Taiji Nishizawa

Interactivity in broadcasting and its application to ISDB services

Given that broadcasting is generally characterized by real-time one-way transmission, it is an essential task for this medium to provide interactivity developed in the fields of telecommunications and computers when introducing multimedia into a broadcasting system. This paper discusses how to use and implement interactivity in broadcasting services. It further discusses what functions are required for introducing interactivity into broadcasting. The practicality of interactive services in one-way broadcasting transmission is clarified. A simulation system of ISDB services to evaluate viewers human interface was developed. The results of experiments using the simulation system are also discussed. It is shown that user-friendly ISDB services can be achieved.

Multimedia services in the HDTV MUSE system

Experimental equipment to investigate multimedia service functions for application to MUSE (multiple sub-Nyquist sampling encoding) HDTV broadcasting has been developed. This system is called the multimedia MUSE system. Programs have also been produced to evaluate service functions of the system taking into account the capacity of the transmission path. This paper describes the configuration of the multimedia MUSE System, service examples, and evaluation of transmission capacity making use of test programs. Our studies reveal that multimedia broadcasting services can be provided when storage memory is installed for achieving interactive viewing and multimedia programs are appropriately configured. In addition, the services described here will provide the basic concept for multimedia broadcasting in future digital broadcasts.

Development of MUSE family systems

NHK has developed three ADTV (advanced definition television) systems that comply with US Federal Communication Commissions decision to maintain compatibility with existing NTSC systems: narrow-MUSE (multiple subNyquist sample encoding), NTSC (National Television System Committee)-compatible MUSE-6, and NTSC-compatible MUSE-9. All three systems use program materials produced in the 1125/60/2:1 format converted to the 750 line format and therefore can transmit a vertical resolution of approximately 750 TV lines. Among the three systems, narrow-MUSE has the highest quality, because there are no NTSC compatibility constraints. NTSC-compatible MUSE-6 has both NTSC and 6-MHz channel compatibility. So does NTSC-compatible MUSE-9, which also provides higher moving resolution by introducing a 3-MHz augmentation channel. The authors describe the features of these systems and the band compression techniques used. >

Improvement of HDTV-PAL Standard Converter Using Motion-Compensation Technique and Detection Probability of Motion Vectors

HDTV signal can be converted into the present standard TV signal with a high spatial resolution. However, some problems have been pointed out in the standard conversion with different field frequencies, which are the degradation of resolution and jitter for moving pictures. To avoid such problems, the motion compensation frame conversion method was developed, which realized a practically satisfactory standard conversion. In the development of a practical system for the standard conversion from HDTV to PAL, the quality of the converted picture is improved by improving the detection of motion vector and the processing of motion-compensated picture. The detection probability for the motion vector is investigated, and the usefulness of the motion compensation based on the detection of the motion vector used in the proposed system is verified.

Hi-Vision Standards

Research in television image quality under the current standard format has been going on for about half a century. Much research and experience have been gained during that time on the relationship between physical factors such as signal-to-noise ratio or signal bandwidth and image quality. However, practically no investigations have undertaken the advanced study of visual and auditory psychological effects as carefully as has Hi-Vision research. Thus in the development of the Hi-Vision system, numerous psychological experiments and studies were conducted to establish the basis for the fundamental parameters.

A luminance signal bandwidth expansion method for NTSC system

Bandwidth expansion of the luminance signal is discussed as a method of picture quality improvement in the NTSC television system. By modulating the high-frequency component over a 4.2-MHz luminance signal using a new subcarrier whose phase is field-alternated and multiplexing the aliasing component resulting from that to a low-frequency component, the transmissible bandwidth of the luminance signal can be expanded, with compatibility to NTSC receivers. A method based on this principle is proposed. Expanding the bandwidth as described, the transmissible two-dimensional spatial frequency area is matched with the visual characteristics and an improved image sharpness is achieved. Experiments confirmed that the bandwidth can be expanded while maintaining compatibility with NTSC receivers. In addition, subjective evaluation tests indicated that there is not much deterioration of image sharpness through the methods deletion of the oblique high spatial frequency component, and that sharpness is improved in pictures including detailed images through the proposed method. A novel phase regeneration circuit is also proposed. >