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在日本,NHK(日本广播公司)正在带头着手研制一种高清晰度宽屏幕电视系统,作为未来广播系统的目标。该项研究主要集中在三个参量的关系上,即图象尺寸,扫描行数和视觉效果。实施方法是采用影片模拟方法和实际的电视系统。根据研究的结果和考虑目前可以达到的工艺水平,扫描行数暂定为1125行,现已研制出一种实验摄象机,70毫米胶片的电视电影和轮廓校正器。对于显示器件,已研制出一种30英寸(76厘米)、纵横比5:3的彩色阴极射线管接收机。并研制了两种传输系统:在一种系统里,两个分离的载波分别受亮度信号和色度信号的频率调制;而在另一种系统里,则用彩色副载波传递复合彩色信号。传输试验用实验广播卫星(两个信道的每个信道都是12千兆赫,100瓦)进行。采用2.5米直径的接收天线就能收到非常吸引人的图象和声音。在未来22千兆赫的系统里,也提出了防止由于下雨而引起电波衰减的措施。
In Japan, NHK (Nippon Broadcasting Company) is taking the lead in developing a high-definition wide-screen television system as the future broadcasting system. The study focused on the relationship between the three parameters, namely, image size, scanning lines and visual effects. The implementation method is to use the video simulation method and the actual television system. Based on the results of the study and considering the level of technology currently available, the number of scanning lines is tentatively scheduled to be 1125 lines and an experimental video camera, 70mm film telecine and contour corrector have been developed. For display devices, a color cathode ray tube receiver of 30 inches (76 cm) and an aspect ratio of 5: 3 has been developed. Two transmission systems have been developed: In one system, the two separate carriers are frequency modulated by the luminance and chrominance signals, respectively; in the other system, the composite color signals are transmitted by the color subcarriers. Transmission experiments were conducted using experimental broadcast satellites (12 GHz, 100 W for each of the two channels). Using 2.5-meter diameter receiving antenna can receive very attractive images and sounds. In the future 22 gigahertz system, measures have also been put forward to prevent the attenuation caused by the rain.