Atlanta Fiber System Experiment: Results of the Atlanta Experiment

Tests of an experimental lightwave transmission system operating at 44.736 Mb/s (DS3), the third level of the Bell System digital hierarchy, were begun by Bell Laboratories in January, 1976. 1 " 3 The system, operating in an environment simulating field conditions, included all the elements necessary for a practical transmission system at the DS3 rate: a small, ruggedized cable containing 144 fibers, lightguide cable splices, single-fiber connectors, a fiber distribution frame, regenerators* employing avalanche photodiodes and GaAlAs lasers, and terminal circuits to interface with the DS3 signal format. The main goals of the system experiment were to gain experience with a digital lightwave transmission system and to obtain the data necessary to turn this new technology into practical telecommunication equipment. * A regenerator is a 1-way device, a repeater comprises two 1-way regenerators. 1857 Before the system experiment began, the individual elements comprised by the system were thoroughly tested and characterized. The system experiment brought all these elements together in a simulated field environment. Experiments were performed to measure important system parameters and to evaluate system performance. These included experiments on fiber crosstalk, fiber dispersion, timing jitter, system recovery, and dc powering.