Method and apparatus for selectively delivering telephony signals on a hybrid coaxial cable network

• US 5,592,540 A
• Filed: 10/06/1995
• Issued: 01/07/1997
• Est. Priority Date: 05/28/1993
• Status: Expired due to Term

• Current Assignee: Comcast MO Group Incorporated (Comcast Corporation)
• Original Assignee: U.S. West Advanced Technologies, Inc.
• Inventors: Beveridge, Gregory J.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US08/540,365
• Time in Patent Office: 459 Days
• Field of Search: 379/177, 379/183, 379/184, 348/6-8, 348/12-17, 455/1, 455/4.2, 455/5.1, 455/26.1
• US Class Current: 379/184
• CPC Class Codes: H04H 20/79 using downlink of the CATV systems, e.g. audio broadcast via CATV network
• CPC Class Codes: H04H 60/94 Telephonic networks for accessing the Internet H04H60/84
• CPC Class Codes: H04H 60/97 using uplink of the CATV systems
• CPC Class Codes: H04N 7/17354 in an intermediate station common to a plurality of user terminals
• CPC Class Codes: H04Q 11/02 for frequency-division multiplexing H04Q11/0001 takes precedence

Abstract

An interdiction device and method to jam or delete selected video and telephony signals. The interdiction device includes amplifiers and forward couplers to prevent the telephony signals from appearing at other undesired subscriber locations on the network.

Claims

1. A device for transmission of telephony signals in a downstream frequency range and an upstream frequency range on a bus based coaxial cable network including at least a first signal path and a second signal path to and from a subscriber location comprising:

an interdiction device connected to said coaxial cable network, said interdiction device including;

a jamming oscillator connected to said coaxial cable network;

an amplifier connected to said coaxial cable network;

a forward coupler connected to said coaxial cable network; and

a modulator/demodulator connected to said coaxial cable network;

whereby said interdiction device jams telephony signals in said downstream frequency range on said second signal path said amplifier and said forward coupler isolate telephony signals in said upstream frequency range on said first and second signal paths and said modulator/demodulator demodulates selected baseband telephony signals in the downstream frequency range on said first signal path and modulates baseband telephony signals in the upstream frequency range on said first signal path such that said baseband telephony signals to and from said subscriber location may not be monitored at another subscriber location on said bus based coaxial cable network.

2. A device for transmission of telephony signals in a downstream frequency range and an upstream frequency range on a bus based coaxial cable network including at least a first signal path and a second signal path to and from a subscriber location comprising:

an interdiction device connected to said coaxial cable network, said interdiction device including;

a negative trap connected to said coaxial cable network;

an amplifier effectively connected to said coaxial cable network;

a forward coupler connected to said coaxial cable network; and

a modulator/demodulator connected to said coaxial cable network;

whereby said negative trap eliminates telephony signals in said downstream frequency range on said second signal path, said amplifier and said forward coupler isolate telephony signals in said upstream frequency range on said first and second signal paths and said modulator/demodulator device demodulates baseband telephony signals in said downstream frequency range on said first signal path and modulates baseband telephony signals in said upstream frequency range on said first signal path such that said baseband telephony signals to an from said subscriber location may not be monitored at a different subscriber location on said bus based coaxial cable network.

3. A method for delivering secured telephony service in a bus based coaxial cable network including at least a first signal path and a second signal path to and from a subscriber location comprising the steps of:

demodulating a baseband telephony signal on said first signal path to said subscriber location in a downstream frequency range;

jamming telephony signals in said downstream frequency range on said second signal path to said subscriber location;

modulating a telephony signal in an upstream frequency range on said first signal path from said subscriber location;

isolating telephony signals in said upstream frequency range from said subscriber location on said first and second signal paths; and

whereby modulated telephony signals to and from said subscriber location may not be monitored at another subscriber location on said bus based coaxial cable network.

4. A method for delivering secured telephony service in a bus based coaxial cable network including at least a first signal path and a second signal path to and from a subscriber location comprising the steps of:

demodulating a baseband telephony signal in a downstream frequency range on said first signal path to said subscriber location;

eliminating telephony signals in said downstream frequency range on said second signal path to said subscriber location by reducing the amplitude of said signals below the noise level;

modulating a telephony signal in an upstream frequency range on said first signal path from said subscriber location;

isolating telephony signals in said upstream frequency range from said subscriber location on said first and second signal paths; and

whereby telephony signals to and from said subscriber location may not be monitored at another subscriber location on said bus based coaxial cable network.