bluuebunny/crossref_metadata_2025_split huggingface dataset:
All digital phase‐locked loop with a wide locking range
Authors: Hikawa Hiroomi , Zheng Nanning , Moris Shinsaku 
Published: July 2007

AbstractThe phase‐locked loop (PLL) is used widely in communication engineering as one of the key functions. Recently, some attempts have been made to construct a digital circuit for the phase‐locked loop. However, the common problems in those attempts is that there is a trade‐off between the locking range and the output phase jitter. To solve this problem, this paper proposes a new structure for the phase‐locked loop with a wide locking range by combining the frequency control technique. For this purpose, a new digital VCO is constructed, which can vary the central frequency of the system using the programmable divider and the adder. Theoretical analyses are made for the transient behavior from the viewpoints of the locking range, frequency and phase, and the noise characteristics of the loop. The result is compared with the results of experiment and simulation. The theoretical value, experimental value and the result of simulation agreed well, indicating that the phase‐locked loop has a wide locking range.
Unified analysis of ridge‐waveguide slot antenna in three‐dimensional space and time
Authors: Kashiwa Tatsuya , Yoshida Norinobu , Fukais Ichiro 
Published: July 2007

AbstractRecently, there has been much interest in research and development of a high‐power heating system for nuclear fusion plasma heating. Since these systems deal with high power, there are several problems that are different from those in the sources for communication systems. A structure is proposed which is based on the T‐type ridge waveguide, a simple and sturdy configuration. In these systems, the complex near field due to the three‐dimensional structure including the medium conditions has a significant effect on the characteristics. Especially, in a high‐power system, the effect of higher‐order modes with relatively small power distributions cannot be neglected. Also, transient field distributions strongly affect the characteristics so that the time domain response must be analyzed. This paper applies an analysis technique for the three‐dimensional space and time based on the Bergeron method to the systematic analysis of the radiated near field from the entire system of a T‐type ridge waveguide slot antenna including the waveguide, slot and the heating regions. The power distribution of the field determining the fundamental properties of the heating system is found in terms of the Poynting vector and the fundamental properties of the system are obtained. Specifically, the effect of the dielectric material on the field distribution is found. The cutoff characteristics of the ridge waveguide and the fundamental properties of the slot are studied and their characteristics are investigated.
Reflecting characteristics of lossy anisotropic materials inserted into the rectangular waveguide
Authors: Hashimoto Osamu , Shimizu Yasutaka 
Published: July 2007

AbstractIt is known that a large anisotropy exists in the plane of a rubber sheet composed of rubber mixed with carbon fibers or carbon particles with a subsequent pressing by a roller. This anisotropy can be used for fabrication of microwave absorbers and shielding materials. For this objective it is necessary to measure the complex permittivity tensor of these materials. The standing wave method in a rectangular waveguide has been extended for an application of measurement of tensor materials. The analysis of the reflection coefficient is studied for a short‐circuited waveguide containing an anisotropic lossy material. If this reflection coefficient can be found, a least square method may be applied to the measured data to determine the tensor component. In this paper, for the analysis of hybrid mode propagating in the anisotropic material, a set of generalized transmission equations is used. For each hybrid mode calculated by this method, the mode matching method is applied to find the reflection coefficient. The calculated results by this method are compared with the measured data. It is found that the agreement is excellent even if the direction of the rolling during the fabrication and that of the electric field are different. It is confirmed that the present method can be applied to the measurement of the permittivity tensor.
Centrality functions defined by minimum cuts in a network
Authors: Takeuchi Masashi , Itoh Yutaka 
Published: July 2007

AbstractIt is of interest in graph theory to discuss the degree of centrality of a vertex in a graph or to locate the most central point in the graph representation of systems with network structures such as communication and traffic networks. Various expressions for the centrality of a point in a graph or a network have been considered in association with the above problem and are called centrality functions in general. Most of them are based on the distance between two points, while an expression for the centrality by the gauge between two points in a network is also proposed. Most of the previous centrality functions were defined by distance, whereas in this paper we consider the centrality function defined by the minimum cut separating two points in a network (or the maximum flow between two points). According to this centrality function, the centrality of the point under consideration may happen to be the sum of the maximum flows from the point to every other point in the special case and hence it seems to be significant in estimating traffic networks and reliability with respect to circuit faults in communication networks.
Low‐sensitivity switched‐capacitor integrators
Authors: Ishikawa Masayuki 
Published: July 2007

AbstractThe integrated circuit switched‐capacitor filter (SCF) has the merits that the temperature dependence and the effect of aging are small. To utilize these features, it is important to design the low element‐sensitivity to realize the initial characteristics with a high accuracy. A number of low element‐sensitivity designs have been proposed for SCF's, which concentrate on the ways of combining the SC integrators. This paper aims at the low element‐sensitivity of the whole system, by decreasing the element‐sensitivity of the SC integrators themselves. The low‐sensitivity SC integrators of differential‐input and differential‐output types are proposed. Both types can be easily compensated for the effects of the parasitic capacitance and the number of operational amplifiers can be reduced by multiple uses. The determination of the element values to realize the required integrator coefficient is discussed, and a method is presented to minimize the element‐sensitivity. The leapfrog type low‐pass filter is considered as an example. Compared with the traditional circuits using SC integrators, it is shown by a computer simulation that the element‐sensitivity has been reduced by a factor approximately 1/2, compared with the circuits using traditional SC integrators.
Systolic decoder for reed‐solomon codes
Authors: Kimura Masayuki , Imai Hideki , Dohi Yasunori 
Published: July 2007

AbstractThis paper proposes the systolic decoder for Reed‐Solomon (RS) codes based on systolic algorithms. Three steps of decoding procedures for RS codes can be reduced to simple repetitive algorithms and thus can be realized by one‐dimensional systolic arrays, each operated by simple controls. The decoding system is a cascade connection of these cell arrays in one dimension. In this paper we also design three types of cells building arrays for RS codes on GF(28). Each cell has a size that permits its integration in a one‐chip LSI and we can determine the number of cells according to the error correcting ability for codes.
Decoding error probability of maximum likelihood decoders on intersymbol interference channels
Authors: Sasano Hiroshi , Kasahara Masao , Namekawa Toshihiko 
Published: July 2007

AbstractComputational complexity in deriving and numerically evaluating the upper bounds of decoding error probability of maximum likelihood decoders with Viterbi algorithm for intersymbol interference channels increases significantly with the length of intersymbol interference. A new upper bound of the decoding error probability is derived for intersymbol interference channels of length 1 and 2. The bound can easily be calculated, and for the intersymbol interference of length 2, the formula is not as complicated compared with the Viterbi‐Omura bound. Numerical results show that the bound is tighter than the Viterbi‐Omura bound by a factor of ten for a wide range of SN ratio. Simulation results show that the new bound is tight when the intersymbol interference is not so large.
Improvement of algorithm using interval analysis for solution of nonlinear circuit equations
Authors: Okumura Kohshi , Kishimas Akira , Saeki Shuichi 
Published: July 2007

AbstractThis paper describes an improvement of the solution by Krawczyk, Moore and Jones (KMJ algorithm) for nonlinear equations based on the interval analysis. When the KMJ algorithm is applied to practical problems such as the determination of the operating point of a multistable electronic circuit, a large computation time is required. The reason for the large computation time is as follows: (i) The existence of the solution is determined using the direct‐replacement type interval extensions of functions, which enlarges the search region for the solutions; (ii) the region partitioning is repeated until a region X is obtained such that K(X) ⊆ X, where K(X) is Krawczyk's interval function and X is the interval region. The situation is demonstrated by an example. As a solution for these problems, the following method is proposed.(1) The given initial region is partitioned into subregions, and some subregions are excluded from consideration if the solution is judged as nonexistent by the interval extensions of functions; (2) when K(X) ⊆ X, does not apply, the region X is partitioned into XC δ X ‐ (K(X) ∩ X) and XK ∩ K(X) ∩ X, and the KMJ algorithm is applied to XC and XK to examine the existence of the solutions. Finally, as a computation example, the KMJ algorithm with the above two elaborations is applied to the nonlinear circuit equations with two to four variables. It is demonstrated that the computation time can be reduced considerably with the original KMJ algorithm.
Role of formant frequencies and bandwidths in speaker perception
Authors: Kuwabara Hisao , Ohgushis Kengo 
Published: July 2007

AbstractThis paper considers the relation between the vocal tract characteristics under the personality of speech. A pitch synchronous analysis‐synthesis system was constructed in which the formant frequencies and the bandwidths can be modified independently. The speech was synthesized by controlling these parameters in natural speech, and an experiment was made on the discrimination of personalities. As a result, it is seen that the personality is strongly sensitive to the formant frequency shift, especially to the shift of the lower three formants, and it is lost by the uniform shift of 5 percent. On the other hand, the personality is well preserved for the change of formant bandwidth, and is sensitive to the bandwidth change in the fourth‐ and higher‐order for‐mants. In the case of uniform change of the bandwidth, deformation of wider than 5 times or narrower than one‐fifth times completely eliminates the personality.
Ultrasonic cell with IDT's for measurement of liquid acoustic velocity
Authors: Shiokawa Showko , Moriizumi Toyosaka , Kikuchi Tsuneo 
Published: July 2007

AbstractThis paper proposes a measuring system for the small changes of sound velocity, using the leaky surface wave excited by the interdigital transducer (IDT) on a piezoelectric substrate. The ultrasonic cell was fabricated and an experimental investigation was made. It is shown that the sound velocity change of the order of 2 ppm can be measured. When the propagation surface is loaded by a liquid, the elastic surface wave excited by IDT is converted into the leaky surface wave, which excites the ultrasound into the liquid. By constructing the measuring system utilizing this ultrasound excitation in the water, little spurious wave is excited, and a differential measurement can be successfully performed in the present system. The characteristics of the fabricated ultrasonic cell are examined and the measurement limit and accuracy are discussed. As examples, the change of sound velocity in KCL solution by concentration and some other measurements are discussed, indicating the usefulness of the proposed measuring system.
Small‐sized waveguides with periodically loaded posts
Authors: Kim Ki‐Chai , Tokumarus Shinobu 
Published: July 2007

AbstractTo develop a transmission line with a small cross section, a waveguide periodically loaded with posts is proposed. Various characteristics such as phase constants and field distributions are obtained theoretically. The structure is below cutoff if the posts are removed. However, if appropriate external reactances are connected to the posts the wave can be made to propagate. Also, the nature of the wave can be controlled freely from the slow wave to fast wave. In the analysis, the electric fields inside the waveguide are calculated first from the current on the post. Next, the internal impedance seen from the post terminal is obtained. From this impedance and the reactance loaded externally, the determinantal equation for the phase constant is derived. The magnetic field in the waveguide is then computed. As examples, the field distributions are shown for the slow and fast wave cases. The normalized transmission power and the losses with perturbation concepts are evaluated and numerical examples are given. The numerical results are verified experimentally.
A reduction method of tracking errors due to multipath waves in direct sequence spread spectrum systems
Authors: Maruyamatoggle Satoshi , Iwanami Yasunori , Ikedas Tetsuo 
Published: July 2007

AbstractThe speed spectrum (SS) communication is a communication system which has excellent characteristics against noise and is suited to the code‐division multiplex. Numerous applications have recently been considered. The delayed lock loop (DLL) is employed frequently as the tracking circuit for SS communication, where, however, a phase tracking error is produced by multipath waves. This phase error degrades the large processing gain, which is one of the most remarkable features of SS communication. We have attempted to reduce the phase error. Here, it is assumed that the peak of the correlation function of the received wave is fixed as long as the object wave has an amplitude much larger than those of multipath waves. Under such an assumption, a circuit is proposed which aligns DLL to the peak of the correlation function. As a result of the operation experiment for the circuit, it is shown that the phase error due to the multipath wave can be reduced to approximately one‐fifth.
Traffic characteristics of digital pair‐loop network in common usage of channels
Authors: Inoue Yukio , Hirano Junzo 
Published: July 2007

AbstractAn integrated digital pair‐loop network with ring topology of optical fiber cables as a new type of communication systems for interoffice trunk networks in regional service areas is proposed. The pairloop network has a feature in that several switching offices share bidirectional transmission channels, and thus the channels can be utilized in common by several trunk groups of offices belonging to the system. However, if vacant channels are selected arbitrarily and assigned to any calls, blocking probability depends on the office location and a definite grade of service can not be expected. This paper shows that the channel assignment following an algorithm called the channel‐pair selection rule makes it possible for the trunk group to achieve a definite grade of service and improves channel efficiency. It is shown also that analytical results are in good agreement with simulation results.
Design of discrete–time recurrent control systems
Authors: Shinnaka Shinji 
Published: July 2007

AbstractThis paper presents a new method for designing the discrete‐time recurrent control system. Often it is required in the plant control to follow a periodic object trajectory. The recurrent control is one devised for such a plant. It has an attractive property in that the purpose of the control ultimately is achieved with a high accuracy, as long as the control system is stable as a closed‐loop system, even if the plant is not identified accurately. In the previous methods, except for one, it is not easy to ensure the stability, nor has the convergence speed to the object trajectory been sufficient. For the disturbance contaminating the plant, the importance is pointed out of coping with the disturbance, but a design method has not been presented which positively takes the situation into consideration. This paper presents an excellent design method for the highly practical discrete‐time recurrent control system, which is very simple and general, solving simultaneously the problems of stability, convergence and disturbance suppression. The features of the proposed design method are due entirely to the new approach of processing polynomial of the time‐delay operator, which is different from previous approaches.
Coupling coefficients and injection–locking characteristics of microwave oscillators
Authors: Fukumoto Katsumi , Nakajima Masamitsu 
Published: July 2007

AbstractInjection‐locking phenomena are often studied for the purpose of application to synchronous operation and parallel operation of multiple oscillators. With respect to the coupling of multiple oscillators, synchronization stability, mode control and long‐time effects are problems. In this paper, it is pointed out first that the difference in the locking characteristics at low frequencies and at microwave frequencies is caused by treatment of the incident signal as the voltage and current or as the traveling wave. It is shown that use of the wave concept is more practical and rational in the microwave region. In such cases, the strength of the coupling between oscillators should be considered in two separate aspects: magnitude of the coupling (C ≧ or ≦ 1) between the oscillator and the coupling transmission line, and coupling coefficient r of the oscillator coupling circuit. As a result, it is found that a symmetric coupling with a rather weak coupling factor (r < 1) or, if coupling is strong, an asymmetric coupling is desirable for power combining of Van der Pol oscillators.
Power spectrum, anti–intercept and SN ratio characteristics of direct sequence spread spectrum communication systems using FIR and IIR filters
Authors: Kusaka Hiroji , Nishida Fujio , Simazaki Yoshihito 
Published: July 2007

AbstractThe time series generated from a direct sequence spread spectrum (DS‐SS) signal can be expressed in terms of an auto‐recursive (AR) model. An all‐zero FIR filter (FIRF) and an all‐pole IIR filter (IIRF), which are the inverse to each other, consist of the parameters of the AR model. We propose a spread spectrum communication system using an FIRF on the transmission side and an IIRF on the receiving side as well as a system using an IIRF on the transmission side and an FIRF on the receiving side. The former is called the DS‐SS communication system using FIR‐IIR filters and the latter using IIR‐FIR filters. When the order and the delay time in the delay element (the order and the sampling time interval, respectively, of the AR model of filters are selected properly by the former system, the power spectral density (psd) of the transmission signal can be spread more than that of the DS signal so that the density is lower and the peak value is suppressed. By the latter system, an optimum transmission becomes possible in the sense that the SN ratio is maximum within the main lobe of the psd of the DS signal. Further, the pulse duration time of the rectangular pulse train of the transmitted signal in both systems is transformed to the selected delay time. Since the amplitude of the pulse train changes randomly, both systems have an anti‐intercept property such that interception is almost impossible.
Cyclically orthogonal sequences with low multiplicity of values derived from quadratic residues
Authors: Tanada Yoshihiro 
Published: July 2007

AbstractOrthogonal cyclic sequences with low multiplicity of values are given for application to spread spectrum communications systems. Two‐, three‐, and five‐valued orthogonal cyclic sequences are obtained by representing real orthogonal cyclic sequences of length N by cosine series possessing phase constant of odd function, or even function with values {0, }, and by relating the phase constant to quadratic residues of N. We use the fact that an extended quadratic residue sequence taking values {0, +1, ‐1} becomes a sequence of odd function satisfying homogeneous equation of discrete sine transform when N is a prime number of the form N =4° ‐ 1 ( is a natural number). When N is a prime number of the form N =4° + 1, the sequence becomes that of even function satisfying a homogeneous equation of discrete cosine transform. Three‐valued orthogonal cyclic sequences are obtained by adding a dc component, to quadratic residue sequences of these odd and even functions. A two‐valued orthogonal cyclic sequence is obtained when a phase constant is given by a quadratic residue sequence of odd function multiplied by a constant. Moreover, when the phase constant is a monomial of odd power and is related to the quadratic residue sequence, a three‐valued orthogonal cyclic sequence is obtained for the prime N =4° ‐ 1, and a five‐valued orthogonal cyclic sequence is obtained for the prime N =4° + 1. Since N sequences obtained by shifting one of those sequences form an orthogonal system, cross‐talk does not occur when these sequences are applied to synchronous spread spectrum multiple access.
DPCM‐PCM hybrid coding and its properties
Authors: Hayashi Akira 
Published: July 2007

AbstractDifferential PCM (DPCM) is a method use to encode analog information sources with greater efficiency than PCM. However, due to its characteristic decoding mechanism, where the decoded signal values depend on previous ones, DPCM is unsuitable for progressive decoding.This paper proposes a new method, “DPCM‐PCM Hybrid Coding,” which is highly efficient similar to DPCM and also is suitable for progressive decoding.The principle of the proposed encoding method is described and computer simulation results of its quantization error performance are presented. Finally, the performance of the encoding method proposed herein is compared with that of the conventional DPCM.
Studies on pulse transmission capabilities of a ping‐pong transmission system
Authors: Komiya Ryoichi , Tamaki Norio , Yamano Seiichi 
Published: July 2007

AbstractThis paper describes the design philosophy of a line driver and an automatic line equalizer applied for a 200 kbit/s ping‐pong transmission system using existing metallic pair cables. The semiimpedance matched line driver is appropriate from the viewpoints of transmitted pulse distortion and power consumption. The automatic line equalizer is composed of a frequency domain equalizer as well as a time domain equalizer. The frequency domain equalizer is used to compensate for wide line‐loss variations, while the time domain equalizer is used to compensate for intersymbol interferences due to cable gage changes and bridged taps. The decision feedback equalizer is used as the time domain equalizer. Gain vs. frequency characteristics of the frequency domain equalizer and number of required taps of the decision feedback equalizer are determined to minimize intersymbol interferences due to deviations between automatic line equalizer characteristics and various line characteristics. As a result of the design, the 200 kbit/s ping‐pong transmission system is operative for 99 percent of NTT's existing subscriber cables with 100 percent cable fill.