Digital optical CATV system using hubbed distribution architecture

A hubbed distribution architecture based on a bus-star configuration, three-level single single-mode fiber transmission using M-TPC line code, and high-speed IC technology is proposed. The architecture is cost-effective and compact. It is well suited to metropolitan area CATV systems and would allow a gradual transition to a broadband ISDN (integrated-services digital network) subscriber loop in the future. The proposed architecture is applied to a digital optical CATV system prototype. The equipment making up this system consists of a transmitter, hubs including video selectors, and subscriber unit. Two video channels are selected for each subscriber from eight video channels at hub stations. The transmission speed is 900 Mb/s, three-level for the trunk line and 200 Mb/s, three-level for each subscriber loop. Very compact and low-cost equipment is realized by using recently developed high-speed ICs. Experimental results show that the system satisfies requirements and that its commercial application is feasible