bluuebunny/crossref_metadata_2025_split huggingface dataset:
Switched‐capacitor amplifier and applications
Authors: Seki Hideaki , Yamamoto Masahiro , Mori Shinsaku 
Published: July 2007

AbstractSwitched‐capacitor amplifiers are proposed which consist of a switched‐capacitor circuit in the bias circuit and the load circuit of the amplifier. In this switched‐capacitor circuit, the characteristics can be changed simply by change of control clock. The circuit is suitable for integration. Recognizing that the active device in the switched‐capacitor amplifier operates intermittently, we can feed back the amplified signal to the input and amplify further. This signal recursive switched‐capacitor amplifier is discussed. Even though this switched‐capacitor amplifier is equivalent to a conventional multistage cascaded amplifier, it can be configured with only one active device and one set of peripheral components. Hence, it has a small size and a high gain. Finally, it is demonstrated by means of an example of configuration of a bandpass filter that the conventional switched‐capacitor network can be miniaturized further with the use of the proposed switched‐capacitor amplifier.
Dielectric waveguide‐type millimeter‐wave modulator using photoconductivity
Authors: Member Kazuhiko Ogusu, Regular , Member Ikuo Tanaka, Regular 
Published: July 2007

AbstractOptical control of millimeter‐wave propagation in dielectric waveguide can be achieved by using the photoconductivity of a semiconductor. A semiconductor with short lifetime and an intense light source are required for high‐speed modulation. The present paper proposes a new waveguide structure providing the greatest possible attenuation with a given light intensity. The theoretical and experimental considerations are presented. The proposed structure is a rectangular waveguide in which a thin semiconductor layer is supported by a dielectric layer with small dielectric constant. Numerical results are presented on the variation of the attenuation constant of millimeter waves for various waveguide dimensions and dielectric constants. It is also shown that this waveguide structure can be utilized as a mode filter. The modulator and mode filter are made of Si, SiO2 and Teflon and tested at 50 GHz. It is found that modulation up to ∼100 kHz can be achieved even by using conventional light‐emitting diodes.
A discrete optimization method of switched capacitor filters
Authors: Fushimi Shigeo , Nakayama Kenji 
Published: July 2007

AbstractWhen constructed on a monolithic IC, switched capacitor filters (SCF's) composed of capacitors whose values are integer multiples of a unit value are desirable for miniaturization and reduction of power consumption, since high‐precision capacitance ratios are realized using a small unit capacitance value. This paper describes a discrete optimization method of SCF. Variables which are effective to optimization are selected based on “normalized sensitivities,” which are sensitivities at a certain sampled frequency point divided by the absolute sum of sensitivities at all sampled frequency points. The min‐max method which minimizes the maximum deviation is used to evaluate the optimization error. Initial discrete values of capacitances are determined by multiplying the pre‐quantization capacitance by a positive constant and then minimizing the mean square error of their ratios. Finally, this optimization is applied to an 8th‐order biquad bandpass filter and a 5th‐order leapfrog lowpass filter and its effectiveness is confirmed.
Stability analysis of electrical networks containing lossless transmission lines – algebraic system theoretical consideration
Authors: Ohguro Katsuhiko , Maeda Hajime 
Published: July 2007

AbstractThis paper deals with electrical networks containing lossless transmission lines and discusses the stability from the viewpoint of an algebraic system theory. Specifically, we discuss the effect of the initial conditions of the transmission lines on the stability of the system. We point out that the coprimeness of certain matrices determined by the transmission lines is crucially important for stability and derive an equivalent condition to coprimeness in terms of the pole‐zero cancellations, as well as the structure of the interconnections among transmission lines. An easily tractable stability criterion is developed.
Brightness induced by opposite polarities o'brien pattern
Authors: Sakata Haruo 
Published: July 2007

AbstractAs one of the psychological phenomena, where the brightness of the background changes by the existence of a figure, this paper describes a psychophysical measurement of O'Brien pattern with positive and negative polarities. The following results were obtained. (1) The O'Brien pattern with negative polarity has a stronger induction effect. (2) When the modulation index of the O'Brien pattern is increased, the background becomes dark by the existence of a pattern, except for the edge of the positive polarity pattern. The appearance of a Cornsweet pattern, which is composed of positive and negative O'Brien patterns, was also examined. It is concluded from the observations that the positive polarity figure has a stronger lateral inhibition, but the negative polarity figure with larger modulation index has little lateral inhibition.
Appearance of spatio‐temporal transient phenomenon on retinal locality–parallel pathways at peripheral vision
Authors: Member Haruo Sakata, Regular 
Published: July 2007

AbstractThe spatio‐temporal transient responses at the fovea and the periphery of the retina were measured, arriving at the following conclusions: (1) In the peripheral vision (at 9 deg. from the fovea), a bright line is produced at 1 deg. from the boundary after 100 ms from the presentation of the spatial step pattern. This indicates the existence of two pathways with temporarily different transient responses; (2) Setting a fixation point and presenting a temporally sweeping spatial step pattern, the rise‐width of the brightness step approaches the response of the temporal‐dominant pathway as the observation point goes away from the fovea. At the same time, a differentiated pattern is produced in the brightness boundary of the spatial step pattern, indicating the response of the spatio‐dominant pathway.
An estimation method for rain attenuation distribution in microwave multirelay links–compound lognormal distribution model
Authors: Member Kazuo Morita, Regular 
Published: July 2007

AbstractEstimation of the rain attenuation distributions in microwave multirelay links at frequencies over 10 GHz involves estimation of the rain intensity distribution at various locations, the rain attenuation distribution in each relay path and the simultaneous probability in multirelay paths. In this paper, the yearly rain intensity distribution data at various locations are studied. It is found that the distribution can be approximated by a compound lognormal model. From the yearly rain data of the weather bureau, the rain intensity distribution parameters of compound lognormal distribution are estimated at 80 locations. It is assumed that the rain intensity is of compound lognormal distribution and the spatial correlation of rain intensity is e‐αd (α: parameter, d: distance between two points). The simultaneous probability of rain attenuation in multirelay paths is calculated. Also calculated is the correction factor Mp (the probability that at least one out of n paths/n times the probability that the attenuation exceeds the specified value at one path) of the added rain attenuation in a multirelay link with respect to the sum of probabilities of attenuation in each path. The measured Mp in the 20‐GHz multi‐relay link between Musashino and Yokosuka agrees well with the estimate Mp from the compound lognormal distribution model.
Design of two‐dimensional fir digital filters on asymmetric half‐plane
Authors: Hinamoto Takao , Muneyasu Mitsuji , Maekawa Sadao 
Published: July 2007

AbstractA technique for designing asymmetric half‐plane two‐dimensional FIR digital filters in the frequency domain is presented. This filter includes the class of causal two‐dimensional digital filters as a special case. To design a linear‐phase FIR digital filter, a mirror‐image polynomial is presented for the asymmetric half‐plane two‐dimensional digital filters. The technique has an advantage of ensuring the linear phase of the resulting filters. Moreover, it is possible to design the filter by solving a set of linear equations. Two examples, low‐pass filter and fan filter designs, are solved to illustrate the proposed technique.
A design method for cascade form digital nyquist filters with zero intersymbol interference
Authors: Nakayama Kenji 
Published: July 2007

AbstractIn data communication systems, a Nyquist waveform shaping filter is an important element. The Nyquist filter not only restricts the bandwidth of the data signal, but also realizes zero intersymbol interference where the time response intersects zero at equal intervals except at one point. This paper discusses a design method of a digital Nyquist waveform shaping filter for sampled signals. In particular, the method proposes realization of overall zero intersymbol interference when an identical transfer function is used for both the transmitter and receiver filters. In this method, the transfer function coefficients are used as approximate variables. They are divided into coefficient xf for time response approximation and xf that approximates the frequency response. The condition for zero intersymbol interference is given as the linear equation for xt. Therefore, the approximation variable xt for realization of zero intersymbol interference is obtained from solution of the linear equation. On the other hand, the frequency response is optimized with the iterative approximation due to the observation that the relation between xf and the approximation function is nonlinear. The proposed method is applicable to both the FIR filter and the IIR filter for which the conventional method is not applicable. Further, the effect of the quantization errors in the multiplier coefficients and in the internal signal on the intersymbol interference is analyzed, and an estimation formula is obtained.
Appearance of the “movement” of a spatio‐temporal sine‐wave pattern with the retinal locality
Authors: Sakata Haruo 
Published: July 2007

AbstractThe appearance of the “movement” with the retinal locality is measured via a brightness spatio‐temporal sine‐wave pattern. Thus, it is clarified that the velocity threshold is superior at the fovea, the sensitivity is degraded at low spatial frequencies, and the velocity upper limit does not depend on the retinal locality. It is understood from the experimental results that the subjective appearance of movement is detected in terms of vs = DLx/Δt and is determined by the subjective temporal frequency characteristic and spatial frequency characteristic at each retinal locality.
A method for estimating the protection ratio in fm television transmission
Authors: Kubota Keiichi , Ishida Junichi 
Published: July 2007

AbstractA calculation method for estimating the protection ratio in FM‐TV transmission is described. The interference between two FM carriers modulated by the NTSC or TCI color bar signal is analyzed and the baseband interference is expressed in a simple form as beat interference. Applying several weighting functions of the visual system to the beat interference, a subjective interference index which expresses the degree of subjective impairment is defined and then a method for estimating the protection ratio using this index is proposed. The protection ratios calculated by this method for various signaling systems and modulation parameters agree well with the results of subjective assessment tests. The method permits determination of the protection ratio in any FM‐TV system without subjective assessment tests for various parameters. It can be used to estimate the protection ratio in introducing new services to existing satellite broadcasting channels and to develop new channel plans.
An automatic transversal‐type ghost canceller
Authors: Obara Masaharu 
Published: July 2007

AbstractA system study has been conducted on an adaptive transversal filter Ghost Canceller to achieve system optimization, and prototype ghost cancellers have been conducted on a trial basis. The results of tests showed that: (1) a Ghost Canceller for picture signals using an LSI CCD transversal filter could improve the quality of TV pictures by more than one grade in a five‐grade subjective evaluation against multiple ghost images of up to a 12‐μs delay time; and (2) a non‐CCD and totally digitalized Ghost Canceller for Teletext signals has shown a significant improvement in reducing strong short‐delay time ghost echoes and equalizing waveform distortion. This paper clarifies the system structure and the design method for both of the cancellers and shows the practical usefulness of the Ghost Cancellers.
Digital signal processing syllabic compander
Authors: Tajima Jun , Kobayashi Katsumi 
Published: July 2007

AbstractAt present, analog circuits are used widely for syllabic companding which effectively improves the quality of speech communication. The digitalization of the syllabic companding circuit promises several advantages, namely, the possibility of adapting filter coefficients to the condition of the radio communication system, the elimination of adjustments, the possibility of large‐scale integration, etc. The present paper considers such a new approach, a digital signal processing syllabic compander. The realization method is described and the results of both theoretical and computer aided investigations concerning the characteristics of the compander are presented. First, the construction of the digital signal processing compander is shown. Then detailed theoretical investigations are given on the influence of the distortion which is a specific problem of the digital realization. The results obtained agree well with those of the computer‐aided analysis. According to the investigations presented it has become clear that the sampling frequency should exceed 24 kHz in order to attain a signal‐to‐distortion ratio of above 40 dB in the voice frequency band for a separate compressor and an expander. However, if the compressor and expander are connected in a system, then a distortion cancellation effect arises which allows a considerable reduction of the sampling frequency. The transient response has also been investigated, and the same characteristics have been obtained as in the case of analog companders.
A unified analysis of multipath degradation in multilevel modulation radio systems
Authors: Murase Takehiro 
Published: July 2007

AbstractIn microwave digital radio transmission, waveform distortion due to frequency selective fading becomes a dominant factor of degradation. To evaluate the degradation of different systems in a unified way, the waveform factor is defined first. With the aid of concept “waveform factor,” the eye aperture is easily obtained. We also evaluate the waveform factors for various modulation schemes. Next, on the basis of the relation between propagation parameters and waveform factor in two‐ray fading, the estimation formula of the outage probability for various digital radio systems in line‐of‐sight propagation is derived. The proposed factor is determined uniquely by system parameters, such as modulation scheme, system impulse response, and symbol rate. With the aid of this factor, digital radio system performance during multipath fading is easily evaluated.
Visual response features by opposite polarization of brightness figure
Authors: Sakata Haruo 
Published: July 2007

AbstractA difference in the brightness of the background by figures with opposite polarities is obtained by means of a psychophysical measuring method. In this method, the appearance of the background by figures with opposite polarities is a psychological phenomenon related to the receptive field of ON‐center type and OFF‐center type in electro‐physiology. The following results are obtained by psychophysically measuring the brightness within the circle of the ring target and the brightness of the intermediate portion between parallel two‐bar with positive and negative polarity.(1) With positive polarity, lateral inhibition occurs regardless of the contrast. With negative polarity, lateral emphasis occurs when the contrast increases.(2) The effect described in item (1) is more remarkable with the ring target than with the parallel lines.(3) When the target size is greater, the phenomenon is closer to the brightness contrast phenomenon.
Communication media control schemes in an integrated service circuit switching network environment
Authors: Yokoyama Masaaki , Uose Hisao , Mase Kenichi , Kajiwara Masaichi 
Published: July 2007

AbstractThis paper examines communication media selection control schemes assuming the environment expected in the near future in which users with many kinds of communication media communicate with each other. As the number of communication media increases, the necessity to match the communication medium before the establishment of the communication channel arises in order to reduce the invalid circuit connection caused by the medium mismatch. Assuming the circuit switched network, two medium selection algorithms are proposed: one in which the calling party preassigns the communication medium first (preassign method), and the other in which the calling party inquires about information on the available communication media of the called party (inquiry method). As terminal control schemes, algorithms are proposed which reserve all pertinent terminals while the media selection algorithm is under processing (reservation method), and which do not reserve the terminals (nonreservation method). It is shown that the preassign method is superior to the inquiry method as the medium selection control, and the reservation method is superior to the nonreservation method as the terminal control.
Highly efficient error recovery protocol for satellite link (MN‐SREJ)
Authors: Matsuo Kazunori , Iisaku Shun‐Ichi , Takizuka Takashi , Members Kinji Ono, Regular 
Published: July 2007

AbstractData communications over a satellite link makes possible high‐speed data transmission and simultaneous transmission of information to multiple receiving stations. Unless a high‐quality link is provided, the throughput efficiency with the existing HDLC error recovery methods tends to decrease. Therefore, we have developed a new error control scheme (named Multi‐Numbered Selective Reject (MN‐SREJ) method, an improved version of SREJ of HDLC, which would permit high speed and reliable communication even under long propagation delay and poor transmission quality. By the use of MN‐SREJ, more than one solution retransmission request can be made within one round‐trip delay and, furthermore, at the checkpointing, all the unreached frame numbers can be sent to the sending station. The MN‐SREJ method can be expanded easily from point‐to‐point communication to multicast communication, and the degradation of the throughput efficiency as the number of receivers is increased, is small. Furthermore, an approximate formula of the point‐to‐point communication throughput efficiency is derived for an arbitrary maximum number of outstanding frames and round‐trip delay, and the analytical result is shown to coincide well with the simulation result.
An automatic whistler direction finder
Authors: Ohta Kenji 
Published: July 2007

AbstractFrom information about the time‐variation of the occurrence number of whistlers and its dispersion, we can estimate the physical information about the electron density at the whistler propagation path in the ionosphere and the magnetosphere plasma and the occurrence of the propagation path. The ionospheric exit point of a whistler is clarified by measuring the magnetic and electric components at one measuring point induced on two mutually orthogonal loop antennas and one vertical antenna by the whistler arrival. Conventional whistler direction finders are not automatic and require operator's manipulation and part exchange. A new whistler direction finder has been developed which has enabled automatic direction finding for whistlers. The equipment consists of the whistler detector using the PLL discriminator, A/D converter, and an 8‐bit microcomputer. High‐accuracy numerical data of 28 whistler waves are stored continuously in 56 Kbyte memories. At a low latitude, the occurrence number of whistlers is small and hence its automatic measurement is indispensable. For this purpose the proposed method provides an effective measurement procedure.
Two‐stepped association procedure and its application to reduction of memory areas of associative memory
Authors: Murakami Kenji , Izumida Masanori , Aibara Tsunehiro 
Published: July 2007

AbstractThis paper proposes a new association scheme (called two‐stepped association scheme) which executes the traditional distributed association scheme in two steps, analyzing its association ability. As an application of this association scheme, a method in the distributed associative memory is proposed which can reduce optimally the size of the memory area for memorizing information to the sense of the least‐mean‐square error. In the two‐stepped association scheme, two‐step associations are performed, which are from the key to the mediate vector and from the mediate vector to the data. The associative process in the associative memory can be made flexible by a suitable selection of the mediate vector. One advantage of the two‐stepped association scheme is that the model acquires a larger degree of freedom in its structure by executing the associative process in two steps. In this paper, this point is utilized and a discussion is made for the condition and the determination of the mediate vector, which leads to the construction of the associative memory with the memory area of specified size and the least mean‐square‐error between the association output and the data. It is verified by a computer simulation that the associative memory constructed in this way can realize the desired associative ability.
A method of interference cancellation in binary PSK coherent receiver
Authors: Segawa Kunio , Nakagawa Masao 
Published: July 2007

AbstractThe wide application of digital radio communication systems in recent years has resulted in increasing demands for allocated frequencies and, due to the overcrowded spectrum, interference has become a crucial problem. In many cases, such interference appears in the upper sideband or in the lower sideband of the useful signal. In the present paper a binary PSK communication system with interference in either the upper or the lower sideband is considered and a method of interference cancellation is proposed for the Costas loop widely used in PSK receivers. Experiments are conducted to demonstrate the efficiency of this method. The results show that the maximum cancellation with a simple circuit added to the Costas loop is 23 dB if Af (the difference between the frequencies of the PSK carrier and the interfering signal) is above 0.3 fβ (fβ the data bit rate). At the same time, the bit error rate in the digital signal is greatly improved. Also, with respect to the impairment due to jitter caused by interference, the performance of the Costas loop is practically unchanged within the specification range of an ordinary Costas loop. The advantages of the present method are that the circuit is simple, it is stable because there is no feedback in the interference cancellation part and the cancellation is effective even for interfering signals of unknown δf.