Broadband communications system

Abstract

A broadband communications system for coupling telephony or other digital networks to a CTV network. The system includes transmitting a multiplex of telephony signals in 3 MHz channels in the forward band of the CTV network. Each 3 MHz channel is QPR modulated on a carrier and contains multiple subscriber telephony signals. The forward telephony channels are demodulated and demultiplexed by a plurality of subscriber terminals into the individual telephony signals directed to an addressed subscriber. The individually addressed telephony signal is then applied to a line card which connects the subscriber telephone equipment to the system. Audio and control signals returning from the subscriber are digitized into standard telephony signals and modulated on a carrier in 50 kHz reserved telephony channels onto the reverse band of the CTV network. The multiplicity of reverse band telephony channels are demodulated and multiplexed into a standard telephony signal which can be directly interfaced to the telephony network. In the illustrated embodiment, the CTV network has a fiber to the serving area architecture that can be used to increase the number of reverse band channels which are available to the broadband communications system. Several configurations for the system are described where the input and output interface can both be coupled at the headend or both coupled at a fiber node, or either one coupled at the headend while the other is coupled at a fiber node.