映像情報メディア学会誌

自由視点映像とは, ユーザが自ら自由に視点を移動して見ることができる映像のことである. 本稿では, 自由視点映像を定式化するとともに, 撮像系, 生成法について概観し, 最新の研究動向について解説する.

Digital Broadcasting using Metadata (DBM) is a term describing new broadcasting services offered by utilizing a receiver with storage capacity. The services include program viewing that does not depend on normal broadcasting hours and highlight viewing that uses program-related information, called metadata. Preventing unauthorized use of stored programs is a critical issue in these services. It is extremely easy to edit programs that the broadcaster requires by using a program usage control mechanism. We propose an advanced Conditional Access System (CAS) for DBM. It achieves a secure environment for content and metadata, by preventing tampering and ensuring that only metadata certificated by the broadcaster can be utilized. We also developed a prototype receiver on a PC and an advanced CAS card on a Java Card to evaluate the system. We confirmed through on the implementation experiment that the CAS could be utilized in broadcasting services..

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While relaying broadcast waves of digital terrestrial broadcasting, the transmission-signal quality becomes degraded along the propagation path and must be improved at the relay station. However, we must give special consideration to co-channel interfernece because the relay station is usually located at a place that has a high probability of receiving undesirable broadcast waves. This paper describes a co-channel interference canceler which uses the MMSE adaptive array for the digital broadcast wave relay station. In the proposed scheme, the scattered pilot is used as a reference signal to minimize errors which is defined as the difference between the known symbol and the combined one. The received data symbols are combined in each subcarrier based on interpolated optimal weights, thus canceling the interference. Numerical examples and indoor experimental results are presented in this paper to verify the effectiveness of the proposed scheme.

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A field pickup unit (FPU), which is a microwave link that is used for electronic news gathering (ENG) systems, usually consists of a transmitter or a receiver and a parabolic reflector antenna. A conventional parabolic reflector antenna is made of solid metal. We developed a deployable mesh reflector for the FPU to improve the mobility of the FPU for prompt news gathering. We describe a method for designing a deployable mesh reflector whose aperture diameters are 0.3, 0.6 and 0.9 m. Two prototypes of the deployable reflector with a radial rib structure were introduced; one was made of stainless-wire mesh and the other of gold plated molybdenum. Stainless-wire mesh is easily obtained. The electrical performance of each prototype was comparable to that of a conventional reflector.

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