Hybrid fiber-coax system having at least one digital fiber node and increased upstream and downstream bandwidth
First Claim
1. A method for use with a CATV transmission system which transmits information from a head-end to individual subscribers and which transmits information from subscribers to the head-end, comprising the steps of:
- transmitting upstream information in analog format over a first fiber to a head-end from a fiber node, wherein it is received in analog form in a first frequency band from via a coax cable from subscribers;
transmitting downstream information in analog format over a second fiber from the head-end to the fiber node, wherein it is modulated in a second frequency band in analog form for transmission on the coaxial cable to the subscribers;
transmitting downstream information in a digital format over a third fiber from the head-end to the fiber node, wherein it is modulated to an analog format and shifted to a third frequency band for passage on the coaxial cable to subscribers; and
transmitting upstream information in baseband digital format over a fourth fiber to the head-end from the fiber node, wherein it is received in a fourth frequency band on coaxes from subscribers and is regenerated.
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Abstract
Noise is reduced and bandwidth may be increased in a CATV transmission system by modulating a portion of subscriber-generated upstream signals to a high frequency band (e.g., 750-100 MHz) and then digitally regenerating such signals. To further reduce noise, the digitally regenerated upstream signals are transmitted by in a baseband digital format to the head end (120) via a digital E/O converter (330). Increased downstream bandwidth is obtained by modulating a portion of the downstream signals to a higher frequency band (e.g., 500-750 MHz) and then digitally regenerating such signals.
68 Citations
14 Claims
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1. A method for use with a CATV transmission system which transmits information from a head-end to individual subscribers and which transmits information from subscribers to the head-end, comprising the steps of:
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transmitting upstream information in analog format over a first fiber to a head-end from a fiber node, wherein it is received in analog form in a first frequency band from via a coax cable from subscribers; transmitting downstream information in analog format over a second fiber from the head-end to the fiber node, wherein it is modulated in a second frequency band in analog form for transmission on the coaxial cable to the subscribers; transmitting downstream information in a digital format over a third fiber from the head-end to the fiber node, wherein it is modulated to an analog format and shifted to a third frequency band for passage on the coaxial cable to subscribers; and transmitting upstream information in baseband digital format over a fourth fiber to the head-end from the fiber node, wherein it is received in a fourth frequency band on coaxes from subscribers and is regenerated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for reducing aggregated ingress upstream noise and for increasing upstream bandwidth in a CATV transmission system that transmits downstream information from a head end to individual subscribers via at least one main coax trunk and that transmits upstream information generated by subscribers to the head end at least in part on said main coax trunk, comprising the steps of:
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aggregating onto the main coax trunk upstream information generated by said subscribers; digitally modulating a first portion of the upstream information to a first frequency band above the downstream information; digitally regenerating the first portion of the upstream information for transmission on the main coax trunk to a fiber node; transmitting the digitally regenerated first portion of the upstream information from the fiber node to the head end in an optical baseband format; and digitally regenerating at least a portion of the downstream information lying in a second frequency band lying immediately below the first frequency band. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification