METHOD OF TRANSFORMING HFC CATV ANALOG FIBER TRANSMISSION TO DIGITAL FIBER TRANANSMISSION

摘要

A method of converting legacy HFC CATV cable systems, which transmit data over the optical fiber portion of the system using the optical counterpart of analog RF waveforms, such as RF QAM waveforms transduced to corresponding optical QAM waveforms, to improved HFC CATV systems that transmit data over the optical fiber using optical fiber optimized protocols, such as Ethernet frames and other optical fiber optimized digital transport protocols. According to the method, most aspects of the legacy HFC CATV system may be retained, however at the CATV head end, the optical fiber transmitter system is replaced by an improved system that extracts the underlying symbols from legacy waveforms, packages these symbols into optical fiber optimized packets, and transmits downstream. The legacy optical fiber nodes are replaced with improved nodes capable of receiving the packets and remodulating the symbols into RF waveforms suitable for injection into the system's CATV cable.

主权项

1. A method of digitally transmitting downstream data over at least the optical fiber portion of a Hybrid Fiber Cable (HFC) network, said HFC network comprising at least a head end and at least one digital optical fiber node (DOFN) that is connected to at least one set of neighborhood CATV cables, and wherein said data comprises downstream QAM channels, said method comprising:
transmitting at least one downstream QAM channel over the optical fiber as a plurality of QAM constellation symbols by encapsulating said QAM constellation symbols into a plurality of Ethernet frames or other digital transmission format frames, and digitally transmitting said plurality of Ethernet frames or other digital transmission format frames over said optical fiber; using said DOFN to receive said plurality of Ethernet frames or other digital transmission format claims, extract said downstream QAM constellation symbols, and use said downstream video QAM constellation symbols to modulate at least one DOFN QAM modulator, thus producing downstream QAM RF signals, and transmitting said DOFN generated downstream QAM modulated RF signals further downstream over said at least one set of neighborhood CATV cables.