Installation and Performance of the Chicago Lightwave Transmission System

The first lightwave communications system that provides a wide range of telecommunications services to customers has been carrying commercial traffic in the Chicago Loop area since early May, 1977. The exploratory system furnishes POTS (plain old telephone service), analog data, and digital data services from the Franklin central office (CO) to customers in the Brunswick building, over an optical cable approximately 0.6 mi long. Picturephone
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meeting service, a 4-MHz video service, is delivered over an optical cable from the Wabash CO to the Franklin CO, then on to the Brunswick building, a total distance of 1.6 mi. The optical cable was placed inside a small plastic pipe, which had been installed previously along the cable route. The plastic pipe, or innerduct, was used to reduce pulling tensions and provide environmental protection. The optical cable was installed using a novel 2-way installation technique by which the two ends of each section were fed successively in opposite directions from an intermediate manhole toward the splicing manholes. The connectorized optical cable was then spliced in five manholes along the cable route. This paper describes the installation and splicing of the lightguide cable and the transmission characteristics of the installed medium. It also contains a discussion of the manner in which the various telecommunication services are provided and a performance evaluation of the lightwave transmission system to date.