TABLE OF CONTENTS DR. HISASHI KANEKO
Vice President, Nippon Electric Company (NEC)
Kawasaki City, Japan
T.ISHIGURO
Manager, Digital Television Laboratory
Nippon Electric Company (NEC)
Kawasaki City, Japan
Digital transmission and data-compression coding have long been viewed as promising and powerful means to achieve efficient TV transmission. Recent progress in large-scale integration (LSI) and digital technologies have made complicated signal processing a technically feasible reality and have led to progress in digital TV encoding, particularly in interframe coding by which the transmission bit rate can greatly be reduced. At the same time, progress in frequency spectrum usage by multiphase modulation or multilevel quadratic amplitude modulated (QAM) has allowed the use of digital transmission format in terrestrial microwave and satellite links. Also, digital fiber optic transmission is being introduced rapidly in communication networks. These trends have motivated serious efforts to develop and use digital approaches in actual TV transmission.
In addition, video-conferencing services are growing. Visual communication is a key to teleconferencing, because a full-motion video signal is very helpful in accomplishing interactive communications. However, a full-motion TV signal requires a bandwidth a thousand times wider than a voice telephone channel. Bandwidth compression is, therefore, a powerful means to provide economical teleconferencing systems with compression ratio of 1:40 or even less. Such high data compression can be achieved only by digital video-processing techniques.
Many investigations have been made to realize efficient digital encoding (Timb, 6.1; Netravali, 6.2; Pratt, 6.3; IEEE, 6.4]. Digital TV-encoding schemes are generally categorized into three classes: (1)...
