bluuebunny/crossref_metadata_2025 huggingface dataset:
Graphical analysis of oscillator stability and noise in several kinds of circuits
Authors: Member Susumu Hamaya, Regular
Published: July 2007

To achieve increased output and frequency stability in solid‐state oscillation it is necessary to reduce the oscillator noise. Measures that may be employed to achieve this include operation of a number of oscillators in parallel, external injection locking, self‐injection locked operation or a combination of such measures. The purpose of this paper is to clarify the nature of the mechanism which causes improved stability or improved noise characteristics due to injection‐locked operation and to develop an intuitive grasp of the stability and noise characteristics of such complex oscillator circuits. In the analysis technique we consider oscillators operating above the microwave band using traveling waves. The Rieke diagram of the oscillator is transformed so that the traveling wave analysis can be performed and a graphical presentation is used to show how arbitrary frequency components of noise are outputted. It is clearly shown how the oscillator output signal (angular frequency ω0) interacts parametrically with the noise equivalent input signal (ω0 ‐ ωn) due to the input signal amplitude dependence of the Rieke diagram, producing a noise output signal of angular frequency ω0. We are also able to show on the Rieke diagram how the noise characteristic varies with the magnitude and frequency of the injection signal.
Nonlinear analysis of response characteristics of ganglion cells in the retina
Authors: Fukushima Yoshihisa , Members Masayuki Kimura, Regular , Member Kenichi Hara, Regular
Published: July 2007

Research has been reported in which Wiener's nonlinear system theory is applied in order to analyze the information processing ability of the visual nervous system. As a result, some remarkable results have been presented concerning the response characteristics of certain kinds of cells in the retina. However, to discuss the higher‐order nonlinearity based on such a theory, a large amount of computation is required, and it becomes difficult to give an insight into the physical meanings of the obtained result. For a quantitative investigation of the response characteristics of the ganglion cells, this paper proposes a new nonlinear analysis method based on the physiological findings concerning the basic connections among neurons and their response characteristics in the retina. The method of anlaysis is applied to ganglion cells in the cat retina to demonstrate the effectiveness. The response characteristics of receptive fields of ganglion cells are also examined. Hence, it is seen that a large contribution comes from bipolar cells to X‐type ganglion cells, resulting in an almost‐linear response. The Y‐type ganglion cell receives a large contribution from amarcrine cells, resulting in a remarkable nonlinear response.
The sleeve monopole antenna in a warm plasma
Authors: Morita Yuzuru , Members Shigeru Egashira, Regular
Published: July 2007

A sleeve monopole antenna in a warm plasma with length almost the plasma wavelength has been analyzed in the frequency region where electron plasma waves exist. The current distribution and the input impedance have been obtained. When Landau damping is not considered, the current distribution is similar to that for a dipole and oscillates violently near the plasma frequency. It approaches a triangular shape as the frequency is increased. The input impedance varies considerably near the plasma frequency depending on the sleeve length. On the other hand, if Landau damping is taken into account, the amplitude of the oscillatory component of the current distribution becomes extremely small. For the input impedance, the effect of the sleeve beyond 25 times the Debye length can be neglected. This result agreed well with the measured input impedance values. It is found that the sleeve as the external conductor of the coaxial feeder has the effect of reducing the input impedance.
An automatic filter using switched capacitors—performance as an automatic equalizer at low s/n
Authors: Yoshida Yuichi , Murahara Yuji , Kuwabara Hiroshi
Published: July 2007

An automatic filter with an analog transfer characteristic is desirable as a receiver filter for data transmission over a channel in which both the channel distortion and the additive noise are generated and these interferences fluctuate. In this study an automatic filter that is easily integrated and readily controlled digitally is realized with SCF and its capability is demonstrated. As the fundamental configuration, the Laguerre function system is employed and the gradient method by zero crossing spacing is used as the automatic adjustment algorithm. The analog pre‐filter, indispensable in a sampled‐value system, is practically eliminated since the only resistor in the automatic filter is used for this function as well. This is made possible by choosing the switching frequency of SCF sufficiently higher than the baseband. The experiments have been performed for the preset type and for the adaptive type and the symbol error rate has been obtained. It is found that the present type exhibits a performance close to the theoretical value of the optimum filter, and the adaptive type also demonstrates a sufficiently acceptable performance.
Quick‐response phase‐shifter using digital phase‐locked loops
Authors: Iritani Tadamitsu , Satonaka Hisashi , Kinouchi Yohsuke , Ushita Tomiyuki
Published: July 2007

Three types of new quick‐response phase‐shifters are proposed using digital phase‐locked loops (DPLL). They use a new method of level‐slicing the sawtooth waveform of PLL's VCO. The response time for a phase shift (0° ∼ 360°) is less than one period of the input frequency, and is faster than that of conventional ones. Moreover, we group these phase shifters into three classes according to the step response of the input frequency in the DPLL. The first‐class phase shifter has the simplest structure, where a quick response to the input frequency change is not expected so much and a stress is put on eliminating the noise in the input. Its phase shift error increases due to VCO waveform distortion if its response is improved. The second‐class phase shifter realizes a quicker response at the quantization error level by linearizing the VCO waveform. Finally, using the time‐optimal DPLL with the fastest settling time, the response time of the third‐class phase shifter can be made less than one period of the input frequency regardless of the input frequency change.
A constructive approach to the analysis of nonlinear resistive circuits based on the fixed point algorithm theory
Authors: Member Yuzo Sumi, Regular , Oishi Shin'Ichi , Takase Tadaaki , Members Kazuo Horiuchi, Regular
Published: July 2007

The existence problem for solution of a nonlinear resistive circuit and the problem of identifying the number of the solutions are classic and basic problems in circuit theory. In their paper “On the application of degree theory to the analysis of resistive nonlinear networks” (Int. J. Cir. Theor. Appl., 5, pp. (1977)), Chua and Wang presented a unified theory for the existence of solutions for nonlinear circuit equations. That is, on the basis of the degree theory the existence of solutions of many nonlinear resistive circuits can be guaranteed in a unified manner by showing that the circuit equations are homotopic to certain odd fields. Their arguments are, however, not constructive. In this paper, an algorithm based on the fixed‐point algorithm theory is presented and it is proved that by this algorithm at least one solution can always be constructed for nonlinear circuit equations whose solutions are guaranteed to exist by Chua and Wang's theorems. Usefulness of the algorithm is also demonstrated by a few examples.
Structural controllability of electromechanical networks
Authors: Suzuki Yoshihiko , Mio Masao
Published: July 2007

This paper discusses structural controllability for non‐strongly connected networks, especially an electromechanical network connected by an energy conversion device. The energy conversion device is nonlinear and all other associated devices are linear. Thus, this paper considers the linearized state equation for studying the structural controllability in the neighborhood of an equilibrium point. Because of the nonlinearity of the energy conversion device, the coefficient matrix of the equation is decomposed into the product of matrices for graph incidence information and resistances and the matrix for element values other than resistances. The sufficient condition for the structural controllability is characterized by using only the first of these matrices. It is shown that the sufficient condition for the structural controllability of the electromechanical network is that its equivalent electrical network graph have no capacitor‐only cutsets and no inductor‐only loops.
On single layer routing with no wires passing between adjacent pins
Authors: Masuda Sumio , Kashiwabara Toshinobu , Fujisawa Toshio
Published: July 2007

This paper examines whether a circuit is realizable on a single‐layer printed wiring board. Linear time algorithms for this problem have been proposed under the constraint that no wiring is permitted below the mounted modules. However, this problem becomes NP‐complete when wiring below the mounted modules is permitted and the number of wires available between adjacent pins of a module is given. This paper presents an algorithm for this problem under the constraint that wiring is permitted under modules but no wires are allowed to pass between adjacent pins. The time complexity of this algorithm is proportional to the total number of pins of the circuit.
Control of the chrominance pattern with the luminance pattern
Authors: Sakata Haruo
Published: July 2007

The visual transmission of information consists of luminance information and chrominance information, which basically are dependent on each other. However, a new visual phenomenon in which chrominance information is controlled by luminance information has been found. It is described as follows.

(1) When a stationary luminance noise pattern is superposed on a chrominance spatial sinusoidal pattern (yellow‐blue), the chrominance sinusoidal pattern is deformed. As a result, the light portion appears as yellow and the dark portion as blue. This phenomenon occurs at 2 ± 3 cpd of the luminance noise frequency.

(2) A small‐field achromatic sine‐wave pattern enclosed by a yellow‐blue chrominance sine‐wave is perceived as yellowish in the white portion of the achromatic sine‐wave pattern, and as bluish in the black portion (4±6 cpd of the spatial frequency). These phenomena can be explained by lack of or no working of blue cones at the retinal fovea and the influence of the surrounding color on the appearance of color at the fovea.

Acknowledgement. Several helpful discussions on this study with each member of the visual psychology group at NHK Broadcasting Science Research Laboratories are gratefully acknowledged. The author also would like to thank Miss Y. Okada and Miss Y. Yamaoka for the evaluation experiments.
Adaptive transform coding of speech using vector quantization
Authors: Moriya Takehiro , Honda Masaaki
Published: July 2007

A digital wireless communication and speech packet transmission are two types of communication in which medium‐band (4.8‐9.6 kbps) speech coding for transmission and storage is essential. This paper investigates the minimization of waveform distortion using a waveform coding which is affected little by ambient noise.

An adaptive transform coding of speech using vector quantization (ATC‐VQ) is proposed. Two methods are introduced to utilize vector quantization in a frequency domain.
Active RC networks realizing immittance function and their applications
Authors: Fukai Sumio
Published: July 2007

The inductances, FDNRs, etc, in active RC networks are realized as immittance elements. Considering the existence of high‐order elements, a new method of constructing networks can be devised. In this paper, we present active RC networks realizing immittance functions. From fundamental circuits based on unilateral immittance circuits, high‐order networks realizing immittance functions with positive coefficients are derived. Their applications are demonstrated by inverted L‐type circuits. It is shown that the realized networks can be simply constructed and that desired values of the network parameters are easily obtained. It is confirmed by experiment that non‐pole type 5th‐order low‐pass filters constructed with the proposed networks are practical and the circuit sensitivity and dynamic range of the filters are studied.
Design and performance of a small cesium tube
Authors: Kihara Masami
Published: July 2007

The introduction of cesium oscillators as standard clocks in communication networks of the future is expected. It is known that the frequency stability and life of a cesium oscillator mainly depends on the cesium beam tube employed. This paper describes a design method of a cesium tube considering the short‐term frequency stability ± y(T) of the oscillator. The main factors controlling the S/N ratio of the cesium beam tube are considered. Using the figure of merit relating to ± y(T), a method is presented for optimizing the basic parameters (signal current, beam current and half‐amplitude frequency) relating to the Ramsay resonance signal. If the ratio of the beam current to the signal current is constant in the atomic beam tube without an electron multiplier, it is possible to obtain the same S/N ratio as in the conventional cesium‐beam tube with an electron multiplier by increasing the beam current. The figure of merit can be increased by increasing the signal current even if the half‐amplitude frequency is wide. Analysis of the operation of a small atomic beam tube is carried out to determine the optimum arrangement of components in the tube. It is confirmed by manufacturing a prototype beam tube that the figure of merit of 0.64 can be obtained as predicted.
Pole assignment for two‐dimensional systems using a multifunctional observer
Authors: Hinamoto Takao , Maekawa Sadao , Shimonishi Jiro
Published: July 2007

This paper considers the problem of arbitrarily assinging the poles for two‐dimensional (2‐D) systems by means of a dynamic output‐feedback including a multifunctional observer. The Roesser state‐space model is used to represent the 2‐D system in this paper. A method for designing a multifunctional observer is proposed for 2‐D systems and a sufficient condition for arbitrary complex‐number pairs to be assigned as the poles of the closed loop system is also presented. The proposed method has a property that the poles of a multifunctional observer are independent of the characteristics of the closed‐loop system.
Nonlinear oscillations in a series‐resonant circuit with an iron core of highly saturable characteristic
Authors: Kitahara Noriyuki , Ohshima Kenji , Abe Minoru
Published: July 2007

When ac voltage is impressed on a series‐resonant circuit with a core with third‐order characteristics, the m/n harmonic oscillation is often observed with the frequency in commensurate ratio m/n to the excitation frequency. Also, it sometimes happens that the m/n harmonic oscillation exhibits irregular transitions. For example, it may repeat transitions between unstable 1/2 and 3/5 harmonic oscillations. To characterize these oscillation phenomena, this paper considers the series resonant circuit with a core with highly saturable characteristic, and discusses the nonlinear oscillation when an ac voltage is impressed on the circuit. The fundamental equation for the circuit is derived and a numerical analysis is performed using a transformation method. As a result, it is shown that for a certain range of the system parameters, there exist 1/3 harmonic oscillations, which, by themselves are unstable and have different amplitudes. The two oscillators alternate for each three periods of the excitation voltage, resulting in a stable 2/6 oscillation. The physical interpretation is discussed for this periodic solution between chaos. The validity of the analysis was verified exprimentally by direct observation using an electrical circuit.
Realization method of approximate wave‐digital filter d‐section based on lumped/distributed network
Authors: Tokinaga Shozo
Published: July 2007

This paper proposes a reduction method for the D‐section which realizes the complex attenuation poles in the wave digital filter (WDF) design. The reduction is based on the lumped/distributed network. First, an approximate lumped network (called A2‐section) is introduced for the transmission line (UE) with the length T where Richard's variable u = tanh TS is replaced by the rational function qrs/(p2 + t2S2) (p ± 1.6, q ± 2.8). The A2‐section has a set of complex attenuation poles if the values t, p, q are chosen so far as the attenuation pole s = (± y ± j ± ‐ y2)/2(y = q/t, ± = p/t) is complex. In this case, the A2‐section is called the A2‐section. Then it can be shown that the cascade connection 2‐port of two GA2‐sections and series coils is equivalent to the D‐section, and the D‐section is also approximately equivalent to the 2‐port composed of two UE's and LC elements: By applying the well‐known WDT realization method by Fettweis and Swammy, simultaneously, an approximate but very simple D‐section of WDF is obtained. When the length of UE is small, the deviation of WDF response from the design specification is small. As an example, the design of the WDF bandpass filter is shown and the low coefficient sensitivity property compared to the conventional cascade synthesis method is verified.
Synthesis of multifeedback active filters based on the simulation of LC filters
Authors: Hayahara Etsuro , Takumi Ichi
Published: July 2007

This paper presents a synthesis method for the LC simulation‐type active RC filter. In the proposed method, the second‐order active RC filter, which has been used as the unit section in the traditional cascade structure, is modified into a multifeedback structure. The node equation of the original LC filter is set up and then simulated using the multi‐input circuit for each node voltage, which is a modification of the second‐order active RC circuit. The desired circuit is then obtained. As the original second‐order active RC circuit, Sallen‐Key's network and the SAB circuit of Friend are used in this paper. The design method for the circuit is summarized in a table as the design formula. The low element‐sensitivity property of the resistor‐terminated LC filter is retained in the proposed circuit. In particular, the element sensitivity is low when the relative errors among R‐ and C‐elements are small as in the thin‐film hybrid circuit. Finally, a design example and experimental result are shown for the fifth‐order elliptic filter, verifying that the circuit operates in accordance with the theory.
Analysis of the pull‐in range of phase‐locked loops by the galerkin procedure
Authors: Endo Tetsuro , Tada Kenzo
Published: July 2007

Numerous ways to analyze the pull‐in range of the phase‐locked system have been proposed, These include harmonic balance, the phase plane method and numerical analysis. In most of these methods, however, it was difficult to determine the actual pull‐in range with high accuracy. This is because of the limitations in the applicable phase detector characteristics and loop filters, or the need to perform a complex numerical analysis. This paper proposes Galerkin's procedure to determine the pull‐in range of the phase‐locked system, demonstrating that the pull‐in range can be determined with a high accuracy in a relatively simple way. Galerkin's procedure is a method of numerical analysis which can determine the periodic function for the nonlinear ordinary differential equation. By applying the procedure, the periodic solution of the second kind, corresponding to the out‐of‐lock condition of the system, is determined. From the critical input‐output detuning for the solution to exist, the pull‐in range is determined. This method can be applied to any phase‐detector characteristics and loop filters, and by taking higher harmonics into consideration, a highly accurate solution can be determined. In this paper, as examples, the pull‐in ranges are determined for a wide range of natural angular frequency and damping factor, for the phase detector characteristics which are sinusoidal, triangular, tanlock and sawtooth with fast jitter.
A computing method for obtaining derivatives of denominator and numerator of network functions with respect to elements and sensitivity analysis
Authors: Honma Hitoshi , Itoh Kouichi , Sagawa Masahiko
Published: July 2007

Various sensitivities necessary for prediction and evaluation of changes in characteristics of networks due to the changes in the value of elements and for optimization of networks, can be computed by using the derivatives of denominators and numerators of network functions with respect to elements. However, existing computing methods of derivatives are not suitable when the number of elements m is m > n (where the size of the matrix representing the network is n × n), that is, the sensitivity analysis which must be computed with respect to many elements. This paper presents a method to compute higher‐order derivatives of denominators and numerators of digital, analog and switched capacitor networks, using Vlach's redundancy improved method. Also, the proposed method and existing methods are compared with respect to the memory size and the number of multiplications required. It is shown that this method is more effective for analyzing the sensitivity for many elements. Finally, the method is implemented here and applied to several examples for element sensitivity analysis.
Improvement of noise attenuation of autoassociative memory using two‐stepped association procedure
Authors: Murakami Kenji , Aibara Tsunehiro
Published: July 2007

By means of autoassociative memory we can read out (or associate) original complete information from incomplete memorized information. If we assume that incomplete memorized information is made of additive noise and original information, autoassociative memory can be regarded as a noise attenuation filter. In this paper, using the twostepped association procedure we proposed earlier, we compose autoassociative memory and with its characteristics, propose a new method to improve the ability of noise attenuation in associative memory. This method restricts the width of the associative output space by changing the dimensionality of the mediate vectors in the twostepped association procedure in accordance with noise condition. This minimizes the influence of noise on the associative output as long as inferiority of information will not occur. In this paper, to examine the ability of this noise attenuation method, we calculate the mean square error (that is, correctness of association or ability of noise attenuation) of association theoretically and execute the association experiment (computer simulation) using the actual image information as the memorized information. From the results, it is clear that our proposed method has high ability of association (ability of noise attenuation) compared with the conventional methods.
Application methods of variable circuit assignment in satellite communications
Authors: Nakajima Seiichi , Suyama Masato , Usui Yukihiro
Published: July 2007

The satellite circuit has various features which cannot be observed in the terrestrial circuit. From the viewpoint of network construction, a significant feature is that the circuit between terrestrial stations can be modified flexibly. This paper discusses the application and features of the timed pre‐assignment (TPA) and demand assignment (DA), which are methods of the variable circuit assignment of satellite circuit. A problem in TPA is the circuit in use in the circuit group at the time of switching. Assuming the method of sequential group selection and pre‐blockade, the probability is calculated for the circuit to be in use at the time of switching. The result is compared with the method based on rearrangement indicating that the proposed method is more realistic. For DA, the call between stations, the cost of terrestrial detour route and ether parameters are used, and the possible range of application for DA is determined in comparison with the pre‐assignment method (PA), considering the terrestrial circuit. It is indicated that DA has a wider range of applications, even if the terrestrial circuit is considered. The reduction effect of the day‐to‐day traffic variation by DA is analyzed, indicating that one can really expect such a merit. The application ranges for the circuit‐based assignment and the group‐based assignment in DA are described. It is indicated that the circuit‐based assignment is desirable from a realistic viewpoint.
Hierarchical control by functional allotment
Authors: Hagino Kojiro
Published: July 2007

Most of the studies in the past on the hierarchical control have been concerned with the computational allotment between higher and lower levels, or among lower levels. In the actual system with a hierarchical structure, however, it often happens that the functional allotment is made between higher and lower levels. From such a viewpoint, the following scheme is considered in this paper. Consider a hierarchical control scheme with a functional allotment between higher and lower levels. The higher‐level controller views the whole system by a macroscopic view, and makes decisions so that the system is optimized from a wide range of viewpoints. Then the instruction is issued toward the lower‐level controller. The lower‐level controller views his own subsystem in detail and makes finer decisions so that the subsystem is optimized, while observing the instruction from the higher level as far as possible. The problem is formulated for the hierarchical control with functional allotment, considering the controllable linear discrete‐time stochastic system with a quadratic cost function. Then a situation is assumed where the information concerning the state estimation and the control input can be exchanged at each time between the higher and lower levels, and an algorithm is derived which can successively determine the control input at each time for the higher‐ and lower‐level controllers. Furthermore, it is shown by a numerical example that the intention of the higher‐level controller is reflected on the actual control by the lower level, by a suitable definition of the cost function of the higher‐level controller.
Duplex modified‐read coding scheme for facsimile transmission of documents
Authors: Tanaka Kiyoshi , Nakamura Yasuhiro , Matsui Kineo
Published: July 2007

This paper proposes a new duplex modified‐READ (MR) coding scheme for transmitting a facsimile picture on which other information can be embedded. When the vertical mode on the coding‐scanning line is coded, the MR coding is carried out by moving the run‐length of a black or white pel using the bit‐series of an information source to be duplexed. This method offers a facsimile picture which has almost the same quality as its original without increasing the quantity of the MR‐coding, and can transmit the second information without notice by a third person. For example, the second information with 2 k to 14 kbytes can be transmitted with one of the CCITT test documents. This is an answer to conventional facsimile systems which have a lack of secrecy. This method also contributes to double the transmission rate so that transmission lines can be used more efficiently.
Influence of pulse interference for fiber‐optic star‐ring lan using optical accessors
Authors: Sasaki Jun , Suzuki Shigeru
Published: July 2007

To realize a ring‐type optical LAN which is affected little by node failure and cable failure and yet is flexible in wiring, a star‐ring LAN with optical accessors within an optical cabinet is proposed. Although the present system has an advantage of realizing a high reliability with a one‐fold ring configuration, the system is susceptible to signal interference in optical accessors. The effect of this signal interference on the transmission quality has been evaluated by means of the equation for the equivalent transmission loss by Tokura et al. However, this equation was derived in the case where the discriminating level is always set at the optimum value of the main signal and is not applicable to a general receiving system which is set at the optimum value of the composite signal.

In this paper, a configuration of the star‐ring LAN is proposed first and its advantages are described. Next, an approximate equation for calculation of the equivalent transmission loss is derived for an optical receiver system which is set such that the discrimination level is an optimum value of the composite signal. Further, by means of experiments, the relationship is derived between the degree of interference and the equivalent transmission loss, and the experimental values are compared with the computed results. It is demonstrated that the computed and experimental results agree well. Finally, by the use of the results, the optimum value of the transmission loss of the optical accessors in a star‐ring LAN is determined.
Reflection and transmission of a gaussian beam from an anisotropic dielectric slab
Authors: Sonoda Takahiro , Kozaki Shogo
Published: July 2007

This paper describes the characteristics of reflection and transmission when a three‐dimensional Gaussian beam of fundamental mode is launched into a uniaxially anisotropic dielectric slab in which the optical axis has an arbitrary direction. The Fourier transform and solutions are obtained in integral form. Amplitudes of reflected and transmitted beams are calculated numerically by using FFT. To check the theory, experiment is performed by using laser and calcite. The numerical results are in nearly good agreement with the experimental ones.
Phase‐locked loop with a binary quantized phase and frequency comparator
Authors: Guonai Xu , Mori Sinsaku
Published: July 2007

To suppress the phase jitter in digital PLL as is done in analog PLL, it is necessary to narrow the bandwidth of the loop. On the other hand, the narrow‐band loop has an adverse effect on the range of synchronization and the initial pull‐in. Several proposals have been made to solve this problem [3, 6].

This paper proposes a new DPLL to solve the problem using a binary quantized phase and frequency comparator (PFC) composed of a general‐purpose shift register, monostable multivibrators and OR gates. Assuming the same jitter suppression performance, the proposed DPLL can broaden the range of synchronization by several times, compared with the traditional DPLL. The performance of the proposed loop structure is calculated theoretically, and the agreement with the result of experiment is verified.
Received signal level characteristics with adaptive transmitter power control in mobile communications
Authors: Fujii Teruya , Kozono Sigeru
Published: July 2007

The adaptive transmitter power control (ATPC) which controls the transmitter power in accordance with the propagation loss between the base station and a mobile station in the land mobile communication is effective in reducing the interference within a channel and that between the adjacent channels of the base station. Also, the portable mobile station which must be small and lightweight is required to reduce the average power consumption. One of the ATPC methods is the ATPC feedback control in which the up‐ and downlinks can be controlled independently.

In this paper, the receiving level probability density function is derived theoretically as the basic characteristics in the case of an ATPC feedback. Finally, the effects on the receiving level profile from the control parameters such as the controlled delay time, maximum amount of control, control step width and control level setting are investigated theoretically and experimentally.
Ray‐tracing analysis of anomalous propagation through horizontally nonuniform surface duct
Authors: Oka Eiichi
Published: July 2007

In a radio communication system using a frequency in the UHF and higher band, the fading due to change of the refractive index profile of the air is a significant problem which must be predicted. In this paper, an analysis using the geometrical optics theory is attempted to determine the propagation characteristics in a nonuniform air in which the refractive index varies in both height and range due to a small‐scale nonuniform air mass occurring in the propagation path.

After the refractive index of atmosphere is modified by the Earth‐flattening approximation, the Euler‐Lagrange differential equation is solved directly by numerical means so that the ray path is determined. In regard to low‐layer propagation with transmission and reception heights of less than several hundred meters, an air model was conceived in which a surface duct occurred in a part of the propagation path.

The relation of the location and size of the duct along the propagation path to the maximum arrival distance (line‐of‐sight) of the direct ray, divergence and convergence of the direct ray and the reflected ray and the arrival angle at the receiving point was studied in detail. It was found that the maximum arrival distance of the direct ray increases significantly depending on the location of the surface duct if it is small in size, the effect of the ray flux is greater on the convergence of the reflected ray than the divergence of the direct ray, and no significant change in arrival angle is seen at the receiving point for both the direct ray and the reflected ray.
Priority Go‐Back‐N ARQ schemes
Authors: Komatsu Masaharu
Published: July 2007

The go‐back‐N scheme is one of the error control methods in the satellite link. Various improvements have been made on this scheme, and the resulting throughput characteristics and packet delay characteristics have been described. However, in those methods, the priority of the class of the packet to be transmitted is not considered.

This paper discusses the go‐back‐N scheme where priority rules are useful when several packets with different priority classes are to be transmitted on the satellite link are introduced. Two priority rules are introduced: nonpreemptive priority queueing and preemptive priority queueing. The go‐back‐N ARQ scheme with those priority rules can easily be realized by adding the packet sort function to the transmitter buffer in the conventional basic go‐back‐N ARQ scheme. The traffic analysis is made of the go‐back‐N ARQ scheme with those two priority rules for an arbitrary number of priority classes, and the packet delay expression is derived for each class. Then by numerical calculation examples, the average packet transmission delay characteristics in the two methods are examined.
Theoretical analysis of a leaky millimeter‐wave antenna consisting of a layered magnetic slab image line with periodic corrugation
Authors: Erkin Sidic , Chang Nion Sock
Published: July 2007

In this paper, a millimeter‐wave antenna is constructed with layered magnetic thin films with different saturation magnetizations placed on a grounded conductor and with a periodic structure on the upper layer interfacing with air. Under the condition in which a dc magnetic field is applied externally, the scanning characteristics and the radiation efficiency of the antenna are analyzed with a perturbation method. In the analysis, the multiple scale method also is applied.

From the primary field, the coupling characteristics of the radiation field with the guided field and the incident field are derived while the amplitude transport equation is derived from the secondary field. By means of these results, the expressions for the radiation efficiency and the radiation angle of the antenna are obtained. Numerical calculations are carried out in the millimeter‐wave frequency range so that the magnetic field dependence of the beam scanning angle and the radiation efficiency are investigated.

From the numerical results obtained, it is found possible to construct a magnetically tuned millimeter‐wave antenna with a large radiation efficiency and a large beam scanning angle by adjusting the structural parameters of the antenna consisting of two layers of magnetic slabs with different saturation magnetizations.
Hierarchical service control scheme for intelligent network services
Authors: Kondo Yoshitsugu , Sato Kiyomi
Published: July 2007

With the introduction of communication services into business activities, such as telemarketing, customer requirements for these services are becoming more varied. Since communication service has become competitive, quick provision of services has become important.

This paper proposes a hierarchical service control scheme aimed at achieving service specification independence and the software architecture of an experimental intelligent network service system based on this new scheme. In the proposed new scheme, elementary functional parts are prepared beforehand and a service is realized using interpreter control based on the information about an execution order of functional parts.

To localize modifications in software when a new service is introduced, functional parts are arranged in a hierarchical manner. This experimental system can change complicated service specifications in a few minutes. Processing volume is about half of that for an existing system in which service specification is described by a programming language and service associated data are managed by a common data management program.
Study on performance improvement of CRV collision detection method
Authors: Hakamata Yoshiro , Oguchi Kimio
Published: July 2007

This paper considers the CRV collision detection method which detects the signal collision in the star configured optical local area network by detecting CRV, using the dipulse code and the partial response (1, ‐1) circuit. The result of theoretical investigation of the performance improvement also is presented.

First, the reflection‐type partial response (1, ‐1) circuit using a delay line is considered, and the transmission characteristics are formulated for the case where the delay line has a loss. Based on the result of formulation, a method to prevent the increase of the CRV rate due to the loss of the delay line without signal collision is considered.

The methods which are shown to be effective are the method to set the driving source impedance for the delay line at approximately 1.08 times the characteristic impedance of the delay line, and the method to employ a first‐order high‐pass filter with the 3‐dB cut‐off frequency at approximately 0.046 times the bit‐rate frequency fo.

Then, as a method to increase the CRV rate due to the signal collision, a method is considered in which two CRV detectors are used with the decision levels at Δ‐ and Δ+, respectively. It is shown to be effective to lower the decision level as far as possible.

Next, the use of two CRV detectors with the phase of the driving clock signal differing by π is considered, and it is shown that the end of signal collision can be detected in the CRV collision detection method by forming the logical sum of the two outputs.
Clamping circuit design for Multi‐Gbit/s baseband transmission systems
Authors: Hakamata Yoshiro , Takemoto Kenji
Published: July 2007

The transmission rate of several Gbit/s is required at present for the optical fiber baseband transmission system. From such a viewpoint, a clear design principle must be established for the transmission circuit, which operates at the Gbit/s band. This paper describes especially the result of studies on the design and experimental construction of the clamping circuit, which is indispensable in the capacitor‐coupled optical receiver. The elements to be employed in the clamping circuit for several Gbit/s transmission are different for the conventional transmission system of several hundred Mbit/s. The distortion of the transmitted waveform is enhanced in the Gbit/s band. Consequently, the operation of the clamping circuit is different.

From such a viewpoint, the behavior of the clamping circuit in the Gbit/s band is clarified by the analysis. An experimental circuit is constructed using the Schottky‐barrier GaAs diode and the depression‐type GaAs MESFET, and the operation is verified. As a result, it is shown that the characteristics of the experimental circuit agree well with the result of calculation, and the proposed method is useful in practice as the circuit design for the case with a large waveform distortion.
Interrupted voice quality evaluation and adaptive delay control in a voice packet communication system
Authors: Tanaka Yoshiaki , Ueno Tomoyuki , Inoue Jungo , Akiyama Minoru
Published: July 2007

In voice packet communication, a fluctuation is produced in the delay time in the network. This makes the packet, which is originally continuous, discontinuous at the receiver, and results in an interruption. The interruption deteriorates the voice quality. Then it is necessary that a delay should be provided at the side of the receiver to absorb the interruption. If the delay for absorbing the fluctuation is too small, the delay cannot sufficiently be absorbed; and if it is too large, the total delay is increased. In either case, the quality of the voice or speech is deteriorated.

From such a viewpoint, this paper discusses the absorption of the delay fluctuation of the voice packet. To set the delay for absorbing the fluctuation, the quality of the voice containing interruptions must be evaluated.

First, an objective evaluation measure is presented which is well aligned to the subjective evaluation of the deterioration of the voice quality with interruption. A control method to ensure the voice quality above a certain level is presented, which examines the objective evaluation measure for the varying traffic in the network. The method adjusts adaptively the delay for absorbing the delay fluctuation so that the voice quality is kept above a certain reference value.
Impedance characteristics of the normal mode helical antenna with a nearby conduction plate
Authors: Cho Keizo , Yamada Yoshihide
Published: July 2007

To improve the efficiency of a small‐sized antenna, a normal mode helical antenna (NMHA) is promising with a high radiation resistance. However, its efficiency is subject to degradation due to a nearby human body or radio equipment. In this paper, we replaced the human body, etc., by a conductive plate as a basic problem to analyze the influence of the human body and calculated the impedance when NMHA is in proximity of a conductive plate. In our calculation method, the influence of the conductive plate was replaced by an electric image of NMHA. We obtained the current distribution of a two‐element NMHA array which was placed in parallel by the improved circuit theory method which is similar to the moment method. As a result, we found that the real part of the mutual impedance between the array was positive, negative or zero depending on the value of the structural parameters of the antenna. The radiation resistance with a nearby conductive plate was the real part of subtracting the mutual impedance from the input impedance of a NMHA in a free space. In the shapes for zero or negative the real part of mutual impedance, the radiation resistance was equal to or greater than that of the unit antenna so that the conductive plate could be utilized effectively. We showed that the NMHA is a combined model of a dipole antenna and a loop antenna. For shapes with zero mutual impedances, we found that the far radiated field components of the dipole and those of the loop antenna were equal to the structural parameters which were almost equal to 2π2a2=pλ (a: helical radius, andp: pitch).
Simple go‐back‐N ARQ scheme for satellite channels with double acknowledgements
Authors: Komatsu Masaharu
Published: July 2007

This paper discusses a simple go‐back‐N ARQ scheme in which the satellite is provided not only with the repeater function but also with the processing function. The satellite detects the error in the data block sent from the transmitter. It returns ACK/NACK to the transmitter and relays the correctly received data block to the receiver. The receiver detects the error in the received data block and returns ACK/NACK to the transmitter. The transmitter examines two acknowledgement signals returned from the satellite and the receiver, and transmits the data block based on the basic go‐back‐N ARQ protocol. This paper analyzes the scheme in which the hardware complexity of the satellite is minimized. It is shown that the throughput can be increased and the average transmission delay can be decreased.
Experiments on suppression of differential lobing using an integrated SLS antenna
Authors: Kaku Nobuyuki
Published: July 2007

Since conventional secondary surveillance radar for air traffic control uses an antenna with wide beamwidth in the vertical plane, the deep lobing that appears makes aircraft detection very difficult. When the interrogating and SLS signals are transmitted from two different antennas, the period of lobing variation differs for both the signals and differential lobing is also observed. To prevent the problems caused by differential lobing, the integrated SLS antenna that was developed transmits the SLS signal from the same phase center as an interrogating antenna; moreover, the period of lobing variation in both cases becomes equal.

Experiments were defined out to compare the suppression capability of differential lobing of the integrated SLS antenna with the previous methods. The results show that the mainbeam killing and the sidelobe punch‐through due to differential lobing have been clearly suppressed and aircraft detection capability has improved by 10 percent as compared to the conventional method.
12/14‐GHz bands double‐flare type triple‐mode horn
Authors: Ebisui Takashi , Ishida Osami
Published: July 2007

This paper describes double‐flare type, triple‐mode horns made of two sets of cascaded combinations of a circular waveguide and a flare with a mechanism to generate higher order modes. This horn is intended to be used in two frequency bands. At a lower frequency band, the horn works as a dual‐mode horn, while it operates as a triple‐mode horn at a higher frequency band. Desired electrical characteristics can be obtained in both frequency bands.

In this paper, a design method of this triple‐mode horn is described first and the condition for minimizing the cross‐polarization components is presented. Next, the double‐flare type triple‐mode horn is described. It is shown that this condition is satisfied in two frequency bands. Various characteristics of the triple‐mode horn fabricated for 12/14 GHz designed on the basis of the present design procedure are presented. Excellent electrical characteristics are measured including the level of the cross‐polarization components of less than ‐29 dB with respect to the peak level of the co‐polarization component. The measured results are similar to the designed data.
Signaling protocol architecture for a digital mobile communications network
Authors: Nakajima Akihisa , Yamamoto Kouji , Utano Takanori , Suzuki Shigefusa
Published: July 2007

This paper proposes a signaling protocol which can be applied to high‐capacity digital mobile communications networks.

First, a hierarchical network function model based on the Intelligent Network (IN) concept is described. In the model, the need for mobile transit switching capability and subscriber line signaling transfer capability is discussed.

Second, interoffice signaling protocol and subscriber line signaling protocol are proposed. The interoffice signals consist of circuit‐related signals which are based on the SS No. 7 ISDN User Part (ISUP) and noncircuit‐related signals which apply SCCP and TCAP. The subscriber line layer‐3 signals are designed for expansion and radio frequency efficiency. The layer‐3 grouping function is applied for efficient use of radio frequency.

Third, some examples of procedures using those signals and comparisons of signal number and signal volumes between the digital system and the present analog system are shown.