bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversible predictive coding of continuous‐tone picture signals using block adaptive variable‐length codes — A scheme of reversible coding for picture data base
Authors: Saitoh Takahiro , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

In the picture data base the allowable distortion is dependent on the various uses for each picture signal. an efficient reversible coding for continuous‐tone picture signals, which does not increase the distortions of PCM original picture signals, is necessary to construct the picture data base efficiently. In most of the former proposed reversible coding schemes, the compression characteristic deteriorates remarkably as the number of picture signal gradations is increased. In this paper, a scheme of reversible predictive coding using block adaptive variable‐length codes is proposed for 8 bit/6 bit PCM continuous‐tone picture signals. A simple method of selecting the appropriate variable‐length code in every block based upon threshold logic, which is designed by means of numerical calculation, is shown to be able to achieve almost the same efficiency as in the optimum selection scheme. Besides, a method of adapting its block size is introduced to cope with the block size dependency of the compression characteristic. This coding scheme yields a performance advantage of approximately 0.2 ‐ 0.4 bit/pel for 8 bit PCM picture signals and 0.11 ‐ 0.17 bit/pel for 6 bit PCM picture signals over Rice Machine 1.
Experimental study of the relationship between the propagation distance and the polarization characteristics of whistlers
Authors: Okada Toshimi , Tanaka Yoshihito , Hayakawa Masashi , Iwai Akira , Shimakura Shin
Published: July 2007

Wideband (0‐8 kHz) measurements were performed for VLF whistlers at Moshiri (geomag. lat. 35°N) in Hokkaido in January, 1983 to investigate the relationship between polarization characteristics of whistlers and their propagation distance after the ionospheric transmission in the Earth‐ionosphere waveguide. the phase differences of the two signals of whistlers detected by orthogonal (E‐W and N‐S) loop antennas have been measured and the following results found: (1) the polarization of whistlers which penetrate the ionosphere close to the observing station is righthanded over a wide frequency range; and (2) some whistlers are found to have propagated over a distance of ∼1500 km. These whistlers exhibit a right‐handed polarization at some frequencies and a left‐handed polarization at other frequencies. However, the averaging of the observed polarizations over a wide frequency results in a nearly linear polarization; this agrees qualitatively with previous theoretical calculations by Crary.
Improvement of K‐band satellite link transmission capacity and availability by the transmitting power control
Authors: Egami Shunichiro
Published: July 2007

To cope with the rain attenuation in K‐band (quasi‐millimeter waveband) satellite communication, the effect of a transmitting power control scheme which controls adaptively the onboard transponder transmitting power toward each earth station according to the downlink rain attenuation, is clarified quantitatively. Also, the design of the FDMA satellite communication system with transmitting power control is made possible. Probability distribution of the downlink rain attenuation is used to represent each FDMA carrier transmitting power. the total transmitting power of the transponder is obtained as the sum of these FDMA carrier powers by using the central limit theorem. By the probability density function of this total power and the upper limit of this total power which is determined by the transponder maximum transmitting power and the output backoff, the maximum allocatable FDMA channels per transponder is derived. Further, the channel capacity of the overall system is calculated, taking account of rain attenuation distribution, regional differences of satellite antenna gain, and regional distribution of earth stations. By these procedures, the allocatable number of channels and the link availability are derived, and the design of the FDMA satellite communication systems with transmitting power control is made possible. As an example, considering Japanese CS‐2 satellite, the number of channels and link availability for 64 Kbps and 1.544 Mbps earth stations with antenna diameter 3 mø, are shown.
A synthesis of an active RC filter with reduced GB effect of operational amplifier
Authors: Watanabe Hiromichi , Hoshi Hideaki , Kikuchi Hisakazu
Published: July 2007

In synthesizing RC filters by simulation of LCR filters, the advantages are simplicity of synthesis and low element sensitivities. Ordinarily, the operational amplifiers used in this synthesis method are all considered to have ideal characteristics which hold only at low frequencies. Researches on the effect of the frequency characteristics of the operational amplifiers on the filter characteristics have been done for Biquad circuits in several cases but none at all for higher‐order active RC filters. In this paper, first, a synthesis method different from the conventional method is shown for a filter with finite zeros. Then a method for reducing the effect of the finite GB product on active RC filters is shown by contradicting the unnecessary phase‐rotating component of the operational amplifiers with the entire circuit, assuming that all operational amplifiers used in the filter have the same GB product. Furthermore, actual circuits are synthesized and experiments are performed. As a result, the effectiveness of the proposed compensation technique is shown by the fact that the frequency range for possible synthesis is extended. Finally, a synthesis method and experimental results are shown for a filter with all poles.
Measurements of wave normal directions of magnetospheric VLF emissions observed on board satellites
Authors: Yamanaka Yukio , Hayakawa Masashi
Published: July 2007

The wave normal directions of magnetospheric VLF/ELF chorus have been determined by using data from the geostationary satellite GEOS 2. They will provide useful information on the emission generation mechanism.
New planar magnetron system for ferromagnetic targets–Magnetic field distribution near the target surface
Authors: Takahashi Takakazu , Yoshida Junsaka , Takeda Fumio
Published: July 2007

A new exposed pole‐type planar magnetron system for sputter deposition from ferromagnetic targets is proposed. Because the system uses a washer‐shaped target, both magnetic poles are exposed at the target surface. This allows great increase in the tangential magnetic field component at the target surface. We used three targets herein: the new washer‐shaped ferromagnetic (Fe), conventional nonmagnetic (A1), and ferromagnetic (Fe) targets. the magnetic field distribution over each target was measured as a function of the current through a field confinement solenoid coil. the tangential component of the magnetic flux density over the washer‐shaped Fe target was much larger than over the conventional ferromagnetic target, showing clearly the effect of the exposed poles. However, when compared with the nonmagnetic target, the tangential component is still small and the effect of the solenoid coil weak. the tangential component of the magnetic flux density is changed by the vector addition of the horizontal component of the solenoid coil field.
Interactive fuzzy decisionmaking for multiobjective nonlinear programming problems
Authors: Sakawa Masatoshi , Yumine Toru , Nango Yuji
Published: July 2007

This paper presents an interactive fuzzy decisionmaking method for the solution of multiobjective nonlinear programming problems. Considering the imprecise nature of the decision maker's judgments, we assume that for each of the objective functions, he has fuzzy goals expressed in words such as “x should be somewhat larger than a,” “y should be substantially less than b” or “z should be in the vicinity of c.” to quantify the fuzzy goals of the DM by eliciting the corresponding membership functions, we propose five types of membership functions: linear, exponential, hyperbolic, hyperbolic inverse and piecewise‐linear functions.

Through the use of five types of membership functions, the fuzzy or imprecise goals of the decision maker are quantified. Then by selecting one of the three possible fuzzy strategies, the compromise solution of the decision maker can be derived from among (local) Pareto optimal solutions. On the basis of the proposed method, a time‐sharing computer program is written in FORTRAN and an illustrative numerical example is demonstrated together with the computer outputs.
Influence of an interfering second target on a certain amplitude‐comparison monopulse radar system
Authors: Endo Tetsuro , Suzuki Toshiaki
Published: July 2007

This paper examines angular tracking performance in an amplitude‐comparison non‐pulse tracking radar employing both AGC and phase synchronization (PLL) for the case where an interfering target as well as the main target are present within the beam of the tracking radar. the interfering target causes generation of an incorrect error output signal and the antenna boresight cannot be held on the main target. the effects of the interfering target are quite complex as they are dependent on the difference in Doppler frequencies of the two targets and on the bandwidths of the AGC and PLL systems. In this paper we calculate the error output using both the harmonic balance method and Galerkin's method for an arbitrary PLL bandwidth in combination with a narrowband AGC and a wideband AGC. From these results, we find that when the PLL has a comparatively narrow bandwidth the approximate analysis using the harmonic balance method gives sufficiently accurate results for practical application.
Bipolar monolithic very‐wideband amplifier
Authors: Kamoto Tsutomu , Ohara Mamoru , Kobayashi Yoshiji , Aiki Mamoru
Published: July 2007

Analog basic amplifier ICs (e.g., differential amplifiers, parallel feedback amplifiers, gain control amplifiers) and equalizing amplifier ICs for repeater circuits of high‐capacity optical transmission systems are designed using high‐speed bipolar technology (e.g., SST‐2). Particular consideration is given to reduction of base resistance, optimization of current density and pattern layout and improving breakdown voltage in applying this technology to analog circuits. Moreover, a peaking technique is applied to wideband amplifiers and a gain control amplifier is constructed which has wide linearity and can be directly connected to other differential circuits because of its constant dc level. For a differential amplifier with peaking, a gain of 15 dB and bandwidth of 1.4 GHz are realized. Expansion of bandwidth by peaking is also applied for the gain control amplifier and a gain of 28 dB, bandwidth of 630 MHz and a variable gain range of 30 dB are obtained. In addition, an equalizing amplifier with transimpedance of 70 ∼ 620 dB and bandwidth of 410 ∼ 620 MHz is constructed. Thus, it is evident that integrated repeater circuits for use in high‐capacity optical transmission systems can be realized.
A time‐series analysis method based on the directed transinformation
Authors: Kamitake Takashi , Harashima Hiroshi , Miyakawa Hiroshi
Published: July 2007

In a previous paper we presented procedures of analyzing causality between a time series based on information theory and information flow between time series based on a concept of directed transinformation, which is an information quantity with a direction. In principle, the directed transinformation is defined based on joint probability density between time series. As the length of the time series becomes larger, however, the volume of computation needed also increases exponentially. In this paper, we will discuss efficient computation algorithms. First, we assume Gaussian properties with the time series to present the “correlation function method” as a means of computing of the directed transinformation from correlation function. Second, we present a “linear production model method” in which the information quantity is computed by means of impulse response of a linear production model of the time series. Also, we proved that the linear production model can easily be composed by auto‐regression if the time series is steady. Finally, we discussed the validity of time‐series analysis based on the directed transinformation through analysis of an artificially produced simulated series. We have concluded that the proposed computation method can provide correct analysis even if the causality of the time series can not be analyzed correctly based on the correlation function.
Pattern synthesis of array fed reflector antennas
Authors: Mano Seiji , Katagi Takashi , Tsutsumi Takashi
Published: July 2007

Phased array reflector antennas are used in practice for beam scanning in a limiting range of angles. Compared with the complete phased array systems, these antennas have a simple structure and can be constructed with a smaller cost. These arrayss fed reflector antennas can be replaced with generalized array antennas by considering the secondary radiation pattern of each feeding element of the array element pattern. This paper is a theoretical study of the maximization of the gain and suppression of the sidelobes for this generalizeed array. These problems are important for pattern synthesis. From the study, it was found that the computation time of the synthesized secondary pattern can be reduced for the array fed reflector antenna due to exploitation of the secondary element patterns. Also, the array excitation distribution optimum for the desired pattern can easily be determined from the theory of the generalized array. These findings have been confirmed experimentally by means of an X‐band linear array fed reflector antenna.
Analysis and control of reattempt phenomenon
Authors: Shinohara Masaaki
Published: July 2007

The hysteresis phenomenon caused by the reattempt process can be observed in overloaded communication networks and the intensity of this phenomenon is affected by the reattempt parameters, such as reattempt probability, reattempt interval, etc. This paper proposes a macroscopic analysis method for the reattempt system model and clarifies the mechanism of the hysteresis phenomenon by introducing the concept of stability index which characterizes the transient behavior of the system. Moreover, the optimum control strategies of the number of repetitions for two different service models are discussed.
Stress birefringence in YIG and Bi:YIG thin films
Authors: Mizumoto Tetsuya , Tsuchida Manabu , Banno Junichi , Naito Yoshiyuki
Published: July 2007

To obtain a mode converting optical isolator it is necessary to achieve phase matching of the TE and TM modes propagating through the magnetic film, such as a rare‐earth garnet, etc. One of the methods of phase matching employs the birefringence induced by a lattice parameter mismatch between film and substrate. This paper presents measurement of the birefringence in YIC and Bi:YIG films grown on a GGG substrate using liquid phase epitaxy. Moreover, birefringence evaluated from the optoelastic effect and the stress calculated using a bimetal model agree well with the measured values. From these results, the birefringence induced in YIG and Bi:YIG films can be obtained theoretically. It is established that a phase‐matched magnetic waveguide can be obtained using Bi:YIG thin film. Further, by using such films nonreciprocal mode convertors and isolators can be realized.
A method to obtain the specified N‐port networks from voltage and current graphs and its application to the topologically minimal realizations for generalized immittance converters
Authors: Matsumoto Tadashi , Hibino Kazuhisa
Published: July 2007

A report was previously made on problems, for given port characteristics of a functional resistive two‐port, to determine the lower bound for the number of elements needed in the topological realization of the characteristics with nullors and resistors, or to determine the voltage and current graphs GV and Gi. The algorithm to determine the two‐port in the nullor model from Gv and Gi has also been published for simple cases [7, 8]. This paper describes, for given Gv and Gi for an Nth order real square matrix, a generalized algorithm to determine the nullor model N‐port with specified port characteristics. The algorithm is applied to the topologically minimal realization of the generalized immittance converter (GIC) to determine all possible minimal GIC realizations. The algorithm forms a basis for the proposed topological network synthesis, which is a kind of structured system synthesis. Various applications of the idea as well as the determination of Gv and Gi from an Nth order real square matrix are also discussed.
SAW‐resonator stabilized voltage‐controlled‐oscillator for PLL‐FM modulator
Authors: Urabe Shuuji , Habuka Tatsuji , Matsuura Takashi
Published: July 2007

A voltage controlled oscillator using a SAW resonator does not need multiplication and tuning in the 100 MHz ‐ UHF band so that miniaturization and circuit simplification can be achieved. It also has the feature that less power is dissipated than with a SAW delay line. In this paper the SAW resonator voltage‐controlled oscillator (SAWR‐VCO) is used as a modulator suitable for a phase locked loop (PLL) and its modulation sensitivity and distortion are analyzed. Tests confirm the analysis of SAWR‐VCO performance. Finally a PLL modulator structure and the modulator circuit for use in an automotive mobile telephone unit is described.
1‐GHz 2‐modulus prescaler MSI with a direct feedback loop
Authors: Yamashita Kiichi , Kaji Tadao , Kanouta Keiji , Sekine Yasushi
Published: July 2007

This paper describes the design and observed performance of a 2‐modulus prescaler MSI developed for a pulse‐swallowing variable frequency divider at 1 GHz. The output of the final stage is fed directly back to the first stage to achieve high‐speed operation. The operating speed is 1 GHz for a source voltage of 5 ± 0.5 V and ambient temperature from −40 to +85 C; the maximum speed is 1.3 GHz. The power consumption is 400 ‐ 450 mW. The frequency division ratio is 1/64 and 1/65. Series gate ECLs are used for the basic circuit and the logic amplitude is 0.5 V. The chip size is 1.78 × 2.08 mm2and includes 285 transistors and 170 resistors. Transistors with emitter size of 3 × 5 μm2and qualityn‐type resistors are used in the high‐speed circuit.
Fast convolution methods for hexagonally sampled two‐dimensional signals
Authors: Morikawa Yoshitaka , Kaneda Masahiro , Hamada Hiroshi
Published: July 2007

For fast convolution operations on one‐dimensional signal sequences there is the fast cyclic convolution (FCC) method based on sectioning. Also, for a two‐dimensional signal sequence in the convolution operation of a rectangularly sampled signal sequence and a convolving sequence arranged in rectangular blocks, an FCC method based on rectangular sectioning has been reported. On the other hand, two‐dimensional signals band‐limited over a circular region are sampled hexagonally. This arrangement of the convolving sequence in hexagonal blocks to provide it with 12‐fold symmetry is most effective. This paper describes an FCC method based on sectioning for such types of hexagonally sampled signal sequence and convolving sequence arranged in hexagonal blocks, Presupposing the use of a fast Fourier transformation (FFT) of base number 2 in the discrete Fourier transformation in FCC, two types of FCC (hexagonal sectioning and parallelogrammatic sectioning) are proposed and overlap‐and‐save algorithms for these two are given. Also, it is shown that there exists an optimal sectioning block size for which the number of numerical operations becomes minimum in both methods. Next, for both types, the number of numerical operations are calculated and compared. Due to the limited memory capacity useable in FFT calculation, if convolution is not possible with optimal sectioning, the hexagonal sectioning method is advantageous. However, when the memory size is sufficiently large, it is difficult to say which of the two is better.
Line codes and repeater fault location schemes for optical transmission systems
Authors: Kitami Tokuhiro , Yoneda Etsugo
Published: July 2007

In this report, the line code structures of optical transmission systems are compared from the viewpoint of providing bit sequence independence (BSI). Repeater fault location schemes are also studied. Initially, we shall describe what considerations should be made to avoid consecutive identical codes as well as pseudo‐synchronism in accordance with the inherent meaning of BSI, and we shall show a specialized code pattern to be considered for protecting pseudo‐synchronism and a frame format to avoid pseudo‐synchronism. Furthermore, we shall show the repeater fault location schemes for the phase‐difference‐detection type of CMI code transmission system and the m BIP code transmission system with odd parity, and we shall indicate how simple they are to realize. Then the transmission line code schemes of the 100 Mb/s optical cable transmission system are compared, and it is concluded that the preferable frame format is that in which frame synchronization pulses are inserted at positions different from the parity bits based on the 7 BIP code. In addition, experimental studies of the characteristics of the timing system in the repeater of the DF‐100M system [1] will indicate the appropriateness of the design jitters and the selection of the frame format of the repeater.
A consideration on broadbanding of n‐way hybrid power dividers
Authors: Watanabe Hiroshi , Nagai Nobuo , Ono Koujiro , Hatori Kozo
Published: July 2007

A method is presented for broadbanding an n‐way power divider in which an absorbing resistor is used in one section. In the conventional Wilkinson power divider, it is known that the waves, equally reflected at the terminations, are absorbed by a resistor at the center frequency if a quarter‐wave line is connected to one of the output ports. To construct a 2n‐way power divider from a combination of these two‐way power dividers, 2n sections of lines are needed. In this paper, we constructed a network, which absorbs reflected waves, by connecting a 1/4‐wavelength section to an n‐way one‐section power divider if the characteristic impedance of the line and the absorbing resistor are optimized by numerical calculation. The circuit shown in the text has a broadband VSWR characteristic if attenuation of the transfer at the center frequency is permitted. The transmission characteristics then become flat, and the isolation characteristics are also improved.
An untrimmed monolithic 14‐bit D/A converter
Authors: Maio Kenji , Hotta Masao , Kaneko Kenji , Yokozawa Norio , Nagata Minoru , Hanada Seiji
Published: July 2007

Recently, a need has arisen for an economical untrimmed 14 ‐ 16‐bit D/A converter in the field of digital audio and precision metrological systems. However, the precision of the monolithic D/A converter is about 10 bits to date, which can be improved to 12 ‐ 13 bits by applying a special trim technique. In order to obtain the required high‐precision converter, a self‐correcting equation is established to treat the error involved. The result—a monolithic IC—has been studied experimentally.

For the most part, this paper discusses the circuit structure and the test results of the monolithic 14‐bit, DAC developed on the basis of this self‐correcting equation. The monolithic DAC was prepared by combining the type I2L digital analog process and the two‐layer microwiring technique and exhibited a linearity of ±1/2 LSB (±0.003%) and a setting time of 1.2 μsec.
A method for measuring amplitude and phase of each radiating element of a phased array antenna
Authors: Mano Seiji , Katagi Takashi
Published: July 2007

In the phased array system, excitation amplitudes and phases based on the design are specified for each antenna element in order to synthesize desired beam scannings and radiation patterns. However, due to fluctuations of antenna and feed network characteristics, the amplitude and phase of each antenna element deviate from the desired values. To correct these deviations, the amplitude and phase of each antenna element must be accurately measured under specific operating conditions. In this paper, we employ variable phase shifters connected to the antenna elements and measure only the amplitude variation of the composite electric field of the entire array when the phase of each element is modified. The rotating element electric field vector method in which the measured amplitude variation is numerically processed for obtaining the amplitude and phase of the particular element is theoretically discussed and experimentally tested for its usefulness. The present method can be easily attained by simply adding software to the computer‐controlled phased array system.
On the interleaving for elimination of destuff errors due to 4B‐3T code transmission error extension
Authors: Ohue Kenji , Yoshikai Noriaki
Published: July 2007

The error extension of 4B‐3T code causes some problems to destuff error of the stuff indicating pulses. This paper investigates the characteristics of error extension associated with 4B‐3T code transmission, and proposes a method to eliminate the adverse effects of the error. Involved are the interlease and rearrangement of the stuff indicators, pulses in the binary code before conversion to ternary code. The optimum conversion method is described. An experimental 4B‐3T code transmission system is constructed to evaluate the characteristics of error extension and destuff error. Further, this system demonstrates that the proposed 16 bits interleave method results in a destuff error rate comparable to that of the AMI transmission method and only a few hundredth of that of the conventional 4B‐3T code transmission without interleave.
Probabilistic analysis of a heuristic graph coloring algorithm
Authors: Kawaguchi Tsuyoshi , Nakano Hideo , Nakanishi Yoshiro
Published: July 2007

In this paper a heuristic graph coloring algorithm as applied to random graphs is analyzed theoretically. The result obtained by expanding on the results of [4] is presented first: let x1(n, cnδ−1) be the random variable representing a solution obtained by applying the algorithm to a random n‐vertex graph having edges with probability p(n)=cnδ− (where c is a constant and 1/2≪δ≦1). Also let x1(n, cnδ−1) be the random variable representing the chromatic number of the graph. Then x1(n, cnδ−1)/x*(n, cnδ−1)≦(1+ϵ)2δ/(2δ−1)(pr.) holds. Here ϵ represents a value sufficiently smaller than 1. By contrast, it is important from the practical point of view to find an algorithm that is effective for an arbitrary random n‐vertex graph. In this paper the above‐mentioned algorithm is evaluated using models with p(n)≪ It is found that this algorithm is effective for all n less than N, where InInN is about the same as np(n).
A solution to a multi‐object decision problem for distributed‐parameter control system
Authors: Shimizu Kiyotaka , Katayama Ryu
Published: July 2007

This paper discusses the static multi‐object control problem for a distributed system in which more than one geographically distributed decision‐maker (control station) performs control based on their own object functions. The object function of the control station is given in an integral form, with the range of integration being limited to an interval which is of interest to the control station. Then the multi‐object control problem is formulated as an optimization problem for a vector functional, leading to the optimality condition. The paper further discusses the multi‐object decision problem to determine the unique optimal control input from the set of non‐inferior solutions of the multi‐object control problem. The problem is called the central decision problem, where there exists an upper‐level decision maker and his preferable solution is determined based on the global viewpoint and the central object function. The problem is called a set decision problem when such an upper‐level decision maker does not exist, and the solution preferable to the set members is selected for the benefit of the whole set. A method of solution with two steps is proposed using the restricted simplex method and internal point penalty method. The gradient method is used for numerical computation to optimize the system of partial differential equations.
On a hybrid network system of circuit switching and packet switching
Authors: Nakamura Yatsuka , Noda Akishige
Published: July 2007

This paper describes the architecture of a hybrid switching network employing both circuit switching and packet switching. The network usually operates in a packet switching mode, but, depending on the traffic conditions, it can use special control packets to temporarily change certain lines to a circuit switching mode. The change between the two switching modes is performed dynamically depending on the traffic load of the network. Also described in this paper is the concept of metapacket which can be employed in some relatively small‐scale networks to average the load of packets and to reduce data transmission time.
An optimization method of super‐synthesis observation by “number of weighted holes”
Authors: Morita Koh‐Ichiro , Ishiguro Masato
Published: July 2007

In radio astronomy by a super‐synthesis array the element antennas are rearranged and the rotation of earth is also used. By such arrangement, the spatial frequency components of radio source distributions are measured and are subsequently Fourier transformed for radio photographs. Spatial frequency components detected are determined by the element arrangement. Therefore, the element arrangement is important for effective tive use of the array. This paper discusses the number of weighted holes, which is proposed as a criterion for evaluation of the characteristics of element arrangement. As a method for analysis, we use random number trial experiments by computer and show from the results that the number of weighted holes becomes a good indication of the peak sidelobe level under an appropriate condition. Further, we propose a method of optimizing the element arrangement using this evaluation criterion. Its usefulness is confirmed by a simulation of super‐synthesis.
Speech recognition by polarized linear predictive error coding—POLPEC method
Authors: Akagi Masato , Iijima Taizo
Published: July 2007

This paper describes the polarized linear predictive error coding method (POLPEC), which is a new scheme for speech recognition. Although the residual waveform power method, which is a method of speech recognition using an inverse vocal tract filter, has the advantage that the processing for recognition is simple and is suited to parallel processing, it has the drawback that it is sensitive to deviation of the input waveform to the inverse filter (i.e., the speech waveform). From such a viewpoint, this paper introduces the polarized linear predictive error coding method, which is a recognition scheme, in which it is assumed that deviation in the speech waveform is due to change in the pole of the transfer function of the filter for speech generation (called vocal tract filter) and, by improving the residual waveform power method, the sensitivity to the change of poles is decreased. The POLPEC method has the effect of decreasing the residual power by subtracting from the residual waveform sequence the component which is due to the deviation of poles. It is verified by experiment using synthetic speech that this reduces the sensitivity to the predetermined deviation of poles.
Four‐terminal circularly polarized self‐complementary antennas
Authors: Kasahara Takeshi , Mushiake Yasuto
Published: July 2007

Circularly‐polarized high gain antennas are needed for communication via broadcast or maritime satellites. With a view to developing a wideband circularly‐polarized antenna, we discuss experimental results for a structure consisting of a planar four‐terminal self‐complementary antenna on a core. The four conductors have a toothed shape which improves linear polarizability. The entire antenna structure is such that the sizes of the gaps and conductors are either equal or slightly modified. First, coupling between two opposing plates is qualitatively studied by measurement of the impedance and the radiated electric field. The self‐complementary nature of the antenna is confirmed. Next, the directivity, beam width and axial ratio of the circular polarization are studied. When the sizes of the conductors and gaps on the core are identical, the coupling between two orthogonal terminal pairs is small and the self‐complementary nature is practically preserved. This antenna has highly constant impedance and excellent directivity. The axial ratio of the antenna system, including the hybrid feed structure, is less than 0.8 dB over a large bandwidth.
Radiation pattern analysis of reflector antennas
Authors: Ando Makoto
Published: July 2007

A method is proposed for accurately calculating the radiation pattern of reflector antennas in the entire angular range from the main beam direction to the off axis region. The principle of the method is similar to the physical optics diffraction theory, and consists of the result obtained by conventional physical optics corrected with the contribution from the edge current calculated by the geometrical theory of diffraction. However, the edge current is expressed in a simple form by means of a local coordinate system defined by the peripheral line and the mirror normal at each edge point and of the incident electromagnetic vector components in reference to this coordinate system. Therefore, it is possible to treat an arbitrarily shaped mirror surface and an antenna with a primary radiator using an arbitrary pattern. It is confirmed that the results obtained by the present method approach those obtained by the physical optics method near the main beam and those obtained by the geometrical theory of diffraction at the off axis. Accuracy is tested by applying the present method to the problem of diffraction from a circular disk for which a rigorous solution exists. The present method makes unnecessary the distinction of the use of physical optics (main beam) and the geometrical theory of diffraction (off axis) performed so far, in an empirical manner. It is possible systematically to obtain the pattern near the first‐third side lobes where two methods may be connected.
Linear programming design of IIR digital phase networks
Authors: Sugahara Kazunori
Published: July 2007

This paper demonstrates that the IIR digital phase network can be designed by linear programming. The phase network is used not only to compensate the phase distortion of the signal by the filter, but it is used also in various other problems in communication area. In particular, the network with chirp characteristics is well known. There are IIR and FIR digital phase networks, but it is difficult to design completely flat amplitude characteristics for the latter. The design problem for the IIR digital phase filter has been considered as a nonlinear programming problem. By reducing this problem to that of linear programming, the optimal solution can be obtained, if it exists, without any particular consideration for the convergence of iteration or the initial values. This paper also discusses the order of the digital phase network so designed, and it is shown that the order is determined from the given design specifications. Finally, several design examples are illustrated, indicating that the proposed method is effective.
Speech analysis‐synthesis system and quality of synthesized speech using mel‐cepstrum
Authors: Kitamura Tadashi , Imai Satoshi , Furuichi Chieko , Kobayashi Takao
Published: July 2007

The quality of synthesized speech in the speech analysis‐synthesis system based on the mel‐cepstrum method is described. Mel‐cepstrum is defined as the Fourier coefficients of the log spectrum on a nonlinear frequency scale approximating the mel scale. The true mel‐log spectral envelope is estimated in this system by an improved cepstral method in the analysis part and a mel‐log spectrum approximating filter is used in the synthesis part. The preference score by pair comparison tests is used for subjective evaluation and spectral distortion on a nonlinear frequency scale is used for an objective evaluation. Using this system, 1.7 kbit/s, high‐quality synthesized speech is obtained.
Fast search algorithms for vector quantization in orthogonal transform domain
Authors: Nakaide Hiroshi , Aizawa Kiyoharu , Harashima Hiroshi
Published: July 2007

To realize fast search at vector quantization applied to high‐efficiency coding of signals, we propose a partial distance algorithm and a nearest‐neighbor search algorithm, both in the orthogonal transform domain. These algorithms provide efficient search for signals such as, for example, picture signals which have a concentration in the transform domain power distribution. Further, we propose a nearest‐neighbor search algorithm in orthogonal transform domain with component selection which is effective also for memoryless random information sources with Gaussian distribution.

The proposed algorithm is applied to vector quantizers of picture signals, separating‐mean‐normalized vector quantizers, and vector quantizers of memoryless Gaussian sources and its efficiency is demonstrated for these cases. Particularly, in the case of vector quantizers of picture signals, it is shown that the proposed method requires fewer multiplications to determine the optimum reconstructing vector than the conventional tree search algorithm.
Sign structures of 3 × 3 stable matrices and their generalization to higher‐order matrices
Authors: Miyamichi Juichi
Published: July 2007

A matrix A is called stable if all its characteristic roots have negative real parts. This paper discusses the stability of sign matrices (matrices for which only the sign of the elements is given) and presents some basic sign patterns of stable matrices. The stability of a matrix and the stability of a system whose interaction matrix coincides with the matrix are related closely and thus the sign pattern consideration is a useful method to study the internal structures of stable systems. We discuss the potential stability (the property that there exists a stable matrix with the sign pattern) and the sign instability (the property that there are no stable matrices with the sign pattern) of sign matrices. A signed digraph is defined for each sign matrix and the connection between its structure and the matrix stability is discussed. Methods to check potential stability and sign instability of sign matrices are given. Through the computer stability check of all 3x3 matrices, the relationships between graph structure and matrix stability are clarified and seven basic sign structures of 3x3 stable matrices are obtained. Finally, based upon these seven basic structures, potentially stable structures of higher‐order matrices are considered. Some stable sign patterns of nxn matrices together with their stability proofs are given.
Analysis of transient response of electromagnetic waves scattered by a perfectly conducting sphere. The cases of back‐ and forward‐scattering
Authors: Hosono Toshio , Yuda Kouhachi , Itoh Akira
Published: July 2007

Transient responses of back‐ and forward‐scattering are analyzed by a perfectly conducting sphere. For numerical calculation the numerical inversion of Laplace transform (FILT) developed by Hosono was used. The truncation error for the transient response of the scattered fields was examined by increasing the number of modes of the electromagnetic fields and the number of terms in the FILT method. Based on these results we confirmed that we could control the accuracy of numerical calculation for transient responses of the scattered fields. In this paper the relative error of the results of calculation is maintained less than 2 percent.

The results of analysis are shown mainly for far fields. When the incident wave was a half‐sine pulse, we obtained the following results: (1) the creeping wave was confirmed to exist in transient responses of back‐scattering; (2) the transient responses of forward‐scattering observed at a far point had waveforms which were nearly the derivatives of the incident waves; (3) the waveform of the near field was examined in detail to confirm that the result of the foregoing item (2) was not in violation of the causality law.
Null synthesis based on the principle of pattern multiplication
Authors: Inagaki Naoki
Published: July 2007

In this paper we propose a new method for an economical and realizable null synthesis to prevent interference between wireless communication lines and mixing with interfering waves. Existing methods are based on the principle of a subtraction of the directivity of a cancelling beam which has a maximum value along the prescribed null direction from that of the original array. These methods cannot avoid a degradation of the directivity in directions other than the null direction.

In this paper we have applied the concept of an array of the arrays. We have synthesized nulls by the array factor of an (M + 1) element array which has M nulls in the directivity of an N element array. In total, we used M + N elements for the array. This method depends on the principle of the products of directivities.

As long as the null direction is far removed from the main beam direction, there is, in principle, no degradation of the array directivity. By approximating element weights, we can synthesize nulls by controlling the weights of only terminal 2M elements. Past methods have noted experimentally a possible null synthesis by controlling the weights of the terminal elements.

This paper provides clearly for the first time its theoretical reason and limits. We have applied the present analysis method for cases of Taylor directivity for the side‐lobe level ‐30 dB for n = 5 in a linear array with elements placed one‐half wavelength apart. We show calculations in examples for syntheses of cases of one null and two nulls. We found that by synthesizing two symmetric nulls with respect to the main beam, there was almost no degradation of the array directivity.
Near field monitoring system for the dsb d‐vor
Authors: Tanaka Shuichi , Nihei Shiro , Nagaoka Masashi
Published: July 2007

Of the VORs providing directional information to aircraft, the new DSB‐type Doppler VOR has recently been employed as the domestic standard. In this system, the required receiving signal is obtained in the far field whereas the received signal is distorted if it is received near the VOR station. On the other hand, when a VOR station is installed, it is difficult to secure a larger area than the present one because the acquisition cost of the land is high and selection of the land becomes even more difficult if the traditional land requirement is modified. Therefore, the receiving antenna for monitoring the operating condition and the performance of the equipment is often installed near the VOR antenna so that the signal can be distorted for accurate monitoring unless an appropriate distance is maintained.

This paper studies a method in which the DSB‐type Doppler VOR can be monitored even if the receiving distance is short. The circuit configuration is complicated in the method in which the phase of the carrier being received is forced to follow the phase change of the side band signal. Instead, this paper proposes a method for simplifying the circuit configuration by replacing the carrier wave with a new carrier with an appropriate fixed phase, and an experiment is carried out. It is found that the distortion is reduced significantly and a VOR direction characteristic close to the case for a far field reception even with a short receiving distance is obtained.
Block demodulation method for psk signal by sequential regression estimator
Authors: Ohsawa Tomoki
Published: July 2007

This paper considers the block demodulation method with carrier phase synchronization without preamble, and presents a proposal and evaluation for the new carrier phase synchronization method based on the sequential regression estimator. The block demodulation has a feature in that the traditional way of real‐time demodulation is not adhered to, and the preamble is not required. This improves greatly the throughput especially in a short packet communication.

The traditional system is based on the least‐square scheme, noting that the cumulative carrier phase variation between data symbols is represented in a linear form. It has a problem in that the linearity is lost due to noise in deriving the cumulative value for the phase variation, which may greatly deteriorate the demodulation performance.

The sequential regression estimator proposed in this paper is based essentially on the least‐square principle. However, the cumulative value is not determined for each time as in the traditional method but the estimation is updated based on the difference between the observed value and the value estimated from the data up to the previous sample. Consequently, the problem in the traditional system essentially is eliminated.

Because of this elaboration, the computation in the proposed system is very small compared with traditional systems. It is seen as a result of simulation that the tolerable noise margin for 80 percent synchronizing probability, which has been used as the evaluation criterion, is improved by 11 dB for BPSK.

In the satellite packet communications network such as VSAT (very small aperture terminal), the throughput is improved remarkably. Applying the proposed principle to the design of the present link, the time‐ratio, where the burst synchronization error is 1 percent or less in the Ku band, is 0.03 percent. In VSAT, a random access scheme is employed. Considering the burst collision probability of the access, it follows that the burst synchronization error probability of 1 percent does not affect the overall performance, and the proposal in this paper can be considered as sufficiently practical.
Diagnosing hang‐ups and automatic restoration for nodes in networks of ring topology
Authors: Fuwa Yasushi , Nakamura Yatsuka
Published: July 2007

This paper proposes a method to diagnose and restore automatically hang‐ups at the nodes connected into networks of ring topology and afterward reports the place where the hang‐ups occurred to an arbitrary equipment. Various measures have been taken to prevent hang‐ups from occurring at the nodes. These hang‐ups affect the network seriously when they occur, and it is important to determine and restore them immediately.

The following method is introduced. Each node sends a mutual checking packet at regular intervals, and each node itself determines whether or not its hang‐up occurs from the result of receiving this packet and restores it. After restoration is completed, the node reports to the equipment connected with an arbitrary node the place where hangups occurred. This method has the following features:

It can be applied generally to networks of ring topology;

little hardware is needed;

diagnosing, restoration and reporting are done at each node. A special‐purpose control system is useless.
Multimedia burst‐type multiplexing based on fuzzy requirement
Authors: Sakai Yoshinori , Su Jing
Published: July 2007

In multimedia communication, the quality requirement from each medium to the network is not a definitive measure but usually contains a fuzziness. This paper represents, by a fuzzy set, the propagation delay of the network that can be tolerated by each medium and discusses the optimal burst multiplexing method for the required quality.

First, various kinds of fuzzy quality requirements are examined, and it is shown that the quasi‐optimal quality measure is obtained in common with the control at the network node.

Then based on the quasi‐optimal quality measure, two control methods at the network node are proposed: the variable priority and fuzzy priority methods. The performances of these methods are examined by numerical analysis and computer simulation, and the results are compared with those of the traditional control methods.

Finally, it is shown that the variable priority method is better when the packet delay at each node can be measured, and the fuzzy priority method is better when it cannot be measured.