bluuebunny/crossref_metadata_2025 huggingface dataset:
A method of time‐domain approximation using tbt polynomials as the denominator of the transfer function
Authors: Kishi Genya , Kida Takuro , Fukuda Yutaka
Published: July 2007

TBT polynomials are polynomials with roots which interpolate the poles of the transfer functions of the maximally flat amplitude filter and the maximally flat delay filter. This paper discusses a method in which a desired waveform is approximated by the impulse response of the transfer function using TBT polynomials as the denominator and gives a selection principle for two parameters for which the squared error in the time domain is minimized. Examples are given to show that the impulse response obtained by this method can approximate various practical desired waveforms very well. The above method based on the TBT polynomial is compared to the method involving the iterative process in which the least squares method is applied alternately to denominator and numerator of the transfer function to further decrease the squared error. It is shown that the approximation error for the above method is only about 1.5 times larger than that by the latter method. The properties of the approximated waveform are examined when not only the square norm but also the nth norm of error are used as error measures. Moreover, considering the band limiting in a real transmission line, we investigate a method of waveform approximation in the time domain in which the attenuation is prescribed and minimization is accomplished by the quadratic programming method. The method based on the TBT polynomials also performs well in this case.
A function measuring the centrality (or mediality) of an edge in an undirected network with edge capacity
Authors: Sengoku Masakazu , Shinoda Shoji
Published: July 2007

There have been many investigations regarding a function measuring the centrality of a vertex in a network. In a network, the edges are as important as the vertices; nevertheless, almost no investigation has been made regarding a function measuring the centrality of an edge. The centrality of a vertex is often measured by the degree of relation between vertices (e.g., distance, capacity and the like). Similarly, in this paper, the centrality of an edge is measured by the degree of relation between edges in a connected and undirected network with edge capacity. We propose a new method for evaluating the degree of relation between edges by the capacity of the minimum cutset with the edges. It is shown that this degree of relation between edges is the quasi‐distance which satisfies the triangular inequality and other relations. Also, we introduce several analogous to the center of vertices, namely, the center, radius, diameter and median of edges, and examine their basic properties. Further, we propose several indices to represent the centrality of an edge and use them in an attempt of generalization to a function measuring the centrality of an edge. These functions may be useful in evaluating the vulnerability of a network which can be modeled such that two edges drive flow in common (simultaneously).
Operating frequency range reduction in a series resonant converter
Authors: Muroyama Seiichi , Sakakibara Kazuhiko
Published: July 2007

A problem of the series resonant converter is the generation of audible noise under a light load since the operating frequency must be controlled approximately in inverse proportion to the load if a constant output voltage is desired. To reduce this operating frequency dependency on the load, this paper proposes the addition of an auxiliary resonant circuit to the output circuit of the conventional series resonant converter. The characteristics of the proposed converter have been analyzed and confirmed experimentally. It has the following features:

The proposed circuit can maintain constant output voltage by keeping the operating frequency in the range above the auxiliary resonant frequency. Therefore, no audible noise is generated if the auxiliary frequency is selected above the audio frequency range.

In the constant voltage control of the proposed circuit, the level of current necessary to maintain output voltage can be lowered by increasing the auxiliary resonant frequency.

In the range below the auxiliary resonant frequency, the output voltage increases despite decreasing operating frequency. Therefore, it is necessary to control and not operate the circuit in this range.
Characteristics of new types of quasi‐optical diplexers
Authors: Sha Kokusho , Kurashima Hiroyuki , Shoji Toshiaki , Suzuki Michiya
Published: July 2007

The quasi‐optical diplexer presently is considered to be as interesting as a special‐purpose filter, which divides or mixes the electromagnetic waves above microwave frequency in free space. This paper reports on the new types of diplexers: the gridded square, gridded square frame and gridded double square frame types. The feature of these new types is that various frequency characteristics from broad to sharp, can be realized by adjusting independent parameters, and the symmetry or linearity around the resonant frequency can also be realized. This has been difficult in past diplexers. By a systematic experiment, the frequency characteristics of the new types of diplexers are examined. Empirical formulas are derived for the resonant and anti‐resonant frequencies, as well as fractional bandwidth as functions of dimensional parameters. Based on these expressions of the characteristics, the design protocols are presented to meet various requirements. Although there still exists an error in the sense of reproducibility, which is less than 15 percent, the design for the proposed diplexers is established. Thus, the diplexers proposed in this paper have desirable characteristics, which have not been observed in the past. With the detailed design formulas for a wide range of frequencies from roughly 1 to 100 GHz, the diplexers can cope with various requirements, and a diversity of applications can be expected.
A new automatic equalizer for digital subscriber loops
Authors: Ono Shigeru , Kondoh Noriaki , Kobayashi Masaki , Hata Masayasu
Published: July 2007

This paper describes a new automatic equalizer for digital subscriber loops. The new equalizer is composed of a √f equalizer and a BT equalizer. The √f equalizer is a new type of linear equalizer which is based on the approximate theory of exponential orthogonal functions. The BT equalizer is a decision‐feedback equalizer. Subscriber loops can be closely approximated to RC‐dis‐tributed constant circuits. Since the new √f equalizer is composed of a linear combination of RC low‐pass circuits, the required hardware is small in scale. By adjusting the multiplication weights for both the √f equalizer and the BT equalizer, the equalizing characteristics can be controlled continuously. Moreover, since the multiplication weights of the √f equalizer are performed digitally by C‐2C ladder circuits and the main part of the BT equalizer is composed of digital circuits, the equalizing characteristics can be controlled by a digital controller and neither analog multiplication circuits nor analog delay circuits are required. As a result of our trial manufacture and performance tests that were conducted in a 320 Kb/s time‐division burstmode transmission system, it has been verified that this automatic equalizer has sufficient equalizing capabilities.
A numerical calculation method for nonlinear equations from geometrical viewpoints
Authors: Suzuki Yoshihiko , Ueno Satoshi
Published: July 2007

Numerical solution of nonlinear equations is studied from a new viewpoint. That is, the concept of conventional solution methods of nonlinear equations which are based on mainly algebraic points of view is derived from the geometrical point of view. In this way, it is shown that various solution methods of nonlinear equations can be unified as determining a one‐dimensional path in the space spanned by the unknowns of the equation. As a result, it was made clear that the differences of various known solution methods come from different choices of this path. By the properties of the rank of the Jacobian matrix Fx of the equation F(x) = 0, the solution algorithms are classified into three types. The proposed solution technique contains a multiple number of parameters in the nonlinear equation. The case of a unique solution is illustrated by a control problem of a multiple‐joint robot arm and the case of a multiple number of solutions is illustrated by a problem that calculates operating points of a nonlinear resistive network.
Synthesis of switched capacitor filters using voltage and charge variables
Authors: Ishikawa Masayuki
Published: July 2007

The switched‐capacitor filter is distinguished by low temperature dependence and small aging effect. In realizing those features in actual filter implementation, the element sensitivity is a problem. In previous construction of the switched‐capacitor filter only the voltages have been considered, which results in limitation of the derived low element sensitivity. In order to improve the circuit with respect to element sensitivity, this paper proposes a construction method using both voltages and charges as the network variables. It is shown first that the basic SC circuit composed of a capacitor and a switch has both the differential‐input property with respect to voltage and the differential output property with respect to charge. By applying these properties, four kinds of integrators are derived. It is shown by computer simulation that the proposed construction, permits enlargement of the range of element sensitivity in cases such as scaling the output of the operational amplifier in the leapfrog switched‐capacitor filter, which has been known as a filter with low element sensitivity. Integrators in which the effect of parasitic capacitance of the original filter is compensated are also discussed.
A frequency–domain design of two–dimensional recursive digital filters
Authors: Hinamoto Takao , Akeno Kazuhiko , Maekawa Sadao
Published: July 2007

This paper presents a technique for the design of two‐dimensional recursive digital filters in the frequency domain. The filter consists of the denominator being structurally stable and the numerator being a mirror‐image polynomial. To find the denominator, a stable two‐dimensional all‐pole filter is designed first so as to approximate the constant group delay specified in each direction. This is done by using the Davidon‐Fletcher and Powell algorithm. The numerator is then designed so that the whole rational transfer function approximates the desired magnitude response under the assumption that the denominator is fixed. This is done by solving a linear equation. The present technique has the advantage of always ensuring the stability of the resultant filter. Two examples are given to illustrate the utility of the proposed technique.
Some location problems on grid graphs
Authors: Yamaguchi Tadashi , Kaji Ikuo
Published: July 2007

Numerous works have been reported on the facility location problem to minimize or maximize various objective functions for the locations of one or more facilities on graphs. A general approach to these problems is algorithmic, but solutions are seldom found in an explicit manner. By restricting the object graph to grid graphs, this paper gives solutions in an explicit manner to the center problem and the median problem which are fundamental in facility location problems.

Strictly speaking: (i) we derive the relationship between the center and median of general graphs G1 and G2 and the center and median of the product graph G1 x G2; then (ii) we find a multicenter and multimedian of the path graph Pn on n vertices and from the results, solve a kind of multicenter and multimedian problem for grid graphs; and (iii) we solve a distance minimization problem on grid graphs.
Electronic switching system software structure considering virtualizing technique and software components
Authors: Soga Tomiji , Kubota Teruhiro , Ohta Tadashi
Published: July 2007

The stored‐program control system presently forms the main‐stream of the switching control system because of the flexibility in function modifications, compared with the wired‐logic hardware. One of the problems which has manifested recently is the large number of steps of the software modifications, which accompany with the modifications of the switching system architecture and the additions of functions. One of the major reasons for the large number of modification steps is the traditional modularisation, where the switching system architecture and the signaling systems are assumed to be retained. Because of this assumption, the modifications have to be made at various scattered points in the software systems, or have to be made at unexpected points, thereby increasing the number of steps in the modifications. This paper aims at improving the versatility of the software, and describes the modular breakdown, where the modification is localized by making the switching system architecture and the signaling system implicit and virtualized. By the same idea as in the hardware architecture, the software component technique is realized, where the program‐unit is subdivided into a set of units depending on the starting conditions of the programs and a set of units not depending on the starting conditions, and the module is composed by combining those two sets of units. By an example, it is shown that the proposed software architecture is useful.
Phase regeneration characteristic of a three–mode oscillator with second and third harmonic resonators
Authors: Umeda Hiroyuki
Published: July 2007

This paper discusses the phase regeneration characteristics of the three‐mode oscillator with two‐phase PSK signal injection composed of three resonators for the fundamental, second and third harmonics and a negative resistor. As the basic synchronization property of the oscillator, it is shown that two stable phase synchronization modes exist as follows. When the oscillator oscillates synchronously to the fundamental and the third harmonic frequencies, and the external signal with the frequency equal to the second harmonic is injected, synchronization takes place migrating among three frequencies with two stable phases. Then the phase regeneration of the oscillator for the injected phase‐modulated signal is discussed. When the change of the input signal phase is small, the oscillator output phase tends to remain at the original stable phase. When, however, the input phase approaches the other stable phase, the output phase changes stepwise to the other stable phase. Thus, the output signal has the phase fixed to either of the two stable phases. Such a phase regeneration phenomenon is demonstrated by the numerical solution for the simplified equation for the amplitude and phase of the oscillator. Finally, a three‐mode oscillator is constructed which oscillates at the fundamental frequency of 3.5 MHz. It is verified experimentally that the characteristics as analyzed by the theory are realized.
Analysis of sleeve antenna with ground wires
Authors: Taguchi Mitsuo , Egashira Shigeru , Ohzono Tatsuru
Published: July 2007

Numerical and experimental studies have been performed on the sleeve antenna. The sperrtopf reduces surface leak currents of the feeder compared to surface currents on the antenna; hence it is confirmed that the feeder does not have a large influence on the antenna properties. Ground wires are attached to the sleeve to match the feeder with the antenna. The effect of the sleeve length, and the length, inclination, and position of the ground wires on the antenna properties have been analyzed numerically and the results compared with experimental results. In the numerical analysis, the feeder is not considered and Galerkin's method was applied to the Poklington integral equation. The 50–Ω input impedance was obtained when the sleeve length is 0.2λ (λ is wavelength), the length of the ground wire is 0.1λ, distance of the ground wires from the feeding point is 0.025λ, and the ground wires are in a horizontal plane; thus the horizontal actual gain is 2.1 dB. This antenna is very useful for mobile radio.
Multiple fir digital filters on a complex integer residue ring
Authors: Murakami Hideo
Published: July 2007

This paper proposes recursive and non‐recursive multiple filters, as a method to realize efficiently a bank of FIR filters on a finite ring. Both types are essentially the application of the isomorphism of the integer residue ring based on the Chinese remainder theorem. For the recursive multiple filter, a bank of filters is realized based on the transfer function defined by z‐transform on the recently introduced complex integer residue ring. Under the isomorphism of the residue ring, the equivalent single filter to the filter bank is realized. For the nonrecursive multiple filter, the number‐theoretic transform on the complex integer residue ring is used to realize the filter based on the equivalence similar to the recursive case. This paper emphasizes the recussive multiple filter. The integer of the form 2n‐1 is proposed as the modulus for the residue operation to be used in the design. The determination of the factors of such an integer and the construction of the residue operation unit are discussed. Finally, the multiple filter is evaluated, and a design example is shown.
Estimation of bit error rate performance of sequential decoding
Authors: Ohashi Masayoshi , Hirata Yasuo
Published: July 2007

An analysis of the BER performance of sequential decoding with stack algorithm is presented for rate 1/2 code. A tight upper bound of BER performance for maximum likelihood decoding is calculated by specific code distance profiles for evaluating the proto error probability of the simulation results. Block error probability is also considered through the random coding theory so that the simulation results satisfy its upper bound. Finally, the coding gain achievable by the sequential decoder is presented for given constraint length of the code and the memory capacity in the decoder, which will be useful for the hardware design.
A low–loss 6–pole canonical dual–mode filter for the output multiplexer of broadcasting satellite transponders in the 12–GHz band
Authors: Nomoto Toshihiro
Published: July 2007

This paper describes the development of a filter for the channel multiplexer in the 12‐GHz band broadcasting satellite transponder with a high transmitting power (above 200 W). The filter for high‐power multiplexer must have a very low loss, to maintain the satellite transmitting power and to secure thermal stability. It was found that the use of a 6‐pole elliptic filter is better than that of a 4‐pole elliptic filter from the viewpoint of the insertion loss and the heat dissipation. The 6‐pole canonical filter is designed using TE113 dual‐mode. In the thermal design, super‐invar with small thermal expansion coefficient is used for the cylindrical waveguides of the filter, and copper with high thermal conductivity is used for the iris plate. Improving the heat dissipation and suppressing the temperature‐rise, the deterioration of the filter characteristics caused by the temperature variation is prevented. The experimental filter realized the insertion loss of less than 0.3 dB, the loss variation of 0.1 dBp‐p and group‐delay variation of 5 nsp‐p within the channel. No significant deterioration of the filter performance was observed through the thermal test of 0°C to 90°C and the high‐power test of 200 W. As a result, it was demonstrated that the proposed filter has better electrical and thermal performance than the previous 4‐pole elliptic filter, being suited as the filter for the multiplexers in high‐power broadcasting satellite transponders.
Design of multirate bandpass digital filters with complex coefficients
Authors: Ikehara Masaaki , Takahashi Shinichi
Published: July 2007

The multirate digital filter is useful in realizing narrowband characteristics because multiplication can be reduced by using different sampling frequencies, at the same time reducing the order of the filter to be realized. This paper introduces the complex coefficient into the traditional design of the low‐pass multirate filter. The construction method is proposed for the multirate bandpass digital filter with complex coefficients. By applying the complex coefficient filters to the decimeter and interpolator composing the multirate filter, bandpass characteristics can easily be obtained. By employing the multistage cascade structure, the number of multiplications and the memory capacity for coefficients can be reduced greatly. Then a new design method for the complex‐coefficient filter is proposed based on the properties of the analytic signal. The discussion in this paper applies to both FIR and IIR filters.
Reflection and transmission of surface acoustic waves at a boundary between metallized and free surfaces on an anisotropic substrate
Authors: Yamada Akira , Shimizu Hiroshi
Published: July 2007

This paper considers the case where the regions of conductor‐deposited surface and the free surface are bordered by a straight line. The reflection and transmission characteristics of the surface acoustic wave are approximately analyzed, which is incident to the boundary. In the proposed analysis, the incident, reflected and transmitted fields near the straight‐line boundary are represented by the linear sums of surface waves, which are a three‐dimensional surface wave in each region with the real and complex wavenumbers, in general. The wavenumber of the surface wave on the substrate is decomposed into the longitudinal wavenumber in parallel to the straight‐line boundary and the wavenumber in the perpendicular direction. The reflection and the transmission coefficients are determined so that the discontinuity of the field near the straight‐line boundary is minimized. As a result, the analytic formula is derived for the reflection and the transmission coefficients, using only the transverse wavenumber of the surface wave. By this elaboration, a simple and approximate method of analysis is presented, which can be applied in general to the arbitrary anisotropic substrate.
Connections of accuracy of least‐square polynomial approximation with degree of polynomials
Authors: Kawaguchi Mayuka F. , Da‐te Tsutomu
Published: July 2007

The least‐square approximation, the minimax approximation, the approximation by partial sum of series expansion and its modifications, are generally used methods of functional approximation, and each has proper advantage for each use. In the case of the least‐square polynomial approximation, the accuracy is expected intuitively to increase as the degree of polynomial is increased, and then reach a ceiling. However, actually, a decrease in accuracy occurs at a certain degree of polynomial when it is run from low to high. As one of its causes, the effect of ill‐condition of simultaneous linear equations in the power series approximation is well known. However, there are phenomena of decrease in accuracy which cannot be explained by the foregoing. To elucidate their causes, this paper shows that the decrease in accuracy as the degree of polynomial increases also occurs in the approximation by orthogonal polynomial in which results are obtained without solving simultaneous linear equations. Also, the differences of the two representative approximations are shown quantitatively by numerical examples. Moreover, the analysis of the cause and experiments on predicting theoretical approximation accuracy by simple formulas are reported.
Extraction of photographic area from document images
Authors: Nakamura Osamu , Koizumi Ichiro , Kikuchi Toshiyuki , Minami Toshi
Published: July 2007

In accordance with the diversification and efficiency promotion of visual communication, various new services have been desired recently. One such service is facsimile which can transmit both black‐and‐white pictures and photographic pictures. However, it is rather difficult to process these two kinds of pictures with a single algorithm. To fulfill the demand for high transmission efficiency and high quality of the reproduced pictures, it is desirable to segment the documents into two categories and process them separately. For this purpose, the extraction of the photographic area included in documents becomes a very important theme.

In this paper an extraction algorithm of the photographic area from the document images using the characteristics of edge elements and background gray levels is proposed. The features of this algorithm are: 1( automatic setting of parameters adaptable for each picture is possible; 2) area segmentation corresponding to the various gray levels of backgrounds is possible; and 3 segmentation accuracy is rather high. In the experiment presented in this paper, 125 document images which consist of 512 × 512 pixels with 7‐bit gray levels have been used. The background gray levels of these images are 27, 36, 42, 57 and 77, and into these images photographic images, which occupy 50, 60, 70, 80 and 90 percent of the total area have been inserted. Experimental results show that in every image the photographic areas have been segmented successfully in the sense of practical use. For 93.8 percent of the images, the differences between the inserted areas and extracted areas are only 0 – 7 blocks (0 – 27 pixels), and the usefulness of this algorithm has been proved categorically.
Performance evaluation of mutal overflow routing for hierarchical packet‐switching networks
Authors: Inamori Hisayoshi
Published: July 2007

This paper presents an evaluation of the traffic characteristics of the overflow routing, which is one of the isolated routings (i.e., only the information in the switching station is utilized) of the packet‐switching network. In the overflow routing, the packet selects the first route if the number of waiting packets in the first route is less than the threshold value, and selects the second route if it is equal to or larger than the threshold. Which of the routes is defined as the first route is determined for each destination of the packet, and the packet deroutes others among the routes. In the first part of this paper, the relation between the transmission‐waiting time in the switching station and the threshold of the overflow routing is derived. Then the two‐level hierarchical packet‐switching network is considered, and the mutual overflow routing, SQ + B routing and the stochastic routing, which is easy to realize with simple processing, are compared from the viewpoint of the transmission delay between the transmitting and receiving stations; SQ + B routing has the best performance in the isolated routings, and the stochastic routing features in the simple processing and the easy representation. As a result, it is shown that the transmission delay in the mutual overflow routing is less than in the stochastic routing and is nearly the same as that of SQ + B routing. Since the processing per packet in the mutual overflow routing is less than that of the SQ + B routing, the mutual overflow routing can be considered as the best among the three routing methods.
A method for signal transmission and processing in vehicles
Authors: He Aiguo , Kawamata Akira
Published: July 2007

This paper discusses the method for controls, signal transmission and processing of the proposed integrated electronic system for vehicles. It is shown that the data transmission within a vehicle can be simplified by utilizing the properties of the signals in vehicles, and a memory structure is presented for the communication and control units of the system. The software is also discussed, indicating that the errors during transmission can be corrected automatically. Finally, the message collision rate during transmission is shown to be proportional to the message occurrence rate in the system, and the proportional constant is determined. It is shown also that the data transmission delay can be ignored for the low‐speed controls; and, however, the data used for the high‐speed controls should be transmitted without the transmission ring.
Centrality functions defined by minimum vertex cuts separating two vertices in a network
Authors: Takeuchi Masashi , Morishima Naohiko
Published: July 2007

The discussion of the centrality of each vertex in a network which is an abstract of communication and transportation, etc., networks is one of interesting topics in network theory, and various centrality functions expressing the centrality of vertices in networks have been proposed regarding this problem. This paper defines a centrality function, using minimum capacity of vertex cuts separating two vertices, as a measure of expressing the relation between two vertices in a network, and describes its fundamental properties. Although this minimum capacity of vertex cuts separating two vertices has not been investigated in the existing literature for centrality functions, it is considered to be one of fundamental quantities expressing the relation between two vertices in a network in which vertices have capacities. Also, defining the centrality function using this quantity seems to be significant.
Decoupling of multiinput‐output system containing two kinds of independent variables
Authors: Kawakami Atsushi
Published: July 2007

Decoupling of a system is a procedure to establish a one‐to‐one correspondence between the input and the output of the system, by giving a state or output feedback to the system. This paper proposes a decoupling method for the general multiinput‐output system containing two kinds of independent variables. An analysis is presented for the realization dimension. The possibility of reducing the dynamical dimension of the dynamical feedback, the dynamical feedforward given to decouple is also discussed. Then to stabilize the decoupled two‐variable system, a method is considered in which the poles of the elements of the transfer function matrix are assigned to the desired locations.
Antenna‐beam allocation for a satellite‐fed millimeter‐wave personal communication system
Authors: Shimada Masaaki , Yoshimoto Shigetoshi , Suzuki Yoshiaki , Iida Takashi
Published: July 2007

The satellite‐fed millimeter‐wave personal communication system that is described requires a satellite with a multi‐beam antenna in order to guarantee the required link availability in point‐to‐point communications between numerous widely distributed small Earth stations. The usual method of antenna beam allocation requires high beam power in the downlink, giving rise to realizability problems due to limitations on the output power of the millimeter‐wave transmitter. This paper proposes an approach to optimizing the allocation of downlink antenna beams in which the beams are assigned to service areas that are chosen with reference to population distribution, rainfall attenuation in the millimeter‐wave region, and constraints on beam power. A computer simulation based on nationwide rainfall attenuation and population distribution data indicates that the proposed approach is more effective than with the usual beam allocation method. The equipment configuration of the satellite is described.
Analysis of balanced stripline branch‐line 3‐dB hybrid circuit based on planar circuit model
Authors: Anada Tetsuo , Jui‐pang Hsu
Published: July 2007

The stripline branch‐line 3‐dB hybrid is an important circuit used frequently at microwave and millimeter‐wave frequency ranges. At high frequencies where the dimensions of the discontinuous sections with respect to the wavelength are no longer negligible, the electromagnetic disturbance needs to be included accurately in the analysis and design. In this paper, an analysis of a balanced stripline branch‐line 3‐dB hybrid is described in which such electromagnetic disturbances are taken into consideration. The balanced stripline is approximated by a planar transmission line so that the entire hybrid circuit is replaced with a planar circuit to which the planar circuit theory is applied. The paper develops a systematic analysis method. Further, based on the analysis method described here, frequency characteristics of the basic hybrid circuit are derived. The frequency range at which the characteristics start degrading, and the causes, are described.
A multiple address data communication system via satellite link
Authors: Shiozaki Akira
Published: July 2007

One of the features of satellite communications is broadcasting ability (multiple address communication). Since a satellite has lengthy transmission delay, transmission errors at each link accumulate and the number of retransmissions increases, resulting in decrease in throughput efficiency if a one‐to‐one transmission control procedure (such as HDLC) is applied to a multiple address communication. This research proposes a multiple address communication system via a satellite link. In this system, information sequence is divided into N blocks based on the Chinese Remainder Theorem and the N blocks are sent with the SREJ (selective reject) procedure. At a receiving station the original information sequence can be restored with at least K(N) received frames. Therefore, the number of frames re‐sent from a transmitting station decreases and a decrease in throughput efficiency is prevented. The transmission characteristics of the proposed system are examined under the assumption that an ideal SREJ procedure is used. As a result, it is revealed that the proposed multiple address communication system can achieve higher throughput efficiency than the iterations of individual one‐to‐one communication.
A unified coding method of dithered image and text data using micropatterns
Authors: Nakamura Yasuhiro , Matsui Kineo
Published: July 2007

This paper introduces a unified coding algorithm for dithered image and text data. When a gray scale image is represented by binary pseudo‐half‐tone, various binary patterns representing the same gray scale are generated based on the degree of freedom in the dither matrix. Then one of the binary patterns is selected to represent the corresponding text data. The proposed algorithm permits approximately 70k bytes of text data to be embedded into a 256 × 256‐pixel image. It enables the transmission and handling of the mixture of image and text data without processing the two types of data separately.
Three‐dimensional analysis of patch antenna by bergeron's method
Authors: Kashiwa Tatsuya , Yoshida Norinobu , Fukai Ichiro , Koike Shoichi
Published: July 2007

Recently, extensive efforts have been expended in research and development of patch antennas which are small in size, lightweight and not very thick. In these antennas, the effect of the near field on the far field characteristics cannot be ignored. The former is affected in turn not only by the antenna element but also by the shape of the structure on which the antenna is installed. This near field has a complex field distribution which is dependent on the three‐dimensional structure and the medium conditions of the system. A systematic analysis in which the three‐dimensional structure and the medium conditions of the system are given rigorous consideration is indispensable. In this paper, a rectangular patch which is a basic form of the patch antenna is analyzed by the Bergeron method in terms of the three‐dimensional time response of the near field. Based on the aperture distribution of the electric field thus obtained, the far field is computed by Fourier transform. A method is proposed for efficiently deriving the far field in the Bergeron method. By comparison with analytical solutions, the validity of the fundamental treatment is verified. Further, by taking advantage of vector analysis, the electric field near the patch is expressed in a vector form for both the linear and circular polarizations. The spatial and temporal evolution of the field and the change from the near field to the far field are exhibited. Also, by means of the representation of the Poynting vector, the energy flow important for understanding the radiation characteristics of the antenna is depicted. The fundamental characteristics of the patch system are thus obtained.
Simulation of an echo distortion automatic canceller in an fm broadcasting receiver
Authors: Kondo Shoji , Date Hikaru
Published: July 2007

In FM broadcast reception, the echo distortion due to the interference between the direct wave and reflected waves produced in the propagation path is one of the factors in deterioration of sound quality. Results of simulation based on the principle reported previously are presented on the system that automatically cancels this distortion within a receiver. The simulation is conducted under the assumption that the cancellation process is carried out by a totally digital operation after the IF signal is A‐D converted. The echo distortion can be cancelled if the tap coefficients of the canceller containing a tapped delay line with a set of corresponding discrete tap delay times is controlled based on the observation result of the amplitude frequency characteristics of the input signal. It is necessary to set several tap coefficients even for a reflected wave with an arbitrary delay time. The results of simulation agreed with the theoretical predictions. As an example, the distortion factor of 37.2 dB of the demodulated output signal for an echo with the reflection coefficient of 0.5 and delay time of 8 μs even with the infinitely large input CN ratio of the receiver was reduced to 67.9 dB by the action of the canceller so that an SN ratio satisfying the broadcast standard is obtained.
An evaluation method for the reflection coefficient of building walls
Authors: Satoh Akio , Ogawa Eiichi
Published: July 2007

It is necessary to evaluate the effect of building wall reflection because the reflected waves interfere with radio communication systems in a built‐up area. As there are many kinds of unevenness on a building wall, the reflected wave consists of several waves that are reflected on different surfaces. The reflected wave has a strong frequency dependence. This indicates that the measurement of a single frequency is insufficient. Thus, an evaluation based on the measurement results at a wide frequency band is necessary.

First, this paper shows that the reflection coefficient of building walls has a remarkable frequency dependence by the measurement results on a 26‐GHz band. The relationship between the frequency dependence and wall surface unevenness is also clarified. Second, an evaluating method using a probability distribution, which is effective for varying the reflection coefficient in the band, is proposed. Third, the reflection coefficient distribution considering various kinds of walls is approximated by a Rayleigh distribution. Finally, the probability distribution of a two‐time reflection coefficient is also derived and the correspondence of distributions between estimated and measured is discussed.
Improvements in TDMA circuit switching services on a tree‐shaped broadband network
Authors: Saito Yoshihiro , Haruyama Hideaki , Ozawa Kazuyoshi , Tanaka Masashi
Published: July 2007

This paper attempts to realize the TDMA circuit switching service on the broadband tree‐shaped network applying the two‐way coaxial CATV techniques. The improvement of the time‐slotted bus system with controller window proposed previously by the authors is discussed.

To make this system practical, such problems as simplification of terminal device and expansion of service scale must be solved. For this purpose, the “center measurement method” and the “variable width control window method” are developed anew. The former is a system which measures such parameters as the round‐trip transmission delay at the central control device and notifies the terminal of the result.

By improving the down‐link transmission quality of the control window, which is important from the viewpoint of the stable operation of the whole system and by reducing the high‐speed operation functions, the terminal device is simplified. The latter is to adjust the control window width according to the traffic. By this scheme, the number of contained time‐slots, i.e., the number of serviceable subscribers, can be increased without reducing the wide service area of the broadband tree‐shaped network. A prototype system was constructed based on those two system improvements, and an experimental evaluation was attempted on the experimental two‐way CATV system with a total length of 7.9 km. As a result, it was verified that the foregoing improvements are useful and matched to each other.
Phase controlling for improving the gain or providing the low cross‐polarization level in circularly polarized phased array antennas
Authors: Chiba Isamu , Ohtsuka Masataka , Matsumoto Souichi , Katagi Takashi
Published: July 2007

When a circularly polarized phased array is used for communication, it is required to maintain a high gain and suppress the cross polarization over the beam scanning region and over the frequency region. However, in the traditional phase‐setting method in which only the feed line length and the array factor are taken into consideration, the desired radiation characteristics cannot be obtained because the elemental electric field in the array environment is fluctuated by the effect of the mutual coupling between the elements and the scattered wave from the structures.

In this paper, a method is presented for improving the gain and suppressing the cross‐polarization level by controlling the excitation phase with the phase shifters inherent to the phased array under these complex electromagnetic environments. The main idea of the present method is in the measurement of the correct and cross‐polarization components for each element antenna and in the derivation of the optimum excitation phases based on the minimization algorithm of the output power. An experiment is carried out in which the proposed method is compared with the phase‐setting method where only the feed line length and the array factor are taken into account. Thus, the effectiveness of the proposed method is demonstrated.
An optimal scope‐pattern decision method for OSI management operations
Authors: Nagai Yasuhiko , Sugauchi Kiminori , Suzuki Michio
Published: July 2007

Presently, integrated network management systems are being developed based on the open systems interconnection (OSI) management standards to manage information networks under the multivendor environment in an integrated manner. In this paper, an optimal scope‐patterns decision method for efficient OSI management operation is proposed. The scope patterns are common management information service (CMIS) operational range specifications based on the containment relationship between managed objects. The motivation for this study is to improve human interfaces for network management systems by providing a translating function for operator‐specified operational ranges based on various kinds of relationships into CMIS scope patterns. The proposed method provides the ability to translate automatically operator‐specified operational ranges based on any kind of relationship into possible CMIS scope‐pattern candidates and the ability to define optimal scope patterns for minimizing invoked operations by solving an integer programming problem using a fast computing approximate algorithm. Thus, network management operators can achieve user‐friendly human‐machine interaction and efficient management operation.
Elimination of adjacent channel interference Via nonlinear filters
Authors: Nagayasu Takayuki , Sampei Seiichi
Published: July 2007

In recent years, eliminating adjacent channel interference (ACI) for effective utilization of frequency resources has been considered important in digital radio communications. As an effective method for eliminating interference, adaptive equalizers have been utilized and limitations associated with their linear form processing have also been clarified.

In this study, as equalizers showing better interfering wave‐eliminating characteristics of adaptive linear equalizers (ALEs), an adaptive nonlinear equalizer (ANLE) containing the conventional nonlinear ALE and a nonlinear canceller, which eliminates ACI by nonlinear processing, in its body are proposed and their efficiencies are verified by computer simulations.

First, the optimal number of taps of the proposed ANLE was determined by computer simulations and the characteristics obtained with an optimal number of taps have been compared with those of the conventional method. The results showed that the proposed ANLE can effectively eliminate the interfering wave component whose spectrum has become overlapped with a desired wave and thus gives better interfering wave‐eliminating characteristics than the ALE and the nonlinear canceller.
transmission and radiation properties of a surface wave transmission line with a bend
Authors: Nakamura Takashi , Kamiya Shinji , Yokokawa Senji
Published: July 2007

As a cause of generation of unwanted electromagnetic radiation, the bend of a surface wave transmission line is investigated. The transmission and radiation characteristics at the bend are studied analytically and experimentally. First, by applying the traveling wave mode method, it is shown that the transmission characteristics of the surface wave transmission line can easily be obtained. The change of the equivalent voltage near the bend is observed.

Next, the discontinuity of the traveling wave current is considered as a radiating source and the radiation field from the bend in a surface wave transmission line is derived by means of the principle of pattern multiplication. It is found that there exist an electric field component which strongly radiates into the traveling directions of the current in a bent transmission line and the component which radiates into the intermediate direction. It is found that the power is radiated strongly into the intermediate direction. Further, by experiments which agree well with the theoretical results, the validity of the method is presented.
SDH signal transfer method based on ATM techniques
Authors: Ueda Hiromi , Uematsu Hitoshi
Published: July 2007

Asynchronous transfer mode (ATM) networks are nonhierarchical networks that can reduce network cost and simplify network operation, administration, maintenance, and provisioning. During the period in which ATM and existing synchronous digital hierarchy (SDH) networks coexist, it is necessary to convey SDH signals using ATM technologies. First, the SDH signal transport units, the VC or TU/AU level, are considered and the best choice is found to be TU/AU. Next, algorithms for handling lost and misdelivered cells using the sequence number SN and its protection SNP are presented. Finally, SDH signal phase information transport methods are discussed.
ATM switching system with bandwidth control function
Authors: Kozaki Takahiko , Takase Akihiko , Yanagi Jun'Ichirou , Tanabe Shiro , Gohara Shinobu
Published: July 2007

In the 21st century, 10∼30 Mbps video services will be the main traffic services of B‐ISDN. Therefore, bandwidth control is effective for dividing a 150‐Mbps line into the call bandwidths. A shared buffer‐type ATM switch with this function can be achieved by queueing call by call and by reading out cells from the queues according to the bandwidth control table sequence. When the traffic is random with utilization of 0.9, the switch with 128∼512 queues on the 4000‐cell shared buffer has sufficiently small cell loss characteristics.

Multiqueueing technology is provided by embedded RAMs which point to the first addresses and last addresses of the queues. Queue length control, which limits each queue length, for multiqueueing is provided by the embedded RAMs. A one‐board switch with 128 queues on a 4000‐cell shared buffer is developed.