Research and Development on High-Definition Television in Japan

In Japan, NHK (Japan Broadcasting Corp.) is taking the initiative in developing a high-definition wide-screen television system as a target for future broadcasting systems. Investigations have been carried out on the relationships among three parameters: picture size, number of scanning lines, and visual impact—using both a film simulation method and a real television system. As a result of these investigations and taking into consideration the currently available technology, the provisional number of scanning lines was set at 1125; and an experimental camera, 70-mm film telecine, and contour corrector have been developed. For a display device, a 30-in (76-cm) color CRT receiver with 5:3 aspect ratio has been built. Two transmission systems have been developed: one in which two separate carriers are frequency modulated by the luminance and chrominance signals respectively and another system which transmits a composite color signal using a color subcarrier. A transmission test has been carried out with the Experimental Broadcasting Satellite (12 GHz, 100 W for each of two channels), and very attractive pictures and sound were received using a 2.5-m diameter receiving antenna. A countermeasure against attenuation due to rainfall in future 22-GHz systems is also proposed.