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目前,日本NTT公司提供的图象通信传输服务,除广播电视的中继服务外,只有ITV-4M系统,但可以预料今后对电视会议系统的需要量将大增。关于数字数据通信服务,在专用线和交换服务中,使用DSU构成200b/s～48kb/s各种速率的系统。但是,随着计算机的迅速发展,需要在事务所之间传输高速数据的业务越来越多,因此,急需开发适用于用户线的高速数字传输系统。基于上述情况,开发了可同时进行双向图象传输和高速数字传输的宽带光纤专用线系统。本文叙述初次用于用户线的宽带光纤专用线系统的构成、传输技术以及现场试验的结果。
At present, only the ITV-4M system is provided for the image communication transmission service provided by Japan’s NTT Company except for the radio and television relay services, but it is expected that the demand for the video conference system will increase greatly in the future. Regarding digital data communication services, DSUs are used in dedicated lines and switching services to form systems of various speeds of 200b / s~48kb / s. However, with the rapid development of computers, there is an increasing number of businesses that need to transfer high-speed data between offices. Therefore, there is an urgent need to develop a high-speed digital transmission system suitable for subscriber lines. Based on the above situation, a broadband optical private line system that can perform bidirectional image transmission and high-speed digital transmission simultaneously has been developed. This article describes the composition of the broadband optical fiber line system for the first time for subscriber lines, transmission technology and field test results.