Preface
Digital High Definition Television -Dawning of the new era 1993 will be remembered as the beginning of the new era of digital high definition television. Rapid advances are made world wide in system technology, equipment and standards. The essential pieces in terms of technology infrastructure are mostly in place already, covering all phases of the HDTV chain: from acquisition (camera) to storage (recorder), and from distribution (satellite, cable, terrestrial) to display (CRT, rear projection). In answering the question posed in the Preface of last year's Special Issue [1] whether all-digital HDTV is a dream or reality, the unequivocal answer must be: "digital HDTV is a REALITY".
With the completion of testing of the five HDTV proposals in the United States, a single digital HDTV system proposal will emerge, combining the best features of the individual proposals. The adoption of an advanced television broadcast standard for the United States will be made in 1995.
History was made in November 1991 when NHK pioneered 8 hours of HDTV broadcasting daily. Through the HDTV broadcast service, valuable experiences gained on the technical management of day-to-day production and studio operations are critical to any television broadcast service. While digital HDTV broadcasting is being planned in the near future, Japan's cutting edge research and noted manufacturers' interests continue to play a major role in advancing the state of the art.
Continuing its strong research tradition, Europe is directing its effort with a number of national and multinational research programs, aiming at the development of a digital HDTV service. Of particular significance is the work on hierarchical coding for compatibility of HDTV with conventional TV and the thrust in digital broadcast via satellite.
Among the immediate challenges facing HDTV is the question of graceful degradation of digital transmission and the efficient utilization of the channel bandwidth. Good solutions are known, but more practical and efficient solutions are needed. Another challenge is the cost reduction of HDTV equipment, for both professional and consumer applications. Just how fast can the cost be brought down and by how much will it have a significant impact on the acceptance of the new service. HDTV is regarded by many as a good basis for format conversion. How to best perform the various cross and down conversions economically using the latest signal processing knowhow is an important topic. To extend HDTV technology beyond the traditional entertainment field to such applications as education, design, medicine, etc. will require more than a mere modification of the image parameters. It will require a through examination of the entire system configuration and development of specialized equipment for these applications.
The 14 papers collected in this Special Issue cover a wide range of topics and reflect the ongoing HDTV activities in Asia, Europe and North America. The paper by Hopkins is a summary of the analyses and comparisons of the test results of five proposed HDTV systems in the US. This is followed by two papers on HDTV transmission, one by Tourtier et al. on terrestrial broadcasting using orthogonal frequency division multiplexing (OFDM) and dual polarization at 70 Mbits/s in an 8 Mhz channel, and one by Moeneclaey and Van Bladel on CATV using either single carrier or an OFDM of many carriers. Three papers dealing with Elsevier Science Publishers B.V.