bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel phase‐locked loop with digital control techniques
Authors: Guonai Xu , Mori Shinsaku 
Published: July 2007

AbstractRecently, a number of digital phase‐locked loops (DPLL) have been studied. In the usual DPLLs, a divider is added to the output so that the discontinuous and sudden variations in the frequency and phase adjustment by digital operations can be averaged and smoothed. Hence, in the usual DPLLs, an internal clock oscillator with its frequency several tens times the input frequency is needed. This requirement places a certain limit in the input frequency by the maximum operating frequency of the digital logic circuit if the DPLL is used for a high input frequency.This paper proposes a phase‐locked loop (DC‐PLL) in which no divider is used and a clock frequency is almost equal to that of the input signal used for digital control. The free running frequency of the loop is equal to the clock frequency. The waveform of the clock signal is transformed to a saw‐toothed signal and the content of the reversible counter is transformed to a dc signal by a D‐A converter.These two signals are injected simultaneously to the voltage comparator so that the comparator outputs at the moment the former exceeds the latter. This is the output signal of the system.By the phase control signal, the content of the reversible counter varies and the output dc level of the D‐A converter also varies. At the same time, the phase of the output signal changes so that the phase control is accomplished. The characteristics of the proposed phase‐locked loop are confirmed to be identical to those of the conventional DPLL in which a divider is used.
Self‐routing benes network distributively controlled by dynamic load balance
Authors: Kishimoto Ryozo , Sakurai Naoya 
Published: July 2007

AbstractThis paper proposes a self‐routing Benes network controlled distributively by dynamic load balancing. This Benes network consists of a distribution network and a routing network. The distribution network is controlled by a proposed method called “Dynamic Load Balance,” where load information is fed back to the input side via each unit switch so that loads at intermediate unit switches are equalized.The routing network is self‐routed by an output tag. The computer simulation results show that mean time delay vs. throughput characteristic of the proposed dynamic load balance Benes network is superior to those of conventional networks.
Optimum design of a pipelined time slot interchanger with time slot sequence integrity
Authors: Obara Hitoshi , Nakazawa Yutaka 
Published: July 2007

AbstractThe time slot interchanger (TSI) is employed widely in practice as the switch fabric of digital cross‐connect systems or exchange systems in the digital synchronized network. With the increasing need for ISDN with the fundamental rate of 64 kbit/s as the background, it is desired to realize a large‐capacity TSI. This paper discusses the optimum design of the pipelined TSI which has been proposed in the past, aiming at the realization of a large‐capacity TSI.First, the TSI configuration is proposed which realizes the time slot integrity in multislot connection, which has been a problem in the traditional pipelined TSI. The proposed method corresponds to the traditional TSI using RAM, where the time slot sequence integrity is realized by employing the double‐buffer structure.Then the optimum design method for the proposed pipelined TSI is presented, where the evaluation measure is the performance index, defined as the product of memory capacity and the operation speed. For comparison based on the defined performance index, the pipelined TSI optimized by the proposed method has several tens to several hundred times better performance than the conventional TSI using RAM or shift registers. Thus, it is demonstrated that the proposed construction is effective in realizing a large‐capacity TSI.
Error rate performance in high‐speed gmsk transmission on mobile satellite channel
Authors: Konishi Ken‐Ichi , Miyagaki Yoshiya 
Published: July 2007

AbstractIn high‐speed digital transmission in mobile satellite and land mobile communications, one of the serious problems is the effect of waveform distortion due to the frequency‐selective fading. This paper considers the GMSK modulation system, which is considered as useful as the modulation scheme for digital mobile communication.The effect of the waveform distortion produced by the time‐delay spread of the scattered interfering waves in the Nakagami‐Rice fading channel is considered and the bit error rate is calculated theoretically. Numerical examples of bit error rate performance are illustrated. It is shown that the bit error rate is improved when there is an average delay time or a time‐delay spread in the scattered interfering wave, compared with the case without a delay. However, the effect is relatively small.
Focusing properties of fresnel zone‐plate and its application to a helix radiating a circularly polarized wave
Authors: Yamauchi Junji , Honma Shin'Ichi , Honmas Teruaki , Nakano Hisamatsu 
Published: July 2007

AbstractThis paper discusses applications of the Fresnel zone‐plate (FZP) made of metal foil to microwave antennas. First, the focusing effect and the far‐field pattern for the FZP are analyzed using the Kirchhoff‐Huygens diffraction integral. It is found that a phase‐reversing FZP, in which the phase of either its even or odd zones is inverted, has a sharp beam with a low sidelobe level.On the basis of the fundamental analysis, an antenna syctem in which a reflector‐type FZP fed by a backfire helix is proposed as an application of the phase‐reversing FZP. It is pointed out that a sharp circularly polarized beam with a half‐power beam‐width of 9 deg is obtained when the outermost radius of the FZP is about 4 wavelengths.Next, the gain variation by the change in the ground plate radius of the axial‐model helical antenna is explained by the Fresnel zone principle, and an axial‐mode helical antenna with a zoned ground plate is proposed. An absolute gain of 12.2 dB is realized by a two‐turn short helix with a zoned ground plate.
An asynchronous correlation receiver for a bus‐type twisted pair LAN
Authors: Member Hideo Kishimoto 
Published: July 2007

AbstractLANs are used to achieve mutual communication among microcomputers and workstations and their wiring flexibility with terminals is becoming a necessity. However, the wiring flexibility of a bus‐type twisted pair LAN is low because of limited tap connection.Although the equalization of a transmission line is necessary to improve wiring flexibility, a long sequence of training signals (more than a kilo bit long) must be sent before data transmission. Therefore, the transmission efficiency becomes significantly low in the case of a short data transmission such as in an LAN, and hence the application of conventional equalization techniques becomes difficult. Thus, wiring system technology to improve wiring flexibility becomes important in a private network system.This paper proposes an asynchronous correlation receiver which improves wiring flexibility for a bus‐type twisted pair LAN by allowing taps. Hence, a received waveform is decoded by pattern matching between the received waveform and the reference waveforms. The reference waveforms are stored in a memory in a prior training period using the multiple sampling method.Several experiments are carried out and their results revealed that the training time can be shortened (e.g., to 19 bits), the required clock accuracy is well realized by an ordinary crystal oscillator, and the transmission error rate can be made less than 10−6 under the worst transmission condition for a bus‐type LAN.
Tracking accuracy of astronomical objects in the nobeyama millimeter array
Authors: Morita Koh‐Ichiro , Ishiguro Masato , Chikada Yoshihiro , Kanzawa Tomio , Takahashi Toshikazu 
Published: July 2007

AbstractThe authors have developed the tracking control system of astronomical objects in the Nobeyama millimeter array. A system was studied which can accomplish sufficient tracking accuracy for an interferometer, such as delay tracking, phase tracking, and fine delay correction. It was found that the location error of an astronomical object can be made less than 1 percent of the maximum spatial resolution on a synthesized map and the radio intensity degradation less than 0.1 percent if the phase tracking is executed at an interval of about 10 s and the fine delay correction at 1 ‐ 2 s. Further, from the actual observation results, it was confirmed that this system has realized an extremely high tracking accuracy.
Measurement of polarimetric backscattering characteristics of random media
Authors: Kobayashi Osamu , Matsuzaka Yukihiko , Hirosawa Haruto 
Published: July 2007

AbstractRadar polarimetry is considered a new subject of study in the field of microwave remote sensing. This paper describes a measurement method to obtain polarimetric microwave backscattering characteristics of random media using a power‐measuring type, indoor‐use microwave scatterometer.In general, the polarimetric backscattering characteristics are measured in the form of scattering matrices. However, in the method here, modified Mueller matrices of random media were obtained by measuring backscattering coefficients for multiple polarizations. For transmitting and receiving polarizations, the horizontal linear, vertical linear, left‐handed circular, right‐handed circular, 45 degrees tilted linear, and 135 degrees tilted linear were combined.In comparing the measurement method to obtain scattering matrices, the method herein has these features: i) the modified Mueller matrices which represent the back‐scattering characteristics of random media are derived directly; ii) since phase measurement is avoided, the measurement system is simple and the calibration technique becomes stratightforward. In this paper, the measurement method, also with the fabricated scatterometer for the C band and the experimental results for backscatters from the random media composed of needle‐shaped scatters are discussed.
An analysis of the crossed twin delta loop antennas with circular polarization
Authors: Kumon Yasunori , Tsukiji Takehiko 
Published: July 2007

AbstractIn the circularly polarized antenna with two orthogonally placed wire antennas of identical shape, each antenna is fed with a phase difference of 90 degrees. In this paper, a crossed twin delta loop antenna is proposed in which two triangular delta loop antennas of different sizes are placed orthogonally. It is demonstrated in principle that this antenna can work as a circularly polarized antenna without any phase shifter. To make the phase difference of the currents between the orthogonal delta loops 90 degrees, the peripheral length of one of the triangular delta loop antennas is longer that that of another by the length corresponding to the phase delay of 90 degrees of the transmission line (=1/4 wavelength × 2). These orthogonally placed triangular delta loop antennas are fed in parallel with a single source.In this paper, a circularly polarized orthogonal equilateral triangular delta loop antenna with a reflector is considered. Detailed numerical studies are carried out for the axial ratio of the radiation field and the gain characteristics versus the spacing between the antenna and the reflector. As a result, an optimum shape is found in which the gain is high and the axial ratio of the circular polarization is good. For this structure, the input impedance, current distribution and radiation pattern are computed numerically so that the general characteristics of the present antenna are evaluated. The validity of the theory is confirmed by comparison with experiments.
Performance evaluation of layered communication protocol
Authors: Inai Hiroshi , Yokohira Tokumi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractThis paper proposes a queueing network model for the layered communication protocol and its approximate analysis method. The performance of the layered communication protocol is evaluated by using the proposed model and analysis.First, the queueing network model is constructed for the connection‐oriented and connectionless data transmissions between peer layers. In each queueing network model, the transmission delay in the lower layer protocol is represented by an infinite‐servor queue.The performance model for the layered communication protocol is constructed by piling up each model. Then an approximate analysis is presented for each queueing network model. Based on the relation to be satisfied by the packet transmission delay in each layer and the throughput between adjacent layers, an approximate analysis of the whole model can be executed iteratively.In numerical examples, the validity of the approximate analysis for the model is shown. The effects of window size, the time‐out period, and receiver buffer size on the transmission delay are discussed.
Fully digitalized transversal equalizer for digital radio systems
Authors: Shirato Tadashi , Matsue Hideaki , Murase Takehiro 
Published: July 2007

AbstractIn digital radio communication employing multilevel modulation, the waveform equalizer is needed to eliminate the waveform distortion generated in the transmission channel or in other components. This paper aims at a highly accurate automatic equalizer which is applicable to the ultramultilevel modulation, such as 256 QAM, and discusses the fully digital realization of the equalizer which has been constructed by analog circuits.First, the transversal equalizer to be used in 256 QAM is considered, and the relation between the number of taps and the equalizer performance is described theoretically. Then the construction of the fully digital waveform equalizer is proposed based on the digital signal processing techniques. The decision range expanded (DRE) method is proposed, aiming at the maximum utilization of the equalization performance of the waveform equalizer. Finally, the transversal automatic equalizer is implemented on LSI.As a result of experiment with the clock rate of 12.5 Mbaud and 256 QAM signal, a satisfactory result agreeing with the theoretical investigation is obtained. Especially, it is demonstrated that the DRE method is very useful in constructing the digital waveform equalizer. Thus, a highperformance transversal automatic equalizer is realized, which is applicable to the ultramultilevel modulation system.
Analysis of ferrite absorber considering hysteresis and relaxation characteristics by spatial network method
Authors: Morita Takashi , Yoshida Norinobu , Fukai Ichiro 
Published: July 2007

AbstractRecently, various microwave absorbers have been studied and developed for electromagnetic interference problems. One of the important materials for absorbers is ferrite in which the high‐frequency magnetization mechanism consists of a superposition of the motion of the magnetic wall and the rotation of the magnetization. Its complex permeability has a frequency dispersion; therefore, it is difficult to develop a rigorous theoretical analysis as an absorber. If a numerical analysis based on a simulation model is possible, the design of the absorber will be expedited.In this paper, the spatial network method is used for treating the hysteresis characteristics of the shift of the magnetic domain wall and the relaxation characteristics with an absorbing characteristic for the rotation of magnetization. A basic equivalent circuit model is proposed in which both are combined, and then this model is used to analyze the frequency characteristics of the reflection coefficient of a plane wave. The results based only on the basic relaxation model are shown to agree well with the theory. The basic validity of the model is verified by showing that the reflection coefficient is reduced at less than the matching frequency due to the hysteresis loss, and that the matching frequency and the tendency agree with the experimental results by Ishino et al.
Error performance improvement of digital transmission with π/2‐TFSK in the mobile radio environment
Authors: Horikoshi Jun , Kawano Osamu , Kurihara Kazuo 
Published: July 2007

AbstractTo construct a digital mobile radio system, it is necessary to select a modulation scheme to satisfy conditions for the error performance, the occupied bandwidth and the out‐of‐band radiation. It is especially important to develop a modulation scheme with compact spectral characteristics which is affected little by the multipath interference at a high transmission rate.In this paper, the power spectral density of π/2‐TFSK proposed by one of the authors is obtained first and then the detection ability accounting eye opening of 1‐bit and 2‐bit differential detector is discussed. It is revealed further that the magnitude of the eye opening of RC‐π/2‐TFSK (raised cosine Nyquist filtered π/2‐TFSK) is larger than that of RC‐MSK (raised cosine filtered minimum shift keying) and the applicability to the mobile radio channel is shown. The preferable receiving bandwidth of RC‐π/2‐TFSK is obtained. These are confirmed by the hardware experiments in the laboratory.
Suppression of radar clutter via nonparametric CFAR
Authors: Chikara Sakae , Saji Keiichi , Sekine Matsuo , Musha Toshimitsu 
Published: July 2007

AbstractIn radar signal processing, clutter must be suppressed to discriminate a target. For this purpose statistical properties of clutter have been investigated and an ordinary CFAR (constant false alarm rate) circuit based on clutter statistics works very well. A nonparametric CFAR circuit, however, does not depend on clutter statistics; and this technique was applied to sea clutter suppression in which a ship was detected with good accuracy.
Quality control at the cell level and its characteristics in the ATM network
Authors: Nogami Shinya 
Published: July 2007

AbstractIn the ATM network, information is transmitted by the continuous transmission from node to node of a fixed‐length packet called a “cell.” The requirements of the cell on the traffic characteristics and the network depend on the kind of information source. The information from a video terminal arriving at a node, for example, is bursty, and a severe condition is imposed on the delay. When cells from more than one medium arrive in a mixed way at the network, a certain control mechanism will be needed to satisfy the respective requirements from the cells. On the other hand, this control mechanism should be realized by as simple a structure as possible.This paper discusses the necessity of the quality control at the cell level and the basic concept in the control for the node handling different kinds of calls. First, the characteristics for the case of a single kind of call source (such as voice, video or data) are analyzed. Then the necessity and usefulness of the control methods when various kinds of calls are mixed and arrive at the node are discussed for different control methods using numerical examples.
Capacity assignment algorithm for packet‐switching network with unreliable links
Authors: Yokohira Tokumi , Sugano Masashi , Nishida Takeshi , Miyahara Hideo 
Published: July 2007

AbstractIn this paper, a link capacity assignment algorithm for a packet switched communication network is presented. This algorithm, called max‐delay‐link algorithm, prevents sharp performance degradation in a network even in case of link failures. An optimal link capacity assignment can be obtained with respect to link cost minimization, subject to the constraint that the average packet network transmission delay does not exceed a predetermined value.Robust networks against failures can be designed by assigning large capacities to links where overflow traffic and packet delay are expected to increase in case of a failure. Several numerical examples also are shown to examine the effectiveness of the algorithm in comparison with the conventional capacity assignment algorithm where link failures are not taken into account.
A method for transporting sdh signals using existing transmission systems
Authors: Ueda Hiromi 
Published: July 2007

AbstractThis paper discusses a signal transmission method based on the existing digital hierarchical transmission system that transmits signals as defined in the network node interface (NNI) of the new CCITT synchronous digital hierarchy (SDH). The method transmits the information corresponding to two virtual containers (VC‐3s) with the capacity of 28 of 1.5 Mbit/s over existing transmission systems using the fourth digital level, which is the basic unit of operation in the existing network. The fourth digital level signal in Japan has a bandwidth of 97.728 Mbit/s as specified in Rec. G.702. If two VC‐3s are to be contained according to the basic SDH philosophy of NNI, the required transmission capacity is 103.68 Mbit/s. The method that allows two VC‐3s to be transmitted at 97.728 Mbit/s should be considered.It is shown first that the use of the pointer introduced in SDH is adequate. A pointer scheme with a fourmultiframe structure is proposed, aiming at efficient information transmission. The characteristics of the fourmultiframe‐type pointer are then discussed, and the assignment of the overhead required in the transfer of maintenance/operation information is considered. Based on those discussions, the frame structure for the 97.728 Mbit/s signal is derived, which is the fourth level of the existing digital hierarchy.
Bandwidth assignment control in ATM system
Authors: Kuribayashi Shin‐Ichi 
Published: July 2007

AbstractATM (asynchronous transfer mode) system transfers and switches the information from various media such as voice, data, and video in a unified way. Since media with severe requirements for high‐speed transfer or real‐time processing must be handled, there is no flow control function during communication. As a result, a certain bandwidth must be assigned to each call to ensure service quality.This paper considers first the case where the same bandwidth is shared by several classes with different service requirements. The “flexible processing” system is proposed as a priority processing method where the qualities of other classes are not deteriorated even if there arises an unexpected traffic flow of a particular class. For bandwidth assignment to each call in the same class, the “volume declaration” method is proposed, wherein the user declares the maximum information content (= volume) that can be transferred in the specified time, in addition to the maximum information transfer rate. It is shown that the service quality of the call can be insured by this method.Then we examine the case in which physically distributed bandwidths are utilized by more than one service quality class, and it is shown that the results of past studies on the multirate circuit switching can be applied, by assuming the forementioned volume declaration method.