Wideband digital signal distribution system

• US 4,760,442 A
• Filed: 07/10/1985
• Issued: 07/26/1988
• Est. Priority Date: 07/10/1985
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: O'Connell, Steven S., Utberg, Daniel N.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/753,535
• Time in Patent Office: 1,112 Days
• Field of Search: 179/2 TV, 179/2 TS, 358/85, 358/86, 455/4, 455/5, 379/53, 379/54, 379/94, 370/77, 370/85
• US Class Current: 725/119
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 7/17354 in an intermediate station common to a plurality of user terminals

Abstract

Wideband digital signals, such as video program signals, are distributed to multiple customer locations by providing the wideband digital signals to all customer line interface units in an intermediate selection terminal which is remote from a central wideband signal distribution office. The individual signals are made available to all line interface circuits by way of nonreflectively terminated transmission lines and high-input-impedance signal tapping circuits. Control signals from customer terminals are used at the corresponding line interface circuit to control digital selection of channels for customer use, any number of customers being able to select simultaneously a common one of said transmission lines. Other control signals from the central office are used to limit customer access to all wideband signals.

Claims

1. A wideband digital signal distribution system comprising

a plurality of signal transmission paths each including a different substantially non-reflectively terminated transmission line,

means for separately tapping signals from different locations along each of said transmission lines,

a plurality of subscriber line interface circuits each including one or more output connections and controllable means for selectably coupling signals from among the tapping means of more than one of said transmission lines to the one or more output connections of the line interface circuit,

said selectably coupling means comprising

means for receiving control signals,

means, responsive to said control signals, for coupling a selected one of said tapping means to one of said one or more output connections of said each interface circuit,

means responsive to said control signals for coupling a selected one or more additional ones of said tapping means to the one of said one or more output connections of each interface circuit, and

means for time multiplexing the digital signal from said selected one of said tapping means and the digital signals from said selected one or more additional ones of said tapping means onto one of the one or more output connections of said interface circuit.

2. A wideband digital signal distribution system comprising

a plurality of signal transmission paths each including a different substantially non-reflectively terminated transmission line,

means for separately tapping signals from different locations along each of said transmission lines,

a plurality of subscriber line interface circuits each including controllable means for selectably coupling signals from among the tapping means of more than one of said transmission lines to an output connection of the line interface circuit,

a central office remotely located with respect to said transmission lines and said subscriber line interface circuits, said office having plural wideband digital signal output connection,

means for coupling said office output connections to said transmission line, respectively, and

a plurality of customer terminals located in the vicinity of said transmission lines and said subscriber line interface circuits, and

means for coupling an output connection of each of said interface circuits to a different one of said customer terminals.

3. The signal distribution system in accordance with claim 2 in which

said terminated transmission lines are grouped into sets of such circuits,

said line interface circuits are grouped into subsets of such circuits, each interface circuit subset being coupled to a different one of said sets of said transmission lines, and

said office output connections coupling means comprises

means for separately amplifying each on said wideband digital data signals for presenting it at plural fanout output connections of a different one of such separately amplifying means, and

means for coupling a different output to each of said separately amplifying means to respective lines of a different one of said sets of transmission lines, such different output coupling means including buffer amplifier means at an input to each transmission line for isolating such line from lines in other ones of said sets coupled to the same one of said separately amplifying means.

4. The signal distribution system in accordance with claim 2 in which said selectably coupling means in each line interface circuit comprises

means for receiving transmission line select control signals from one of said customer terminals coupled to such line interface circuit, and

means, responsive to said transmission line. select control signals, for coupling one of said at least one tapping means to said output connection said each line interface circuit.

5. The digital signal distribution system in accordance with claim 2 in which said central office receives any one or more of voice, data, and video program signals for at least one of said customer terminals and in which there are provided in each of said line interface circuits

means, including said line interface circuit output connection, for bidirectional transmission of voice and data signals from and to said line interface circuit with respect to one of said customer terminals, said bidirectional transmission means including means for receiving control signals from a customer terminal,

means for transmitting customer voice data signals received from a customer terminal to said central office,

means for applying at least a portion of said control signals to control said selectable coupling means,

means for time multiplexing together voice and data signals received from said central office with video program signals from said selectable coupling means, and

means for applying multiplexed signals from an output of said multiplexing means to said output connection.

6. In a system for distributing selectable ones of plural wideband digital signals on respective supply circuits to individual customer terminals via respective customer line signal paths, each of said supply circuits being a transmission line substanially terminated in its characteristic impedance, and a separate line interface circuit for interfacing each customer line signal path with said supply circuits, the improvement in each of said line interface circuits comprising

a plurality of means for receiving wideband digital signals from respective ones of said transmission lines, each receiving means having a sufficiently high impedance for coupling signals from one of said transmission lines without significantly loading that transmission line,

means for receiving from said each said line signal path of said interface circuit customer signals for controlling selection of said wideband digital signals, and

means, coupled to one of said plurality of transmission line signal receiving means, respectively, and responsive to said customer signals, for selecting one wideband digital signal from the output of its transmission line signal high input impedance receiving means,

means coupled to another of said transmission line signal receiving means responsive to said customer signals for selecting at least one additional wideband digital signal from the output of said another of its transmission line high input impedance means, and

means for time multiplexing said selected one wideband digital signal and said selected at least one additional wideband digital signal onto one of said line signal paths.