bluuebunny/crossref_metadata_2025_split huggingface dataset:
A reconfigurable wiring concentrator in hierarchical star with dual‐ring LAN
Authors: Nakayashiki Susumu , Kashio Jiro , Harakawa Takeshi 
Published: July 2007

AbstractThe in‐house information communication network using local area network (LAN) is required to cope flexibly with the expansion/modification of the system and to avoid the system‐down in the generation of a fault by detaching the fault domain.This paper considers the star‐ring LAN with the ring spurs and a dual ring. It proposes also the structure and control of the wiring concentrator of ring LAN with the dedicated automatic reconfiguration control by the ring spur bypass and the ring wrapback. Since the ring contains both the ordinary terminals and WC, the reconfiguration‐dedicated medium access control (MAC) frame is introduced anew and can be sent only by wiring concentration (WC), making unnecessary the specification modification of the MAC layer of the terminal.The WC which handles the localization and detachment of the fault point is determined by this mechanism. The test ring is automatically expanded from the local ring in WC to the ring containing the ring spur and the ring containing the dual ring successively by testing the conductivity.Using WC, a ring LAN system with the automatic ring degeneration/expansion function can be realized, while providing the terminal with the function of connection/detachment/shift on LAN (hot‐pluggability). The time required for reconfiguration by the proposed reconfiguration control is evaluated by summing up the times for the major control steps and by experimental examination.
Effects of transmission delay in audiovisual communication
Authors: Kurita Takaaki , Lai Satoru , Kitawaki Nobuhiko 
Published: July 2007

AbstractTo provide audiovisual communication such as television telephone and television conference economically and efficiently, high efficiency coding, satellite communication and asynchronous transfer mode (ATM) are considered for introduction to the communication network. However, these technologies may degrade communication quality since they increase the signal propagation delay time. The effect of the propagation delay on the communication quality has been studied frequently for voice communication by telephone, but there have been few studies on audiovisual communication. Further, the effect on the delay quality by the addition of video to the voice has not sufficiently been understood.
Transmission loss budget design of the optical star‐shaped ring network
Authors: Hakamata Yoshiro , Sueyoshi Yoshinao , Okuno Masayuki 
Published: July 2007

AbstractOne high‐fidelity ring‐type optical transmission network is the star‐shaped ring network having a multi‐port accessory in its hub. The present paper describes the transmission loss budget design for the star‐shaped ring network that takes into account continuously received interference signals. Conventionally, the S/X value, which is the ratio of the main signal power to an interference signal power, has been used to evaluate the degree of interference.First, the factors responsible for determining this ratio are discussed and then a design chart is derived to correlate the S/X value with the level difference between the transmitter and the receiver for the network. Based on this design analysis, multiport optical accessors are fabricated; and measured results are presented. It is demonstrated that the star‐shaped ring network with, desirable performance can be realized successfully. Finally, a method to lower the level difference between the transmitter and the receiver using multiwavelengths is proposed.
Scattering of circularly polarized waves by a conducting cylinder–a representation in terms of circularly polarized energy flux densities
Authors: Tokumaru Shinobu , Ping Wang 
Published: July 2007

AbstractTo understand the radiation and scattering phenomena of electromagnetic waves visually, streamlines of the electromagnetic energy flux density are drawn. This paper attempts to show the scattering phenomena of circularly polarized waves in the presence of an infinitely long perfectly conducting circular cylinder by graphical presentation of the streamlines. This is based on the Poynting vector and circularly polarized electromagnetic energy flux densities proposed recently.From the viewpoint of circularly polarized electromagnetic energy flux density, the conversion of a circularly polarized field to a cross‐polarized field on the cylindrical surface is drawn specifically. Even though the structure of the scatterer is two‐dimensional, the streamlines of the electromagnetic energy flux density is threedimensional. This phenomenon originates from the nature of toroidal fields of the Poynting vector and the cross Poynting vector.
Fault location in optical lines of passive double star networks by pattern matching of OTDR waveforms
Authors: Takeda Kazutoki , Koga Hiroaki 
Published: July 2007

AbstractPassive double‐star networks (PDS) in which optical branches are used to connect local offices and subscribers have been intensively studied. If optical time domain reflectometry (OTDR) is used to test optical cables, the return wave will be a complex superposition of many reflected waves from many optical branches. Therefore, the determination of fault locations by conventional analytical methods is difficult. To detect fault locations more accurately, a new method using pattern matching of the reflected waveforms obtained by OTDR with the waveforms calculated by a computer is proposed. The scattering matrix and an algorithm for calculating the waveform are described and the principle used in detecting the fault location is discussed. A theoretical equation for the error due to noise in the optical circuit is formulated and is used to derive an equation relating the measurement error to the location of the fault, the number of branches, the bandpass frequency, and the pulsewidth. An experimental optical cable (about 3 km long) with four branches was fabricated and used in tests of the accuracy of fault location with a pulsewidth of 1 μms. The error was found to be less than 12 m.
A dynamical system model and equivalent steering signal concept in adaptive arrays
Authors: Ueno Motoharu , Kawabata Kazuaki , Moro‐oka Tasuku 
Published: July 2007

AbstractThe versatile and affluent adaptive array antenna (adaptive array) is studied as a linear dynamical system. Also, the concept of the equivalent steering signal is introduced by expanding the concept of the steering signal of a maximum signal‐to‐noise ratio (MSN) array. The adaptive array is considered as a system which is expressed by two equations, i.e., the state equation and the output equation, and its model is proposed. As the input signal to this method, the equivalent steering signal is defined. Based on the correlation coefficient between the equivalent steering signal and the array input signal, the characteristics of adaptive arrays are analyzed.From this viewpoint, a simple, clear and systematic investigation method for adaptive antennas is proposed for several characteristics of adaptive arrays for which the analysis is cumbersome and the physical meaning is not clear in the conventional methods. Further, it is illustrated that the equivalent steering signal is related closely to the a priori information of the desired signal which is important in the adaptive array. The importance of the a priori information in the adaptive array is emphasized.
A method to estimate normal mode noise voltage induced on indoor telecommunication lines due to adjacent AC supply lines
Authors: Ideguchi Tsuyoshi , Hattori Mitsuo , Ootsuki Fumio 
Published: July 2007

AbstractWhen metallic telecommunication lines carrying digital signals are laid adjacent to ac supply lines in an office or a house, then the noise generated by the ac supply lines is induced on the telecommunication lines and the quality of transmission may be degraded. To calculate the induced voltage generated directly between the cores of a telecommunication line requires accurate values of the coupling admittance or coupling impedance between the two lines corresponding to the cable construction and the problem becomes very complicated.This paper proposes a simple method of estimating the voltage induced between the cores of a telecommunication line when the telecommunication line is laid adjacent to an ac supply line. The amount of coupling from the primary circuit with an open‐circuited terminal and with a short‐circuited terminal to the secondary circuit is measured. Using this value, the characteristics of the induced voltage corresponding to an arbitrary value of terminal impedance of the primary or secondary circuit simply are estimated. The validity of the estimation method was confirmed by experiments.
Improving the sensitivity of electric field sensor with linbo3electrooptic crystals by loading inductance
Authors: Tajima Kimihiro , Amemiya Fujio , Kuwabara Nobuo , Kobayashi Ryuichi 
Published: July 2007

AbstractRecently, with the diversification of electromagnetic compatibility (EMC) problems, the need for an electric field sensor to measure the electromagnetic pulses and the electric field near the equipment has increased greatly. An electric field sensor using LiNbO3, which has an electrooptical effect, has been used for such measurements; but the sensitivity is not satisfactory. However, the sensitivity can be improved by increasing the sensitivity of the optical modulator or by increasing the output of the optical modulator source.Here, we describe a method to improve the sensitivity at resonance frequency by loading inductance. First, an equivalent circuit representing the sensor with loading inductance is derived. Second, the frequency characteristics are analyzed theoretically by applying the moment method to this equivalent circuit and the improvement in sensitivity by loading inductance is demonstrated. Moreover, the validity of analysis is confirmed by performing the experiments using the GTEM‐cell.As a result, it is found that the measured results show good agreement with the calculated results and the sensitivity can be improved by inductance loading. It has been confirmed that the sensitivity of the electric field sensor with element length of 150 mm could be improved by about 40 dB at 200 MHz by using the loading inductance of 600 nH.
Observation of k‐distributed sea clutter via an x‐band radar
Authors: Ishikawa Yoshihiro , Sekine Matsuo , Musha Toshimitsu 
Published: July 2007

AbstractIn radar signal processing, it is important to eliminate unwanted noise called clutter and to detect the desired target so that the degree of discrimination is improved. To this end, the statistical characteristics of the clutter have been investigated. In such instances, it is necessary to have a process which obtains a constant false alarm rate (CFAR).In this paper, the amplitude intensity distribution of the sea clutter measured by an X‐band radar is studied quantitatively by means of the Akaike Information Criterion (AIC) under an assumption that the intensity distribution is Weibull, log‐normal and K‐distributions. It is confirmed that, for a high sea state with wave height of 6 to 9 m and wind velocity of 25 m/s, the sea clutter follows a log‐normal distribution as a whole and a K‐distribution within the antenna beamwidth.With regard to the CFAR circuit by normalization of the standard deviation which is considered effective for suppression of the clutter following a Weibull and a log‐normal distribution, a CFAR processing was carried out with both Monte Carlo simulation and raw data. From the results of computer simulation, it was confirmed that the CFAR circuit is effective for suppression of clutters following a K‐distribution. Also, by processing the raw data by this circuit, it was successful in correctly detecting targeted ships while the clutter was suppressed.
A subband‐dpcm codec for HDTV and its performance
Authors: Irie Kazunari , Okumura Yasuyuki , Sakurai Naoya , Kishimoto Ryozou 
Published: July 2007

AbstractTransmitting high definition television (HDTV) signals over digital networks requires bit‐reduction coding techniques if cost‐effective services are to be provided. This paper describes a high‐quality HDTV codec that can encode original 1.2 Gbit/s HDTV signals into 60 and 300 Mbit/s. These bit rates are selectable and are compatible with the transmission rate used in B‐ISDN based on the synchronous digital hierarchy (SDH). A subband DPCM (differential pulse‐code modulation) coding algorithm capable of distortion‐free encoding is used. A new type of perfect reconstructive short‐kernel subband filter that reduces subband signal entropy is introduced. the performance of the codec is evaluated using actual video signals. Experimental results show that a very high percentage of the component signals can be transmitted distortion‐free at 600 Mbit/s. High‐quality images can be regenerated from the 300 Mbit/s signal.
Computer experiments for excitation mechanism of upshifted electromagnetic emission observed in ionospheric heating experiments
Authors: Ueda Hiroko , Goodman Simon , Matsumoto Hiroshi , Omura Yoshiharu , Okuzawa Takashi 
Published: July 2007

AbstractThe component wave called the BUM (broad upshifted maximum) excited at the time of electromagnetic heating experiment of the ionosphere is seen on the higher‐frequency side band of the pump wave or its harmonics. Therefore, its excitation mechanism cannot be explained by a simple parametric instability. There fore, the mode instability theory based on the nonuniform density plasma has been proposed.In the present research, in reference to the theoretical prediction as a starting point of analysis of the excitation mechanism, computer experiments are carried out by means of the electromagnetic particle code. It was confirmed that the density nonuniformity of the plasma is important for the excitation of the BUM. Also, an excitation mechanism of the BUM conceivable from the computer experiment results is proposed.
Virtual path restoration techniques based on centralized control functions
Authors: Hadama Hisaya , Kawamura Ryutaro , Sato Ken‐Ichi 
Published: July 2007

AbstractTo create a highly reliable ATM transport network, one of the most important issues for network providers is to identify the most efficient restoration technique against network failure. This paper determines which virtual path route alteration techniques can restore virtual paths against single‐link failure in a nationwide ATM transport network within a few seconds.First, centralized restoration techniques are classified and the relative benefits of the techniques are clarified. Then the evaluate restoration time, necessary spare capacity, size of data storage and necessary time for data distribution from the control center to cross connect systems for restoration are evaluated. This study shows that virtual path grouping and predetermined route alteration scenarios are extremely effective in restoring damaged virtual paths rapidly. High‐speed data distribution links or predistributed route alteration data also are important for rapid restoration from failure.
SN improvement ratio by time delay and integration for high‐resolution earth observation system
Authors: Nagura Riichi 
Published: July 2007

AbstractThe improvement of the signal‐to‐noise (SN) ratio is one of the most important issues for the high resolution earth observation system. A time delay and integration (TDI) method combining plural CCD output signals should provide the solution for acquiring high SN ratio without increasing the optical diameter. However, for an actual satellite, there are various fluctuations in the satellite attitude or jitters from other equipment, which degrade the SN improvement ratio achieved by the time delay and integration method. This paper analyzes SN improvement ratio characteristics under the above fluctuations. the paper reveals optimum integration times and the maximum SN improvement ratio and also the requirement on satellite attitude variation and jitters from other equipment. the paper also discusses the methods to obtain the maximum SN improvement ratio using correlation detection between adjacent CCD for the time delay and integration method even under the presence of the above fluctuations.
Characteristics of a slot‐couped microstrip antenna using high‐permittivity feed substrate
Authors: Takeuchi Kazunori , Chujo Wataru , Fujise Masayuki 
Published: July 2007

AbstractThe slot‐coupled microstrip antenna can be used for constructing a thin and lightweight active antenna without a feed loss by electromagnetic coupling of such active circuits as MIC and MMIC on the back side directly with the radiating element via the slot. Hence, this structure is promising as a highly functional mobile communication antenna. In this case, the feed substrate has a high dielectric constant as MIC and MMIC and are used while the antenna substrate has a low dielectric constant so that a large bandwidth and a high radiation efficiency can be obtained. It is important for the design of active devices to understand various characteristics of the present antenna constructed from substrates with different dielectric constants.In this paper, the effect of the dielectric constant of the feed substrate on various antenna characteristics is derived both by measurement and by computation using the spatial network method. It is found that the resonant frequency changes if a high dielectric consant material is used, although the amount of change is less than the relative bandwidth and that the relative bandwidth of the antenna does not depend on the dielectric constant of the feed substsrate. When an MIC or an MMIC is attached to the back side, the radiation from the feed line including the slot to the back side is coupled directly with the active device and causes intermodulation. the effect of the dielectric constant of the feed substrate on the back‐side radiation is an indispensable item of investigation for development of active antennas. This investigation also is carried out in this paper which deals with the effect of the dielectric constant on the backside radiation.
Approximate analysis of a bidirectional looped dual‐bus network
Authors: Shi Guizeng , Fukuda Akira 
Published: July 2007

AbstractThe characteristics of a system consisting of a number of terminals (queues) connected to two buses with slots in opposite directions are analyzed here. Cells arrive independently at each terminal and are sent to a gateway station on an empty slot. In addition, cells to be emptied at terminals may be loaded on the slots transmitted from the gateway station. Such a slot can be utilized by a destination terminal and its downstream terminals. A bidirectional bus structure is used to alleviate unfairness among terminals and to improve system reliability. A rigorous solution of a basic model consisting of only one queue is first obtained in analyzing this system. Next, an approximate analysis is performed on the target model utilizing the foregoing result. Since rigorous analysis of the characteristics of the target model is difficult, two approximate analyses are proposed here. the validity of these approximate analyses is evaluated by making comparisons with simulation results. the results indicate that the analyses presented in this paper are useful and are sufficiently accurate for the case without cell unloading.
SDH line‐error detection method using reduced BIP
Authors: Tokizawa Ikuo , Ueda Hiromi , Uematsu Hitoshi 
Published: July 2007

AbstractFor STM‐N transmission lines in a synchronous digital hierarchy (SDH), a 24N bits interleaved parity (BIP) detection code is established in order to monitor transmission line errors. the hardware required for BIP code calculation increases in proportion to the speed of the transmission line. For example, with STM‐16 (2.48832 Gbit/s), the BIP code uses 384 bits, and the line‐error detection function occupies a large portion of the SDH interface hardware.This paper proposes a method to solve the foregoing problem, which implements line‐error detection by using a shorter BIP code obtained by conversion of the received BIP code, at the receiving end. At the transmitting end, BIP code conforming with the ITU‐T (formerly CCITT) standard is generated. This method allows integration with international standards, without degrading performance. That is, with an STM‐16, the hardware size is reduced by about 3000 gates, which is approximately a 20 percent reduction in the total gate count of an SDH processor.
Number of wavelengths required for constructing optical path network considering restoration
Authors: Hamazumi Yoshiyuki , Nagatsu Naohide , Okamoto Satoru , Sato Ken‐Ichi 
Published: July 2007

AbstractOptical networks that support high‐speed, low‐cost communication services are required. an optical path is proposed that utilizes wavelength multiplexing technology at the path layer of transport network layers. Optical path schemes, wavelength path (WP)/virtual wavelength path (VWP) that can realize optical path networks are also proposed. Although wavelengths are a resource in optical networks, the number of wavelengths required to construct an optical path network has not been evaluated.This paper describes a method of network protection using the optical path technique that enhances network reliability and proposes a method for establishing a restoration path that restores failed active paths in both WP and VWP schemes. Proposed herein is an optical path accommodation design to establish WPs or VWPs in a physical network considering the proposed restoration method. Furthermore, optical path networks are constructed by establishing WPs or VWPs on a physical network that has a regular structure and the number of wavelengths required in the network are evaluated. This evaluation makes it clear that the VWP scheme requires fewer wavelengths than the WP scheme.
NTSC interframe direct coding scheme by composite motion compensation on hadamard transform
Authors: Hamada Takahiro , Matsumoto Shuichi 
Published: July 2007

AbstractAs a highly efficient coding scheme for the TV signal, the component coding based on the motion‐compensation DCT is employed widely because of its high coding efficiency. On the other hand, the TV signals in the studio in the broadcast station, etc., are based mostly on the composite TV signal configuration including NTSC. In the composite TV signal, the subcarriers modulated by the chrominance signal are superposed on the luminance signal. Consequently, the algorithm for the component coding cannot be apolied directly.With such a situation as the background, this paper proposes an NTSC direct interframe coding scheme in which the motion compensation can be applied directly to the composite TV signal. the direct coding is realired in the proposed scheme using the composite motion compensation that compensates the phase errors of the color subcarrier component and the chrominance component on the Hadamard transform.It is shown as a result of computer simulation that the motion compensation, with the same efficiency as that of the original luminance/chrominance separated motion compensation DCT, can be realized by directly applying the proposed scheme to the composite TV signal. It is shown also that the generated information content, when there is no distortion, is reduced by approximately 30 percent compared to the original scheme.