bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scattering of electromagnetic plane waves by two parallel finite planes
Authors: Shimoda Michinari , Itakura Tokuya 
Published: July 2007

AbstractA scattering problem of two parallel conducting plates of finite widths is analyzed by a new formulation. It was shown that an analysis of multiple scatterings by a system of parallel plates can be obtained formally by the representation of the scattered fields by one plate. The representation was derived for scattered waves using Wiener‐Hopf simultaneous equations which must be satisfied by each scattered field. Through an approximate integral by the saddle point method, we obtained numerically the diffraction patterns concretely for the far‐field diffracted waves. In a case where the distance between edges of parallel plates is almost or more than one wavelength, we showed that a system of conducting plates can be analyzed taking into account multiple scatterings by the present formulation.
Chase's second algorithm using received carrier level as CMI for decoding block codes in mobile data communication
Authors: Matsumoto Tadashi 
Published: July 2007

AbstractIn digital mobile radio, it is well known that the error control by block codes is effective for improving the code error performance in the multipath fading channel. Chase has proposed efficient soft decision decoding algorithms for block codes. In this paper, the word error rate performance of Chase's second algorithm using the received carrier level as CMI (channel measurement information) is described in the Rayleigh fading. First, the upper and lower bounds of the word error rate in the Rayleigh fading channel are derived theoretically assuming independent variations of received carrier level corresponding to each bit in a received block. The computer simulation results agree well with the theoretical results. Next, for the case where received carrier level variations are correlated, the word error rate performance is obtained by computer simulation using the Golay code as an example, and the bitinterleaving size required to make the variations of the received CNR statistically independent, and to randomize the errors occurring in a received block is calculated.
Delay and jitter property of mutually synchronized networks using complete digital plls
Authors: Luan Zaihua , Mori Shinsaku 
Published: July 2007

AbstractThis paper discusses the effect of delay propagation in the mutually synchronized network using completely digital PLL. A difference equation is derived with the risetime differences among nodes as the variables. The dynamical properties of the mutually synchronized network including the propagation delay, the steady‐state and the jitter characteristic are derived. As a result, the following properties are demonstrated. When the delay is less than half of the steady‐state period, the dynamical property and the jitter of the network are the same as those of the network, without delay. However, when it is larger than the half‐period, the dynamical property and the jitter of the network are affected by the delay. It is also shown that the jitter suppression of the N‐node mutually synchronized network is approximately proportional to the number of nodes N.
Quantities of higher‐mode generations in linearly tapered waveguides
Authors: Suga Takashi , Shirasaki Hirokimi , Ishihara Fujio 
Published: July 2007

AbstractWhen the electromagnetic field method is used in analyses of tapered waveguides, solutions can be obtained with the same degree of accuracy inside or outside the cutoff regime. If the length of a taper is of the order of, or more than, the wavelength, we need to consider only the fundamental mode in practice. However, we cannot neglect the influence of higher‐order modes if the length is shorter than the wavelength. We must examine the quantities of higher‐order mode generations.
Fault recovery processing in a switching control multiprocessor
Authors: Yamada Takahiko , Ogawa Satoshi , Suyama Masato , Hori Yoshinori 
Published: July 2007

AbstractFor a switching system which must operate 24 hours a day with high reliability, the requirements are secure recovery from a fault and minimization of the effect of the fault recovery (i.e., system down time). On the other hand, when a multiprocessor system is employed, competition may be produced among processors, leading to complex and difficult problems in the fault recovery. Several techniques are shown in this paper concerning the following points: (1) local fault processing in the unit processor; (2) the upper‐level fault processing, realized by combining the local fault processing; and (3) improvement of reliability of the fault recovery by a hierarchical monitoring of the overall system. With regard to the effect of the fault recovery, the factors affecting the down time are analyzed. The relations among those factors, the performance of the processor, and the fault rate are modeled. The effect of the fault recovery is compared between the proposed system and the existing single‐processor control system. As the result of comparison, it is shown that the proposed multiprocessor control system can localize the effect of the fault, and is more desirable than the traditional single‐processor control system.
FDM‐FM interference evaluation on digital radio‐relay systems
Authors: Sango Jun‐Ichi 
Published: July 2007

AbstractOne of the factors determining the performance of the digital radio‐relay system is the interference from the existing FDM‐FM systems. Traditionally, the FDM‐FM interference characteristics have been evaluated by analyzing the effect on the error rate by the interference wave which is approximated by a sinusoidal wave. The method tends to underestimate the effect on the error rate in a digital system when the analysis is compared with the case where an interference wave is actually given. This paper proposes a method for evaluation in which the FDM‐FM interference wave is divided into the carrier and the sideband components. Based on the new method, the interference characteristics have been analyzed. It is found from a laboratory experiment that the present evaluation method is valid.
Malfunction of digital circuits caused by noise induced in breaking electric contacts
Authors: Uchimura Keiichi , Michida Junji , Nozu Shinji , Aida Teizo 
Published: July 2007

AbstractThe malfunction of a digital circuit has been investigated from the viewpoint of the IC as its constituent. However, little has been reported from the viewpoint of electrical contact which is one of the principal causes of the malfunction. In the research reported here, simple automatic measurement equipment has been developed which counts the malfunctions of a digital circuit. Measurement has been done with this equipment under various circuit conditions. As a result, it was found that malfunctions of digital circuits not only increase with the load circuit current, but may decrease when the circuit current exceeds a certain value depending on the parallel capacitance between contacts. As the parallel capacitance between contacts increases, the region in which malfunctions are likely to occur shifts toward a larger current side. It was found that these elements are related closely to the region of showering arc generation which is one of the discharge modes at the time electrical contacts open. Also, since the parallel capacitance between contacts is larger, the 0 percent malfunction rate is approached while the wiring spacing between the inductive and induced wires is closer. For this characteristic, the frequency spectrum of the dielectric breakdown region of the showering arc voltage waveform has been derived.
Accuracy of XPD measurement at the CS‐2 experimental earth station related to satellite tracking systems
Authors: Maekawa Yasuyuki , Chang Nion Sock , Miyazaki Akira , Segawa Tetsuro 
Published: July 2007

AbstractThe problems in measurement of the beacon wave XPD are pointed out when the satellite is tracked automatically by the step tracking method in the CS‐2 operation test station. Since the antenna is driven on a trial‐and‐error basis in the step tracking system so that the beacon receiving level always increases, measured values of the beacon receiving level and the XPD vary during the tracking operation. If the tracking operation is performed periodically at a constant time interval to avoid these unwanted variations, the pointing error of the ground station antenna to the satellite during this interval causes degradation of the antenna gain and the XPD. In this paper, the antenna pattern of the ground station antenna is measured. In addition, the characteristics of the location variation of the satellite on the elevation and azimuth angles are determined. The reduction of the maximum beacon receiving level and the XPD degradation are computed which are likely to occur if the tracking interval is 10 ‐ 210 min. It is pointed out that the satellite tracking must be done at least once every 50 – 90 min to perform the on‐propagation‐path XPD measurement in the satellite channel with an estimated accuracy of about 40 dB.
Reflector error of large deployable antennas and its effects on radiation characteristics
Authors: Takano Tadashi , Ui Masaaki 
Published: July 2007

AbstractThere is a need for large deployable antennas with diameters larger than 10 m for space‐VLBI satellites and mobile communication satellites. Several deployment mechanisms have been proposed, each of which uses determined lines and points on a smooth prototype reflector surface. The basic structure is to use the reflector surfaces which are located between them as meshes or films.This paper examines types of mechanical errors of a deployable antenna and its relation with the radiation characteristics. Its effects on the radiation characteristics are shown numerically. As a result, it is shown that the gain reduction is less than 0.18 dB by subdividing the reflector surfaces by equilateral triangles whose side is about one‐eighth the radius for a 2‐GHz band tension‐truss type antenna of 15 m diameter. With a penalty of an additional 0.1 dB, the number of approximating triangles can be reduced by about 30 percent by subdividing the outer portion of the reflector twice as roughly as the interior portion. However, it is important to add phase offsets.It is shown that grating lobes appear in the sidelobe characteristics due to the periodic errors. The relationship between mechanical error and the effective error of the reflector surface is also clarified.
An experimental system of two‐dimensional tat bandwidth compression for television signals
Authors: Tanimoto Masayuki , Kageyama Masahiro , Murakami Masayuki 
Published: July 2007

AbstractIn the TAT (time‐axis transform) picture bandwidth compression system the pixels are selectively utilized. Because of its high reproducibility of the details of a picture, an application is expected to the bandwidth compression of HDTV (high‐definition TV) and other pictures of high quality. In the one‐dimensional (1–D) TAT system, the pixels are reduced and interpolated along the horizontal direction. This paper reports on the two‐dimensional (2–D) TAT system which reduces and interpolates the pixels not only in the horizontal direction but also in the vertical direction. Using this system, a system for the color TV signal with 7–MHz bandwidth was constructed, which compresses the bandwidth to one‐half in real‐time. Compared with the 1–D system, the number of modes is reduced from 3 to 2, and the size of the block is increased from 8 to 16 pixels. Then the mode information is reduced to approximately one‐third the 1–D system. On the other hand, a faithful picture is obtained with little degradation of resolution both in moving and still pictures. Sometimes a flicker is observed due to the time‐variation of the mode in the reconstructed picture, which can be suppressed by the new mode decision scheme with a hysteresis.
Multiphase pulse counting FM demodulator
Authors: Sawahashi Mamoru , Yamao Yasushi , Murota Kazuaki 
Published: July 2007

AbstractA new pulse counting FM demodulator which requires no extra outer part and is suitable for monolithic circuit integration is proposed. Although a pulse counting FM demodulator composed of digital logic circuits is suitable for monolithic circuit integration, it is difficult to realize high demodulation sensitivity with a quadrature demodulator or a Foster‐Seeley demodulator. Considering the application to narrowband FM mobile radio communication, a new FM demodulator based on multiphase pulse counting (MPC) scheme is proposed. The proposed demodulator has demodulation sensitivity nearly equal to that of existing demodulators, requires no adjustment, and has a low distortion rate. Its mechanism and circuit configuration are described. Basic characteristics, especially the demodulation sensitivity improvement, are then theoretically analyzed. Demodulation sensitivity and demodulation SINAD characteristics are experimentally validated; finally, single‐chip monolithic circuit integration of the MPC‐FM demodulator is prefabricated and its feasibility is shown.
A new channel assignment scheme in demand‐assignment radio communications system
Authors: Tajima Jun 
Published: July 2007

AbstractTo make the utilization of radio frequencies more effective, a large number of investigations has been made from the viewpoints of frequency, space, and time. Among the forementioned investigations, relatively few studies are from the viewpoint of time, and thus a new approach is desired. At present, a multiplicity of services are provided; these include mixed analog‐digital communications, and the approach from this viewpoint should be emphasized more. With this as background, this paper discusses the effective utilization of the frequencies in the demand‐assignment radio communication system, and proposes a new control scheme for the radio channel assignment. The technique described here is based on the hand‐off (channel switching) technique in the mobile communication system. By applying the technique to “pack” the radio communication traffic, a drastic improvement in the frequency utilization efficiency is demonstrated. As typical demand‐assignment systems, the radio communication system with heterogeneous calls with the same transmission bandwidth, and the system with heterogeneous calls with different transmission bandwidth are considered. The application of the proposed technique to those systems, as well as the behaviors of the systems, are discussed in detail, both by theory and computer simulation.
Half duplex optical communication system using an LED as source‐and detector‐device
Authors: Enomoto Masayoshi , Nakano Minoru , Matsushita Kenji , Shimizu Eiji 
Published: July 2007

AbstractAlthough optical fiber communication systems have recently been utilized in many fields, most of these have been realized by using a light source‐detector pair. Therefore, two fibers have been needed for bidirectional communication. Alternately, for small‐scale systems such as communication between personal computers and measuring systems, for which not too high a speed is required, a single‐fiber half‐duplex optical communication can be realized by using an LED as source and detector. However, the LED as source stores many excess charge carriers, and the LED as detector has a large depletion capacitance. Therefore, the transceiver must be constructed to minimize these effects for possible high‐speed communication.This paper proposes a transceiver applied to a multivibrator, which has both functions of switching between transmitting‐ and receiving‐mode and modulating the data to FSK signal. The characteristics of trial system including the methods of data‐input and demodulation are investigated. Although the transmitting speed by the proposed method depends on the LED characteristics, we have established a transmitting speed of about 200 k‐bit/s in unidirection by the trial system.
Theoretical analysis of error sequence characteristics in digital land mobile radio channels
Authors: Sasaoka Hideichi 
Published: July 2007

AbstractIt is important to clarify error sequence characteristics in digital land mobile radio channels with memory for accurate performance evaluation of error control schemes such as error correction coding. This research deals with the theoretical analysis of error sequence characteristics in digital land mobile radio channels with very slow Rayleigh fading. First, the digital channel model is studied on the basis of the error generation mechanism in digital land mobile radio channels and the analytical model is simplified, assuming that the envelope fading effect is dominant and fading rate is very small. The quasi‐static approximation method is applied to simplify analysis. Numerical expressions of gap probability and joint gap probability, which are important in making the mathematical model of error process, are derived for binary PSK under the Rayleigh fading environment. The calculated result from the anlytical model and the experimental measured result from the laboratory experiment are shown to agree well when the effect of fading variation is small.
Lowpass type quasi‐optical diplexer by rectangular metallic patch array
Authors: Iwata Ryuichi 
Published: July 2007

AbstractThis paper investigates theoretically and experimentally a rectangular metallic patch array as a low‐pass quasi‐optical diplexer. By complementary principle and experiment, it is demonstrated that the brick arrangement of rectangles is also available for broadbanding. In a previous paper the author proposed such an arrangement for high‐pass quasi‐optical filters by rectangular mesh.Also, the method of analysis for the dielectric multilayered patch array is presented, and the design method for the diplexer based on the analysis is described. The validity of the analysis and the design method are confirmed by experiment.
Multifrequency dipole antenna with closed‐spaced parasitic elements
Authors: Ebine Yoshio , Kagoshima Kenichi 
Published: July 2007

AbstractIt is shown theoretically and experimentally that a multifrequency dipole antenna can be realized by placing parasitic elements close to an excited element. Numerical data for two‐frequency and five‐frequency operations are presented. In the theoretical analysis, current distribution along both the excited and parasitic elements are calculated, and it is verified that large density current is induced on the parasitic element, as well as on the excited element.It is also shown that the length of a parasitic element should be less than about 1/1.2 of the excited element to realize a new resonant frequency. Calculated results of the radiation pattern in the horizontal plane are also presented.
A microstrip antenna of circular polarization over wide angles using λ/4 short‐circuit patches
Authors: Chujo Wataru , Teshirogi Tasuku 
Published: July 2007

AbstractIn mobile communication using a satellite, it is required to use a mobile antenna which has a circular polarization with a good axial ratio over wide angles. If a conventional microstrip antenna is used as an element antenna, it is difficult to improve the axial ratio over a broad angle even if a good axial ratio is obtained in the boresight direction. This paper investigates a circularly polarized microstrip antenna with a good axial ratio over wide angles. A method is proposed in which a combination of λ/4 short‐circuit microstrip antennas and the principle of operation is confrimed experimentally. First, it is shown that a good axial ratio cannot in principle be obtained over wide angles, since the directivity is restricted by the permittivity in a conventional microstrip antenna.Next, configurations and characteristics are presented for combinations of rectangular λ/4 short‐circuit microstrip antennas and circular λ/4 short‐circuit microstrip antennas suitable for obtaining a good circular polarization over wide angles. Conditions for a good axial ratio over wide angles are presented for both rectangular and circular structures. Further, experiments have been carried out for combinations of circular λ/4 short‐circuit microstrip antennas. Performance observed is the axial ratio less than 2 dB over wide angles of $60 degrees.
A broadband ATM switching system
Authors: Murakami Koso , Hajikano Kazuo , Abe Shunji 
Published: July 2007

AbstractThis paper proposes a switching system for the broadband integrated service digital network (B‐ISDN). The proposed system uses self‐routing and a multistage switching configuration. Asynchronously arriving information blocks are switched one by one at high speed. This configuration suppresses cell collision that can occur in asynchronous transmission. This paper describes the system configuration, a technique for designing the system's basic parameters, and system effectiveness.
Coding parameter optimization for the block truncation coding of still pictures
Authors: Ishibashi Satoshi 
Published: July 2007

AbstractBlock truncation coding is a highly efficient compression coding for the natural picture. It is useful in reducing the cost for storage and transmission of full‐color still pictures, such as those in the picture data base and the videotex. In the application of the highly efficient compression coding to the practical system, it is required to adjust the coding complexity and the picture quality, according to the cost and quality of the service provided by the system. From such a viewpoint, this paper discusses the control of the coding parameters, which determine the coding condition, and then the optimization of the coding parameters, to arrive at the coding complexity and the picture quality to meet the requirement.First, the traditional adaptive block truncation coding is extended to improve the coding efficiency and to expand the realizable range of coding complexity and picture quality. Then the control of coding is discussed which determines the coding parameter values in an adaptive and automatic way, according to the required picture quality and the property of the object picture in the considered system, to arrive at the desired quality. It is shown that it is possible to realize the coding with the desired quality simply by specifying SNR, independently of the property of the object picture.
Significant digit requirement for fm demodulation using digital signal processing
Authors: Kondo Shoji , Hattori Masaaki , Akiyama Hideki 
Published: July 2007

AbstractThe effect of the number of significant digits on the demodulator output noise is analyzed and examined by a simulation in relation to the FM broadcasting system specification. The quantization noise Nq generated at A‐D conversion of IF signals is regarded as a white Gaussian noise similar to the thermal noise Nz fed to a receiver input. From the condition of C/Nz satisfying the broadcasting specification, Nq such that Nq Ni‐ 10 [dB] is obtained and then the quantization precision satisfying this condition (being translated into the precision at the output of a digital signal processing demodulator) is obtained. As a numerical example, it is shown that only 6‐ and 9‐bit precisions are necessary for monophonic and stereophonic reception, respectively. The simulation result agrees with the numerical result. Reduction in the number of filter taps at the demodulator with the introduction of a window function is also studied. Given the system specification, the obtained result is also applicable for digital FM demodulators of any use.