Interstellar Communication: The Case for Spread Spectrum

Spread spectrum, widely employed in modern digital wireless terrestrial radio systems, chooses a signal with a noise-like character and much higher bandwidth than necessary. This paper advocates spread spectrum modulation for interstellar communication, motivated by robust immunity to radio-frequency interference (RFI) of technological origin in the vicinity of the receiver while preserving full detection sensitivity in the presence of natural sources of noise. Receiver design for noise immunity alone provides no basis for choosing a signal with any specific character, therefore failing to reduce ambiguity. By adding RFI to noise immunity as a design objective, the conjunction of choice of signal (by the transmitter) together with optimum detection for noise immunity (in the receiver) leads through simple probabilistic argument to the conclusion that the signal should possess the statistical properties of a burst of white noise, and also have a large time-bandwidth product. Thus spread spectrum also provides an implicit coordination between transmitter and receiver by reducing the ambiguity as to the signal character. This strategy requires the receiver to guess the specific noise-like signal, and it is contended that this is feasible if an appropriate pseudorandom signal is generated algorithmically. For example, conceptually simple algorithms like the binary expansion of common irrational numbers like Pi are shown to be suitable. Due to its deliberately wider bandwidth, spread spectrum is more susceptible to dispersion and distortion in propagation through the interstellar medium, desirably reducing ambiguity in parameters like bandwidth and carrier frequency. This suggests a promising new direction in interstellar communication using spread spectrum modulation techniques

The changing shape of sport through information technologies

The aim and focus of this study was to examine the changes in sport and with the sport's stakeholders with the introduction of technologies. The examination was conducted through series of interviews (n=36) and a review of the literature to gain understandings from three areas: (1) Professional players and coaches of professional players (2) Amateur players and coaches at amateur levels and (3) Spectators. The findings presented that players at the professional level are using various technologies such as GPS vests to manage workload and reduce risk of injury. With amateur level sport, technologies are not as prevalent and the possible introduction of technology was surprisingly not considered as imperative. Spectators, in general, considered that the introduction of technologies changed the dimensions of their involvement positively and negatively. The findings provide a basis for further studies and possible trials with additional technologies to further assist the athlete and coaches and innovatively enhance the spectator's experience

1 Comparison of Transform Coding Techniques for Two- Dimensional Arbitrarily-Shaped Images 1

Envisioned advanced multimedia video services include arbitrarily-shaped (AS) image segments as well as regular rectangular images. Images segments of the TV weather reporter produced by the chromo-key technique [1] and image segments produced by video analysis and image segmentation[2,3,4] are typical examples of AS image segments. This paper explores efficient intraframe transform coding techniques for general two-dimensional (2D) AS image segments, treating the traditional rectangular images as a special case. In particular, we focus on transform coding of the partially-defined image blocks along the boundary of the AS image segments. We recognize two different approaches — the brute-force transform coding approach and the shape-adaptive transform coding approach. The former fills up the uncovered area with the optimal redundant data such that the resulting transform spectrum is compact. A simple but efficient mirror-image extension technique is proposed. Once augmented into full image blocks, these boundary blocks can be processed by traditional block-based transform techniques like the popular Discrete Cosine Transform (DCT). In the second approach, we change either the transform basis or the coefficient calculation process adaptively based on the shape of the A

High definition systems in Japan

The successful implementation of a strategy to produce high-definition systems within the Japanese economy will favorably affect the fundamental competitiveness of Japan relative to the rest of the world. The development of an infrastructure necessary to support high-definition products and systems in that country involves major commitments of engineering resources, plants and equipment, educational programs and funding. The results of these efforts appear to affect virtually every aspect of the Japanese industrial complex. The results of assessments of the current progress of Japan toward the development of high-definition products and systems are presented. The assessments are based on the findings of a panel of U.S. experts made up of individuals from U.S. academia and industry, and derived from a study of the Japanese literature combined with visits to the primary relevant industrial laboratories and development agencies in Japan. Specific coverage includes an evaluation of progress in R&D for high-definition television (HDTV) displays that are evolving in Japan; high-definition standards and equipment development; Japanese intentions for the use of HDTV; economic evaluation of Japan's public policy initiatives in support of high-definition systems; management analysis of Japan's strategy of leverage with respect to high-definition products and systems