bluuebunny/crossref_metadata_2025 huggingface dataset:
A design of high‐Q dielectric resonators for MIC applications
Authors: Imai Nobuaki , Yamamoto Kazuyuki
Published: July 2007

A design method of radiation‐suppressed high‐Q dielectric resonators with a metal cap loaded above a dielectric material with high dielectric constant is studied. For exact evaluation of the effect of the radiation‐suppressing metal cap, a semispherical dielectric resonator model with simplified boundary conditon of the metal cap is introduced. As a result, it is found that there exist two modes in this resonator, a dielectric resonator mode and a hollow cavity mode, depending on the size (diameter) of the metal cap, and almost constant resonant frequencies for the change of metal cap size and high unloaded Q factors are obtained in the dielectric resonator mode by selecting the cap size on the optimum range. the validity of the analysis result is confirmed by experiment. Moreover, the resonant frequency and its temperature variation for a cylindrical resonator are studied and it is found that the frequency variation does not depend on the material of the metal cap but greatly depends on the temperature coefficient of the high‐constant dielectric material itself.
A data converter for analog/fuzzy‐logic interface
Authors: Uehara Kiyohiko , Watahiki Takeshi , Miyata Takeo , Taguchi Eiji
Published: July 2007

Input signals are often fed as analog quantities into fuzzy logic processing systems. This paper proposes a method for configuring interface necessitated by fuzzy logic systems featuring analog inputs and digital processing. This interface is a data converter which processes input analog voltage signals and outputs digital signals suitable for fuzzy logic processing.

The conversion principle is based on the concept of level sets within the fuzzyset theory, i.e., depending on whether a given analog signal belongs to level sets, the signal is quantized and converted to membership grade, simultaneously. Having programmable conversion characteristics, it can realize typical membership functions such as Z‐, ‐, and S‐functions.

The operation of the converter, which is configured of counters, a memory, a digital‐to‐analog converter, and a comparator, is verified experimentally as regards a non‐monotonic and asymmetric membership function. the conversion accuracy is then discussed and the causes for error are described.
Two‐dimensional analysis of hot‐electron emission current in MOS FET
Authors: Morimoto Takahashi , Muramoto Susumu
Published: July 2007

There has been growing concern about degradation in MOSFET characteristics due to hot‐electron emission into the gate oxide as device dimensions are scaled down. This paper reports on a two‐dimensional analysis of hot‐electron emission. The emission current is related to the electric field and current distribution in a MOSFET for the purpose of identifying the factors contributing to its increase with device miniaturization. A variety of MOSFET structures, such as conventional, LDD, and double‐diffused MOSFETs are analyzed and compared. The analysis on a conventional MOSFET clarifies that the major factor contributing to the increase in hot‐electron emission in a small‐size MOSFET is the surface electric field intensity near the drain. This implies that the impurity distribution in the diffused drain has a great influence. The numerical analysis shows that the electric field near the drain is decreased in LDD and double‐diffused structures. For a given device size, the impurity density in the lightly doped portion of the drain can be properly chosen to homogenize the drain electric field, resulting in drastic reduction in hot‐electron emission current.
Analysis of soft error in MOS dynamic RAM
Authors: Yoshihara Tsutomu , Takano Satoshi , Taniguchi Makoto , Harada Hiroshi , Nakano Takao
Published: July 2007

The soft error rate of a MOS dynamic RAM is strongly influenced by the energy spectrum of the incident alpha particles, the collecting processes of electric charges generated by them, and the critical charge of the device. When the collected charge distribution is Gaussian, the error rate is well approximated by a complementary error function of the critical charge, which can explain the voltage dependence of the soft error rate; the dispersion of the distribution is also obtained experimentally. The dispersion depends on the thickness of the polyimide film coated on a chip, and the coating improves the error rate by absorbing alpha particles as well as attenuating their energies. The stopping power of the polyimide film is 1.47 × 103times as large as that of air, which is in good agreement with the calculated value.
Piecewise polynomial galerkin approximation to invariant densities of one‐dimensional difference equations
Authors: Kohda Tohru , Murao Kenji
Published: July 2007

Proposed herein is a piecewise polynomial Galerkin approximation to invariant densities of 1‐dimensional nonlinear difference equations xn+1 = τ(xn) (n = 0,1…), in which map τ is an endmorphism of an interval I. The piecewise polynomial is a linear combination of N × K polynomial bases of degree K‐1; N is the number of partitioned subintervals of I. The approximate solution for K = 1 is shown to be identical to the Ulam‐Li solution. Forthermore, the sufficient condition for the L1 convergence of the approximate solution (K = 2, 3) for large N is given. Numerical experiments demonstrate that the approximate solution for K = 3 produces a significant improvement of the Ulam‐Li solution.
Performance of comb filtering noise reduction method and application to quality improvement in PCM speech
Authors: Nagabuchi Hiromi , Member Regular
Published: July 2007

This paper proposes a method for reducing additive noise from noisy speech signal. The effectiveness of this comb filtering method is demonstrated via experiments. The method is applicable to noise with varying power and non‐flat spectrum. Listening experiments show that the proposed method improves the subjective S/N and the sound articulation of extremely noisy speech. Application of this method for the reduction of quantization noise and noise caused by bit error in PCM speech is investigated. Experimental results indicate that:

For error‐free 2‐to‐5 bit PCM the proposed method improves the subjective quality of the speech equivalent to one bit;.

For bit error rate ranging from 10−3to 10−1, the proposed method improves the quality of 8‐bit PCM speech equivalent to the reduction of error rate down to about 1/3∼1/5. It is very effective for reducing the quantization noise in 4‐bit PCM speech.

The proposed method is particularly useful for improving the sound articulation of extremely noisy speech.
Circuit design of dynamic MOS RAM with consideration of soft error
Authors: Nagayama Yasuji , Kumanoya Masaki , Yamada Michihiro , Yoshihara Tsutomu , Taniguchi Makoto
Published: July 2007

Dynamic MOS RAMs (MOS (D) RAMs) have been developed according to scaling relationships. But it is necessary to correct the scaling relationships because of soft error. In this paper, a modified scaling law is described based on the assumption that the soft error becomes the governing condition of the scaling law. In addition, a new device structure and circuit configuration are proposed to realize high‐speed, low soft error rate and low power consumption. As a result of applying it to a 5‐V 16‐K MOS (D) RAM, a performance index of 0.6 pJ/bit and soft error rate of 4 × 107device. hours are obtained. The adequacy of the modified scaling law is examined by considering a 12‐V 16‐K MOS (D) RAM with scaling constant k = 1 and a 5‐V 16‐K MOS (D) RAM with k = 2. It is shown that circuit design with consideration of soft error cannot achieve large improvement of the performance index of high‐capacity MOS (D) RAM and that the soft error is an impediment to high‐performance MOS (D) RAM.
The minimum track number of the narrower channel in the signal‐row single‐layer routing
Authors: Manabe Yoshifumi , Hagihara Ken'Ichi , Tokura Nobuki
Published: July 2007

Single‐row single‐layer routing is critically important for the design of printed circuit board or LSI. It is used to obtain realizations for minimal upper and lower channel track numbers U(R) and L(R) out of realizations R that are to make a connective relation without cross connection. Such a relation N̈ (net set) for a set of vertices on a straight line is given, such that (1) U(R) + + L(R), (2) max(U(R), L(R)) or (3) min(U(R), L(R)) can be decreased to a minimum, respectively. Among these tasks, the time complexity of (1) remains unresolved, and (2) has been proven to be NP‐complete. This paper discusses the problem (3), that is, to obtain a realization Rm that makes track number t either for upper or lower channel that has lower number of tracks as a minimum. We will introduce α(N̈), a tangle number of N̈, as a new measure and prove that the measure will be the minimal value of t. Also, we will present an algorithm to obtain α(N̈) and Rm and show that the time required for their computation be linear to the product of numbers of nets and vertices, even in the worst case. This is a fundamental problem that is to be applied to determination of the number of layers needed for a multilayer approach to realize a given net set on the condition that both the upper and lower channel track numbers be limited.
Construction and analysis of a mathematical model in quantum communication processes
Authors: Ohya Masanori , Members Noboru Watanabe, Regular
Published: July 2007

The communication of information by means of laser is an important technique. Therefore, it is necessary to construct a communication theory (quantum information theory) including quantum effects of laser action. Ohya, one of the authors, has studied the quantum communication channel and constructed a compound state for systematic formulation of the mutual information in quantum systems. In this paper, (1) we briefly review the mathematical formulation of quantum communication theory and (2) construct a physical model of the optical fiber communication process in order to examine the qualitative properties of the communication channel.
Group parity check system for important information
Authors: Tanaka Hatsukazu , Momohara Taketoshi , Kaneku Seiko
Published: July 2007

Can we prevent human deception or computer crime by cryptography? The main functions of cryptography are “secrecy” and “authentification,” and they are certainly effective for those outside a computer system. However, for the professional insiders who want to attempt deception, no cryptosystem will work well even if the information is protected by advanced cryptography because of the dependence on human conscience. Therefore, based on the concept that only humans can check human deception, we propose a new scheme of data security, the “Group parity check system for important information.” This scheme checks human deception arising in information input by mutual surveillance among people related to the information system. Furthermore, we show how to realize this scheme using the public key cryptosystem, and on a microcomputer. Although this scheme is inefficient because it requires duplex input of information, it will be effective if applied to only important information.
Assessment on characteristics of b‐adjacent error‐correcting code
Authors: Fukunaga Tetsuya , Tazaki Saburo
Published: July 2007

An application of b‐adjacent error‐correcting codes is discussed. The correction of these codes is b‐bits length sub‐block and their word length is b × N (bits) for improving the reliability of the digital video tape recording (VTR) system under the condition that check bits and synchronization bits are within a redundancy of horizontal blanking size. First, analysis is made of word error detection probability when burst errors and random errors are generated independently, and sub‐block error correction probability considering erroneous correction in a compound channel model containing random errors and burst errors. As a result, it is clarified that the generation of erroneous correction can be made extremely small by increasing the sub‐block length, although the sub‐block error‐correction probability increases slightly. Furthermore, the improvement on sub‐block error correction probability by applying the interleaving to sub‐block units is studied and the necessary interleaved length is clarified. Finally, a simple study on the application to digital VTR is made and it is shown that this code is effective as an error‐correcting code for DVTR.
Fiber selection in subscriber optical loop
Authors: Member Eiji Maekawa, Regular
Published: July 2007

This paper considers the effect of the fiber selection method on transmission distances in subscriber optical loops. The fiber selection method divides the fibers in an optical line into two groups according to optical losses, and is an effective method since there is no problem of connections, etc., as in the test splice. First, the optical loss improvement effect is investigated in the case where the group with smaller losses is used as a standby fiber for dedicated optical lines of large‐demand subscribers. As a result, it is understood that the optical loss can be reduced considerably with a small number of standby lines. Next, we consider using the group with larger losses to subscribers in short transmission distances, and clarify the grouping method which can serve all the subscribers along the line. Using this and the previous results, it is clarified that the transmission distances in subscriber optical loops can be made longer and the coefficient utilization of fibers can be achieved.
Broadband characteristics of bodies of revolution
Authors: Kawakami Haruo , Sato Gentei , Harada Hisashi
Published: July 2007

A monopole antenna consisting of a body of revolution is given by a set of simultaneous equations on the rotationally symmetric surface current of a conductor separated with respect to the variable of the envelope length on the surface of the body of revolution and the variable in the rotating direction. The structure is analyzed in detail by means of an extended moment method based on the present theory.

As an application, this analysis is applied to a conical monopole antenna. Studies are performed to find body shapes providing broadband characteristics. It is found that antennas with cross sections approximated by straight lines, ellipses and circles have an impedance of 50 ω over a wide range of frequency. When these shapes are replaced with wire elements for analysis, 16 elements are found sufficient to provide the characteristics for the bodies of revolution. Theoretical calculations and experimental results are compared. Agreement is excellent and the method is found useful.
Piezoelectric ceramic filters using the edge‐mode vibration
Authors: Iseki Yuji , Shimizu Hiroshi , Watanabe Hiroshi
Published: July 2007

For a conventional MF‐band piezoelectric filter, the contour vibration has mainly been used in which the whole of the vibrator body vibrates, and the vibrator is supported at its nodal point by a spring or a soldered wire. This degrades the characteristics of the filters, widens their manufacturing deviations, and limits their reliability and miniaturization. This paper proposes a new type of piezoelectric ceramic filter for the MF‐band using the edge‐mode vibration. This type of filter has a simple shape and a small size, and can be supported by vibration‐absorptive means such as a trapped‐energy type vibrator. The three‐terminal single‐mode filter is presented in which the electrode is divided with a gap into two parts to be used for the input and output. The relationship between the width of the gap and the fractional bandwidth of the filter is calculated theoretically, and the upper limit of its bandwidth is given. By using Pb(Zr, Ti)O3 pieaoelectric ceramics, two types of 455‐kHz filters having the 3‐dB fractional bandwidth of 1.3% and 1.6%, respectively, have been produced experimentally. By connecting 3 or 4 units of either type of the filters in cascade, a filter having the out‐of‐band attenuation greater than 50 dB over the wide frequency range up to ten times the center frequency has been produced successfully. To widen the bandwidth of the edge‐mode piezoelectric filter, the double‐mode filter consisting of two acoustically coupled resonators is also proposed. Experimental results confirm the practical usefulness of this type of filter.
Digital filter realization based on simulation of the node equation of lc filters
Authors: Kitamura Tadashi , Hayahara Etsuro , Konishi Masayuki
Published: July 2007

One method of synthesizing a digital filter involves the simulation of an LC analog filter. This method retains the low element sensitivity that is characteristic of an LC filter and is generally attractive in that it requires only a small number of bits in the multiplier that is used to produce the filter coefficients. The web digital filter is a typical application of this design method and is known to possess low‐element sensitivity, but it involves a somewhat complex configuration and the transfer functions which can be realized are therefore limited. This paper discusses a method of designing digital filters by simulation of the node equation of LC filters. Using this method, the transfer function of an analog filter which can be implemented by means of LCR elements, including transformers, can always be realized. With this method, we first transform the LC filter into an equivalent circuit and determine the applicable node equation. Then bilinear transformation is used to transform the s‐variable into the z‐variable and, to prevent the occurrence of a delay‐free loop within the circuit, after rearranging the circuit equation it is realized as a digital filter. In addition, a study is made of methods reducing the number of multipliers without degrading the coefficient sensitivity. Finally, the effectiveness of this design method is verified by means of computer simulation.
Methods of controlling sound image distance by varying the cross‐correlation coefficient between two‐channel acoustic signals
Authors: Kurozumi Kohichi , Ohgushi Kengo , Nikaido Seiya
Published: July 2007

A number of problems is involved in controlling sound image distance and such control has been realized only over a very limited range. This paper presents three methods of sound image distance control based on the knowledge that “if we vary the correlation coefficient continuously from 1 to ‐1, the sound image will move from a remote point to approach close to the observer's head.” Using one of these methods (the 90° phase shift method) in psychological tests, it has been found that the sound image broadening can be held almost constant while the sound image distance is varied. However, because the orientation of the sound image shifts within a horizontal plane with that system, it is necessary to employ an orientation‐correcting sound attenuator. As a means of automatically achieving this correction, we propose the α° phase‐shift system and it is shown that the approach of the sound is practically linear when α° is 70°. In addition, as a simpler circuit configuration, we propose the delay circuit system, which is shown to be effective for sound image distance control.
Measurement of lightning currents with different signs by magnetic links
Authors: Nagano Toshiharu
Published: July 2007

In regions experiencing intense thunderstorm activity, there are frequent failures of communication lines and equipment due to direct lightning strokes. For the effective application of lightning protection measures, it is extremely important that we have a good understanding of lightning current distributions. The magnetic link is known to be a convenient method of measuring lightning currents at a large number of grounding points. However, when currents of different sign are flowing, due to fluctuation in residual magnetism of the magnetic link, in regions experiencing concentrated lightning strokes it has not been possible to measure the lightning current by means of magnetic links.

Using the nonlinearity of the magnetization curve, this paper examines the measurement of currents of different signs using magnetic links. We place magnetic links at two locations having magnetic fields of different strengths and when currents of different signs are present, from the measured values of the residual magnetism in the two magnetic links, we prepared a calibration curve from which we can determine the magnitudes of the currents in each direction. In addition, this method was used in the west central region of Africa to measure cable sheath currents, obtaining lightning crest value distributions which can be considered to be essentially the same as the distributions in Europe and America. This work has verified the effectiveness of this method of lightning current measurement.
Stable approximation methods by the interpolation of phase spectrum
Authors: Sakai Masayoshi , Member Nozomu Hamada, Regular
Published: July 2007

This paper proposes a method of stable approximation based on the phase characteristics, utilizing the properties of phase and the stability of discrete‐time all‐poletype transfer function. The feature of the method is that the characteristics to be approximated can be modelled by the ω‐coordinate (real‐frequency) of the interpolating points and a real coefficient parameter. When the method is used in the approximation in the time domain, the characteristics of the nonminimum phase system can also be approximated by the transfer function with zeros and by the processing using complex cepstrum. The extension of the method to the two‐dimensional signal processing is also discussed, although the discussion has to be limited to the separable case.
Chromatic temporal frequency response–appearance at retinal location under the superthreshold condition
Authors: Member Haruo Sakata, Regular
Published: July 2007

The chromatic temporal frequency response of human vision under the isoluminant condition has been measured psychophysically by using a color‐television monitor. The following results were obtained.

(1) Under the superthreshold condition, the chromatic frequency response shows the lowpass filter type pattern.

(2) The periphery between 5 to 10 degrees eccentricity is more sensitive than the fovea under 5 Hz.

(3) In the fovea, the (y ‐ b) channel has the lower sensitivity similar to a tritan. In the peripheral retina, the (r ‐ g) channel has sensitivity lower than the (y ‐ b) channel similar to a deutan.
Boundary element analysis of polarization holding fibers
Authors: Matsuhara Masanori
Published: July 2007

The boundary element method has drawn wide attention as a novel numerical method of the boundary integration equation, and it has already been applied to the electromagnetic initial value problems. In this paper, we apply the boundary element method to the electromagnetic wave eigenvalue problems and establish a numerical method which is applicable to analyze the guided modes of waveguides with arbitrary structure. Then as an application example of the present method, we make numerical calculation of the elliptical core optical fiber, which is the typical polarization holding optical fiber, and clarify the cutoff frequencies of the first‐ and second‐order higher modes of the fiber. Also, the propagation constant and the geometrical anisotropy of the fundamental mode of the fiber are obtained. Again, the maximum anisotropy of the elliptical core fiber is shown to be obtained for the normalized frequency of 1.85 and ellipse factor of the core equal to 0.8. From these results we conclude that the boundary element method has high accuracy of calculation, is easy to apply, and has highly stable solution.
Dc stability of nullator‐norator‐modeled resistive networks realized with practical electronic devices
Authors: Member Yoshinobu Kato, Regular , Member Tadashi Matsumoto, Regular
Published: July 2007

This paper discusses the stability problem when a network is realized by using practical elements such as operational amplifiers and transistors for the nullors of the given nullator‐norator‐modeled resistive network. In other words, determination of the polarities of input and output terminals of the practical elements as well as the combination of nullators and norators is discussed. The stability of the network realized using practical elements is determined from the return difference matrix of the associated controlled source representation network. First, the first‐order phase‐delay ki/(1 + sTi) is assumed for the practical element and dc stability is defined as the asymptotic stability when the time constant Ti approaches zero. It is shown that the necessary condition for dc stability is that the determinant of the return difference matrix is positive when the phase‐delay of the practical element is ignored. Then, depending on the process of activation of the practical elements and their possible ranges of dc amplification factors ki, the absolute sequential, finite‐gain, equal‐gain and conditional dc stabilities are considered. The necessary and sufficient (or sufficient) condition is derived for each dc stability in terms of the expansion coefficients with respect to the dc amplification factors of the determinant of the return difference matrix. These results are useful in deriving the stable realization network using the practical elements from the nullator‐norator resistive network.
A synthesis method for the integrator of noninteger order in the continuously variable form
Authors: Matsuda Tsukasa , Kawakami Atsushi , Takahashi Shin‐Ichi
Published: July 2007

This paper proposes a method to synthesize an (differential) integrator of non‐integrator order applicable to a number of engineering problems in the continuously variable form. First, we approximate the desired characteristics by rational transfer functions which contradict two variables, the complex frequency s and the variable parameter λ corresponding to the order. These transfer functions have an approximation accuracy which is good enough for practical applications. The obtained approximated transfer function can be constructed by active networks consisting of a minimal number of dynamical elements and variable elements. It is also shown that the proposed method in this paper is applicable to a synthesis problem of a variable equalizer.
An analysis of repeated call model with a finite number of sources
Authors: Ohmura Hiroyuki , Takahashi Yoshitaka
Published: July 2007

Repeated call model is one of the queueing models which appear in various communication systems. Repeated call model has been studied, but there has been little study on the finite source repeated call model. This paper deals with a single‐server service system with a finite number of sources and with repeated calls. Assuming that the arrival process is quasi‐random, the service time is drawn from an arbitrary distribution and the repetition interval is exponentially distributed. Traffic measures such as mean waiting time and mean number of waiting calls are derived by using the supplementary variable technique and the discrete transforms. A numerical example for the traffic characteristic is shown. The effect of repetition interval distribution is also studied by computer simulation. An application to disk memories in the Facsimile Intelligent and Communication System is given and the process waiting time is quantitatively analyzed. This evaluation is compared with the evaluation by the existing theory.
A test of the stability of the two‐dimensional recursive digital filter
Authors: Miura Hiroki , Koga Tosiro
Published: July 2007

A test for the stability of a two‐dimensional recursive digital filter is proposed. Bilinear transformation reduces the stability test outside the unit circle in the complex plane to a test in the right half plane (i.e., to a test of a two‐variable Hurwitz polynomial for a continuous system). Conditions for a two‐variable polynomial to be a Hurwitz polynomial are given. The necessary and sufficient conditions for a two‐variable rational function to be a strict‐sense positive real function are given in a theorem. It is shown that a strict‐sense two‐variable positive real function can be found for each two‐variable Hurwitz polynomial. From the theorem it follows that the test of a two‐variable Hurwitz polynomial reduces to a test of a Hurwitz polynomial of a lower order with respect to one variable and to a sign test of a real two‐variable polynomial. The test of the two‐variable Hurwitz polynomial reduces to tests for signs of a set of real two‐variable polynomials. This is an extension of Sturm's test for the roots of a one‐variable algebraic equation.
Control algorithm and traffic analysis of PRT grade‐separated interchange
Authors: Satou Kousei , Kurihara Masahlto , Kaji Ikuo
Published: July 2007

A control algorithm and a probability‐theoretical traffic analysis of a grade‐separated intersection model of the personal rapid transit (PRT) systems under the quasi‐synchronous scheme is presented. At the intersection, vehicles diverge from the less preferential subline and merge into the preferential mainline. To realize efficient cell‐assignment, this algorithm makes a slot‐slipping decision before the diverge point and performs the actual slot‐slipping after it on the off line. Even a diverge‐minded vehicle is forced to go straight (be adopted) when the number of maneuvering cells exceeds its limit and passes the intersection without the maneuver. The behavior of this algorithm under the random arrival assumption is formulated as a Markov chain, the analysis of which leads to the explicit expressions for the delay distribution, the average delay, and the abort rate.
Fundamental theory on natural observation of waveform
Authors: Iijima Taizo
Published: July 2007

Observation of the waveform is a fundamental problem common to the problem treating various waveforms such as the voice. This paper attempts to provide a rational answer to this problem. Originally, the theory has been developed with the assumption of a simple condition called the natural observation condition. As a result, a simple and complete observation system has been developed which consists of only one original function and two observation types.

Traditionally, the concept of a running spectrum has been known for the observation problem of waveforms. In such a concept, the temporal transition of the short‐term spectrum is studied. From this viewpoint, the present method is an extension of the concept and places a new theoretical foundation in a rational manner so that unclear points and self‐contradictions of the previous theory are corrected.
ARMA digital lattice filter with white gaussian input
Authors: Miyanaga Yoshikazu , Nagai Nobuo , Miki Nobuhiro
Published: July 2007

This paper presents a new synthesis method for ARMA digital lattice filters. These filters are obtained by a fast algorithm for estimation of ARMA parameters. Some fast algorithms for such estimation have already been proposed in which approximation models are derived using the input and output signals and can be applied to arbitrary input signals. Among these methods, the Mullis‐Roberts algorithm estimates the parameters by the autocorrelation coefficients and impulse response of observed signals. The method is similar to the parameter estimation using white Gaussian process for the input signals. Though the Mullin‐Roberts algorithm can estimate the parameters with less calculation cost than other algorithms, it is not suitable for designing different orders of the AR and MA parts. The fast algorithm proposed in this paper estimates the parameters with the same calculation cost as in the Mullis‐Roberts algorithm when the input signal is restricted to a white Gaussian process and obtains the ARMA parameters as the AR and MA orders are independently increased.

The new ARMA lattice filter is synthesized by three prediction errors defined in the new algorithm and consists of a simpler structure than the usual filters of this type. By processing time series signals using the algorithm and the lattice filter, we show the feasibility of estimating the minimum realization for an ARMA model.
Indirect lightning surge at office terminal point on subscriber loop
Authors: Deguchi Fumihiko
Published: July 2007

With the objective of providing basic data for the design of lightning protection for communication devices connected to subscriber loops, this paper presents experimentally determined lightning surge characteristics of the office terminal point on subscriber loops or aerial and underground cable, covering such items as equivalent internal impedance, current and voltage distributions between lines and current additivity.

The initial step in this effort was the assembly of a high‐precision multichannel lightning surge measuring equipment (80 channels) and, after verifying the equipment performance characteristics, measurements were made at the office terminal points on subscriber lines in actual use. As a result of the measurements it is shown that the lightning surge as seen from the office side of the subscriber loop can be modeled as a constant‐voltage source with the dc resistance of the underground cable subscriber loop wire as its internal impedance. In addition, it is verified that with a multiplicity of on‐premises terminations at the same point on the subscriber loop, regardless of the termination conditions, the lightning surge will be practically the same and will reach the office termination point with the same phase. Further, this study clarifies the nature of the lightning surge voltage and current distributions and the surge current additivity and also defines a detailed lightning surge model.
Theoretical and experimental study on rectenna array for microwave power transmission
Authors: Shimanuki Yasushi , Adachi Saburo
Published: July 2007

In using the rectenna array as a receiving antenna in microwave power transmission it is necessary to prevent spurious radiation of higher harmonics and from interfering with wireless communication paths and to achieve high efficiency in conversion of microwaves to dc energy. In this paper the conversion efficiency and spurious radiation of higher harmonics are examined by solving circuit equations which are transformed to difference equations with the use of Newton's method. The input impedance of the antenna is obtained by assuming an infinite planar array on a perfectly conducting plane. Consistent with the theoretical analysis, an experimental rectenna array is constructed and its performance is confirmed experimentally. The rectenna array is fabricated by mounting the diode and other components in a thin‐film LC circuit with soda‐glass substrate using MIC technology and by connecting it to a 69‐element half wave dipole array above an aluminum sheet.
Markovian model and analysis of a PRT 2‐berth station
Authors: Nakamura Takashi , Kurihara Masahito , Kaji Ikuo , Yoneyama Tadaaki
Published: July 2007

Vehicle behavior of a PRT (Personal Rapid Transit system) multiberth station has already been analyzed as a continuous time system under the assumption of Poisson vehicle arrival and exponential passenger loading and unloading time [2]. However, it is more realistic to model it as a discrete time system considering a widely used point‐follower control. Thereby a general passenger loading and unloading time can be easily treated. An off‐line station with two berths in PRT, in which vehicles move on a guideway under point‐follower control, is modeled and analyzed as a discrete‐time Markov chain in this paper. The state quantity is defined based on the physical state of two berths at the arrival instance of a cell. First it is shown that the inter‐entrance time can be calculated numerically for a general passenger loading and unloading time. Then, several measures of the station behavior such as mean inter‐entrance time, entrance frequency and entrance factor are analytically obtained for the case of fixed passenger loading and unloading time, the opposite of the exponential distribution. The differences between two berths and one berth are discussed by showing numerical examples.
A study of temperature characteristics for rectangular GT‐cut quartz crystal resonators
Authors: Kawashima Hirofumi
Published: July 2007

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

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

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

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

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

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

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

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

A nonradiative dielectric waveguide has no radiation from the bends or discontinuities, it has low loss, and is suited for millimeter‐wave integrated circuits. This paper studies the bandpass and band‐rejection filters built by using such waveguides at the 50‐GHz frequency band. In general, the filters are designed by the coupling coefficients of resonators and loaded Q‐factors, but theoretical evaluation of these values is not necessarily easy. Here, an experimental design tecnnique is discussed which can also be applied to the filter structure that is difficult to solve analytically. As an example, we designed and fabricated 3‐pole bandpass and bandstop filters having center frequency of 49.5 GHz built from circular post resonators of Teflon. Excellent characteristics were realized.

The measured value of the insertion loss of the bandpass filter is 0.3 dB and the transmission loss of the bandstop filter is 30 dB. These are good practical values.
An analysis of meandering lines
Authors: Nakamura Takashi , Sekine Toshikazu , Yokokawa Senji
Published: July 2007

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