bluuebunny/crossref_metadata_2025 huggingface dataset:
Non–preemptive priority queue with server's walking process
Authors: Fukagawa Yukinori , Yanaru Torao , Yoshida Sho
Published: July 2007

This paper considers the non‐preemptive priority queue problem, where the server in a station participates in a walking process. When the server arrives at the station, he/she processes the job with the highest priority at that time and begins the walking process. The jobs arrive with the external priority r and with Poisson distribution. If two or more jobs have the same priority, they are processed on a first‐come first‐served basis. The processing time and the walking time of the server follow general distributions. Starting from the generating function and the normalizing condition for the number of jobs at the arrival of the server, the state probability for the number of jobs at that moment is derived. Next, the jobs are considered and partitioned into two classes (priority jobs and ordinary jobs), and the following functions are derived: (i) generating function for the number of priority jobs at the arrival of the server; (ii) generating function for the number of priority jobs at the end of service by the server; and (iii) generating function for the number of priority jobs at the completion of the priority job. From these generating functions, the waiting time distribution and the mean waiting time are derived for each class of priority. Numerical examples are shown.
A queueing system with server's walking‐time and serial service
Authors: Fukagawa Yukinori , Yanaru Torao , Yoshida Sho
Published: July 2007

This paper considers two queueing systems with the server's walking process, where the service of the job is composed of more than one serial process. The first system is the scheme where the server arriving at the station serves in the last service stage for a job. The second system is the scheme where the server arriving at the station can serve more than one service‐stage from the last to the first stage in the reverse order. When a job goes through a service at a certain stage, either it proceeds to the next service stage or leaves the system, following a specified probability. For both systems, the case of three serial stages in the stationary state is considered where the service time and the walking time follow general distributions. For the first system, the generating function for the number of jobs at the arrival of the server, the generating functions for the number of jobs at the departure of the job, queue waiting time and the stationary‐state condition are derived. For the second system, the equilibrium equation is presented for the generating function of the number of jobs at the arrival of the server, but the explicit solution is not derived.
Hierarchical coding method of still pictures with component separation
Authors: Ishibashi Satoshi , Ogura Kenji
Published: July 2007

In the interactive information retrieval system using images with wide areas such as aerial photographs, in general, it is difficult to display the entire image with a sufficient resolution because of the limited number of pixels that can be displayed by the device. Consequently, it is desirable in such a system that an arbitrary subarea of the image can be retrieved and displayed with a high speed. From such a viewpoint, this paper proposes and discusses the hierarchical component separation coding. In the proposed method, the image information is separated into two components such as the gray level and the resolution components in the block truncation code, and the two components are coded hierarchically in regard to the resolution from rough to detailed levels. By this scheme, an arbitrary part of the image can be retrieved and displayed with the specified resolution. An experiment was made by computer simulation, wherein the block truncation code is applied to the proposed code. It is shown that hierarchical representation of the image in regard to the resolution as well as the code compression of one‐half to four‐fifths can be realized. It is shown also, by applying the proposed coding to the actual image retrieval system that, the code complexity in terminal transmission for the retrieval of the object image can be reduced from one‐fifth to one‐half the traditional method, leading to a high‐speed retrieval and display.
Equivalent transformations and sensitivity of wave digital filters
Authors: Watanabe Eiji , Nishihara Akinori
Published: July 2007

Wave digital filters (WDF's) are well known to have a low‐sensitivity property in general. In addition to several existing design approaches, new circuit realizations of series and parallel sections are proposed in this paper. Also, equivalent transformations are presented which enable new WDF's to be derived from those of Fettweis. Accordingly, many kinds of equivalent WDF's can be designed from a single analog prototype filter. The comparison of sensitivity characteristics of these circuits shows that far less sensitive WDF's can be realized by an appropriate choice from the conventional and the new sections depending on the value of their internal multiplier coefficients.
An array fed multibeam antenna using equal phase–shift active elements
Authors: Egami Shunichiro , Kawai Makoto
Published: July 2007

A multibeam antenna allows a large communication capacity and is suitable for satellite‐borne instrument. The present paper proposes a new array antenna with a reflector. The array is composed of active elements with equal phase shifts and is spatially fed by a multibeam horn. The array emits a spherical wave to a reflector. Its compact size fits satellite‐borne instrument and at the same time a good quality is expected for the gain and the sidelobe properties. Optimal values of the parameters are theoretically determined for S band operation with array construction, array position, number of elements, and apertures, and the properties of this antenna are derived. It is theoretically predicted that the space feed gives rise to a uniform power distribution over the elements. This prediction has been experimentally verified with a 19‐element array antenna. High power repeaters are no longer required and an arbitrary power distribution over the elements is readily realized.
A new image data compression method–extrapolative prediction–discrete sine transform coding (in the case of one–dimensional coding)
Authors: Yamane Nobumoto , Morikawa Yoshitaka , Hamada Hiroshi
Published: July 2007

This paper proposes the extrapolative prediction‐discrete sine transform as a new highly efficient coding for the gray‐level image. In the proposed method, an extrapolative prediction is made from the immediately preceding pixel to the present pixel block, and the prediction error signal is encoded by the orthogonal transform. Assuming that the information source for the image is a stationary first‐order Markov process in the wide sense, it is shown that the orthogonal transform which decorrelates the prediction error signal can be approximated by a certain kind of sine transform. An algorithm is presented for the high‐speed execution of this data. The rate‐distortion characteristic is discussed for the case of one‐dimensional coding, and it is shown theoretically that the coding efficiency of the proposed method is nearly the same as those of the discrete 16‐pixel cosine transform with block length of 4 pixels and the 8‐pixel fast Karhunen‐Loéve transform. Comparing the coding complexities of those methods, the proposed method is shown to be especially advantageous in the hardware realization. Computer simulations were made for actual images using the fixed‐rate coding and variable‐rate coding (entropy coding), and the result supports the idea.
Beam scanning characteristics of front fed offset cassegrain–type multibeam antenna
Authors: Makino Shigeru , Kobayashi Yuji , Urasaki Shuji , Katagi Takashi
Published: July 2007

This paper shows theoretically and experimentally that the front‐fed offset Cassegrain (FFOC) antenna is suited as a multi‐beam antenna to be borne on an international satellite. First, the problems are identified for conventional reflector configurations. Then the beam deflection characteristics are shown numerically in the case where an FFOC reflector surface is used as a multibeam antenna. The performance of the test antenna is confirmed experimentally. From the measured results of a test antenna of 120 wavelengths, it is found that the reduction of the gain in the beam deflection within a circle of the visible radius of 10° is less than 1.8 dB which agrees well with the computed results. The cross‐polarization level is less than‐34 dB. Because the cross‐polarization component generated by the primary radiator is −40 dB, the cross polarization generated by the reflector system is quite small.
Analysis of queueing systems with randomly changing population states
Authors: Fukuda Akira
Published: July 2007

The queueing system, in which the property of the population is changing randomly, frequently is observed in various problems, and it is important to know its property. However, the analysis of the characteristics of such a system in general is difficult. From such a viewpoint, this paper considers the simplest example of the M/M/1 system, where the inter‐arrival‐time distribution or service‐time distribution changes following a two‐stage Markov chain. A strict solution is derived for the behavior of the system. Using the state‐transition rate diagram of the system, the system equation for the steady‐state is derived. Then the z‐transform of the steady‐state probability distribution and the Laplace transform of the waiting time distribution are obtained. Their inverse transforms and the mean behaviors such as the mean number of waiting customers and mean waiting time are derived. Then the fundamental properties of the system are examined. For example, when the systems have the same mean load, the mean waiting time is longer if the load difference between the two states is large, or if the mean sojourn time at each state is long. These properties have been noticed by simulation, but they are verified quantitatively by analysis. However, in this paper the major aim is only to present an accurate method of analysis, and a detailed examination of the system is left for another paper.
Estimation of random modulating signals in transmission systems with nonlinearly coupled noises and additive non‐gaussian noises
Authors: Amano Masaaki
Published: July 2007

Noise in a transmission system often is assumed to be additive to and independent of the signal of interest. This paper discusses estimation of random modulating signals, where noise is assumed to be either nonlinearly coupled to the signal or additive non‐Gaussian. Such noise appears in an optical link, biological system, or control system.
Structural analysis for instantaneous waveform by natural observation method
Authors: Iijima Taizo
Published: July 2007

It is fundamentally important in waveform recognition to provide a method for systematic description of the changing nature of the given waveform at an arbitrary time. This paper presents a solution to this problem based on the natural observation method proposed by the author. After the definition of the instance is introduced, regulating the infinitesimal time interval at the time of interest, the instantaneous derived waveform series is derived from the input waveform by successive observations. A set of practical analysis methods has been studied theoretically for determining the mathematical structure of the instantaneous waveform for the observations.
Bandwidth necessary and sufficient for the determination of a periodic quantized signal
Authors: Sakaniwa Kohichi
Published: July 2007

The periodic quantized signal in this paper is defined as a piecewise constant signal which has a finite number of jumps in a period and has constant levels between adjacent jumping points. Periodic quantized signals are classified into four groups according to whether the jumping points and/or the height of jumps at the jumping points are, respectively, restricted to integer multiples of prescribed quantities or not.

This paper considers the two groups among them: (1) the set of signals whose levels {aK} between adjacent jumping points are allowed to take arbitrary real values but the jumping points {tk} are restricted to integer multiples of T/N, where T is the time interval of a period and N is the number of jumping points in a period (signal set III); and (2) the set of signals whose levels aK} between adjacent jumping points and jumping points {tK} are restricted to integer multiples of a specified step size δ and respectively (signal set IV). We have studied the smallest amount of Fourier coefficients required for the determination of the original periodic quantized signal having N jumping points in a period. Our results assert that the Fourier coefficients necessary and sufficient for the determination of the original periodic quantized signal are given by:

Up to the [N/2]th order for signals belonging to the signal set III, where [x] denotes the maximum integer not exceeding x.

Up to the N0 ( N/p1)th order for signals belonging to the signal set IV, where p1 is the smallest prime factor of N.
Local convergence of waveform relaxation method
Authors: Urahama Kiichi
Published: July 2007

This paper discusses convergence of the waveform relaxation method based on the decomposition of the circuit, and presents several sufficient conditions for the numerical procedure to converge locally. Then the block‐diagonal dominant property is defined for the block matrix, and some properties of the block‐diagonal dominant matrix are indicated. The algorithm in RELAX, which is a typical simulator based on the waveform relaxation method, is discussed. It is shown that the numerical procedure converges locally if the capacitance or conductance matrix is a block‐diagonal dominant matrix.
A newton algorithm for steady‐state analysis of nonlinear oscillatory circuits
Authors: Yamamura Kiyotaka , Horiuchi Kazuo
Published: July 2007

For the steady‐state analysis of nonlinear oscillatory circuits, the Newton algorithm proposed by Aprille and Trick is well known. However, often the conventional algorithm needs too many iterations or may not converge, because of the discretization error of numerical integration. This paper discusses in detail the Newton algorithm for the steady‐state analysis, and proposes an efficient algorithm which retains the quadratic convergence in the presence of the error of numerical integration.

First, a method of computing the exact Jacobians of the functions obtained by numerical integration is proposed. Then it is shown that the quadratic convergence of the Newton algorithm is retained by suitably controlling the truncation errors of the inner Newton iterations for the corrector equations. The proposed Newton algorithm converges to a solution quadratically even if the step length of the numerical integration is large. Utilizing this property, a mesh refinement strategy is proposed which improves the computational efficiency of the algorithm by determining first an inaccurate solution which is computed by using a large steplength. Then this approximate solution is used for the starting point of the next Newton iteration with a smaller steplength to obtain an accurate numerical solution. Also, it is shown that the foregoing technique can also be applied to the Newton algorithm for computing the bifurcation value of the periodic solutions. The validity and the effectiveness of the proposed method are also verified by numerical examples.
An active‐r all‐pass circuit compensating influence with second‐order pole of the operational amplifier
Authors: Okine Mitsuo
Published: July 2007

With the widespread application of such transmission systems as TV and data transmissions, increasing demands are produced for wideband and high‐performance transmissions. As is well known, numerous all‐pass circuits without amplitude distortion are employed for the equalization of the delay distortion of the transmission channel. Several structures have been proposed which employ the operational amplifier, which is easy to construct and easy to design. A remaining problem, however, is that the operating frequency is low. This paper proposes a first‐order, active‐R, all‐pass circuit with a very simple structure and working frequency extending up to several hundred kilohertz. In this kind of circuit, the amplitude characteristics are affected adversely if the ratio of the center frequency and the second‐order pole frequency of the operational amplifier is large. In the construction in this paper, this effect is compensated to realize a wideband performance. Two methods of compensations are presented: (1) the compensation of the element values in the original circuit; and (2) adjustment of the divider ratio of the resistor‐voltage divider connected to the original circuit. Similar compensating characteristics are obtained by either circuit. However, the latter seems more desirable since the compensation can be made by a single variable‐resistor with less effect on the phase characteristics.
Radiation phenomenon from transmission lines of finite length
Authors: Kami Yoshio , Sato Risaburo
Published: July 2007

This paper presents analytically electromagnetic fields radiated from finite‐length transmission‐lines. The method is based on the fact that the measured power patterns radiated from the finite‐length transmission line are the same as that measured for the coupling, which is a phenomenon when a plane wave excites a transmission line. Under the hypothesis, reciprocity is assumed between the radiation and the coupling. The power radiated from the finite‐length transmission line, which is received by the measuring antenna, is obtained by the use of a circuit‐concept approach, the transmission‐line equation for the coupling. By comparing the computed values with the measured ones, the reciprocity between them is verified. A discussion is also made on the model with a bend, in addition to the straight line, to confirm the validity. As a result, the fields radiated from the finite‐length transmission line are determined from the power received by the antenna.
Transient analysis of electromagnetic field for resonance‐type absorber in three‐dimensional space
Authors: Aoto Tadahisa , Yoshida Norinobu , Fukai Ichiro
Published: July 2007

TV and radar ghosts are becoming an increasingly serious problem, and the radio wave absorber has been developed to solve this problem. This paper presents a systematic analysis of reflection, scattering and diffraction of an electromagnetic wave which is incident on an object covered with a special radio wave absorber of resonance type. The basic formulation is given and the VSWR is calculated with a coaxial cable loaded with the absorber. The result shows the validity of the present method. The electromagnetic field is calculated near a square pillar with and without the absorber and, finally, the time evolution of a wave packet field incident on a square pillar is obtained.
Leapfrog‐type active RC filters with reduced number of operational amplifiers
Authors: Ishibashi Yukio
Published: July 2007

It is known that the active RC filter which simulates a ladder‐type filter has a lower element‐sensitivity than a cascade‐connected active RC filter. Many methods to construct this type of filter have recently been proposed. This paper introduces a method in which an active RC filter is used to realize the relationship between the node voltages and the closed‐circuit currents in a circuit obtained by scaling the impedance of each element of the original LC filter with the s‐function. By choosing the scaling function appropriately, the inverting‐integration circuit in a conventional leapfrog‐type filter can be replaced by an inverting double integrator with two capacitors; and the noninverting‐integration circuit in the same filter can be replaced by an RC first‐order, low‐pass circuit. This reduces operational amplifiers in the circuit to less than half a conventional leapfrog‐type active filter. The element‐sensitivity was analyzed, and the conditions for a low element‐sensitivity were obtained. A fifth‐order Cheby‐shev low‐pass filter was constructed, and its measured element‐sensitivity was compared with the results of a computer simulation.
Electromagnetic wave scattering by a plane metallic grating loaded with three dielectric layers
Authors: Uchida Kazunori , Noda Takeaki , Matsunaga Toshiaki
Published: July 2007

In this paper, electromagnetic wave scattering by a plane metallic grating loaded with three dielectric layers is precisely analyzed by use of a new type of spectral domain method combined with the sampling theorem. Two different polarizations, E‐ and H‐waves, are considered here. Induced surface currents on the conducting strips are expanded in terms of weighted Fourier series taking into account the field singularity near an edge and spectral expressions for the scattered fields are given. Then the unknown coefficients related to surface current expansions are solved in spectral domain by imposing the boundary condition associated with a conducting strip. Accuracy of the numerical results is checked in comparison with extrapolated values, and numerical calculations are carried out for frequency characteristics of reflectivity and transmittivity as well as surface current distributions. Insertion loss of dielectric layers is also described in connection with a polarization discriminator of antennas. Although we cannot compare the numerical results with the rigorous ones as in the case of no dielectric loading, it seems that the present numerical results are considerably good.
Boundary element formulation for sound field problems
Authors: Kagami Shin , Fukai Ichiro
Published: July 2007

Since the sound field is a scalar field, the steady‐state field is expressed by a scalar Helmholtz equation. In application of the boundary element method to this problem, many techniques which have been developed in the two‐dimensional boundary element method can be used, and a technique of spherical trigonometry also is used in evaluating a solid angle. The radiation impedance of a breathing sphere which was evaluated by the present method agreed very well with the analytical value. The present method is applicable to other scalar wave fields as well as to vector fields if the boundary conditions are treated carefully.
The number of spanning trees in an iterative contact graph composed of general cells
Authors: Sato Kimio , Onodera Rikio
Published: July 2007

This paper derives a formula for the number of spanning trees in a contact graph with an iterative structure having k general graphs as cells. Mainly, the cascade, wheel, and prism types of contact graphs which are representative among them, are considered. Until now, G has been restricted to an m‐ cycle Cm or n‐point complete graph Kn, and the calculating formula of electrical networks has been applied to unit‐conductance networks of these contact graphs. Then by considering the equi‐electric potential property, etc., the number of spanning trees with k and m or n being variables has been derived. When cells are general G, however, there are no variables corresponding to m and n because of the instability of its structure. Therefore, in this paper we use the formula between conductance of each branch of a network obtained by equivalence transformation of G into K3 or K4 with respect to vertices of G concerned with contact, that is, contact points and the numbers of spanning trees of G and graphs constructed by shorting contact point pairs of G. Also, we represent traditional point‐contact and branch‐contact in the extensive manner of s‐contact by adding s‐multiple branches to contact portions of contact graphs. In other words, the number of spanning trees of these contact graphs is given by a function of the numbers of spanning trees of G and graphs obtained by shorting specific contact point pairs of G and k and s. Furthermore, this result can be applied directly to the derivation of the formula for the summation of all possible tree admittance products in an admittance network which has no mutual coupling with the forementioned graphs as its interconnection structure.
Traffic characteristics of multimedia packet‐switching system with sources generating packets in bursts
Authors: Takenaka Toyofumi , Akaike Takeshi
Published: July 2007

In a multimedia packet‐switching system handling voice, moving images, data, etc., the bursty traffic generated by moving image terminals can have an unfavorable effect on the traffic quality of other media. To avoid this problem, the handling of bursty traffic should be established.

In this paper, the packet bursts are modelled by a batch arrival and the effect of burstness on packet overflow characteristics is examined by analyzing batch arrival queueing systems with finite waiting rooms. The results obtained are summarized in the following.

(1) To achieve the practical range of packet overflow probabilities (e.g., 10–6) in a system handling burst traffic only, a high buffer size indicator k (the ratio of the buffer size to the number of packets in a burst) is needed to utilize the transmission lines efficiently.

(2) To provide efficient utilization of the transmission lines and to realize practical packet overflow probabilities (e.g., 10−6) in systems transmitting a mixture of burst and nonburst traffic, the share of burst traffic should be very small.
Small‐sized waveguides with periodically loaded double posts
Authors: Kim Ki Chai , Tokumaru Shinobu
Published: July 2007

The authors have already proposed small‐sized waveguides with periodically loaded posts along a single line placed inside the cut‐off rectangular waveguides. This paper proposes small‐sized waveguides with periodically loaded double posts which have two lines of posts inside the waveguides aiming at an increase of the transmitted power there. The phase constants, the field distribution and other characteristics were obtained theoretically. They were evaluated numerically and these numerical results were confirmed by experimental measurements. This paper considers the transmitted power. Using the same size of the waveguide with a single line of posts, the maximum transmitted power increased by a factor of 1.7 and the transmission losses were reduced by about 6.38 percent by using double posts for the same numerical results of the waveguide with a single line of posts. As in the case of the waveguide with a single line of posts, either slow waves or fast waves can be transmitted. The transmission characteristics can be controlled easier by the values of the reactive loads by the double post structure.
Design of a radial line slot antenna with improved input VSWR
Authors: Ando Makoto , Ito Shuji , Kawasaki Hideji , Goto Naohisa
Published: July 2007

A radial line slot antenna is a planar antenna which in principle has high efficiency. An excellent efficiency of no less than 57 percent has been measured in the 12‐GHz band. To realize the predicted 80 percent efficiency, reflection in the antenna feeding structure should be suppressed. In this paper, field analysis by means of the finite element method (FEM) provides the shapes of the feeding structures which minimize the reflection. Numerical results predict that the antenna overall reflection can be suppressed to less than ‐15 dB. The theoretical design is confirmed by the model experiments in 6‐GHz band. The optimum design reduces the efficiency degradation due to reflection from 15 to 3 percent.
Synthesis of a two‐dimensional linear feedback shift‐register capable of generating a given two‐dimensional array
Authors: Sakata Shojiro
Published: July 2007

This paper considers a synthesis problem for the 2‐D linear feedback shift‐register with the minimum number of storage devices capable of generating a given finite 2‐D array. An efficient algorithm for finding a set of polynomials which characterizes a minimal 2‐D pseudolinear feedback shiftregister is proposed. Berlekamp‐Massey's algorithm which determines a 1‐D linear feedback shift‐register with the minimum number of storage devices capable of generating a finite 1‐D array is extended to the 2‐D case. If the given array is a subarray of a doubly periodic array with a sufficiently large size, i.e. at least twice as large compared with the fundamental period parallelogram, the obtained set of polynomials is unique, and it determines the unique 2‐D linear feedback shift‐register as its physical realization.
Synthesis of Balanced Stripline Branch‐Line 3‐DB Hybrid Circuit Based on Planar Circuit Model
Authors: Anada Tetsuo , Jui‐pang Hsu
Published: July 2007

When a transmission‐line type branch‐line 3‐dB hybrid is realized with a strip‐line circuit at high frequencies, electromagnetic disturbances occur near the transmission‐line junctions. Also, due to their mutual interference, the frequency characteristics are degraded from the desired ones. To treat this electromagnetic disturbance effectively, the transmission‐line type branch‐line 3‐dB hybrid circuit is separated into the branching transmission lines and the junction circuit. Based on the analysis for the function of each portion, the equivalent circuits are derived. It is described how these equivalent circuits are realized with stripline circuits with planar breadth. In practice, the balanced striplines are approximated by planar transmission line models so that the entire hybrid circuits are replaced with the planar transmission line circuits. The planar circuit theory is then applied to these structures so that the deviation from the desired hybrid characteristics due to the electromagnetic disturbance at the transmission‐line junctions is incorporated in the synthesis. Further, a hybrid circuit is designed with balanced striplines and the corresponding circuit is fabricated and tested. The measured results agree well with the theoretical frequency characteristics. Hence, the validity and effectiveness of the method are confirmed.
Gateway buffer size of local area network
Authors: Matsumoto Yutaka , Takine Tetsuya , Takahashi Yutaka , Hasegawa Toshiharu
Published: July 2007

When different kinds of local area networks are interconnected, a gateway holds the key to better performance of the interconnected network. Since gateways are lia‐able to overflow easily because of their comparatively long processing time, it is necessary to estimate their appropriate buffer size with regard to the input traffic. This paper considers a local area network working under CSMA/CD protocol. First, we analyze the output process of messages which constitutes a part of arrival process at a gateway, by solving an embedded Markov chain. Second, two stochastic models of the gateway are formulated by queueing theory and loss probability of messages is evaluated in regard to its buffer size. Numerical results show some interesting features of the output and arrival processes.
Fully digital cross polarization interference canceller for multilevel digital radio
Authors: Matsue Hideaki , Ohtsuka Hiroyuki , Murase Takehiro
Published: July 2007

In the digital radio system using dual polarizations, an interference canceller is needed that cancels excessive interference. In this paper, a fully digital cross‐polarization interference canceller is proposed in which digital signal processing (DSP) technology and LSI technology are applied. By means of DSP technology, the cancellation characteristics are determined mainly by the quantization accuracy and the number of taps. The only degradation factor is the rounding‐off error of the operations. High accuracy and large cancellation effects are expected. Also, an application of an advanced control algorithm is possible. Flexible applications are possible for any symbol rate. In this paper, the estimation method for the fully digital cross‐polarization interference canceller is presented. Based on this method, the relationships among the cancellation characteristics, the input signal quantization accuracy, tap coefficient quantization accuracy, and number of taps are analyzed theoretically for the case where the method is applied to the 256 QAM system. Next, the configuration of the canceller is presented. From the results of the experiments using the symbol rate of 12.5 MBaud and 256 QAM signals, good agreement with the theoretical prediction is obtained and, hence, the validity of the present estimation method is demonstrated. It is demonstrated that a high‐performance cross‐polarization interference canceller is realized which can be applied to a multilevel modulation system for a high‐speed region, such as 12.5 MBaud.
A cutoff cavity antenna with resonant posts
Authors: Kim Ki Chai , Tokumaru Shinobu
Published: July 2007

A cutoff cavity antenna is proposed in which excitation and parasitic posts are placed inside the antenna cavity. The input impedance of the antenna can be varied freely and matched. Its fundamental characteristics are obtained theoretically. The values of the load reactances which were connected externally to those posts are controlled and can be matched for a desired operating frequency. The current distribution on the excitation and parasitic posts and the electric field distribution over the aperture were analyzed. Integral equations for those distributions were derived and solved by Galerkin's moment method. In addition, the determinantal equation to obtain matched load reactances was obtained. Numerical examples were presented for the current distribution and the aperture electric field under a matched condition. Experiments were conducted on a test antenna and the validity of the theory was discussed.
Stability analysis of combined random/reservation access methods
Authors: Onozato Yoshikuni , Kato Tatsuhito , Noguchi Shoichi
Published: July 2007

The combined random/reservation access method is one of the access schemes in satellite packet communication networks which exhibits a desirable performance in adapting to the load variation. In the analysis of the system performance up to the present, however, the stability of the system has not been discussed fully. This paper considers the AA/TDMA (adaptive assignment/time division multiple access) scheme as an example of the random combined reservation access. The system is modeled using the equilibrium analysis, and the stability of the AA/TDMA system is discussed in detail using the theory of catastrophe. The change of the stability according to the load variation is described qualitatively using the wedge catastrophe. Furthermore, the stability condition is described qualitatively.
Effect of error control system by range transmission for PCM sound broadcasting
Authors: Kawai Naoki , Yoshino Takehiko
Published: July 2007

In the PCM sound broadcast by digital transmission, the noise due to the bit‐error at low reception field intensity degrades the speech quality, which restricts the range of broadcast reception. A method to reduce the bit‐error noise is the error control by range transmission, where the information indicating the range of the significant bit in the sample in a specified interval is transmitted as the range data. This paper presents a quantitative analysis for the reduction of the bit‐error noise, for the traditional range transmission system and the control system by majority decision, to fully utilize the merit of the method. The improvement from the viewpoint of listening sensation was verified by a subjective evaluation test. It is shown that the proposed method exhibits a remarkable improvement in the low‐intensity reception with a high error‐rate, where the error‐correcting code cannot achieve a sufficient improvement. It is shown by experiment that seven levels of the transmission range are sufficient to achieve the desired performance.
Three‐dimensional electromagnetic analysis by the subspace synthesis method
Authors: Nagaike Masaru , Ichiyanagi Takashi
Published: July 2007

The required computer memory capacity and the calculation time become enormous when analyzing problems for three‐dimensional electromagnetic fields by finite‐element methods. In many cases calculation is difficult even by a super‐computer. To save the required computer memory capacity and computer time, we propose a subspace synthesis method, an outline of which is as follows. First, the object space is divided into several subspaces. In each subspace we apply the finite‐element method. We formulate dispersed equations for each subspace. From these equations we derive reduced equations which relate only the unknown coefficients on connecting regions among sub‐spaces. By combining reduced equations from all subspaces, we obtain the reduced equations for the total object space. By solving them we can obtain the electromagnetic fields. In the proposed method, we execute calculations for a small subspace one at a time. Therefore the required computer memory capacity is reduced greatly from that for analyzing the object space by the direct application of the finite‐element method. The corresponding computer calculation time is also reduced. This paper shows the formulation of the subspace synthesis method, and applies it to several examples. The calculation results by the present method were compared with rigorous solutions or experimental data. The effectiveness of the proposed method was shown from these comparisons.
Optical‐loss change characteristics of fiber organizers for optical‐fiber cable joints
Authors: Shimizu Masatoshi , Kobayashi Hideo , Tomita Nobuo
Published: July 2007

This paper discusses and evaluates optical‐loss change characteristics which occur in the process of installing the optical‐fiber splicing points and slack fibers into an optical‐fiber organizer. First, as the optical‐loss change factors, bend lateral force and twisting were discussed. Their effects on the loss characteristics have been studied theoretically and experimentally so that the main factor for degrading the transmission characteristics is the bending process of the slack fiber. Next, the evaluation method for the optical‐loss change characteristics is studied at the fiber joint for the analog baseband video signal transmission. It is found that the allowable optical output vs. optical‐loss change ratio SNRC is 37.1 dB, and the bend radius is satisfying the present allowable SNRC at all frequency components of the optical loss change is more than 18 mm. Also, the relationship was studied between the bending radius of the fiber satisfying this SNRC and the changing frequency. It is found that the allowable bend radius can be relaxed by about 20 percent by doubling the fiber organizing time. Further, the optical‐loss change characteristics have been evaluated for the individual organization and the simultaneous organization. It is pointed out that the individual organization is suited for subscriber optical cables.
Flame‐Resistant Optical Fiber Cable with Corrosion‐Protective Painted Stainless Steel Sheath
Authors: Kuwabara Tsuneo , Koga Hiroaki
Published: July 2007

A flame‐resistant optical fiber with a stainless steel sheath is proposed. As a result of the flame test (IEEE 383 Standard) on a 12‐fiber optical fiber cable based on the proposal, it was found that only the corrosion‐protective paint on the stainless steel surface, which was exposed to the flame, was burned (burn length 30 to 45 cm). During this IEEE 383 Standard Flame Test, the fiber did not show any increase of optical loss. However, the optical loss began to increase within a certain period of time after the flame test, and the period is longer when the softening temperature of the secondary coating material is lower. The stainless steel surface should be coated with corrosion‐resistance paint. As a result of the corrosion test, the chromate treatment is suitable for surface treatment. Vinyliden fluoride paint, dicarbolic acid paint with glycidyl acrylic or oil‐free melamine polyester paint are effective for corrosion protection.
Experimental study on shielding effect for shielding cable in metallic duct
Authors: Yamane Hiroshi , Kanamori Hisaaki , Ideguchi Tsuyoshi , Motomitsu Tamio
Published: July 2007

When transmission lines are short circuited to the ground by accidents, induced voltages are induced between the conductor wires and the ground at the ends of communication cables. To reduce the induced voltages below the restricted voltage (430 V rms), we used countermeasures employing shielding cables and arrestors. However, studies for installation methods of shielding cables in metallic ducts have been insufficient. Many points of the shielding effect have not been clarified. In this paper we consider the shielding effect of the shielding cables installed inside metallic ducts buried in the ground which have distributed grounding resistances. We proposed a new laboratory measurement method for clarification by using small‐scale models including the current distribution in the metallic ducts. We examined experimentally through this new method, shielding characteristics of shielding cables in metallic ducts. As a result, we clarified that the shielding factor has a minimum value for the induced longitudinal voltage, the shielding effect becomes prominent if the distribution of the grounding resistance of the metallic duct is below 103 ω m, and the shielding effect is in proportion to the cable length. Compared with a case of a shielding cable only, we found that the shielding cables in metallic ducts have larger shielding effects. We clarified that they are effective for shielding in areas with induced fields of high intensities.
Bit error rate analysis for frequency deviation companding and expanding FM (fredece FM)
Authors: Ohno Koji , Daikoku Kazuhiro , Ogose Shigeaki
Published: July 2007

In this paper, bit error rates (BERs) of Fredece FM are analyzed theoretically. The correlative code whose transmission bandwidth is preliminary limited by Nyquist filter, is used for obtaining the Fredece FM signal. The spectrum of the Fredece FM signal is compact enough to adopt for mobile radios. However, the correlative code generally requires a multilevel decision. In the demodulation process, the received signal is frequency‐multiplied prior to the differential detection. This makes it possible to perform the binary decision. It is noted that the BER performance of Fredece FM is the same as that of the case where a multilevel differential detection is performed without frequency multiplication. Therefore the frequency multiplication is regarded as linear amplification in the frequency region. It is easy to analyze theoretically BERs with the multilevel differential detection for Rayleigh fading. Then the BERs for nonfading are derived easily by using the property where the average BER for quasi‐static Rayleigh fading is related to that for nonfading through Laplace transform. Finally, the relationship between the modulation index and the irreducible error level is studied.
Experiments of diffraction error on MLS elevation guidance
Authors: Koremura Kazunobu
Published: July 2007

In the diffraction region of a microwave landing system (MLS) elevation guidance, the field strength fluctuates due to such objects as buildings and hence the measuring error increases. This paper describes experiments to determine the effect of diffraction caused by the upper edges of a building. The results show that the field has a typical diffraction characteristic which can be calculated by regarding the building as a knife edge. It was found that the diffraction error cannot be ignored when measuring an angle, since the scanning beam is sharp in the vertical direction and flat in the horizontal direction. Hence, both the component proportional to the amplitude of the diffraction wave and that proportional to the partial differentiation of its incident angle (slope diffraction component) increase. It was found also that the measurement error characteristic around the shadow boundary, calculated by using the uniform geometrical theory of diffraction taking account of the slope diffraction, agrees well with the observational results. Generally, this method can be applied to the diffraction field strength and its measuring error estimation such as hangers.
Exact radio link design in cellular mobile communication systems
Authors: Kanai Toshihito
Published: July 2007

In the design of a radio link for terrestrial mobile communication, the transmitter power and the cluster size are determined based on the specification derived from the quality requirement and the outage. In the traditional design, the required quality and the outage are allocated according to the two degrading factors, i.e., the noise and the co‐channel interference, and the transmitter power and the cluster size are determined independently. The method is employed widely because of its simplicity, even though there is a certain error in the designed values. By contrast, this paper proposes an exact design for the radio link, where the reliability of the designed value is emphasized, aiming at a more efficient utilization of the frequencies. The concept of the prescribed quality transmission curve which considers simultaneously the two degrading factors, is newly introduced. The expression for the outage is derived from the prescribed transmission quality curve and the joint probability of the carrier‐to‐noise power ratio (CNR) and the carrier‐to‐interference power ratio (CIR). The relations among the outage, transmitter power and the cluster size are determined. As a precise method of calculation, a method is presented which gives the graphical relation between the transmitter power and the outage, with the cluster size as the parameter. Using a design example, it is shown that the minimum cluster size, which has been 12 in the traditional method, is now 9 by the proposed method. Thus, the usefulness of the method in the frequency utilization is indicated.
A study on layered free access network
Authors: Shikata Yoshiaki , Funakawa Kimitoshi
Published: July 2007

A layered free access network is proposed. This network is composed of multichannel circuits of bus type, such as LAN, satellite channel, etc., and traffic nodes which access multichannel circuits. By combining the nodes which can access all circuits and the circuits used only by a part of the nodes, a layered network structure can be constructed in accordance with the internode traffic distribution pattern. The number of access equipment in a node is evaluated and the existence of the optimum network configuration for an internode traffic distribution pattern is shown. An algorithm for obtaining the optimum network configuration is presented and an example of the optimum network configuration based on the traffic model is shown.
Optical fiber cable flexibility design under plastic deformation and its evaluation
Authors: Hayashi Akira , Mitsunaga Yutaka , Koga Hiroaki
Published: July 2007

This paper discusses the flexibility of a cable when it is bent to the range of plastic deformation of the cable material. Considering the situation where the cable material exhibits elastic or plastic deformation, the expression for the maximum bending moment, which represents the flexibility of the cable, is derived in terms of the following parameters: The strain‐hardening exponent n and the plastic modulus which are material parameters; and the outside and the inside radii r1 and r2, respectively, which are the structural parameters. As a method to determine the foregoing material parameters experimentally, the three‐point bending test is discussed. A method is presented which determines the strain‐hardening exponent n and the plastic modulus from the relation between the load P and flexion δ. The method is verified experimentally. The case is considered where the cable is composed of several materials such as sheath, core, and tension member, and it is demonstrated that the bending moment of the whole cable is given as a sum of the bending moments of the component materials. Thus, it is shown that if the material parameters of the cable components are known, the maximum bending moment of the whole cable, representing the flexibility, can easily be designed.