In OFDM transmission, performance is degraded by the existence of time domain impulse noise because this noise has very wide bandwidth, and it affects all the carriers in the OFDM signal. Especially, the influence of impulse noise with large amplitude couse severe degradation. In this paper, a scheme that reduces the influence of impulse noise is proposed. In the proposed scheme, the symbols after decision are re-modulated to generate a time domain OFDM signal to replace the samples that are degraded by the impulse noise in the time domain. The time domain OFDM signal is demodulated again after the influence of the impulse noise is reduced. This results in an improvemed of bit error rate. Moreover, the peformance of the proposed scheme can be further improved by applying it iteratively.
Rendering high quality animations from 3D models is a computationally expensive and challenging task. Recently, distributed computing technologies have been deployed for real-time and effective animation rendering. However, specialized programming skills and specific hardware or software are required to perform animation rendering on the basis of distributed computing technology. Therefore, a distributed computing technology to enable efficient and easy execution of animation rendering is required. In this paper, we propose a method for distributed animation rendering based on Grid computing. The method we propose does not impose any special distributed computing technology on users' and it facilitates effective implementation of distributed animation rendering. In this research, we also developed a scheduler that automatically distributes the animation rendering task to the resources in a Grid computing environment. We constructed a prototype based on the proposed method and confirmed its effectiveness through several animation rendering experiments.
Orthogonal Frequency Division Multiplexing (OFDM) techniques with high level modulation, such as QAM, have received considerable attention recently. This is especially true in the fields of wireless communication system because OFDM has potential capability of achieving higher data rate communications under multi-path fading environments. However, the OFDM system is very sensitive even to the small residual frequency offset (RFO) that remains as the result of initial frequency offset estimation with two preamble symbols inserted at the start of every frame. This paper proposes a novel residual frequency offset compensation method of using a decision feedback algorithm based on the result of demodulated data. The paper also presents various computer simulation results to verify the effectiveness of the proposed method.
We propose a new up-to-the-minute data broadcasting service that uses the latest digital technologies. We produced prototype and carried out experiments to evaluate the performance of the system. The proposed service—the object-linked broadcasting service—provides various information regarding an object chosen by a viewer from a TV picture. We encountered some technical issues, such as observing broadcasting regulations, making dynamic descriptions for the objects, and working with one way transmission, in perfecting the system. To resolve these issues, we employed BML for browsing, ECMA Script for the dynamic description, Binary Table for the data structure, and DSM-CC for the transmission method. The experimental results show the system performance is acceptable. We found that an 80-second data carousel can carry related data for up to 20 objects.
The image quality of flat panel displays and image sensors has become increasingly important due to recent diversification of their uses and their rapid diffusion. In defect inspections of those image devices, particularly in the Mura (luminance nonuniformity) inspection, human sensory inspection has been mainly introduced into the manufacturing process. Recently, the introduction of automatic defect inspection has been started in earnest. However, the varieties of Mura and background conditions make the tuning process for achieving the demanded accuracy difficult. In this paper, we report our subjective evaluation experiments to obtain relations between JND (just-noticeable-difference) contrasts and various conditions of Mura, such as area, background luminance, luminance distribution, and polarity. On the basis of those experiment results, we propose a model based on the MTF (Modulation Transfer Function) of the human visual system, which can calculate the JND contrast under various conditions. In addition, we describe the validity of a quantitative method, in which we quantify Mura levels by using the proposed model.
This paper presents a novel method for synthesizing a virtual view from two sets of differently focused images taken by an aperture camera array for a scene of two approximately constant depths. The proposed method consists of two steps. The first step is a view interpolation to reconstruct an all in-focus dense light field of the scene. The second step is to synthesize a virtual view from the reconstructed dense light field by using light field rendering technique. The view interpolation in the first step can be achieved simply with linear filters that are designed to shift different object regions separately without estimating the depth map of the scene. The proposed method can effectively create a dense array of pin-hole cameras (i.e., all-focused images) so that the virtual view can be synthesized with higher quality.
With the rapid development of the integrated circuit technology, the dynamic reconfigurable circuit has attracted much attention. The single circuit neuron MOS comparator has already been achieved. We propose the expansion of the circuit to achieve a multi-bit comparator. The proposed neuron MOS comparator is constructed by using only a two-stage neuron MOS inverter and an ordinary CMOS inverter. The newly designed circuit with an expanded Floating-Gate Potential Diagram (FPD) is described. The proposed circuit with three comparator functions is achieved using the single circuit. Applying this single circuit design technique, a multiple bits comparator can be achieved in a smaller area compared with that designed using the conventional circuit. The prototype of the newly proposed circuit was fabricated in the 1.2μm double poly-silicon CMOS process. The prototype device operates as well as the simulated one.
For practical holographic video display, generating the holographic fringe as fast as possible is important. In this paper, we report how we used the image hologram for fast calculation and the rainbow hologram for full-color images. In both image and rainbow holograms, image points are located close to the hologram and the diffraction angle is limited. This makes the required computation area much smaller than that of the entire hologram. Therefore, we obtained vastly improved computational speed. From the experimental results with an image hologram with 1.47 million pixels, the speed of ten frame per second was obtained for an object that consists of about 7,000 points. In the rainbow hologram with 1.44 million pixels, the speed of ten frame per second was obtained with an object that consists of about 17,000 points. These results show that the proposed method is quite effective for interactive holographic video displays.