bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptively controlled 4.8 kbit/s speech coders with low distortion
Authors: Hayashi Seiji , Suguimoto Masahiro , Kishis Genya 
Published: July 2007

AbstractAs a low bit‐rate speech coding method to realize a satisfactory quality of reconstructed speech, this paper proposes a 4.8 kbit/s pitch‐controlled multipulse coding method, which adaptively controls the speech pitch prediction interval and represents the multipulse positions for the excitation signals with a small number of bits. As a method to control the pitch adaptively, an algorithm is derived and proposed where the pitch prediction interval is adjusted adaptively for each frame so that the pulse position is determined to minimize the perceptual error power representing subjectively important difference.In addition to the forementioned method, another method also is proposed to improve the speech quality, where the pitch‐controlled multipulse coding is proposed to control adaptively the coefficients of the synthesis filter. An algorithm is proposed for the adaptive control of the coefficients of the synthesis filter, to calculate anew the optimal filter coefficients for excitation pulses derived from the adaptive control of the pitch.A simulation is executed for the two methods, and the following results are obtained as an evaluation of SNRseg. It is 7.5 dB in the conventional MPC algorithm, 8.6 dB in the proposed pitch‐controlled MPC algorithm, and 9.8 dB in the pitch‐controlled MPC algorithm including the adaptive control of the synthesis filter coefficients. In other words, the improvement in the latter two is 1.1 and 2.3 dB, respectively. The performance is satisfactory also from the viewpoint of the cepstral distance. The improvement in the reconstructed speech quality also is verified for the proposed methods by the subjective evaluation.
Measurement and analysis of electromagnetic pulses due to indirect ESD
Authors: Masugi Masao , Murakawa Kazuo , Kuwabaras Nobuo , Amemiya Fujio 
Published: July 2007

AbstractElectrostatic discharge (ESD) usually is accompanied by two phenomena: the injection of discharge current, and the radiation of electromagnetic pulses. The discharge phenomenon can cause transient electrical interference of electronic equipment and the time‐domain measurement of radiated fields associated with ESD is a difficult task because of the very fast and wide‐band waves involved.This paper describes measurement and analytical results of ESD pulses. ESD pulses were measured by three EMI‐type antennas (a loop antenna, a biconical antenna, and a double‐ridged guide antenna) in the time domain. It is shown that the electromagnetic pulses can be evaluated by the energy spectrum without using the phase information of antenna factors.Based on the measurement of waveforms of the known electromagnetic pulses, it is shown that the waveform can be evaluated with an accuracy of 2 to 6 dB. As a result, it was found that radiated ESD energy does not always increase in proportion to discharge voltage and that ESD pulses produced by low‐voltage ESD can cause strong electromagnetic interference.
Two‐wire AGC amplifiers with echo cancellers for two‐way voice signals
Authors: Yasukawa Hiroshi 
Published: July 2007

AbstractA two‐wire voice‐band automatic gain control (AGC) with echo cancellers is studied and applied to an automatic call‐transfer repeater. A four‐wire circuit model of the amplifier and its stability are discussed. Fast tracking and/or stabilizing AGC using variable‐rate control is proposed. Also, a singing protection control method in which the dominant path is selected depending on voice signal powers of the two speech paths is proposed and investigated. The amplifier gain of the inferior path is computed using the measured echo return loss (ERL) values of the echo cancellers. Furthermore, an automatic call‐transfer repeater prototype that is based on the new AGC amplifier and its characteristics is introduced.The maximum amplifier gain of the proposed methods is about 10 dB higher than that of a conventional two‐wire amplifier with a voice switch. The configuration and algorithms proposed in the paper are proven to be effective for two‐wire amplifiers.
Performance of a transversal equalizer for self‐interference passing adjacent channels
Authors: Kagami Osamu , Watanabe Kazuji , Ohtsuka Hiroyuki 
Published: July 2007

AbstractNonregenerative repeating systems on digital microwave radio have the advantage of network flexibility and low‐cost transmission. This paper describes a means of compensating self‐interference passing adjacent channels (S‐IPAC), which degrades the transmission performance. This interference is specific to nonregenerative repeating systems. A transversal equalizer with multitaps is discussed as a countermeasure against S‐IPAC. Bit error rates (BER) and signatures are presented theoretically and experimentally as a parameter of hop numbers.
Fuzzy control of telecommunications networks using learning technique
Authors: Tanaka Yoshiaki , Hosaka Shinichiro 
Published: July 2007

AbstractCommunications services and traffic have become varied with the development of communications and progress in telecommunications network control for call acceptance and routing has been desired. In implementing flexible control in communications networks, which are complicated systems, introduction of fuzzy control techniques which is an application of knowledge engineering is considered to be effective.To realize fuzzy control efficiently, it is necessary to establish appropriately membership functions that are quantitatively homologous with the target of control. However, finding and identifying such membership functions are difficult tasks.From this viewpoint, this paper proposes a method of tuning a membership function by learning and investigates call acceptance control in detail as an example. By this method, the input values to the fuzzy system and the revenues of the network are measured and optimal values are obtained automatically for various parameters of the membership functions by learning based on these data and the past tuning history. In this study, the efficiency of this tuning method is evaluated by simulation. As a result, it has been shown that by this method membership functions converge to appropriate forms and good control characteristics can be obtained.
Analysis of microstrip antennas on a curved surface using the conformal grids fd‐td method
Authors: Oonishi Teruo , Kashiwa Tatsuya , Fukai Ichiro 
Published: July 2007

AbstractWith the development of mobile communication, active research is being done on the small‐sized antennas such as microstrip antennas (MSAs). Moreover, MSAs normally are placed on spherical or cylindrical surfaces as a conformal antenna.Conformal MSAs are expected to have different characteristics compared to planar structure. In this case, numerical analysis is needed before the actual experiment.The method of analysis which has wide applications may be considered as efficient for this purpose. One such method is the conformal grids finite‐different time‐domain method (FD‐TD method).In this paper, an MSA on a curved surface is analyzed using the conformal grids FD‐TD method. Moreover, comparison with the experimental values also is performed. The experimental results and the analytical results are in close agreement which shows the validity of the method of analysis. As a result, it is confirmed that in the range of this paper, the input impedance and radiation pattern varies from their values for the planar patch when the patch surface is curved.
Radiation properties of microstrip array antennas fed by radial line
Authors: Shibata Osamu , Saito Sakuyoshi , Haneishi Misao 
Published: July 2007

AbstractThis paper proposes a new type of radial line microstrip antenna and studies both the design method and radiation characteristics. The following conclusions are obtained.(1) The relationship between the basic design parameters of this new type of planar antenna and the radiation characteristics was demonstrated, and the essential design data of this type of antenna were obtained.(2) A boresight antenna was fabricated based on the design data obtained in the foregoing, and it was shown clearly that such a type of antenna system offers an aperture efficiency of above 90 percent, ranging from the small‐aperture (low‐gain) type to the large‐aperture (high‐gain) type.(3) A beam‐tilt type antenna also was studied theoretically as well as experimentally, and the relationship of its radiation characteristics with the tilt angle and aperture efficiency was explained. It was demonstrated that such an antenna system may be considered to be effectively applicable as a high‐efficiency circularly polarized planar antenna.
System to measure the chromatic dispersion of optical fibers
Authors: Nagaki Yoshiro , Taniguchi Akira , Tsukamoto Takeshi , Tanimoto Takao 
Published: July 2007

AbstractBecause of the progress in optical communication technology, understanding the propagation characteristic of optical fibers has become very important. In particular, since optical networks have been used widely, the evaluation of optical fibers in the field is essential.This paper describes the measurement of the chromatic dispersion of optical fibers and a system suitable for the measurement in the field. The approach is based on the baseband phase‐comparison method. First, the conditions required for this measurement system will be clarified. Then the measurement of wavelengths and wavelength separation satisfying the requirements will be obtained by simulation. The source of each wavelength must be modulated.However, to increase the fiber length and to improve measurement precision, a modulation method based on multiple sinusoidal waves will be proposed, and the upper and lower limit of the optimum modulation frequency will be clarified. The measurement system will be constructed from these results. The technical problems in realizing the system will be shown.Finally, an example of data measured by the constructed system will be shown, and it will be demonstrated that a resolution of 0.01 ps/nm/km and measurement precision of ± 0.3 ps/nm/km can be achieved at wavelengths of 1.3 and 1.55 μm.
A scattering matrix of a slot set for the aperture illumination design of radial line slot antennas
Authors: Takada Jun‐Ichi , Takahashi Masaharu , Ando Makoto , Goto Naohisa 
Published: July 2007

AbstractTo realize the desired aperture distribution in a radial line slot antenna (RLSA), accurate evaluation of the coupling, guided wavelength and radiation phase of slot sets are required. Moreover, for the slot set similarly to the linearly polarized RLSA whose reflection is essentially large, reflection from one slot set should be reduced sufficiently to realize the desired traveling wave operation; therefore, the reflection coefficient should also be evaluated.In this paper, the scattering matrix equivalent circuit of the slot set is presented for the design of the radial line slot antenna. Using this equivalent circuit, the slot set configuration can be optimized for reflection characteristics, and it becomes possible to realize traveling wave operation with arbitrary polarization.Compared with the conventional analysis assuming uniform slot array, this method has greatly reduced the computation time, and the analysis and design of the antenna has become possible. This analysis has established first the designing of a RLSA with arbitrary polarization.
Measurement of a mesh reflecting surface for large deployable antennas
Authors: Hanayama Eiji , Araki Shinsuke , Takano Tadashi 
Published: July 2007

AbstractIn a satellite‐borne large deployable antenna, a mesh‐reflecting surface is used as a reflector material. Its electrical characteristic is an important factor determining the antenna characteristics.In this paper, a measurement system and a measurement method are presented for the transmission loss and the reflection loss of the mesh‐reflecting surface, and an error analysis is made. With a planar mesh made of doubly inlaid knitting of gold‐plated molybdenum wires with a diameter of 30 μm, the transmission loss and the reflection loss are measured systematically, and the data are evaluated. The loss characteristics due to the anisotropy of the mesh and to the dependence on the incident angle and the polarization are found.Further, it is shown experimentally that a loss other than the transmission loss and the reflection loss exists. A quantitative evaluation is made. It is shown that an incident angle dependence exists. A concept of a strip‐aperture model mesh is introduced which simplifies the actual mesh. By comparison with the measured results, the parameters for the strip‐aperture model are determined. Subsequently, the relationship between the actual mesh and the model mesh is discussed.
Comparative evaluation of band management systems considering multichannels in atm networks
Authors: Baba Ken‐Ichi , Saito Toshihiko , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractVarious communications services are provided over asynchronous transfer mode (ATM) networks, and traffic produced by these various services has various characteristics. Thus, in attempting to utilize circuits effectively by statistical multiplexing effects as in ATM networks, band management control reserving bands necessary to ensure communications quality in terms of cell loss probability, etc., is necessary when a call occurs. In addition, since communications quality required by various services differ, band management considering priority processing is effective. In addition, since a number of switching machines exist between transmission and reception nodes and a number of channels exist in links between each ATM switching machine, control to select one of these channels at the time of call setup is important. It is necessary even in this case to sufficiently consider traffic characteristics of calls for each service.In this paper, channel selection methods for such multichannel links are studied. For this purpose, the multiplicity of traffic establishable for a set of channels is obtained analytically following a step‐modeling technique and the efficiencies of various channel selection methods for a number of channels are studied. The characteristics and efficiency of each method are clarified by analyses and simulation using channel utilization rate and call loss rate as efficiency parameters for designing the efficiency of channel selection systems.
Performance of adaptive equalizer using iterative application of viterbi algorithm
Authors: Murata Hidekazu , Yoshida Susumu , Takeuchi Tsutomu 
Published: July 2007

AbstractThe Viterbi equalizer is effective for frequency selective fading in digital mobile communication, but as the multipath component propagation delay time difference increases, the number of states increases exponentially and the computation amount increases drastically. Combining the Viterbi equalizer and interference reduction operation based on the equalization result, this paper proposes a new type of Viterbi equalizer with iterative equalization. It can expand the equalizable range without increasing the number of states. Computer simulation result shows that its performance is better than that of a conventional one.
A paraboloid antenna fed by the equiangular spiral‐bent slotted waveguide
Authors: Ohtera Isao , Ujiie Hiroshi , Yoneyama Tsukasa 
Published: July 2007

AbstractWith a view to focusing the electromagnetic wave, an “equiangular spiral‐bent slotted rectangular waveguide (SSW)” made of an axially slotted rectangular waveguide, which is one of the leaky wave antennas, was proposed and its focusing characteristics were reported. In this paper, a new diffusion‐type radiator based on the operating principle fundamentally identical to that of the SSW as a focusing radiator is proposed. The radiation pattern of the offset parabolic reflector using this radiator as the feed is investigated. First, its far field is treated by a wave optical approach. Using a cylindrical offset parabolic reflector as an example, the radiation pattern and the frequency scanning characteristics are studied numerically. Further, a reflector antenna was actually constructed and the measured results are compared with the analysis so that the offset parabolic antenna with a proposed diffusion‐type slotted waveguide as a feed and its frequency scanning possibility are reported.
A new ground resistance‐reducing material based on water‐absorbent polymer
Authors: Yamane Hiroshi , Ideguchi Tsuyoshi , Tokuda Masamitsu , Koga Hiroaki 
Published: July 2007

AbstractThe increase in communications facilities is accompanied by a rapid increase in the number of groundings required. However, it is difficult to achieve the required ground resistance values in areas of high grounding resistance such as volcanic ash, sandy or rocky soils, so that there is a strong need for the use of ground resistance reducing materials. This article proposes a method of reducing ground resistance using water‐absorbent polymers. The use of water‐absorbent polymer materials is expected to provide approximately twice the resistance reducing effect as currently used materials. When selecting such materials for placement in the soil, it is necessary to consider susceptibility to decomposition by microorganisms as well as temperature characteristics. One type of water‐absorbent polymer, anhydrous maleic acid polymers, is found to satisfy both requirements. In addition, the use of such polymers as ground resistance reducing materials requires approximately 1/160 the quantity of currently used bentonite mixtures and causes approximately 1/10 to corrosion of the copper used in grounding electrodes, demonstrating that water‐absorbent polymers are a highly useful method of reducing grounding resistance.
Design of multibeam satellite networks realized by subchannel switched FDMA (SS/FDMA) system
Authors: Shinonaga Hideyuki , Ito Yasuhiko 
Published: July 2007

AbstractThis paper aims at improvement of the interbeam connectivity of the multibeam satellite for fixed satellite communications under frequency division multiple access (FDMA) operation and proposes the subchannel switched FDMA (SS/FDMA) system, which is realized by installing the filter matrix on‐board the satellite. In the proposed system, each transponder is used to realize multiple interbeam connections and the interbeam connectivity is improved greatly compared to the traditional system. A satellite network among multiple beams can be constructed efficiently.A method is shown in this paper to determine the transmission parameters which maximize the system capacity of the multibeam satellite network and minimize the average transmission equivalent isotopically radiated power (e.i.r.p.) for one carrier. Example calculations are shown for the power‐limited and band‐limited systems. In the band‐limited system, the number of subchannels and the ratio of band widths of the subchannels are important parameters.From such a viewpoint, a method is shown which determines the number of subchannels when the bandwidth ratio of the subchannels is specified. An example calculation is shown taking into account uniform and nonuniform traffic distribution patterns.
Traffic analysis of a hybrid go‐back‐n arq scheme using repeated transmissions
Authors: Komatsu Masaharu , Kinoshita Kozo , Hayashida Yukuo 
Published: July 2007

AbstractThe transmission delay and throughput performances of a hybrid Go‐Back‐N automatic repeat request (ARQ) scheme are analyzed. In the hybrid scheme, multiple alternate transmissions of the copy and parity block of each data block are repeated continuously by transmitter. The receiver detects or corrects errors in a received block by using Wang and Lin's error control algorithm. It is shown that we can obtain the optimum total number of continuous transmissions of copies and parity blocks, which minimizes the average delay time and maximizes the throughput.
Adaptive KL‐transform coding of images based on variable block shapes
Authors: Matsuda Ichiro , Itoh Susumu , Utsunomiya Toshio 
Published: July 2007

AbstractAlthough orthogonal transform coding exhibits superior coding efficiency at low rates, it shows a decreased picture quality of reproduced images as a result of noises unique to transform coding, such as mosquito noise and block distortion.This paper proposes a new transform coding scheme, which has a high coding efficiency and significantly reduced noises. It is based on applications of the concepts of region‐oriented coding, to orthogonal transform coding, and has been attracting attention in recent years. The proposed scheme expresses all the regions by quadrilateral blocks to reduce the number of bits required for coding a region shape. Block segmentations are realized with stability and certainty by repeatedly transforming the shapes of the blocks with the square block as the initial shape.The approximating accuracy of an image is improved by the mean values of the blocks by using a smoothing filter. In addition, KL‐transform coding derived from a correlation function model of images is applied to the luminance elements of each block, and bit allocation is optimized on the basis of this model; and the coding efficiency is improved by using an adaptive control method. Simulation results confirm that this method realizes a coding efficiency which surpasses that of the conventional orthogonal transform coding based on square blocks, and gives visually good reproduced images.
Hitless path protection switching techniques for ATM networks
Authors: Tatsuno Hideo , Tokura Nobuyuki 
Published: July 2007

AbstractThis paper describes a hitless path switching technique that utilizes fully the benefits of an ATM. First, hitless path protection switching in ATM networks is discussed. It is shown that for the path configuration of working and preestablished protection paths, the best switching method switches on the transmitting side. Then the proposed switching algorithm is described, along with several examples of its application to mesh and ring networks.A cell interval compression method suitable for hitless path switching is proposed that empties and disconnects the transmission delay difference absorption buffer. Finally, an approximate formula is proposed that directly determines the multinode queuing delay. This delay is needed to calculate the capacity of the delay difference absorption buffer. The accuracy of the formula is confirmed by simulations.
A common air interface between wide‐area cordless telephone and urban cellular radio: Frequency channel doubly‐reused cellular systems
Authors: Kinoshita Yasuaki , Tsuychiya Toshiki , Ohnuki Sinya 
Published: July 2007

AbstractThis paper proposes a new system [1] in which the frequency channel of the wide‐area cordless telephone is reused doubly by the frequency channel employed in the urban cellular mobile telephone with a weak power. A condition is imposed whereby the two systems can operate with equal telephone qualities when cochannel interferences exist between two systems.The radius of the microcell and the weak power are analyzed and completed. According to the analysis, the theoretical limit of the spectrum efficiency of the new system is doubled compared to the system where the frequency bands of the two systems are placed independently in adjacent bands (AB) [2, 3]. To realize the cooperation between the wide‐area cordless telephone and the urban cellular mobile telephone on the equally coexistent condition, an autonomous spectrum distributed management system is proposed in principle [3] which can maintain in a simple way the cochannel interference sharing.