bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circuit and packet integrated switching in a satellite communication channel
Authors: Suda Tatsuya , Hasegawa Toshiharu , Miyahara Hideo 
Published: July 2007

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

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

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

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

AbstractThe mathematical representation method of treating oscillators was first suggested by van der Pol. Many analyses of oscillators have been conducted employing this method. However, analytical models of oscillators still have some inadequacies. This paper deals with the sinusoidal output wave form of the oscillator and presents the mathematical representation of oscillator properties in a simple but very practical manner. We shall explain how the coefficients in the formulas can be determined from several of the measured points on the Rieke diagram, which is a popular form for the representation of microwave oscillator properties. We shall also give a couple of practical examples.Previously, oscillator properties have been described in graphical form due to the nonlinearity of the device, but they can be described by several numerical values when a mathematical representation is used; with the help of computers, this simplifies considerably the design of oscillator circuits.
Fabrication of high N.A. graded‐index optical fibers by mcvd method
Authors: Okazaki Hisaaki , Ohmori Yasuji 
Published: July 2007

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

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

AbstractIn this paper, DT coding system which includes both DS (direct sequence) and TH (time hopping) systems as special cases is proposed. It makes interchannel interference small and the number of channels large. Furthermore, autocorrelation, which relates to acquisition and trucking performance, can be improved.The DT coding formation is defined and the spread matrix and despread matrix are derived. To calculate the AO (auto‐optimal) phase, LSE (least‐sidelobe energy), r, ik (the average interference parameter) and other important code parameters, direct formulas and the recurrence formulas using these matrices are derived.To show the improvement of interchannel cross‐correlation and autocorrelation characteristics, a numerical example is presented.
An 800 MHz frequency synthesizer for land mobile radio equipment
Authors: Nishiki Sadayuki , Yuki Shuomi 
Published: July 2007

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

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

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

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

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

AbstractThe high‐capacity high‐performance dynamic MOS RAM is an outgrowth of progress in fine‐pattern fabrication techniques. However, as the short‐channel effect of MOS transistors becomes more pronounced it becomes increasingly difficult to reduce the effective channel length because it results in performance degradation of the refresh time or breakdown voltage in the dynamic RAM. In this paper we propose a method of fabricating a SAGOS (Self‐Aligned Small Gate Overlap Structure) MOS transistor with small gate‐to‐source/drain overlap capacitance using ion implantation and lithography technique. Its characteristics are clarified and it is shown that an MOS transistor with no short‐channel effect can be obtained even with a final poly gate length of 2.3 μm (effective channel length 2.3 μm). Additionally, in order to prove that the small gate input capacitance of the SAGOS MOS transistor is effective for high‐speed LSI, it is applied to a 64‐K dynamic RAM. No degradation of electrical characteristics is exhibited with CAS access time of 54 ns at Ta = 75 C and Vcc = 4.5 V. This is a speed improvement of 11% compared to a conventional MOS transistor with identical conductance.
Electrochromism in evaporated WO3‐MoO3‐V2O5 films
Authors: Sato Susumu , Seino Yosuke 
Published: July 2007

AbstractSymmetric and asymmetric EC cells are here fabricated using amorphous W03‐Mo03‐V205 films vacuum‐evaporated on substrates prepared in electrolyte of lithium perchlorate and propylene carbonate. Dependences of the reflection spectra of symmetric cells and the transmission spectra of asymmetric cells on the applied voltage was investigated. Almost black displays were obtained with W03‐Mo03 films to which negative voltages were applied (the reduced state) and the contrast ratio was improved compared with films of pure W03 and V205. Reddish displays were obtained with W03‐Mo03 films, and V205‐Mo03 films gave yellow and bluish displays. Addition of Mo03 to 60% W03 ‐ 40% V205 composition has improved EC properties, giving colors between brown and yellow‐green. Possible colors obtained are represented in the CIE (x, y) chromaticity diagram.
Correlated information source coding with a fidelity criterion
Authors: Member Motoaki Ohkubo, Regular 
Published: July 2007

AbstractThis article derives the achievable rate region associated with correlated information sources coding subject to some fidelity criterion. It defines the distortion corresponding to the decoding error in a dual‐channel situation with correlated information sources. Furthermore, an achievable rate region R(d) is derived corresponding to the channel capacity by using a method similar to that used by Slepian in obtaining the upper bound of decoding error rate for random codes.
200 khz pcm timing tank electromechanical filter
Authors: Tomikawa Yoshiro , Konno Masashi , Gounji Takashi , Kasai Yoshihiko 
Published: July 2007

AbstractThis paper describes the design method and experimental results of a timing tank electromechanical filter for low‐speed digital subscriber transmission networks. A composite longitudinal‐mode vibrator consisting of a piezoelectric ceramic sandwiched by consant‐modulus alloy plates is proposed for the filter. This type of vibrator is convenient to weld with its couplers and supporter. The temperature characteristic of the filter can be compensated by the two types of material. It is confirmed that the filter permits electronic characteristics and physical size compatible with LSIs used for PCM apparatus. The resonance frequencies and capacitance ratios of the vibrators and the conditions for suppressing higher‐order or resonance modes are analyzed. 200‐kHz timing tank filters based on the described analysis are fabricated and their characteristics described.
Baseband response characteristics measurement method and measuring equipment for multimode fiber
Authors: Okada Kenji , Members Ikutarou Kobayashi, Regular 
Published: July 2007

AbstractProblems and solutions for the far end measurement of frequency characteristics of the baseband response of a multimode fiber due to dispersion are presented. Also described is a configuration of the measuring equipment of the baseband response. For the latter, the following are important: (i) removal of the effect of the material dispersion; (ii) stabilization and leveling of the modulation level; (iii) stabilization of the optical output level; and (iv) removal of the effect of the reflected light from the output end and the input end of the fiber. Solutions for these problems are: (i) single‐mode oscillation of the semiconductor laser by reduction of the modulation index; (ii) stabilization and leveling of the modulation level by a negative feedback loop that monitors the modulation level of the backward light of the laser; (iii) stabilization of the optical output by a negative feedback loop that monitors the output level of the backward light of the laser; and (iv) removal of the effect of the reflected light by means of oblique incidence and small input aperture angle. When the baseband characteristic of a fiber a few kilometers long is measured, irregular variations are observed. A solution to this problem is also included.
Effect of compound strategies of error correcting coding, bit interleaving, and diversity combining in mobile radio data transmission
Authors: Member Yoshiya Miyagaki, Regular , Morinaga Norihiko , Members Toshihiko Namekawa, Regular 
Published: July 2007

AbstractThe improvements on bit error rate characteristics due to compounding an error correcting coding, a bit interleaving, and a diversity combining as reliability improvement measures, are evaluated theoretically for mobile radio data transmission affected by the time‐varying fast Rayleigh fading. Although the code, modulation, and decoding are limited to the block code, noncoherent FSK, and hard decision, the time correlation of the fading in a code word is taken into account generally and rigorously in this analysis. On the basis of the calculation results for nine codes, the effect of compound strategies by the degree of bit interleaving, “with or without” diversity, code length, and number of correctable errors, are discussed in detail, and the equivalence among the strategies and the compounding effect is clarified.
Design method of four‐reflector type beam waveguide feeds
Authors: Member Shinichi Betsudan, Regular , Katagi Takahashi , Urasaki Shuji 
Published: July 2007

AbstractWe describe a design method for four‐reflector type beam waveguide feeds composed of a conical horn and four reflectors which are widely used for the first‐stage radiation system of earth station antennas in satellite communication. The relational equation between the design parameters is derived based on beam‐mode expansion and we specify the independent design parameters. We derive the relation between the design parameters and such performance characteristics as spillover loss, cross‐polarization component and frequency. As design criteria (I) we minimize the cross‐polarization component on the condition of maintaining the spillover loss within a tolerable level, and (II) we minimize the spillover loss on the condition of maintaining the cross‐polarization component with a tolerable level. In determining the size of reflectors under prescribed mechanical constraints we establish that the design parameters governing the size of the conical horn and the shape of reflectors can be determined uniquely. Examples of application of this design method are presented to show the effect of the design parameters and to increase the design efficiency.
Hybrid distance and hybrid capacity on networks
Authors: Shibasaki Masashi , Itoh Masaki 
Published: July 2007

AbstractThe distance and the capacity between two vertices in a network are conventionally defined as the shortest path length and the minimum cut capacity between the vertices. In this paper, “hybrid distance” and “hybrid capacity” are proposed as generalized concepts of the shortest path length and the minimum cut capacity, which are defined using the concept of difference decomposition [1] in the matroid theory. These concepts can be measures for evaluating the density or complexity of an edge set between two vertices in a network. It is shown that the hybrid distance satisfies the metric axiom in the same manner as the conventional distance on a network.