Distributed digital loop carriers system using coaxial cable
First Claim
1. A distributed digital loop (DDL) system providing video and telephone services to a plurality of subscribers, comprising:
- a plurality of taps placed at intervals along a coaxial cable carrying video and telephone signals, each one of said plurality of taps having a passive module coupled to an active distribution unit;
a routing terminator coupled at an end of said coaxial cable; and
a network interface unit located at a subscriber premises, said network interface unit coupling subscriber video and telephone equipment to said active distribution unit via a drop cable,wherein, telephone signals travelling down toward said routing terminator pass through said plurality of taps, and are converted into low frequency telephone signals by said routing terminator for transmission back to said plurality of taps in a subsplit frequency channel of said coaxial cable.
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Accused Products
Abstract
A low power, low cost distributed digital loop (DDL) carrier system that combines television and voice telephone signal transmission over coaxial cables. The DDL system employs a passive/active tap module (114) that controls the steering of the video and telephone signals. The high frequency down stream telephone signal is not processed until a routing terminator (110) converts it to lower frequency signal for transmission in the lower frequency subsplit channel. The telephone signal is then transmitted back up through the subsplit where the active circuitry of each tap intercepts the telephone signal, selects the needed signal and transmits it down to a network interface unit (120) located at the subscriber premises.
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Citations
26 Claims
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1. A distributed digital loop (DDL) system providing video and telephone services to a plurality of subscribers, comprising:
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a plurality of taps placed at intervals along a coaxial cable carrying video and telephone signals, each one of said plurality of taps having a passive module coupled to an active distribution unit; a routing terminator coupled at an end of said coaxial cable; and a network interface unit located at a subscriber premises, said network interface unit coupling subscriber video and telephone equipment to said active distribution unit via a drop cable, wherein, telephone signals travelling down toward said routing terminator pass through said plurality of taps, and are converted into low frequency telephone signals by said routing terminator for transmission back to said plurality of taps in a subsplit frequency channel of said coaxial cable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A distributed digital loop (DDL) carrier system for transmission of video and telephone signals, the system having a central office coupled to a plurality of coaxial cables, the DDL system comprising:
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a plurality of passive taps placed at intervals along each of the plurality of coaxial cables; a plurality of routing terminators each coupled to an end of each of the coaxial cables, each routing terminator converting the telephone signal from a high frequency signal to a low frequency telephone signal for transmission in a subsplit frequency channel of the coaxial cable; a plurality of distribution units each one coupled to one of said plurality of passive taps, each distribution unit having active circuitry for processing said low frequency telephone signal; and a plurality of network interface units, each coupled to a distribution unit via a drop cable, and coupled to subscriber telephone and video equipment.
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11. A signal tap apparatus for use on a coaxial cable comprising:
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a passive module insertable into said coaxial cable, said passive module comprising an inductor for passing a power signal through, and a switch for bypassing said passive module; and a detachable distribution unit coupled to said passive module, said detachable distribution unit comprising active circuitry. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A routing terminator coupled at an end of a coaxial cable comprising:
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a filter circuit having an input adapted to receive telephone signals travelling in a first direction from a central office toward the routing terminator; a demodulator/repeater circuit having an input coupled to an output of said filter circuit; and a modulator having an input coupled to an output of said demodulator/repeater, wherein, said demodulator/repeater generates a digital signal that is converted to lower frequency telephone signal by said modulator. - View Dependent Claims (19)
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20. A subscriber network interface unit comprising:
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a band split filter coupled to a cable drop for receipt of a combined to-subscriber higher frequency video and lower frequency telephone signal, said band split filter separating a telephone portion from a video portion of said combined to-subscriber video/telephone signal; a hybrid circuit for lower frequency telephone signals coupled to said band split filter; and a line circuit coupled between said hybrid circuit and subscriber telephone equipment. - View Dependent Claims (21, 22)
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23. A routing bridger for use in a system providing combined video and telephone signals communication between a central office and a plurality of subscribers, said routing bridger comprising:
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a feeder band split filter having an input/output terminal coupled to a single feeder coaxial cable, said feeder band split filter having a high frequency output and a low frequency input; a plurality of branch band split filters coupled to a plurality of network branches, respectively, a high frequency input of each one of said plurality of branch band split filters coupled to said high frequency output of said feeder band split filter; a plurality of data identifier blocks each one coupled to a low frequency output of each one of said plurality of branch band split filters, respectively, each data identifier block identifying timing information of a low frequency telephone signal received from a respective network branch, and generating a control signal; and a control circuit, coupled to said plurality of data identifiers, for combining low frequency telephone signals from the plurality of network branches into a single signal, in response to said control signal from each one of said plurality of data identifiers.
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24. A method of providing combined telephone and video signal communication via a network of coaxial cables comprising the steps of:
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(a) dividing a frequency spectrum of a coaxial cable into a low frequency subsplit channel and a high frequency supersplit channel; (b) transmitting combined video and telephone signals in a first direction from a central office/head end toward a coaxial cable termination, in said supersplit channel; (c) tapping off a predetermined portion of a video portion of said combined video and telephone signals being transmitted in said first direction, for transmission to subscribers; (d) converting, at a coaxial cable termination, a telephone portion of said combined video and telephone signals to a lower frequency telephone signal suitable for transmission in said subsplit channel; (e) transmitting said lower frequency telephone signal in said subsplit channel in a second direction from said coaxial cable termination back toward said central office/head end; and (f) tapping off said lower frequency telephone signal being transmitted in said supersplit channel for transmission to subscribers. - View Dependent Claims (25, 26)
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Specification