THE EFFECT OF A SPLITTER ON THE QUALITY OF DUPLEX COMMUNICATIONS OVERA SINGLE-FIBER LIGHTGUIDE

Optical fiber transmission systems (OFTS) operating at 8.448 Mbit/s ar e widely used throughout urban telephone networks; OFTS's operating at 34.368 Mbit/s are promising. One method of improving the utilization efficiency of fiber-optic cables (FOC), improving the engineering and cost characteristics of OFTS's, as well as the response times in estab lishing communications (in the case of optical fiber breaks, etc.), in addition to spectral division multiplexing, is to establish two-way ( duplex) communications (DC) on a single fiber lightguide (FL). We know [1, 2, 3,] that the majority of duplex OFTS's operating over a single fiber lightguide require optical splitters. The main requirements imp osed on the splitters include low losses in the forward transmission c hannel and strong crosstalk attenuation between the splitter arms. The noise level in such OFTS's and their spectral composition largely dep end on the transmitted signal (transmission rate and pulse waveform), and the line circuit (LC) parameters (optical fiber attenuation, lengt h, and dispersion). The dependence of the crosstalk attenuation of Ray leigh backscatter on the parameters of a fiber-optic channel was inves tigated in [3]. Analytic expressions were derived that enable the effe ct of splitter parameters on data transmission quality in a digital op tical line circuit (DOLC) to be estimated. Results are given from comp uter modeling of an optical duplex line circuit utilizing a single opt ical fiber; these results are compared to experimental research.