We have developed a seven channel multiplexer for FM broadcasting station using new-type ring resonators that we have developed in 1991. It was about a half size of the one using conventional quarter-wave-length coaxial resonators. The results of Power tests were agreed Well with calculated temperature rises.

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In Bangkok. Thailand, the fluctuation of television broadcasting signal as seen at the time of interference wave dependence was observed. The signal level varied in sine wave form, and was to repeat the rise and fall of the signal level several tens times. The number of occurrence of the quasi-periodic level fluctuation exceeding 1 dB was sometimes more than 50 times in one hour. As to the maximum amplitude of the fluctuating level, the large attenuation exceeding 30 dB was observed rarely. The quasi-periodic level fluctuation is observed every day in Bangkok. Between the occurrence number of quasi-periodic level fluctuation and appearance time, clear diurnal variation characteristic is not observed, but it tends to occur more in daytime.

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At the time of rainfall, the increase of antenna noise temperature accompanying raindrop scattering appears in the receivers using low noise converters. The decrease of CN ratio was observed frequently at the time of rainfall. The standard deviation value of the signal level also became large by 0.2-0.5 dB at the time of rainfall. According to the kinds of antennas, there were some, with which CN ratio largely decrease rainy season. Plane type antennas were affected by rainfall, and the deterioration of both CN ratio and standard deviation value was large as compared with offset-parabola antennas. Moreover, when there was night dew, the lowering of CN ratio by 2-3 dB was observed in plane type antennas. Offset-parabola antennas were hardly affected by rainfall.

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When the elevation angle of an antenna seeing a satellite is about 30 or more, the characteristics of radio wave propagation can be treated as the characteristics of a high elevation angle propagation path. When the elevation angle becomes 30 or more, clear diurnal variation characteristics appear in scintillation phenomena. Besides the peak at the time of scintillation occurrence is observed in daytime. The measurement was carried out by using the frequency of the Ku band. The diurnal variation characteristics of scintillation in a high elevation angle propagation path have the good correlation with atmospheric temperature and the refractive index of the atmosphere N_<Wet>.

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Display systems have been and will continue to be playing an important role in automobiles for safety, convenience, warning systems, and so on. In this paper some typical physiological characteristics of drivers and advanced display systems such as Head-Up Display and Virtual Image Display will be discussed from the view point of vision optics. One of the most promising display systems will be Head-Up Display to meet the future transportation society's ever-increasing demand for information in areas such as navigation.

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This paper describes an audio-video teleconference system for 10 Mbps CSMA/CD LAN. This system consists of audio-video teleconference module and work station. This audio-video teleconference module establishes connection by TCP protocol, and transmits audio and video data with 16〜208 kbps. CCITT H.261 and G.728 coding algorithm are used for coding/decoding video and audio respectively. This module is fabricated in a box with 340mm(H)×110mm(w)×400mm(D).

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International standardization recommendation H.261 of a video codec for videophone and video conferencing have specified only the fundamental part, and a pre-processing, a post-processing, coding control can be performed freely. We have developed a human face region adaptive filter, brightness compensation, quantization stepsize control, threshold control, a post filter, etc., and quality of image has been improved 2 or more times compared with before. Moreover, a miniaturization of some circuits has been examined and seven LSIs for the exclusive use have been developed.

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In order to solve the local minimum problem and reduce the excessive learning time in the three-layered perceptron with distributed representation, a four-layered perceptron with localized representation is proposed. In this model any discrete sample can be localized by the outputs of the upper hidden units and any desired discrete outputs can be realized in the output layer by adjusting network coefficients. Computer simulations for on-line hand-written Chinese character recognitions are also reported.

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This paper proposes a three-layerred perceptron for Karhunen-Loeve transformation . The perceptron has the same number N of input units as input variable dimensions, R(≦N) hidden units and R columns of N output-units with unilateral summing networks between adjacent columns. This paper also clarifies theoretically that the perceptron extracts the dominant R components of K-L transform of each input-sample through its hidden unit-outputs after learning for identity-mapping between the input layer and each output-column. Simulations demonstrate exact transformations and rapid learning performances for various kinds of input samples.

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Hopfield has shown that the travelling salesman problem (TSP) can be solved on a neural network minimizing the quadratic energy function. The network converges to the steady state with not the global but a local minimum of the function. The best value of r depends on the structure of the TSP and no systematic method for finding such r has been proposed. We call the minimum r satisfying all the constraints the minimum possible r (r*) and propose an algorithmic procedure to find r*. Furthermore, we introduce the augmented penalty function using the Lagrange multipliers to decrease r* and improve the local minimum of the TSP. We analyze the equivalence between the multiplier and the threshold of the neuron and propose a new analytical and rapid scheme for updating the multipliers.

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