Optical waveguides – Optical transmission cable
Reexamination Certificate
1998-05-11
2001-04-10
Healy, Brian (Department: 2874)
Optical waveguides
Optical transmission cable
C385S109000, C385S112000
Reexamination Certificate
active
06215930
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to data transmission media. More particularly, the present invention relates to factory-spliced fiber optic cables having distribution fibers accessible over substantially the entire length of the fiber cable.
BACKGROUND OF THE INVENTION
Recent advances in technology and the loosening of federal regulations have blurred the once-distinct lines between cable television (CATV) and telephony service. Currently, there is a great demand for a distribution infrastructure that will support the demanding throughput requirements of an integrated CATV and telephony network. The explosion of the Internet and the growing desire for individuals to enjoy interactive television are creating communication throughput demands that the existing copper-cable infrastructure simply cannot satisfy.
Fiber optics as a transmission medium promises a significant increase in information throughput to meet the needs of the telecommunications industries. Existing “fiber deep” distribution systems typically provide optical fiber to the serving area, with coaxial cable or twisted pair copper lines from the serving area to the subscriber's home. The information-transmitting capacity of fiber optics is 10 to 100 times higher than that of conventional copper-conductor communications cable. Consequently, there is a strong desire in both the CATV and the telephony industries to push optical fiber as deeply as possible into subscriber communities and neighborhoods.
Unfortunately, the cost of using fiber optics is typically much greater than copper-conductor cable. The high manufacturing, installation, and maintenance costs of fiber cable have created an economic barrier to providing fiber cable to a subscriber's home. For instance, with existing fiber cable, splice cases are located at discrete locations, called “splice points,” along the length of the fiber cable. A drop fiber must be pulled from a splice case and spliced to a main fiber with an optical splitter. The drop fiber cannot be pulled from the cable at any other point along the length of the fiber cable. Currently, the drop fiber must typically be spliced to the main fiber in the field by a field technician. The field technician is likely to encounter environmental hazards, such as weather or debris, which can result in poor-quality splices. Moreover, preparing the main fiber to be spliced, and actually performing the splice, are very time-consuming and difficult tasks to perform in the field.
Field splicing the fiber cable is a difficult task which increases the cost of installing the fiber cable. Also, having a large number of drop fibers emanate from a single location on the fiber cable makes maintaining the fiber drops difficult for a field technician. There is a strong desire to decrease the costs of using fiber cable to make a Fiber-To-The-Home (Fri) distribution system realizable. A cost-effective fiber optic cable to enable FTTH service has eluded those skilled in the art. Therefore, a need exists for a remote-splitter fiber optic cable that alleviates the problems identified above.
SUMMARY OF THE INVENTION
Generally stated, a fiber optic cable according to the present invention has, within the fiber cable outer sheath, distribution fibers spliced to an optical splitter fed by a main fiber. The distribution fibers lie within a distribution buffer tube and are accessible at substantially any point along a length of the fiber cable. In particular, a subset of the distribution fibers extend downstream from the optical splitter, while the remaining distribution fibers extend in the upstream direction from the optical splitter.
More particularly, a fiber optic cable according to the present invention has a plurality of buffer tubes, including at least a main buffer tube and a distribution buffer tube, within the cable outer sheath. Within the main buffer tube are multiple main fibers. A main fiber is terminated at an optical splitter, and distribution fibers are spliced to the outputs of the optical splitter. A subset of the distribution fibers extends in the downstream direction of the fiber cable in one distribution buffer tube, and another subset of the distribution fibers from the optical splitter extends in the upstream direction of the fiber cable in another distribution buffer tube.
The foregoing configuration, i.e. an optical splitter having distribution fibers extending in both the upstream and downstream directions, is repeated throughout the fiber cable at a predetermined spacing. At each point along the entire length of the resulting fiber optic cable, rather than only at discrete splice points as with existing cables, at least one distribution fiber is accessible. In one embodiment, at a point along the fiber cable, two groups of distribution fibers are accessible. A first group of the accessible distribution fibers is fed by a first main fiber spliced to a first optical splitter. The other group of accessible distribution fibers is fed from a second main fiber spliced to a second optical splitter. Accordingly, at any point along the fiber cable, a service technician can connect a subscriber to one of at least two available transmitters.
In one embodiment, the optical splitters are factory-installed, which results in a splice of improved quality relative to field-spliced splitters, and significantly reduces the installation time and effort. These benefits, as well as other benefits derived from the present invention, result in a fiber optic cable which reduces the overall cost of providing a fiber optic telecommunications network. By reducing the installation and maintenance costs associated with installing fiber optic cable, the present invention makes a cost effective FTTH distribution infrastructure more easily realizable.
Accordingly, it is an object of the present invention to provide an improved fiber optic cable.
It is another object of the present invention to provide a cost effective fiber optic cable which can make a FTTH telecommunications distribution medium realizable.
It is a further object of the present invention to provide a fiber optic cable having factory-installed optical splitters within the cable sheath, pre-spliced to a feeder portion and a distribution portion of the fiber cable.
The various aspects of the present invention may be more clearly understood and appreciated from a review of the following detailed description of the disclosed embodiments, with reference to the appended drawings and claims.
REFERENCES:
patent: 4961623 (1990-10-01), Midkiff et al.
patent: 5071214 (1991-12-01), Jacob et al.
patent: 5410343 (1995-04-01), Coddington et al.
patent: 5440665 (1995-08-01), Ray et al.
patent: 5479202 (1995-12-01), Beriont
patent: 5488413 (1996-01-01), Elder et al.
patent: 5528582 (1996-06-01), Bodeep et al.
patent: 5541757 (1996-07-01), Fuse et al.
patent: 5550579 (1996-08-01), Martinez
patent: 5557316 (1996-09-01), Hoarty et al.
patent: 5606725 (1997-02-01), Hart
patent: 5615246 (1997-03-01), Beveridge
patent: 5630204 (1997-05-01), Hylton et al.
patent: 5631903 (1997-05-01), Dianda et al.
patent: 5642155 (1997-06-01), Cheng
patent: 5659351 (1997-08-01), Huber
patent: 5684799 (1997-11-01), Bigham et al.
patent: 5719872 (1998-02-01), Dubberly et al.
patent: 3706677 (1988-09-01), None
patent: 4435767A1 (1994-10-01), None
patent: 0509299 (1992-10-01), None
patent: 2161614 (1986-01-01), None
patent: WO 94/16534 (1994-07-01), None
patent: WO 94/24597 (1994-10-01), None
International Search Report, US99/10253, No Pub. Date Avail.
Claire et al., “Expanding Communication Services to the Local Subscriber,”IEEE, pp. 2451-2458, (Jun.).
Brose, “Fiber-to-the-Home: East Otter Tail Phone Company Builds for the Future,”World Wide Web, Oct. 1996, 23 pages.
Byte, “A Hybrid Fiber-Coaxial Network,”World Wide Web, (no date), 2 pages.
Corning, “The Cabling Cost Curve Turns Toward Fiber,”World Wide Web, Nov. 1993, 4 pages.
Hewlett Packard, “Architectures for building the broadband distribution network,”World Wide Web, Aug. 1995, 2 pages.
Estes Daniel L.
Levenson David W.
Swanson David P.
BellSouth Intellectual Property Management Corporation
Healy Brian
Kilpatrick & Stockton LLP
Stahl Michael J.
LandOfFree
Remote-splitter fiber optic cable does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Remote-splitter fiber optic cable, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Remote-splitter fiber optic cable will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2442561