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Bidirectional video telephony using shared channels on coaxial cable networks

  • US 5,343,240 A
  • Filed: 11/04/1991
  • Issued: 08/30/1994
  • Est. Priority Date: 11/04/1991
  • Status: Expired due to Term
First Claim
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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 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.

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