| 摘要 |
Producing advanced HFC CATV cable systems while easing the burden of backward compatibility. The system improves CATV data carrying capacity by moving RF QAM modulators from the cable head end to various individually or group addressed optical fiber nodes supplying neighborhood CATV cables, and sending data from the cable head IP backbone to the nodes over optical fiber as IP data packets. For high backward compatibility, the system digitizes legacy RF waveforms, or demodulates legacy QAM waveforms to QAM symbols, also transmits these over the optical fiber as IP data packets, and then reconstitutes back to original waveforms as needed. The system is thus able to easily handle legacy NTSC, FM, QPSK waveforms and do partial (QAM symbol level) compression of legacy QAM waveforms to and from multiple nodes without requiring additional optical fiber wavelengths. The system may use non-standard upstream/downstream CATV frequency splits, filter bank receivers, and FPGA/DSP/ASIC methods. |
| 主权项 |
1. A digital optical fiber node system for a Hybrid Fiber Cable (HFC) network, said system comprising a cable head end;
said cable head end in IP communication with an IP backbone, and in optical fiber communication with at least one digital optical fiber node (DOFN); said at least one digital optical fiber node in RF communication with CATV cable connected at least one CATV cable device; said system comprising: at least one digital optical fiber node, said digital optical fiber node comprising at least one of: A: a RF digital reconstitution device configured to accept digital samples of downstream RF waveforms digitally transmitted downstream over the optical fiber, and to reconstitute these digital samples into one or more downstream digitally reconstituted RF channels; B: a RF remodulator device configured to accept downstream digital QAM symbols transmitted over the optical fiber, and remodulate these QAM symbols into one or more downstream QAM symbol remodulated RF QAM channels; C: an IP to QAM conversion device configured to accept downstream digital IP data packets transmitted over the optical fiber, and to modulate these digital IP data packets into one or more downstream IP based RF QAM channels; and a RF combiner device configured to combine any of said digitally reconstituted RF channels, QAM symbol remodulated RF QAM channels and said IP based RF QAM channels, and transmit said channels downstream over said CATV cable; wherein said digital optical fiber node additionally comprises at least one of: D: a RF digital converter device configured to accept upstream RF waveforms transmitted over said CATV cable, and digitize said upstream RF waveforms, thereby producing digitally encoded upstream RF channel data; E: a RF demodulator device configured to accept upstream RF QAM channels transmitted over said CATV cable, and demodulate said RF QAM channels producing upstream digital QAM symbols; F: a QAM to IP conversion device configured to accept upstream digital IP data packets transmitted by upstream QAM RF channels over said CATV cable, and extract said upstream digital IP data packets, thus producing upstream digital IP packets; and a digital data to optical converter device configured to combine any of said digitally encoded upstream RF channel data, upstream digital QAM symbols, and upstream digital IP packets and transmit said data, symbols, and packets digitally upstream over sad optical fiber; wherein said digital optical fiber node is a plurality of digital optical fiber nodes; wherein each said plurality of digital optical fiber nodes further comprises a processor, memory, an address stored either in said processor or memory, and are configured to process downstream digital data that is directed to their respective addresses; wherein any of said digital samples of downstream RF waveforms, downstream digital QAM symbols, or downstream digital IP data have a specific digital optical fiber node address; wherein said system further comprises a multiple port switch disposed at said head end or between said head end and said plurality of digital optical fiber nodes; wherein said switch is configured to read said specific digital optical fiber node addresses; and direct any of said digital samples of downstream RF waveforms, downstream digital QAM symbols, or downstream digital IP data to said specific digital optical fiber node corresponding to said specific digital optical fiber node address. |
