errors in the decomposed equations and function values, it is important to discuss the convergence of the solution algorithm and to improve the convergence speed taking the effect of those errors into consideration. This paper shows a solution algorithm in which the system of equations is decomposed by Kevorkian's method, and then Merrill's method, a typical fixedpoint algorithm, is applied. Accuracy of simplicial approximation and convergence properties of the algorithm are discussed, indicating that the algorithm exhibits local quadratic convergence under some suitable conditions. By numerical examples, it is verified that the algorithm exhibits quadratic convergence. the method is compared with the past methods, indicating the effectiveness of the proposed method.
ARMA digital lattice filter based on a linear prediction theory
Authors: Miyanaga Yoshikazu , Miki Nobuhiro , Nagai Nobuo
Published: July 2007

This paper proposes some elementary sections of an ARMA lattice filter. an ARMA lattice filter with an arbitrary AR order and an arbitrary MA order is presented. A conventional ARMA lattice filter has already been constructed by a method used to develop an AR lattice filter to a 2‐dimensional filter. Therefore the conventional filter is not suitable for a filter realization when an AR order and an MA order differ from each other, and for the design of a minimum realized ARMA model. the most important characteristic of lattice filters is an orthogonality between every prediction error calculated at each elementary section. Employing this characteristic, we employ the AR lattice filter in a speech analysis, synthesis, an equalizer, and so on. It is shown that the proposed ARMA lattice filter satisfies an orthogonality. Furthermore, the ARMA lattice inverse filter which is an analyzer for an observed waveform and the ARMA lattice filter which is a synthesizer for the waveform are presented.
Block interleavers with maximum pulse distance
Authors: Ohue Kenji , Ohtake Kohhei
Published: July 2007

In block interleavers which reorders digits of pulse sequence in a block, pulse distance distribution and interleaving delay time characteristics depend greatly on readin and write‐out methods of block interleaves and the phase relation between observed pulse sequence and an interleaved block. Hence, it has become necessary to choose an interleaving method in accordance with the purpose. So far, little study has been made which takes account of this condition. This paper analyzes (b, q) interleaver by choosing pulse distance and minimum coding delay time as criteria, and shows that effective block interleavers can be classified into four classes. Furthermore, it is shown that some classes include two kinds of new (b, q) block interleavers which make the pulse distance greater than q ‐ 1, and these methods maximize the minimum pulse distance among (b, q) block interleavers. Finally, an application example to smear transmission systems is presented and it is shown that the proposed (b, q) block interleavers make it possible to suppress more greatly the burst impulse noise than the conventional (b, q) block interleavers.
Performance of improved tangent type FM demodulator using digital signal processing
Authors: Hagiwara Masafumi , Nakagawa Masao
Published: July 2007

FM demodulators using DSP techniques include the DPLL type, the quadrature type, the tangent type, etc. Compared to their analog counterparts, they are more useful with respect to stability, reliability and convenience of adjustment. However, since the detection characteristics for DPLL or quadrature‐type demodulators are sinusoidal, the introduction of distortion cannot be avoided. In particular, if the input signal is wideband FM, there is a marked deterioration in the characteristics caused by distortion. This paper investigates the tangent‐type FM demodulator whose circuit construction only has in the past been shown and whose characteristics have not been studied at all. It is made clear that the parameter‐setting condition is strictly limited. Next, the detection condition is described and an improved tangent‐type FM demodulator, whose detection characteristics are largely elevated, is represented and its better characteristics are shown. Moreover, comparison is made between this and other types of demodulators by means of simulation, and the effectiveness of this type is shown.
Theoretical study on the coupling of two‐dimensional gaussian beam to a dielectric slab waveguide
Authors: Nishimura Eiichi , Morita Nagayoshi , Kumagai Nobuaki
Published: July 2007

Mode coupling and reflection of a two‐dimensional Gaussian beam incident on an arbitrarily shaped end‐surface of a slab waveguide are studied theoretically. the relation between the shape of the end‐surface and the coupling efficiency is studied in detail by means of numerous numerical examples. It is found that: (1) the vertical planar end‐surface exhibits the highest coupling efficiency if the incident beam has neither axial shift nor angular shift and if the beam waist position coincides with the end‐surface; (2) an optimum shape for the end‐surface exists that provides the best coupling if the beam waist position is separated from the end surface; and (3) extremely high coupling efficiency is attained if the TM beam wave is incident with a Brewster angle. Although the analysis is based mainly on the integral equation method, a simple method is also presented for computing coupled power from the fields approximately obtained from the Fresnel formula.
Temporal transient response of color mechanism–Broca‐sulzer effect of chromaticness
Authors: Sakata Haruo
Published: July 2007

This paper discusses the temporal transient response of chromaticness, which was measured by the Broca‐Sulzer effect. (1) the Broca‐Sulzer effect of chromaticness was determined for 8 hues centering around the achromatic color light. the transient time to reach a certain level of saturation was shorter for red and cyan, but was longer for yellow and blue. (2) A pattern was constructed which keeps the saturation constant and varies the hue continuously for 360 deg in the vertical direction and varies the presentation time gradually in the horizontal direction. By using the above pattern, the apparent change of the hue was measured. It was verified that cyan and red with fast rise‐time is observed in a wider range in the region of shorter presentation. (3) By the result of those transient observations in color mechanism, it is concluded that, at least near the fovea, the (r ‐ g) axis in the color mechanism is temporarily of wide‐band and the (y ‐ b) axis is of narrow‐band.
Crosstalk characteristics for symmetrical star quad cable with unbalanced terminations
Authors: Tomita Nobuo , Kawaguchi Tokihiro , Ohmura Makoto
Published: July 2007

In subscriber line signalling systems using the telephone network for selective control of specified on‐premises devices, with consideration of the exchange configuration, there are cases when the subscriber channel is used in an unbalanced condition and the channel crosstalk characteristics become a problem. Up to this time, we know of no studies which have considered the effects of subscriber line crosstalk characteristics with unbalanced terminations. In this paper, we first establish models and derive theoretical equations for two categories of line crosstalk‐the first being the case where either the disturbing or the disturbed line has an unbalanced termination, and the second being the case where both lines have unbalanced terminations. Results obtained in the theoretical analysis are verified by experiments. Next, using a theoretical expression considering the relationship between crosstalk coupling and crosstalk attenuation, it is found that, the subscriber in the low‐frequency region where the coupling impedance has no effect, the single‐circuit unbalanced termination gives about the same performance as the balanced termination, whereas the crosstalk attenuation is about 50 dB lower when both circuits have unbalanced terminations: In addition, for the case where both lines have unbalanced determinations, we present a method of specifying the signal frequency and line termination impedance, which are important parameters for the design of the above‐mentioned signalling systems from the standpoint of achieving the desired crosstalk characteristics.
Transient analysis of microstrip gap
Authors: Koike Shoichi , Yoshida Norinobu , Fukai Ichiro
Published: July 2007

The time domain analysis of electromagnetic field is not only of theoretical interest for rigorous analysis of Maxwell's equations in the time domain, but is important in practice for waveform transmission in a recent high‐speed pulse technique. In the waveform transmission, the time variation of the electromagnetic field at the receiving end is important. This variation is the result of accumulated wave phenomena such as reflection, diffraction, and dispersion due to the boundaries and medium distribution in the system. In particular, in the transient such as the rise of the signal waveform, the time history of each wave phenomenon strongly affects the characteristics. the present paper treats a microstrip line with a gap. A three‐dimensional analysis has been performed with the strip thickness and the surrounding free space taken into consideration. It is shown that the wave exhibits a complex variation even at the gap and that it is a well‐known capacitively coupled circuit. This is confirmed in transient state by means of the time variation of the electric field distributions at the underside of the strip, the side surface of the strip, and the gap end surface. to quantify the steady‐state characteristics, the parameters of the even and odd modes of the μ‐equivalent circuit are derived from the three‐dimensional electric field distributions. They are compared with the conventional two‐dimensional static analysis, and the features of the three‐dimensional analysis including the thickness are clarified.
Dielectric measurement by h‐plane dielectric loaded resonator
Authors: Yamanaka Hideo , Farooq Umar
Published: July 2007

This paper describes the measurement of a complex dielectric constant by a resonance method using a rectangular cavity (cross section 3.48 × 1.58 cm2 and length 8.3 cm) filled with two layers of dielectric materials (the upper layer is air). the experiments are performed in the range of 7 GHz and the test materials are methacrylate and polystyrene sheets.
Metal‐migration of aluminum film on SAW resonator
Authors: Ebata Yasuo , Morishita Shigefumi
Published: July 2007

The SAW resonator has been considered as a small‐sized high‐Q resonator in VHF and UHF bands. High‐density energy is therefore stored within the resonator and the study of drive levels is specifically important among reliability. This paper describes the change in performance due to drive levels of the SAW resonator and their cause, mecahnism, and, further, corrective action against the performance degradation. an aluminum film grating reflector with IDT structure formed on an LiTaO3 substrate is used as the SAW resonator for measurement of the aging of electrical characteristics by means of parameters of the drive level. As a result, deterioration due to migration of grain boundary in the aluminum film is observed in a resonator exhibiting performance degradation. Moreover, from a comparison between the distribution of aluminum damaged and stress distribution due to SAW within the resonator, and theoretical estimation of its intensity, the internal stress in the aluminum film induced by the SAW energy causes migration and the stress is about 3.3 × 107 N/m2. to prevent performance degradation from its generation mechanism, we propose a method using copper‐doped aluminum film. From experiment we found that the drive level causing the performance degradation is improved more than 10 times.
Carried traffic estimate errors for delay systems
Authors: Machihara Fumiaki
Published: July 2007

The carried traffic estimate errors for delay system models are analyzed. Particular attention is given to the traffic models for the switching machine control equipment. It is known that the holding time distribution of the switching machine control equipment is one whose coefficient of variation is less than 1 (exponential distribution). Therefore this paper emphasizes the analysis of the effect of the holding time distribution on the estimate errors. First, the carried traffic estimate errors for M/D/S queue and M/M/S queue are analyzed and it is shown that the estimate errors for the M/D/S queue are always smaller than those for the M/M/S queue for any fixed utilization. As a result, it is conjectured that as the coefficients of variations for the holding time distributions increase, the estimate errors also increase. In the latter part, this conjecture is justified for one server model M/G/1 queue. In analyzing the carried traffic estimate errors for M/G/1 queue, the approximation of the busy period distribution by an hyperexponential distribution is proposed, and its estimation accuracy and its applicable range are studied.
Triple hybrid primary power supply system
Authors: Kawamoto Hisanosuke
Published: July 2007

Various proposals have been made in recent years with regard to hybrid power supply systems for communication system applications. the main common feature of such systems is the incorporation of two or more kinds of power sources. In this paper we first discuss the concept of hybrid systems and then describe experimental results obtained with a triple hybrid system incorporating a wind‐power generator, solar cells and Diesel generating equipment. It is then shown that the continuous time distribution of natural energy in the nonenergized state follows an exponential function. We apply a mathematical model which is in good agreement with the experimental results and develop a theory for derivation of the required storage battery capacity as well as the power to be applied by the Diesel generators. Then, applying this design method to various systems, we present a quantitative analysis of the complementary relationship between wind power and solar illumination and show that the triple hybrid system is most economical.
An analysis of wiring performances of a routing system for high density printed wiring boards
Authors: Asahara Shigeo , Odani Masayasu , Ogura Yasunori , Shirakawa Isao , Ozaki Hiroshi
Published: July 2007

Recent advances in the technology of microelectronics have changed the design rule for printed wiring boards, allowing the number of wiring tracks between consecutive pins of an ordinary dual in line package (DIP) to be two or more. When the wiring density augments to that extent, conventional routers are confronted with various difficulties.

To cope with this situation, the single‐row router which has topological fluidity can be employed in conjunction with the line‐search router. We have already developed a new routing system constructed of a line‐search router combined with a single‐row router and of a maze‐running router. However in each routing process there are many parameters, the combination of whose values have much influence on the wiring performance of the whole system.

In this paper we outline this routing system, describe some experimental results in order to determine values of these parameters, and show that the analysis of implemented results suggests high performance for high density printed circuit boards (PWB's).
Circuit and packet integrated switching in a satellite communication channel
Authors: Suda Tatsuya , Hasegawa Toshiharu , Miyahara Hideo
Published: July 2007

This paper describes a switching scheme for satellite communication systems employing both lightly loaded (bursty) and heavily loaded terminals. In the proposed scheme, the frame is partitioned into two types of subframes for servicing the two types of terminals. The subframe for heavily loaded terminals consists of the reservation channel and the message channel. The subframe for lightly loaded terminals employs a slotted ALOHA scheme for the transmission of packets. The heavily loaded terminals make reservation through reservation‐channel using reservation packet, and send messages by using time slots of the message‐channel. Analysis is performed to derive the mean packet transmission delay for the lightly loaded terminals and the mean message transmission delay for the heavily loaded terminals. It is shown that if one type of delay is controlled then there exists an optimum frame length that minimizes the other type of delay. It is also shown that the transmission delay of the proposed scheme is shorter than those of the conventional TDMA and the slotted ALOHA schemes.
Scattering and mode conversion of guided modes in an optical slab waveguide caused by a cylindrical of arbitrary cross section shape
Authors: Nobuyoshi Terumi , Morita Nagayoshi , Kumagai Nobuaki
Published: July 2007

A theoretical analysis is given for the scattering and mode conversion of the guided modes in an optical waveguide when cylindrical obstacles of arbitrary cross section are present in the slab waveguide. This structure is a complicated inhomogeneous media caused by melt‐connection of the optical fibers during fabrication. When a guided mode enters such a non‐uniform path, the equivalent surface electromagnetic current at the dielectric surface can be found by the successive approximation method which is applicable to the integral equation in which current is an unknown variable. Thus the mode‐conversion power factor and the scattering power pattern of the scattered wave can be determined. As a numerical example, the relationships between the shape and size of the non‐uniform portion is given for the TE mode.
Behavior of phase‐locked loops in the presence of large interfering signal
Authors: Endo Tetsuro , Matsubara Takashi , Ohta Toyomi
Published: July 2007

Various characteristics are compared and studied for three typical phase‐locked loops: the first‐order loop, the imperfect second‐order loop and the perfect second‐order loop in the presence of large interfering signals. Comparison of these characteristics requires that the pull‐in range for the first‐order loop and the imperfect second‐order loop be made equal, and that the natural angular frequency and damping coefficient be made equal for the imperfect second‐order loop and perfect second‐order loop.

The average value and variance of the error angular frequency, the average value of the output angular frequency and the phase jitter, as well as the synchronizing limit to the signals of the phase‐locked loops are determined in this analysis by the harmonic balance method and verified by computer simulation. Furthermore, the synchronization characteristics for the initial phase variations of the phase‐locked loops are determined by computer simulation, and compared and studied mutually. As a result, it is found that the imperfect second‐order loop shows the best synchronization characteristic in the presence of a large interfering signal.
Delay characteristics of packet‐switching network with window flow control mechanism
Authors: Akiyoshi Ichiro , Nakanishi Hikaru , Sanada Hidehiko , Tezuka Yoshikazu
Published: July 2007

Window allocation is an important issue in the design of a packet switching network using window flow control scheme. Most of the research in the past applied to loss system which omitted the waiting (delay) time external to the network. This paper deals with waiting (delay) systems which take into account both the external waiting time and internal delay time. For convenience in the simulation, the time required to send ACK message is assumed negligible. The results indicate that if the window size is about the same as the average number of packets outstanding on the logical channel with no‐control, then the window flow control scheme renders a shorter delay than the no‐control scheme in spite of the external waiting time. The window flow control scheme remains effective even in the expanded networks, and networks using the ACK scheme of the X.25 protocol.
Mathematical representation of microwave oscillators by use of the rieke diagram
Authors: Fukumoto Katsumi , Nakajima Masamitsu , Ikenoue Jun‐Ichi
Published: July 2007

The mathematical representation method of treating oscillators was first suggested by van der Pol. Many analyses of oscillators have been conducted employing this method. However, analytical models of oscillators still have some inadequacies. This paper deals with the sinusoidal output wave form of the oscillator and presents the mathematical representation of oscillator properties in a simple but very practical manner. We shall explain how the coefficients in the formulas can be determined from several of the measured points on the Rieke diagram, which is a popular form for the representation of microwave oscillator properties. We shall also give a couple of practical examples.

Previously, oscillator properties have been described in graphical form due to the nonlinearity of the device, but they can be described by several numerical values when a mathematical representation is used; with the help of computers, this simplifies considerably the design of oscillator circuits.
Fabrication of high N.A. graded‐index optical fibers by mcvd method
Authors: Okazaki Hisaaki , Ohmori Yasuji
Published: July 2007

Cracks in the host material have posed a problem in the fabrication of high‐M.A. silica fibers. This paper examines a high‐NA fiber with a graded refractive index profile to prevent these cracks. A high‐N.A. (= 0.39) graded fiber was fabricated by the MCVD method, in which the accumulation temperature is varied in accordance with the difference in composition of the core glass film. A method was developed for generating a host material with high‐N.A. and low losses. We realized a loss of 2.49 dB/km (at the measured wavelength of 1.67 μm) and a relative index of refraction difference Δ = 3.3%. For the core materials GeO2 ‐ P2O5 ‐ SiO2 and P2O5 ‐ SiO2 we experimentally found a relation between the relative index difference Δ and the loss. Rayleigh scattering, structural imperfection scattering and OH absorption were examined for the propagation loss characteristics. At longer wavelengths, the Rayleigh scattering and the OH absorption can be reduced and the high N.A. fiber is more practical. When Δ is larger than 3%, the structural imperfection loss increases rapidly and it is necessary to improve the processing. For the bending loss the number of windings, the bending radius and the Δ dependence are derived. For a bend diameter R, the bending loss was found to be (1/R)1.31 exp (−k Δ).
Spectral distortion and quality of synthesized speech in cepstral speech analysis‐synthesis system
Authors: Kitamura Tadashi , Imai Satoshi
Published: July 2007

The relation between spectral distortion and the quality of synthesized speech in a speech analysis‐synthesis system based on the cepstrum method (cepstral vocoder) is described. In this system, the true logarithmic spectral envelope is estimated by an improved cepstral method in the analysis part and a logarithmic amplitude characteristic approximated filter is used in the synthesis part. The transmission rate for spectral information is reduced using the differential of the cepstrum due to the differential of the spectral envelope, because the spectra do not change very rapidly. The preference score by pair comparison tests is employed as a subjective evaluation and spectral distortion is used as an objective evaluation to establish the relations among the quantization width, word length, frame rate, cepstrum order, spectral distortion and synthesized speech quality. Furthermore, the factors of spectral distortion and its characteristics are clarified and it is shown that spectral distortion can be estimated from the transmission condition. The result is that 2.8‐kbit/s, high‐quality synthesized speech can be obtained by this synthesis system.
A novel method of spread spectrum communication system using delay transform
Authors: Tachikawa Shin‐Ichi , Marubayashi Gen
Published: July 2007

In this paper, DT coding system which includes both DS (direct sequence) and TH (time hopping) systems as special cases is proposed. It makes interchannel interference small and the number of channels large. Furthermore, autocorrelation, which relates to acquisition and trucking performance, can be improved.

The DT coding formation is defined and the spread matrix and despread matrix are derived. To calculate the AO (auto‐optimal) phase, LSE (least‐sidelobe energy), r, ik (the average interference parameter) and other important code parameters, direct formulas and the recurrence formulas using these matrices are derived.

To show the improvement of interchannel cross‐correlation and autocorrelation characteristics, a numerical example is presented.
An 800 MHz frequency synthesizer for land mobile radio equipment
Authors: Nishiki Sadayuki , Yuki Shuomi
Published: July 2007

It is important to develop a frequency synthesizer that does not require a sophisticated multiplier and which oscillates directly at the local oscillation frequency for use as a local oscillator, with a view to the simplification and miniaturization of a large‐capacity land mobile radio equipment. The mobile frequency synthesizer is required to have a high purity oscillation, fast channel‐switching and high stability when subjected to mechanical vibration. A 1000‐channel switchable type frequency synthesizer with direct oscillation and direct division at 800 MHz has been developed to satisfy these requirements, based on consideration of an 800 MHz voltage‐controlled oscillator of high purity and optimum circuit design of a phase synchronizer. This synthesizer consists of an 800 MHz voltage‐controlled oscillator, two synthesizer LSIs and a crystal oscillator. In comparison with the conventional 150 MHz frequency synthesizer, it is only 1/9 as large. This paper describes the design and performance of this 800 MHz frequency synthesizer.
Consideration of non‐recursive and recursive transfer functions of multi‐section coupled‐line bridged‐T networks
Authors: Sakagami Iwata , Hatori Kozo
Published: July 2007

Some applications of microwave distributed‐line networks have recently become known in the field of ultra high‐speed (gigab its per second) digital communication systems as signal‐processing or waveform‐transformation networks. constant‐resistance, two‐strip, n‐section coupled‐line bridged‐T networks constructed on thin‐film substrates in aplanar‐structure. An equivalent signal flow‐chart is given for an n‐section coupled‐line which is part of the bridged‐T network. This signal flow‐chart shows that both numerator and denominator of the transfer function of the bridged‐T network have real‐coefficient rational functions of order n with respect to 2‐1. However, depending on the choice of element values of the bridged‐T network, we can obtain a non‐recursive transfer function in which the denominator is constant, or a recursive transfer function i n which the numerator is constant. It is demonstrated that in this case all reflection coefficients for the backward‐traveling power waves must be zero in the n‐section coupled‐line. AS a result, the bridged‐T network ma? be used as a digital frequency multiplier, as a code converter lacking the characteristic wave distortion, or as a waveform equalizer to compensate pulse echo distortions.
Facsimile coding scheme using cornered edged point on contour line
Authors: Tominaga Hideyoshi , Hosaka Kenichi
Published: July 2007

Existing facsimile compression schemes include the CCITT recommendation T.4 for a one‐dimensional modified Huffman scheme and the optional 2‐dimensional modified READ scheme. This paper proposes a 2‐dimensional coding method using the corner edge points of a contour line. The features and characteristics of this method are compared to those of the modified READ and other 2‐dimensional methods. The amount of encoded data in the conventional methods generally increases quadratically with the scanning resolution. In coding a contour line, however, the amount of data increases linearly with scanning resolution. Furthermore, only the corner points, not the straight line segment between them, need to be encoded for a contour line with straight edge. This is one of the reasons why the proposed method is more efficient for data compression than the conventional 2‐dimensional methods such as the modified READ scheme.
Speech quality of PCM system in digital telephone network
Authors: Kitawaki Nobuhiko , Itoh Kenzo , Kakei Kazuhiko
Published: July 2007

PCM is the basic coding method in speech transmission in digital telephony for the future information network system (INS). This paper evaluates the speech quality of the PCM system in a digital telephone network. A category judgement test is employed for evaluation of speech quality. This evaluation method distinguishes five grades of overall speech quality by users. First the effects of such basic PCM parameters as the number of quantizing bits, amplitude companding and input speech level on speech quality are examined. Then other factors affecting speech quality such as overall reference equivalent, circuit noise and link connection associated with introduction of PCM into the telephone network are clarified. Finally, for evaluation of the coded speech quality with consideration of network design, white noise is employed in speech envelope correlation and 8‐bit PCM system is adopted as a reference for degradation.
Reactively loaded loop antennas with reflectors for circular polarization
Authors: Okubo Shigeru , Tokumaru Shinobu
Published: July 2007

There have been several attempts to expand the capabilities of loop antennas by impedance loading. In this paper, a new structure is proposed in which a reactance loads a one‐wavelength loop antenna with a reflector. It is shown that this structure is in principle suited as a circularly polarized antenna. The loading reactance is placed at 45o from the feed point. It is shown from numerical calculations that there exists a dimension for which a good axial ratio is obtained if the reactance is changed. Numerical results are shown for this axial ratio, input impedance, current distribution and radiative pattern at this dimension. From these results, general characteristics of this structure are found. From the model experiment, it is confirmed that circular polarization is generated from this structure.
High‐performance 64‐kbit dynamic RAM with small gate overlap capacitance MOS transistor
Authors: Taniguchi Makoto , Nagayama Yasuji , Sato Shin‐Ichi , Hatanaka Masahiro
Published: July 2007

The high‐capacity high‐performance dynamic MOS RAM is an outgrowth of progress in fine‐pattern fabrication techniques. However, as the short‐channel effect of MOS transistors becomes more pronounced it becomes increasingly difficult to reduce the effective channel length because it results in performance degradation of the refresh time or breakdown voltage in the dynamic RAM. In this paper we propose a method of fabricating a SAGOS (Self‐Aligned Small Gate Overlap Structure) MOS transistor with small gate‐to‐source/drain overlap capacitance using ion implantation and lithography technique. Its characteristics are clarified and it is shown that an MOS transistor with no short‐channel effect can be obtained even with a final poly gate length of 2.3 μm (effective channel length 2.3 μm). Additionally, in order to prove that the small gate input capacitance of the SAGOS MOS transistor is effective for high‐speed LSI, it is applied to a 64‐K dynamic RAM. No degradation of electrical characteristics is exhibited with CAS access time of 54 ns at Ta = 75 C and Vcc = 4.5 V. This is a speed improvement of 11% compared to a conventional MOS transistor with identical conductance.