bluuebunny/crossref_metadata_2025_split huggingface dataset:
Required accuracy in manufacturing process of three‐wire transmission line used in inductive radio system for detecting linear motor vehicle position
Authors: Hatta Tohru , Kusakabe Takashi , Asai Takahiro 
Published: July 2007

AbstractThe three‐wire transmission lines consisting of square‐wave‐formed line conductors has a structure in which any two of the three line conductors iterate narrow and wide sections at a specified interval along the longitudinal direction. Among those sections, the narrow section has the following problem. If line conductors deviate even a little from their normal positions due to the inaccuracies in the manufacturing process, relatively large unbalances will be produced in the mutual impedances and admittances between them. This leads to the crosstalk between the positive and negative phase sequence components of the signal and consequently to the detection error in the position of the vehicle. We considered the case where the manufacturing inaccuracies distribute at random or uniformly along the longitudinal direction. A quantitative analysis is made for the problem arriving at a guide for the manufacturing accuracy of the transmission line, which is required to ensure the desired accuracy of position detection. It is desirable in the narrow section that the two conductors maintain a distance above a certain value. It is also desirable that the radius of the line conductor be as small as possible, as long as the transmission loss of the line is within the tolerable value. Compared with the transmission line consisting of helically wound conductors, which we have already reported, there will still be a more strict requirement on the manufacturing accuracy on the transmission line consisting of square‐wave‐formed conductors.
Design and characteristics of low‐loss polarization grid
Authors: Kondo Akira , Kagoshima Kenichi 
Published: July 2007

AbstractPolarization diplexing is possible by means of a grid plate and hence a frequency reuse antenna can be realized. Usually, the characteristics of a grid plate can be evaluated by an analysis based on an equivalent circuit. However, for a practical grid with a support mechanism made of dielectric or honeycomb structures, the reflection level of the unwanted polarization at the time for transmission of the desired wave is larger than the value for the metal grid only and hence the results are different from those by the equivalent circuit analysis. In this paper, the characteristics of the grid with a dielectric support layer are analyzed by means of full‐wave analysis so that the relationship between the thickness of the dielectric support layer and the reflection level of the unwanted polarization is detected. Next, a method is proposed for suppression of this unwanted polarization in a grid with a dielectric support layer. The validity was confirmed by theoretical analysis and experiments. Further, the design method and the numerical results are presented for a low‐loss polarization diplexing grid used in a frequency reuse antenna. It is pointed out that there exists an optimum parameter that minimizes the insertion loss in the operating bandwidth.
A soft decision viterbi decoding method using received carrier level in fading channel
Authors: Yamaguchi Kazuhiko , Tokita Toshio , Imai Hideki 
Published: July 2007

AbstractTransmission channels in mobile communication are extremely unstable due to the effect of multipath fading. Therefore the realization of high‐reliability communication necessitates the introduction of error control in the form of error‐correction coding.This paper considers the decoding of error‐correcting codes that are adapted to digital mobile communication operating under Rayleigh fading conditions. A soft decision Viterbi decoding using the received carrier level is studied for the case of convolutional codes. This soft decision method is based on the level of the received carrier by adaptively determining the metric used in the decoding. In this way a metric is obtained for digital mobile communication.This paper also presents an estimation method using error exponent which provides effective means to realize such a soft decision method. If the channel can be considered memoryless due for example to interleaving, then this method provides an easy way to estimate: (1) the figure of merit for quantizing thresholds, and (2) the gains of the soft decision.First, it is shown that using this kind of estimation in the case of channels which can be considered sufficiently memoryless due to interleaving, extremely large gain is obtained by the soft decision method discussed in this paper.Next, simulations are performed and the efficiency of the estimation method is demonstrated. Finally, the bit error rate characteristics are shown for the case when the channel is not made sufficiently memoryless by interleaving.
Performances of integrated voice/data multiplexing system with controlled arrival
Authors: Fujii Shumji , Hayashida Yukuo , Tezuka Yoshikazu 
Published: July 2007

AbstractIn the integrated voice/data multiplexing system based on a time‐slotted frame format, the expected queue length of data packets increases significantly when the voice calls temporarily occupy all slots, even if the traffic loads of voice and data are light. To reduce such an increase of data queue, the integrated voice/data multiplexing system is investigated in this paper, and the arrival and service rates of voice calls are controlled with the number of slots occupied with voice calls. The system is analyzed exactly as an M/M/X queue by varying the number of servers, and the approximation method is presented for studying the behavior of a large‐number slot system. As a result, in a light data traffic load, it is effective in reducing the increase of data queue that the arrival and service rates of voice calls be controlled when a large number of slots are occupied by voice calls. However, in a heavy data traffic load, it is effective to use the movable boundary scheme in which necessary numbers of slots are reserved for data traffic.
Voice, data and video integrated broadband metropolitan area network
Authors: Kobayashi Hiroshi , Haruyama Hideaki 
Published: July 2007

AbstractThis paper discusses the technical feasibility of the multimedia metropolitan area network based on the tree‐shaped broadband network, employing two‐way CATV technology. In the proposed network, all information can flow on any transmission line through the headend. This leads to the following features, which cannot be realized in the star network as in the telephone network:

Flexible services are provided.
An efficient information communication service can easily be realized.
It is easy to provide the highspeed broadband service at a low cost.
The security of the network can be improved.
The following systems were developed by the authors as examples of the information communication services utilizing those features: TDMA circuit switching service using “time‐slotted bus with control window,” CSMA/CD packet switching service using “beat signal level detection,” and TDMA video switching service, where several video signals are multiplexed as analog signals. Those services can be provided to more than 10,000 subscribers in a service area of diameter 20 km or more. The system is expected to provide the basis for the information communication in local communities, together with the widespread use of urban‐type CATV.
A noncongestion self‐routing control algorithm of generalized benes network
Authors: Sezaki Kaoru , Tanaka Yoshiaki , Akiyama Minoru 
Published: July 2007

AbstractRecently, to realize broadband ISDN, ATM has been studied vigorously. As the switching network for ATM, the delta network and other switching networks have been investigated by a number of researchers. The delta network performs the self‐routing based on the multistage connection of 2 × 2 sized matrix switches. However, this network has a problem in that the throughput is decreased drastically when the traffic imposed on the switching network is nonuniform.To avoid such a situation, a method is proposed to make the whole network a Benes network by placing a distribution network preceding the delta network to balance out the traffic. The addition of the distribution network, however, has only been investigated for the case where all matrix switches are of the same size.With this as the background, this paper discusses the switching network with several sizes of matrix switches. The method of placing the distribution network is discussed together with the characteristics, and application examples are presented.
A study on shared buffer‐type atm switch
Authors: Kitamura Haruo 
Published: July 2007

AbstractThe conventinal shared buffer‐type switch in ATM multiplexes the cells, and a large number of cells is stored in a memory. This produces a problem in that the speed within the switch must be increased, which is limited by the speed of the circuit.This paper proposes a shared buffer‐type switch in which a number of memories are provided, each storing a cell, and the switching is executed without the cell multiplexing. Several features are realized as follows.The required number of buffers is less than in the output buffer type. The priority control and the broadcasting can be realized. There is a flexibility in that the number of input and output lines are arbitrary. If the proposed switch with a high speed is used in the multistage switching network, a switch with an excellent performance such as low‐loss rate and high throughput can be obtained.
Frequency selective surfaces for radio astronomy–characteristics of 40/80‐ghz fss
Authors: Irimajiri Yoshihisa , Takano Toshiaki , Tokumaru Munetoshi 
Published: July 2007

AbstractFrequency selective surfaces (FSS) have been developed for applications to the 45‐m telescope of the Nobeyama Radio Observatory (NRO), the National Astronomical Observatory (NAO), Japan, for simultaneous observations of radio astronomical sources at the 40‐ and 80‐GHz bands.The Jerusalem‐cross array configuration has been used for the conducting array. The designed characteristics satisfy requirements for radio astronomy: small insertion losses and little distortion of polarization. The measured characteristics were in good agreement with the calculated ones. The fabricated FSS has low insertion loss of 0.1 and 0.6 dB at the 40‐ and 80‐GHz bands, respectively.It was found that the distortion of circular polarization is not significant for polarized radio astronomical sources of polarization degree of more than 5 percent. The characteristics of the developed FSS satisfy solar radio astronomical requirements.
Jitter characteristics of an optical repeater module using dpll
Authors: Takahara Mikio , Noda Kenta 
Published: July 2007

AbstractInitially, jitter characteristics of the multistage connection of optical repeater modules using the digital phase‐locked loop (DPLL) for the timing extraction are examined. Then some problems to be solved are pointed out from the results. Next, a system using new modules with a nonresponse period to improve the jitter characteristics of the module is proposed. It is shown that the nonresponse period is nearly equal to one divided period (TDO).The proposed scheme shows much better jitter suppression characteristics than some other systems, e.g., the clock frequency duplication system, the phase correcting‐restriction system and the system using a random walk filter.Finally, experimental jitter suppression characteristics of multistage connection of new modules with a nonresponse period of 0, 0,5TDO and 1.0TDO, respectively, are shown. These characteristics show a good agreement with simulated results. It is confirmed that the system using DPLL with a 1.0TDO nonresponse period shows the most satisfactory result.
Direct sequence/spread spectrum communication systems using chip interleaving and its applications for high‐speed data transmissions on power lines
Authors: Tachikawa Shin‐Ichi , Toda Kiyoshi , Isikawa Takehiro , Manibayashi Gen 
Published: July 2007

AbstractThis paper presents direct sequence/spread spectrum (DS/SS) systems using chip interleaving and its burst noise suppression effect for data transmissions on power lines. First, to protect from the impulsive or periodic burst noise, a convolutional chip interleaving method for randomizing the time intervals of interleaved chips and synchronizing with PN sequence is applied. Second, to obtain the randomness of chip intervals, multielement M‐sequences and Tausworthe‐Lewis‐Payne (TLP) sequences are adopted, and several properties (generation frequency of each element, autocorrelation function, etc.) are shown. Finally, as an application, experimental results for high‐speed (8.2 kbit/s) data transmissions on power lines are shown.
Clamp spring removal and fitting method for optical multifiber connector with index matching material
Authors: Kobayashi Hideo , Ueno Kouji , Uenoya Takuya 
Published: July 2007

AbstractIn single‐mode multifiber connectors, the ferrule endfaces spacing is filled with index matching material and the contact is pushed by the clamp spring. To perform the transfer splicing, the clamp spring must be removed and fitted before and after the transfer action.In this paper, first, the relations among the ferrule pushing force, Young's modulus of the ferrule material, radii of curvature of ferrule endfaces, contact length, etc., are investigated elastomechanically to find the conditions under which the ferrule endfaces‐contact remains stable.Next, the fluidity of index matching material and the applied force, together with loss variations are investigated to clarify the mechanisms responsible for loss generation and the situation in which the losses can be kept small.Finally, based on the results of these investigations, the removable clamp spring and fitting mechanism is manufactured. By evaluation of its characteristics, it is shown that satisfactorily good performances are confirmed.
Self‐healing techniques utilizing virtual path concept for ATM networks
Authors: Kawamura Ryutaro , Hadama Hisaya , Sato Ken‐Ichi 
Published: July 2007

AbstractStrong international effort has been made toward the realization of a B‐ISDN based on ATM techniques. This paper proposes self‐healing techniques for enhancing ATM network reliability. Self‐healing is defined here as failed path restoration with distributed control mechanism by using cross‐connects.First, the characteristics of virtual paths (VPs) are compared with those of digital paths in STM networks. It is clarified that VP benefits can be exploited for network restoration upon failure. Two high‐speed self‐healing algorithms that make the best use of VP characteristics are then proposed for restoring single‐link failures. A technique for multiple‐link failure restoration also is proposed. Finally, restoration performance is evaluated by computer simulation. It is confirmed that the proposed algorithm enables faster restoration than that possible using the existing algorithm for STM networks.
A multiplexing method of multimedia signal in ATM networks
Authors: Kajiyama Yoshio , Tokura Nobuyuki 
Published: July 2007

AbstractIn the ATM network, which handles such multimedia services as voice, video, and data, a traffic control technique must be established to cope with various requirements of the media for transmission quality. From such a viewpoint, this paper discusses the multiplexing control method which can control the quality. Through the discussion, a control method is proposed which multiplexes the multimedia with various quality requirements and the details of the method are presented.The proposed multimedia multiplexing method contains two control schemes: the polling control for the number of queueing cells with an offset; and the control by monitoring the queue length. The two control methods are switched according to the number of waiting cells of the medium in the severest condition so that the cell delay and the cell loss are controlled.Using the proposed design, the optimal hardware configuration can be derived from the input model and the requirements. Based on the designed optimal hardware configuration, the multiplexing performance of the proposed control method is evaluated by a simulation. It is verified that the multiplexing performance meeting the requirement of each medium is obtained, and a higher throughput is obtained than the polling control without an offset or the queue length monitoring control, indicating that the proposed method is an excellent multiplexing control method.
Photonic lattice‐type self‐routing switching network
Authors: Ogino Nagao 
Published: July 2007

AbstractThe asynchronous transfer mode (ATM) is considered as a fundamental technique in constructing the broadband ISDN. High‐speed switching is required in the ATM switching equipment, which forms the core of the ATM network. Then it is desirable to apply the self‐routing switching network. Various self‐routing switching networks have been proposed including the Banyan network, as well as its improvements. This network is composed of the multistage connection of 2 × 2 switches. However, problems remain in such switching networks, for example, the hardware scale in the large network and the hardware reliability.This paper proposes anew a photonic lattice‐type self‐routing network with the following features: (1) the system has essentially a bus structure and excellent expandability; (2) by its structure, the hardware scale increases only slowly in proportion to the number of accommodated circuits. This is an advantage in the large‐scale network; (3) again by its structure, it is possible to deroute the cells thereby avoiding the point of failure which improves the reliability; (4) by restricting the number of cell transfer paths to a certain number, a relatively simple routing control circuit can be employed based on the optical switching circuit; and (5) by the application of the optical switch, the transfer delay of the cell is reduced greatly.
Integrated train access protocol with synchronous and asynchronous traffic
Authors: Hayashida Yukuo , Uchikoshi Tadashi 
Published: July 2007

AbstractIntegrated train access protocol for a high‐speed ring network is proposed in this paper. Using the concept of the train, synchronous and asynchronous traffic is integrated. To consider the fundamental performance, the periodicity of the channel activity is found in the steady state, and the cycle length is derived. On the basis of this cycle length, the train length, channel utilization, and access interval of each traffic are derived.To characterize the proposed protocol more clearly, it is compared with fiber distributed data interface (FDDI), which uses the timed token scheme. As a result, it is shown that the proposed protocol and FDDI have the same high channel utilization.On the mean access interval of the asynchronous traffic, FDDI shows the increase character with the target token rotation time (TTRT), while the proposed protocol shows the decrease character with the number of asynchronous frames contained in the train γ.
Analysis of a coil‐loaded wire antenna
Authors: Taguchi Mitsuo , Yamashita Kiyomi , Tanaka Kazumasa , Tanakas Toshiyuki 
Published: July 2007

AbstractAn analysis method using Pocklington's integral equation is presented for wire antennas with lumped inductive loading along its arm. In the formulation of the integral equation, using the equivalence principle, the equivalent electric and magnetic currents on the coil surface are expressed instead of the current flowing on the coil and the electric field. The boundary condition that the axial component of the total electric field vanishes is applied on the antenna axis including the coil. Piecewise‐sinusoidal functions are used for the current expansion functions and the weighting functions.The numerical calculation is made for the different numbers of turns, pitch, and radius of the coil loaded at the midpoint or the top of a dipole antenna. The good agreement between calculated and measured values for the current distribution and input impedance are obtained. The analysis method proposed in this paper is applicable to antennas with resistive or capacitive loading by changing the expressions for the equivalent currents on the surface of loads.
An interference cancellation method for small earth stations
Authors: Minamisono Kenichi , Satohs Gunkichi 
Published: July 2007

AbstractThis paper proposes an interference cancellation method called the in‐band power minimizing method (IPMM), and describes the use of the method in satellite communication earth stations. In this method, an interfering signal arriving from an earth station antenna is combined by a cancellation circuit with an interfering signal received by an auxiliary antenna and the two interfering signals are arranged to have equal amplitudes but opposite phase. To achieve this condition, the amplitude and phase are adjusted so that the signal power of the output signal from the cancellation circuit contained in the desired signal frequency band is to be a minimum. This method is characterized by the fact that a simple circuit can be used to detect interference rapidly and accurately even at low C/N ratios.This paper also discusses the principle of IPMM and examines the results obtained when it is applied to small earth stations. It was found that IPMM is quite effective in this application.
Computer experiments on electromagnetic disturbance produced by a spacecraft in a fast plasma flow
Authors: Okada Masaki , Omuras Yoshiharu , Matsumoto Hiroshi 
Published: July 2007

AbstractWhen the electromagnetic environment of the space plasma is observed by a spacecraft in space, it is often difficult to distinguish the disturbance due to the satellite itself and natural phenomena. In such cases, it is effective to use a numerical experiment in which the phenomena arising around a spacecraft are reconstructed on a computer. Since the plasma filling the space is extremely dilute, the particles are in a collisionless condition. To treat such a collisionless plasma, the electrons and ions comprising the plasma are treated as individual particles. In such cases, it is a good approach to use the electromagnetic particle code in which the electric field and the magnetic field are solved progressively in time according to Maxwell's equations.To reconstruct on the computer, the environment around the spacecraft flying in space as closely as possible, the authors are developing the electromagnetic particle code in which the spacecraft is included as an internal boundary. This paper reports the numerical experimental results on the electromagnetic environment around the satellite which is formed when the spacecraft is exposed to a high‐speed plasma flow in a space plasma. A plasma flow is given from one end of the free boundary, and a spacecraft is placed in such a flow. By changing the parameters of the plasma, the physical quantities controlling the generation of the disturbance are found. In regard to the mechanism of the disturbance generation and the two‐dimensional configuration of the disturbance, several characteristics different from those predicted are obtained.