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An extremely high speed modulation-demodulation performance is discussed when data-rate becomes close to carrier frequency. A 4-phase PSK modulation-demodulation circuit with a newly designed transformer is described. The error-rate performance on 1.6 Gb/s data-rate was successfully undertaken at a 1.7 GHz carrier frequency.

An intra-city millimetric waveguide system, utilizing a cable tunnel, has been developed. This paper describes the development of waveguides for bends to make a meandering waveguide line with low loss and low wave-form distortion. Field test results are also described.

With the growth of high-speed access networks, we can copy video streaming services (both live streaming and video-on-demand) via the Internet at home. For higher perceptual video quality, it is necessary to monitor the video quality of each user flow in real time and control network source based on it. In this paper we propose a streaming quality management (SQM) system that estimates perceptual video quality of each user flow by capturing control messages of streaming protocol between server and client at server side. In addition, we equipped SQM system for Windows Media Technologies (WMT), Real System, and Mpeg2. The equipped SQM system has desirable characteristics; estimated streaming quality obtained from the system is almost the same as that from DMOS (Degradation Mean Opinion Score) defined by ITU-T [1] and the system has high scalability. Furthermore, we present network control schemes based on the streaming quality, and propose value-added services (ex. which part of content was viewed the most or how many times the content was viewed) using the streaming monitoring record each user, which could be collected by the SQM system.

The authors have conducted research regarding ripple formation on an atomically flat cleaved Si surface by low-energy Ar+ ion bombardment. The cleaved atomically flat and smooth plane of a Si wafer was obtained by cutting vertically against the orientation of a Si (100) wafer. Next, the cleaved surface was sputtered by a 1 keV Ar+ ion beam at ion-incidence angles of 0°, 60°, 70°, and 80°. The results confirm the successful ripple formation at ion-incidence angles of 60°–80° and that the wavelength of the ripples increases with the increase of the ion-incidence angle, as well as the inverse of ion doses. The direction of the ripple also changes from perpendicular to parallel to the projection of the ion-beam direction along the surface with the increasing ion-incidence angle. The authors have also observed the dose effects on surface roughness of cleaved Si surface at the ion-incidence angle of 60°, where the surface roughness increases with the increased ion dose. Finally, to understand the roughening mechanism, the authors studied the scaling behavior, measured the roughness exponent α, and compared the evolution of scaling regimes with Cuerno’s one-dimensional simulation results.The authors have conducted research regarding ripple formation on an atomically flat cleaved Si surface by low-energy Ar+ ion bombardment. The cleaved atomically flat and smooth plane of a Si wafer was obtained by cutting vertically against the orientation of a Si (100) wafer. Next, the cleaved surface was sputtered by a 1 keV Ar+ ion beam at ion-incidence angles of 0°, 60°, 70°, and 80°. The results confirm the successful ripple formation at ion-incidence angles of 60°–80° and that the wavelength of the ripples increases with the increase of the ion-incidence angle, as well as the inverse of ion doses. The direction of the ripple also changes from perpendicular to parallel to the projection of the ion-beam direction along the surface with the increasing ion-incidence angle. The authors have also observed the dose effects on surface roughness of cleaved Si surface at the ion-incidence angle of 60°, where the surface roughness increases with the increased ion dose. Finally, to understand the roughening mec...

Transmission with a BER less than 10−11 has been achieved using an injection-locking technique with a 445.8 Mbit/s RZ signal over a 170 km single-mode fibre. The injection-locking technique provides a single-longitudinal-mode optical source with a 35 dB main/side-mode power ratio and a 1.5 GHz spectral width.