Bidirectional video telephony using shared channels on coaxial cable networks
First Claim
1. A system for making a video telephone call by transmitting a video telephone signal from an originating location to a destination location via first and second cable distribution networks, said first cable network having an associated originating side head end and said second cable network having an associated destination side head end, said system comprisingmeans in said origination location for transmitting a first modulated signal generated by modulating a carrier having a first associated carrier frequency with said video telephone signal generated at said originating location, to said originating side head end via said first cable distribution network, said first carrier frequency corresponding to the frequency of an available upstream video telephone communication channel on said first cable distribution network,means for transmitting said video telephone signal from said originating side head end to said destination side head end connected to said second cable distribution network,means in said destination side head end responsive to said last mentioned means for transmitting a second modulated signal generated by modulating a carrier having a second associated carrier frequency with said video telephone signal, to said destination location, said second carrier frequency corresponding to the frequency of an available downstream video telephone communication channel on said second cable distribution network, andmeans in said destination location for recovering said video information generated at said originating location,wherein said system further includes means for assigning available ones of said upstream and downstream video telephone communication channels only for the duration of said video telephone call.
1 Assignment
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Accused Products
Abstract
A system and method for providing two-way video telephony between an originating location and a destination location, each equipped with an audio/video display (television) and an audio/video source (camera) using available channels dedicated for video telephony on one or more coaxial cable distribution networks which can be part of existing cable television systems. Each location is equipped with a network interface unit (NIU) which modulates outgoing audio/video information (which can be in analog or digital form) together with outgoing control messages onto an attached coaxial cable network. The NIU also demodulates incoming audio/video information and incoming control messages received from the attached coaxial network. Upstream signals may be transmitted to a cable network head end and then to the head end serving the destination location using demodulators, A/D converters (if not already in digital form), multiplexers, and the switched digital telecommunications network. If an intra-cable system call is involved, certain processing steps may be eliminated. Users of the system contend for available channels on the cable distribution network, and channel assignments are made on a per call basis, only for the duration of the call.
249 Citations
44 Claims
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1. A system for making a video telephone call by transmitting a video telephone signal from an originating location to a destination location via first and second cable distribution networks, said first cable network having an associated originating side head end and said second cable network having an associated destination side head end, said system comprising
means in said origination location for transmitting a first modulated signal generated by modulating a carrier having a first associated carrier frequency with said video telephone signal generated at said originating location, to said originating side head end via said first cable distribution network, said first carrier frequency corresponding to the frequency of an available upstream video telephone communication channel on said first cable distribution network, means for transmitting said video telephone signal from said originating side head end to said destination side head end connected to said second cable distribution network, means in said destination side head end responsive to said last mentioned means for transmitting a second modulated signal generated by modulating a carrier having a second associated carrier frequency with said video telephone signal, to said destination location, said second carrier frequency corresponding to the frequency of an available downstream video telephone communication channel on said second cable distribution network, and means in said destination location for recovering said video information generated at said originating location, wherein said system further includes means for assigning available ones of said upstream and downstream video telephone communication channels only for the duration of said video telephone call.
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11. Apparatus for transmitting audio and video information from a first location to a second, remote location, using cable distribution networks, said apparatus comprising
a video camera for generating an audio and video signal; -
means for modulating a first carrier signal with said audio and video signal and a control signal indicative of the address of said remote location, to generate a first modulated signal; means for transmitting said first modulated signal via a portion of a first cable distribution network to an originating side head end; means for demodulating said first modulated signal to retrieve said audio and video signal; means for converting said retrieved audio and video signal to digital signals; means for transmitting said digital signals to a destination side head end, said destination side head end being selected in accordance with said control signal; means responsive to said last mentioned means for converting said digital signals to said audio and video signal at said destination side head end; means for modulating a second carrier signal with said audio and video signal recovered from said digital signals to generate a second modulated signal; means for transmitting said second modulated signal via a portion of a second cable distribution network to said remote location; and means for demodulating said second modulated signal to recover said audio and video signal. - View Dependent Claims (12, 13)
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14. A system for completing a video telephone call to a destination location via a coaxial cable distribution network and a switched digital telecommunications network, said system comprising
a source of audio and video signals activated by placing said video telephone call, a network interface unit (NIU) for applying said audio and video signals to an available video telephone communication channel on said cable distribution network, said particular channel being selected under the control of a microprocessor in said NIU; -
means including a head end for converting received audio and video signals in said available video telephone communication channel to a digital signal; means for transmitting said digital signal as well as routing information indicative of said destination location to said switched digital telecommunications network; and means in said switched digital telecommunications network for routing said call to said destination location in response to said routing information, wherein said particular video telephone communication channel is assigned to only for the duration of said video telephone call.
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15. A system for enabling two way video telephone communication between an originating location and a destination location, comprising
switch means, first means in said originating location for (a) transmitting video telephone signals originating therein to said switch means via a first available channel on a first multichannel cable distribution network, and (b) receiving video telephone signals originating in said destination location and transmitted thereto from said switch means via a second available channel on said first multichannel cable distribution network, wherein others ones of the channels on said first cable distribution network are used for other communications, second means in said destination location for (a) transmitting video telephone signals originating therein to said switch means via a first available channel on a second multichannel cable distribution network, and (b) receiving video telephone signals originating in said origination location and transmitted thereto from said switch means via a second available channel on said second multichannel cable distribution network, wherein other ones of the channels on said second cable distribution network are used for other communications, wherein said switch means is arranged to route calls from said first means to said second means, and vice versa.
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18. A method for making a video telephone call by transmitting video telephone signals from an originating location to a destination location via first and second cable distribution networks, said first cable distribution network having an associated originating side head end and said second cable distribution network having an associated destination side head end, said method comprising the steps of
transmitting a first modulated signal generated by modulating a carrier having a first associated carrier frequency with video telephone signals generated at said originating location, from said originating location to said originating side head end via said first cable distribution network, said first carrier frequency corresponding to the frequency of an available upstream video telephone communication channel on said first cable distribution network, transmitting said video telephone signals from said originating side head end to said destination side head end connected to said second cable distribution network, means in said distribution side head end responsive to said last mentioned means for transmitting a second modulated signal generated by modulating a carrier having a second associated carrier frequency with said video telephone signals, from said destination side head end to said destination location, said second carrier frequency corresponding to the frequency of an available downstream video telephone communication channel on said second cable distribution network, and recovering in said destination location said video information generated at said originating location, wherein said method further includes the step of assigning available ones of said upstream and downstream video telephone communication channels only for the duration of said video telephone call.
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28. A method for transmitting audio and video information from a first location to a second, remote location, comprising the steps of
generating audio and video signals in a video camera, modulating a first carrier signal with said audio and video signals and a control signal indicative of the address of said remote location, to generate first modulated signals; -
transmitting said first modulated signals via a portion of a first cable distribution network to an originating side head end; demodulating said first modulated signals to retrieve said audio and video signals; converting said retrieved audio and video signals to digital signals; transmitting said digital signals to a destination side head end selected in accordance with said control signal; receiving said digital signals in said destination side head end; converting said digital signals to said audio and video signals at said destination side head end; modulating second carrier signals with said audio and video signals to generate second modulated signals; transmitting said second modulated signals via a portion of a second cable distribution network to said remote location; and demodulating said second modulated signals to recover said audio and video signals.
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29. A method for completing a video telephone call to a destination location via a coaxial cable distribution network and a switched digital telecommunications network, said method comprising the steps of
generating audio and video signals by placing said video telephone call, applying said audio and video signals to an available video telephone communication channel on said cable distribution network, said particular channel being selected under the control of a microprocessor in a network interface unit (NIU), converting said audio and video signals received in a head end via said available video telephone communication channel to digital signals; -
transmitting said digital signals as well as routing information indicative of said destination location to said switched digital telecommunications network; and routing said call to said destination location via said switched digital telecommunications network in response to said routing information, wherein said particular video telephone communication channel is assigned to only for the duration of said video telephone call.
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30. A method for enabling two way video telephone communication between an originating location and a destination location via a switch, comprising the steps of
(a) transmitting video telephone signals originating in said originating location to said switch via a first available upstream channel on a first multichannel cable distribution network, (b) receiving video telephone signals originating in said destination location and transmitted to said originating location from said switch via a second available downstream channel on said first multichannel cable distribution network, wherein others ones of the channels on said first cable distribution network are used for other communications, (c) transmitting video telephone signals originating in said destination location to said switch via a first available upstream channel on a second multichannel cable distribution network, and (d) receiving video telephone signals originating in said origination location and transmitted to said destination location from said switch via a second available downstream channel on said second multichannel cable distribution network, wherein others ones of the channels on said second cable distribution network are used for other communications, wherein said method further includes (e) connecting video telephone signals between transmitted in said first available upstream channel on said first cable distribution network to said second available channel on said second cable distribution network via said switch, and (f) connecting video telephone signals transmitted in said first available upstream channel on said second cable distribution network to said second available channel on said first cable distribution network via said switch.
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32. A method for transmitting audio and video information for a video telephone call from an origination location to a switch via a coaxial cable distribution network, including the steps of
generating audio and video information signals, modulating said audio and video information signals in a network interface unit connected to said distribution network to a carrier frequency corresponding to an available channel on said coaxial cable distribution network, recovering said audio and video information signals in a head end connected to said cable distribution network, and applying said recovered signal to said switch, wherein said method further includes the steps of monitoring for the existence of an available channel on said distribution network and providing a control signal to said network interface unit identifying said available channel.
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34. A system for transmitting audio and video information for a video telephone call from an origination location to a switch via a coaxial cable distribution network, including
a source of audio and video information signals, a network interface unit connected to said distribution network for modulating said audio and video information to a carrier frequency corresponding to an available channel on said coaxial cable distribution network, and a head end connected to said cable distribution network for recovering said audio and video information signals and for applying said recovered audio and video information signals to said switch, wherein said system further includes means for monitoring for the existence of an available channel on said distribution network and for providing a control signal to said network interface unit identifying said available channel.
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36. A network interface unit (NIU) for interfacing between video telephony audio/video originating and terminating devices, and a cable distribution network, said NIU including
means for modulating audio/video signals generated in said originating device with a carrier signal to generate an upstream modulated signal which is applied to an available video telephone channel on said cable distribution network, means for demodulating a downstream modulated signal applied to said NIU from said cable distribution network to retrieve audio/video signals to be applied to said terminating device, and processor means for controlling the selection of the frequency of said carrier signal in response to a received signal indicating the availability of video telephone channels on said cable distribution network.
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41. Apparatus for transmitting audio and video information from a first location to a second, remote location, using cable distribution networks, said apparatus comprising
means including a video coder for generating a digital representation of audio and video signals; -
means for modulating a first carrier signal with said digital representation of said audio and video signals and a control signal indicative of the address of said remote location, to generate first modulated signals; means for transmitting said first modulated signals via a portion of a first cable distribution network to an originating side head end; means for demodulating said first modulated signals to recover said digital representation of said audio and video signals; means for transmitting said digital representation of said audio and video signals to a destination side head end, said destination side head end being selected in accordance with said control signal; means in said destination side head end responsive to said last mentioned means and including means for modulating a second carrier signal with said digital representation of said audio and video signals, to generate second modulated signals; means for transmitting said second modulated signals via a portion of a second cable distribution network to said remote location; and means for demodulating said second modulated signals to recover said digital representation of said audio and video signals. - View Dependent Claims (42)
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43. A system for completing a video telephone call to a destination location via a coaxial cable distribution network and a switched digital telecommunications network, said system comprising
a source of audio and video signals activated by placing said video telephone call, said audio and video signals being in digital form; -
a network interface unit (NIU) for applying said audio and video signals in digital form to an available video telephone communication channel on said cable distribution network, said particular channel being selected under the control of a microprocessor in said NIU; means including a head end for combining said audio and video signals received in said available video telephone communication channel with routing information indicative of said destination location and for transmitting said combined signal to said switched digital telecommunications network; and means in said switched digital telecommunications network for routing said call to said destination location in response to said routing information, wherein said particular video telephone communication channel is assigned to only for the duration of said video telephone call.
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44. A system for making a video telephone call by transmitting video telephone signals from an originating location to a destination location via first and second cable distribution networks, said first cable network having an associated originating side head end and said second cable network having an associated destination side head end, said system comprising
means in said origination location for transmitting a first digital signal representing audio and video information generated in said originating location to said originating side head end via an available upstream video telephone communication channel on said first cable distribution network, means for transmitting said first digital signal from said originating side head end to said destination side head end, via a switched communications network; -
means in said destination side head end for receiving said first digital signal from said last mentioned means and for transmitting a second digital signal representing a scrambled version of said audio and video information to said destination location via an available downstream video telephone communication channel on said second cable distribution network, and means in said destination location for recovering said audio and video information generated at said originating location.
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Specification