Video signal distribution system

• US 4,994,909 A
• Filed: 05/04/1989
• Issued: 02/19/1991
• Est. Priority Date: 05/04/1989
• Status: Expired due to Term

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Dittburner, Robert C., Graves, Alan F., Hagglund, Barry B.
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Chan, Wing F.
• Application Number:
  US07/347,136
• Time in Patent Office: 656 Days
• Field of Search: 358/86, 455/3-6, 370/4
• US Class Current: 725/92
• CPC Class Codes: H04N 7/17354 in an intermediate station common to a plurality of user terminals
• CPC Class Codes: H04N 7/54 the signals being synchronous H04N21/23602, H04N21/23614, H04N21/2365, H04N21/2368, H04N21/4341, H04N21/4342, H04N21/4347, H04N21/4348 take precedence

Abstract

A signal distribution system is disclosed for distributing television program signals from a central location to a plurality of subscriber locations via respective optical fibers. At the central location, 4 of 64 signals are selected and multiplexed for delivery to each subscriber location. At each subscriber location, an interface unit selects any 2 of the 4 signals for delivery to each of a plurality of video port controllers, for supply to an associated television receiver and video cassette recorder. Requests for program signals initiated by a subscriber at a video port controller are handled by the interface unit, being granted, denied, or fowarded to the central location as appropriate. The system facilitates the provision of pay-per-channel and pay-per-view television program signals.

Claims

1. A signal distribution system for distributing video signals from a central location to a plurality of subscriber locations via respective communications paths, the system comprising, at the central location:

means for selecting for each subscriber location, from a first plurality of video signals a second, lesser, plurality of video signals and for delivering said second plurality of video signals to the respective subscriber location via a respective communications path;

and, at each subscriber location;

a plurality of control means each for supplying a respective video signal to at least one respective video signal receiver associated therewith; and

interface means coupled to the respective communications path and to each control means for delivering respective video signals thereto;

wherein each control means comprises means for requesting delivery of any of the first plurality of video signals and for communicating such request to the interface means, and wherein the interface means comprises means responsive to such request for;

determining whether the requested video signal is one of said second plurality of video signals delivered thereto via the respective communications path;

if so, delivering the requested video signal to the respective control means; and

if not, communicating a request for the requested video signal to the central location to be selected from the first plurality of video signals and delivered as one of the second plurality of video signals.

4. A system as claimed in claim 1 and including at the central location means for multiplexing with each selected signal an identification of the selected signal.

5. A system as claimed in claim 1 wherein each communications path comprises a digital signal communications path, the system further comprising at the central location means for supplying each of the first plurality of video signals as a digital signal.

6. A system as claimed in claim 5 wherein each control means comprises means for converting a respective digital video signal delivered thereto into an analog video signal for supply to the respective video signal receiver.

7. A system as claimed in claim 5 wherein the communications paths comprise optical fiber communications paths.

2. A system as claimed in claimed 1 wherein the interface means comprises means for supplying to each control means a third plurality, less than the second plurality, of video signals.

3. A system as claimed in claim 2 wherein the first, second, and third pluralities of video signals comprise at least about 64, 4, and 2 video signals respectively.

8. A method of distributing television program signals from a central location selectively to a plurality of subscriber locations, comprising the steps of:

at a plurality of points at a subscriber location, requesting television program signals for delivery thereto;

at the central location, selecting for the respective subscriber location a plurality of requested television program signals from a larger number of available television program signals;

supplying the selected signals from the central location to the subscriber location via a respective communications path; and

at a central point at the subscriber location, receiving requests for television program signals from said plurality of points, receiving the selected signals from the central location via the respective communications path, determining whether requested television program signals are received from the central location and if so delivering the requested television program signals received from the central location to said plurality of points in dependence upon the received requests, and communicating to the central location requests for selecting television program signals at the central location for supply to the subscriber location.

9. A method as claimed in claim 8 wherein the television program signals are supplied as time division multiplexer digital signals via the respective communications paths.