High capacity digital switched fiber optic networks

Television operations require increasing numbers of video transmission circuits to meet requirements such as new program sources, centralized transmission facilities and fast circuit availability. Fiber optic systems can meet these demands but require efficient use of both the optical fibers and associated terminal equipment. Circuit switching is a flexible, simple method to access and route large numbers of video transmission circuits. High data-rate digital switching can be combined with digital fiber optic systems to form switched transmission networks that are digital from end-to-end. This provides various advantages. Efficient use of fiber optic links generally means increasing their `per fiber´ channel capacity. This is achieved by transporting more video channels within a given data rate (video compression), increasing the optical transmission rate, or optical wavelength multiplexing (WDM). The paper includes a description of a multi-channel, switched digital network and a new, very high capacity, fiber optic transmission terminal operating at a data rate of 3.1 gigabits/second