Importance

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Abstract

A communications network uses optical fibers to carry amplitude modulated broadband CATV signals over a considerable distance (6-30 km) to a fiber node. Electrical to optical transmitters at the headend launch, and optical to electrical receivers at the fiber node receive, optical signals corresponding to the broadband CATV signals. Distribution from the fiber node to the subscribers is obtained by transmitting electrical signals through a limited cascade of amplifiers over an electrical transmission line (coaxial cable). The limited cascade is much shorter than the fiber span and may include trunk amplifiers which are insufficient in number to add significant losses or distortion. Line extender amplifiers may be connected to output couplers located off the subscribers premises and the CATV signals then carried via electrical cables to the subscribers. In order to reduce harmonic distortion in the optical portion of the network, all or a portion of the CATV spectrum is translated to a frequency range which is less than an octave. One or more additional fibers are used for the channels in the upper portion of the band which need not be translated. The translated portion of the optical signals is received and translated back to its original frequency range and combined with the other band limited portions to provide a broadband signal for distribution to the subscribers.

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First Claim