Systems and methods for securing a tether to a distribution cable

A securement system includes at least one retention arrangement securing a tether to a distribution cable; and a release device secured to the distribution cable. The release device extends along at least a portion of the length of tether. Pulling the release device away from the distribution cable disengages the retention arrangement to free the tether from the distribution cable. Multiple retention arrangements can be used to secure the tether.

TECHNICAL FIELD

The principles disclosed herein relate to fiber optic cable systems. More particularly, the present disclosure relates to fiber optic cable systems having main cables and branch cables.

BACKGROUND

Passive optical networks are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities to customers. Passive optical networks are a desirable choice for delivering high speed communication data because they may not employ active electronic devices, such as amplifiers and repeaters, between a central office and a subscriber termination. The absence of active electronic devices may decrease network complexity and/or cost and may increase network reliability.

FIG. 1illustrates a network100deploying passive fiber optic lines. As shown inFIG. 1, the network100may include a central office110that connects a number of end subscribers115(also called end users115herein) in a network. The central office110may additionally connect to a larger network such as the Internet (not shown) and a public switched telephone network (PSTN). The network100may also include fiber distribution hubs (FDHs)130having one or more optical splitters (e.g., 1-to-8 splitters, 1-to-16 splitters, or 1-to-32 splitters) that generate a number of individual fibers that may lead to the premises of an end user115. The various lines of the network can be aerial or housed within underground conduits (e.g., see conduit105).

The portion of network100that is closest to central office110is generally referred to as the F1 region, where F1 is the “feeder fiber” from the central office. The F1 portion of the network may include a distribution cable having on the order of 12 to 48 fibers; however, alternative implementations may include fewer or more fibers. The portion of network100that includes an FDH130and a number of end users115may be referred to as an F2 portion of network100. Splitters used in an FDH130may accept a feeder cable having a number of fibers and may split those incoming fibers into, for example, 216 to 432 individual distribution fibers that may be associated with a like number of end user locations.

Referring toFIG. 1, the network100includes a plurality of breakout locations125at which branch cables (e.g., drop cables, stub cables, etc.) are separated out from main cables (e.g., distribution cables). Breakout locations can also be referred to as tap locations or branch locations and branch cables can also be referred to as breakout cables. At a breakout location, fibers of the branch cables are typically spliced to selected fibers of the main cable. However, for certain applications, the interface between the fibers of the main cable and the fibers of the branch cables can be connectorized.

Stub cables are typically branch cables that are routed from breakout locations to intermediate access locations such as a pedestals, drop terminals or hubs. Intermediate access locations can provide connector interfaces located between breakout locations and subscriber locations. A drop cable is a cable that typically forms the last leg to a subscriber location. For example, drop cables are routed from intermediate access locations to subscriber locations. Drop cables can also be routed directly from breakout locations to subscriber locations thereby bypassing any intermediate access locations

Branch cables can be manually separated out from a main cable in the field using field splices. Field splices are typically housed within sealed splice enclosures. Manual splicing in the field can be time consuming and expensive.

As an alternative to manual splicing in the field, pre-terminated cable systems have been developed. Pre-terminated cable systems include factory integrated breakout locations manufactured at predetermined positions along the length of a main cable (e.g., see U.S. Pat. Nos. 4,961,623; 5,125,060; and 5,210,812). However, the installation of pre-terminated cables can be difficult. For example, for underground applications, pre-terminations can complicate passing pre-terminated cable through the underground conduit typically used to hold fiber optic cable (e.g., 1.25 inch inner diameter conduit). Locating and accessing pre-terminated breakouts can be difficult in underground applications. Similarly, for aerial applications, pre-terminations can complicate passing pre-terminated cable through aerial cable retention loops.

SUMMARY

Certain aspects of the disclosure relate to fiber optic cable systems, packaging configurations and methods that facilitate the effective use and installation of pre-terminated fiber optic cable.

DETAILED DESCRIPTION

The present disclosure relates to fiber optic cable systems. In particular, the present disclosure relates to a pre-terminated fiber optic cable system for releasably securing a tether to a distribution cable beyond a breakout location.

FIG. 2illustrates a cable system200including the main cable (e.g., a distribution cable)220and a branch cable (e.g., tether)240that separates (i.e., branches out) from the main cable220at a breakout location206. The breakout location206is protected and sealed by a structure, such as an enclosure208. The tether cable240extends outwardly from the enclosure208along a length L and terminates at one or more connectors256. The connectors256are configured to optically couple to a drop terminal214or other piece of telecommunications equipment at a hand-hole location210.

A typical breakout location is provided at an intermediate point along a length of a distribution cable. For example, the distribution cable220can include six separate buffer tubes222each containing multiple (e.g., twelve) fibers224(seeFIG. 3). The buffer tubes222may be gel filled. The fibers224within each buffer tube222can include either ribbon fibers or loose fibers. The distribution cable220can also include a central strength member226for reinforcing the cable220, and an outer strength layer/member228such as aramid fiber/yarn (e.g., Kevlar®) also for reinforcing the cable (seeFIG. 3). The distribution cable220further includes an outer jacket230that encloses the buffer tubes222(seeFIG. 3). Ripcords232can be provided for facilitating tearing away portions of the jacket230to access the fibers224within the jacket230(seeFIG. 3).

While distribution cables220typically have a large number of fibers, the various aspects of the present disclosure are also applicable to distribution cables220having fewer numbers of fibers (e.g., 2 or more fibers). For example, the distribution cable220can include an outer jacket enclosing a single buffer tube and at least two strength members extending on opposite sides of the single buffer tube. An outer strength member, such as aramid fiber/yarn, can surround the single buffer tube within the jacket. The single buffer tube can enclose loose fibers or ribbon fibers.

The tether (e.g., a drop cable or a stub cable)240most commonly has a fewer number of fibers as compared to the number of fibers provided within the distribution cable220.FIG. 4illustrates a tether cable240configured to join to the distribution cable220at the breakout location206. The tether240is depicted as having a flat cable configuration. The flat cable configuration includes a central buffer tube242containing fibers244(e.g., typically one to twelve loose or ribbonized fibers). Strength members246(e.g., flexible rods formed by glass fiber reinforced epoxy) are positioned on opposite sides of the central buffer tube242. An outer jacket250surrounds the strength members246and the buffer tube242.

The outer jacket250includes an outer perimeter having an elongated transverse cross-sectional shape. An additional strength layer248(e.g., aramid yarn, such as Kevlar®) can be positioned between the buffer tube242and the outer jacket250. As shown atFIG. 4, the transverse cross-sectional shape includes oppositely positioned, generally parallel sides252interconnected by rounded ends254. However, any suitable cable configuration can be utilized for both the distribution cable and the tether cable.

The tether240includes fibers that extend between first and second ends. The first ends of the tether fibers244are preferably spliced to selected fibers224of the distribution cable220at the breakout location206(seeFIG. 2). The second ends of the tether fibers244are configured to optically couple to the telecommunications equipment214at the hand-hole location210(seeFIG. 2). The second ends can either be connectorized or unconnectorized.

Referring now toFIG. 5, in general, the cable system200is installed within underground conduits212by pulling the main cable220through the conduits212. Typically, the cable220is pulled in a direction such that the connectors256of the tether240trail the enclosure208. In other embodiments, the cable220can be pulled in the opposite direction. The distribution cable220is arranged within the conduits212such that a portion of each tether240branching from the cable220is accessible from a hand-hole location210.

In some embodiments, the distribution cable220is arranged such that the connectors256of the tether240are offset from the hand-hole location210in one direction and the enclosure208is offset from the hand-hole location210in an opposite direction. In such embodiments, the enclosure208is located within a conduit212and is not accessible by a technician. In other embodiments, the distribution cable220is arranged such that the connectors256of a tether240are substantially aligned with the hand-hole location210. In still other embodiments, the distribution cable220is arranged such that the enclosure208is substantially aligned with the hand-hole210.

After being optically coupled to the distribution cable at one end, the remainder of the tether240can be secured along a length to the distribution cable220. In certain embodiments, the tether240can be secured to the distribution cable220along the entire length L of the tether240. In other embodiments, only the far end (e.g., the connectorized end) of the tether240is secured. Securing the tether240mitigates the chances of damaging the tether240and tether connectors256during installation of the distribution cable220.

FIG. 5illustrates a securing system300for fastening the tether240to the distribution cable220. The securement system300includes a retention structure302configured to secure the tether240to the distribution cable220. In the example shown, the retention arrangement302secures the tether240to the distribution cable220adjacent the tether connectors256. In other embodiments, however, the retention arrangement302can secure the tether240to the distribution cable220along any portion of the tether240. Multiple retention arrangements can also be used to secure the tether240.

The securement system300also includes a release device304extending along the distribution cable220and the length L (FIG. 2) of the tether cable240. As shown atFIG. 5, the release device304extends generally from the tether connectors256to the breakout location206. Typically, the release device304is positioned to enable at least a portion of the release device to be accessible by a user from the hand-hole location210.

In use, a user can access the securement system300through the hand-hole location210. To separate the tether cable240from the distribution cable220, the user grasps the release device304and pulls. Pulling the release device304disengages the retention arrangement302, thereby freeing the tether240. For example, in some embodiments, pulling the release device304can break or tear the retention arrangement302. In other embodiments, however, pulling the release device304unbinds the retention arrangement302without breaking the retention arrangement302.

Referring now toFIGS. 6-20, the principles of the present disclosure can best be understood through some example applications. As shown inFIGS. 6-11, a tether cable240can be releasably secured to a distribution cable220using a first securement system400having feature that are examples of inventive aspects in accordance with the principles of the present disclosure.FIG. 6depicts an operation flow for a process600by which a tether240can be releasably secured to a distribution cable220using the first securement system400.FIGS. 7-9illustrate the results of the operations of the securing process600.

The securing process600begins at start module602and proceeds to breakout operation604. The breakout operation604attaches a tether to a distribution cable at a breakout location. Typically, the breakout operation604includes splicing the tether to the distribution cable and providing a protective enclosure around the splice. Further details regarding embodiments of the breakout operation604can be found in U.S. Ser. No. 60/781,280, filed Mar. 9, 2006, and entitled “FIBER OPTIC CABLE BREAKOUT CONFIGURATION”; U.S. Ser. No. 60/781,622, filed Mar. 9, 2006, and entitled “MID-SPAN BREAK-OUT WITH HELICAL FIBER ROUTING”; and U.S. Ser. No. 60/781,621, filed Mar. 9, 2006, and entitled “MID-SPAN BREAK OUT WITH POTTED CLOSURE,” the disclosures of which are hereby incorporated by reference.

The process600proceeds to arrange operation606. The arrange operation606provides a wire or other type of release device (e.g., aramid fiber/yarn, etc.) having a length generally twice the length L of the tether cable. The arrange operation606lays a first portion of the wire along the tether from the enclosure to the tether connectors. Typically, the first portion of wire is about half the overall length of the wire. The results of arrange operation606are shown inFIG. 7.

FIG. 7illustrates a tether240extending outwardly from an enclosure208along a distribution cable220. The tether240terminates at one or more connectors256a distance from the enclosure208. A first length414of wire404extends along the distribution cable220adjacent the tether cable240. A first end403of the wire404is secured (e.g., taped) to the distribution cable220adjacent the enclosure208. An intermediate end406of the wire404is secured to the distribution cable220adjacent the tether connectors256. The wire404can be secured around the cables220,240using tape, adhesive, or other such means.

In other embodiments, the first securement system400can include wire404routed in the opposite direction such that the ends403,405of the wire404are secured adjacent the tether connectors256and the intermediate end406of the wire404is secured adjacent the breakout enclosure208.

Continuing with process600, an enclose operation608wraps foil or another type of material (e.g., tape, plastic wrap, etc.) around the distribution cable, the tether cable, and the first length of wire. In a preferred embodiment, the enclosure operation608wraps foil from the enclosure to the tether connectors. The results of the enclose operation608are shown inFIG. 8. Foil402is wrapped around the distribution cable220, the first length414of wire404, and the tether240. The foil402can be secured around the cables220,240and wire404using tape, adhesive, or other such means.

A fold (i.e., loop-back) operation610routes the remaining wire from the tether connectors back to the enclosure. Fold operation610lays the second length of wire, from the intermediate end to a second end of wire over the foil. In some embodiments, the second end of the wire is taped to the foil adjacent the enclosure. In other embodiments, the second end of the wire is secured to the distribution cable. The results of operation610are shown inFIG. 9.

FIG. 9illustrates a second length424of wire404lain over the foil402. The foil402encloses the first length414of wire404, the distribution cable220, and the tether240. In the example shown, a second end405of the wire404is secured to the distribution cable220adjacent the enclosure208. In other embodiments, however, the second end405can be secured at any desired point along the length of the distribution cable220. In some embodiments, the second length424of the wire404is configured to be manipulated by a user. In other embodiments, the second end405is configured to be grasped. In one such embodiment, the second end405includes a ring407suitable for grasping with pliers or other such tools. In another embodiment, the second end405is configured to be grasped by hand. The process600ends at stop module612.

Referring toFIGS. 10-12, the tether240can be released from the distribution cable220after deployment (i.e., payout) of the distribution cable220.FIG. 10illustrates the cable system200including the first securement system400installed in an underground conduit212. The second length424of the wire404of the first securement system400is accessible from a hand-hole location210.FIG. 11shows an operation flow for a process1100by which the tether240can be released from the first securement system400.FIG. 12illustrates the cable system200after the tether240has been released from the distribution cable220and coupled to the telecommunications equipment214at the hand-hole location210.

As shown inFIG. 1, the process1100begins at start module1102and proceeds to an access operation1104. Access operation1104opens a hand-hole location to enable a user, such as a field technician, to view a tether and a distribution cable. In the example shown inFIG. 10, the user can view a portion of the tether240intermediate the enclosure208and the tether connectors256through the hand-hole location210. In other embodiments, however, the user can view the enclosure208or the connectors256of the tether cable240through the hand-hole location210.

In some embodiments, the process1100proceeds to a grasp operation1106, in which a user takes hold of the second length of wire. For example, in one embodiment of the grasp operation1106, a user can cut tape wrapped around the second end405of the wire404to expose a ring407. In other embodiments, however, the process1100proceeds from the access operation1104to a cut operation1108.

The cut operation1108pulls the second length of wire in a direction away from the distribution cable. In a preferred embodiment, the cut operation1108pulls the second length of wire away from the distribution cable and the tether connectors. Pulling the second length of wire causes the intermediate end of the wire to begin cutting the foil securing the tether to the distribution cable. The tether connectors are released from the foil by tearing at least a portion of the foil adjacent the connectors with the intermediate end of the wire. In some embodiments, the cut operation1108pulls the wire sufficient to tear the foil from the tether connectors to the hand-hole location. In other embodiments, however, the cut operation1108pulls the wire sufficient to tear the foil from the tether connectors to the enclosure.

A connect operation1110obtains a sufficient segment of freed tether to optically couple the tether to the telecommunications equipment at the hand-hole location. Results of the connect operation1110are shown inFIG. 12. A portion of the tether240has been released from the distribution cable220. In the example shown, the tether240extends through an aperture in the bottom of the telecommunications equipment214. In other embodiments, however, any desired optical coupling between the tether240and the telecommunications equipment214can be achieved. The process1100ends at stop module1112.

Referring now toFIGS. 13-18, a tether240can be secured to a distribution cable220using a second securement system500having feature that are examples of inventive aspects in accordance with the principles of the present disclosure. The second securement system500includes any combination of a first retention arrangement, a second retention arrangement, and a third retention arrangement.

FIG. 13depicts an operation flow for a coupling process1300by which a tether can be releasably secured to a distribution cable using the second securement system. The coupling process1300begins at start module1302and proceeds to a breakout operation1304. The breakout operation1304attaches a tether to a distribution cable at a breakout location similar to breakout operation604of process600.

A first secure operation1306couples at least the tether connectors256to the distribution cable using a first retention arrangement. In general, the first retention device is configured to disengage the tether from the distribution cable using a first release device. For example,FIG. 14illustrates one operational flow for a process1400for implementing the first secure operation1306ofFIG. 13.FIGS. 15 and 16illustrate the results of the operations of process1400.

The process1400begins at start module1402and proceeds to a couple operation1404. The couple operation1404joins at least the tether connectors to the distribution cable using a first retention arrangement. For example, as shown inFIG. 15, the couple operation1404can wrap vinyl tape512around the distribution cable220and the tether240. In a preferred embodiment, the tape512is looped around the distribution cable220and tether240at spaced intervals (e.g., about every twelve inches) between the enclosure208and the tether connectors256. In other embodiments, a single piece of tape512wrapped adjacent the tether connectors256can suffice.

A thread operation1406engages a first release device with the first retention arrangement. In a preferred embodiment, a flexible strand is looped around the first retention arrangement (e.g., seeFIG. 16at loops508). For example, as shown inFIG. 16, a strand of aramid fiber/yarn (e.g., Kevlar® or other tough, but flexible material)504can be sequentially looped around the tape512. The process1400ends at stop module1408.

Referring back toFIG. 13, the process1300can end at stop module1312or can proceeds to a second secure operation1308. The second secure operation1308couples the tether to the distribution cable using a second retention device.FIG. 17illustrates an operational flow for one process1700by which the second secure operation1308ofFIG. 13can be implemented.FIGS. 18 and 19illustrate the results of the operations of process1700.

The process1700begins at start module1702and proceeds to a couple operation1704. The couple operation1704joins a second release device to one end of a flexible strand of material. In a preferred embodiment, the couple operation1704joins the second release device to the first release device (e.g., the aramid fiber/yarn). For example, as shown inFIG. 18, the couple operation1704can join a pin509to the flexible strand504wrapped around the first retention arrangement512. In a preferred embodiment, the pin509is formed from a bent steel rod. In other embodiments, however, the couple operation1704can join the second release device to a flexible strand other than the first release device.

A first clasp operation1706secures the second release device either to the tether or to a body of the tether connectors using a second retention arrangement. For example, as shown inFIG. 18, two tie-wraps502a,502bor other loop structure can hold the pin509to a connector body258of the tether240. In other embodiments, greater or fewer tie-wraps502can be used.

A second clasp operation1708secures the second release device to the distribution cable using the second retention arrangement. The tether is thus secured to the distribution cable. For example, as shown inFIG. 19, the pin509can be held to the distribution cable220using a third tie-wrap502cand a fourth tie-wrap502d. Tape510(FIG. 21) or another retention device can further secure one or both ends of the pin509to the distribution cable220. The process1700ends at stop module1710.

Referring back toFIG. 13, the process1300can end at stop module1312after the second secure operation1308or can proceed to a third secure operation1310. The third secure operation1310couples the tether to the distribution cable using a third retention device.FIG. 20illustrates an operational flow for one process2000by which the third secure operation1310ofFIG. 13can be implemented.FIG. 21illustrates the results of the operations of process2000.

The process2000begins at start module2002and proceeds to a couple operation2004. The couple operation2004secures a third retention arrangement to the distribution cable. For example, as shown inFIG. 21, the couple operation2004can secure a nose cone514to the distribution cable220. In a preferred embodiment, the nose cone514is secured at a fixed position with respect to the distribution cable220.

An insert operation2006couples the third retention arrangement to the tether or to the tether connector body. For example, as shown inFIG. 21, the nose-cone514can be configured to receive at least a portion of the body258of the tether connectors256. In a preferred embodiment, the insert operation2006slides the body258of the tether connectors256into the nose-cone514.

In some embodiments, the process2000can end at stop module2012after the insert operation2006. In other embodiments, however, a secure operation2008engages the second release device with the third retention arrangement. For example, in a preferred embodiment, the thread operation2008inserts the pin509through a hole515in a side of the nose cone514.

An attach operation2010further secures the second release device either to the distribution cable or to the third retention arrangement. For example, as shown inFIG. 21, a protruding portion of the pin509can be fastened to the distribution cable220with tape510after being fed through the aperture515in the nose cone514. In other embodiments, the protruding portion of the pin509can be taped to the nose cone514. The process2000ends at stop module2012.

Referring now toFIGS. 22 and 23, the tether240can be released from the second securement system500after deployment of the distribution cable220.FIG. 22illustrates a cable system200including one example of the second securement system500installed in an underground conduit212. The tether connector body258is offset from the hand-hole location210in a first direction and the breakout enclosure208is offset from the hand-hole210in the opposite direction. The hand-hole location210provides access to an intermediate portion of the tether cable240.

The second securement system500includes a first retention arrangement (e.g., tape)512wrapped around the tether cable240and distribution cable220at spaced intervals between the enclosure208and the connector body258. A first release device (e.g., a strand of aramid yarn)504forms loops508around the first retention arrangement512.

The first release device504attaches to a second release device (e.g., a pin)509. The second release device509is attached to the distribution cable220and to the tether connector body258with a second retention arrangement502. In the example shown, the pin509threads through a first tie-wrap502cattached to the distribution cable220, a second tie-wrap502aattached to the connector body258, a third tie-wrap502dattached to the distribution cable220, and a fourth tie-wrap502battached to the connector body258.

A third retention arrangement (e.g., nose-cone)514is also coupled to the distribution cable220and to the connector body258of the tether240. The pin509threads through an aperture515in the nose-cone514and couples to the distribution cable220with tape510.

FIG. 23illustrates an operation flow for a release process2300by which the tether can be released from the second securement system. The release process2300includes disengaging or unfastening one or more retention arrangements. The process2300begins at start module2302and proceeds to an access operation2304. The access operation2304opens the hand-hole location to enable a user, such as a field technician, to view the second securement system and tether.

A first release operation2306disengages the first retention arrangement. In some embodiments, the first release operation2306pulls the first release device to disengage the first retention arrangement. In the example shown inFIG. 22, pulling the flexible strand504away from the distribution cable220causes the loops508of the flexible strand504to tighten, thereby cutting the tape512wrapped around the tether240and the distribution cable220.

In some embodiments, the securement system500includes only the first retention arrangement and the process2300proceeds to a connect operation2312. The connect operation2312obtains a sufficient amount of freed tether to optically couple the tether to a drop terminal or other type of telecommunications equipment. For example, the tether connectors256can be optically coupled to telecommunications equipment214(FIG. 2). The process2300ends at stop module2314after the connect operation2312.

In other embodiments, however, the securement system500also includes a second retention arrangement and the process2300proceeds to a second release operation2308. The second release operation2308disengages the second retention arrangement. In some embodiments, the second release operation2308pulls the second release device to disengage the second retention arrangement. In the example shown inFIG. 22, for example, pulling the flexible strand504away from the distribution cable220causes the pin509to pull free from the cable ties502. In the example shown inFIG. 21, pulling the flexible strand504also causes the pin509to pull free from the nose cone514. In a preferred embodiment, the flexible strand504is pulled with sufficient force to break the tape510securing the pin509to the distribution cable220.

In some embodiments, the securement system500includes only the first and second retention arrangements and the process2300proceeds to a connect operation2312after the second release operation2308. In other embodiments, however, the securement system500includes a third retention arrangement and the process2300proceeds to a third release operation2310.

The third release operation2310disengages the third retention arrangement. In some embodiments, the third release operation2310pulls the tether to disengage the third retention arrangement. In the example shown inFIG. 22, pulling the tether240away from the nose cone514disengages the connector body258from the nose cone514. From the third release operation2310, the process2300advances to the connect operation2312and proceeds as described above.

The above specification, examples and data provide a complete description of the manufacture and use of the invention. It will be appreciated that the various aspects of the present disclosure provide numerous advantages. For example, securing the tether mitigates the chances of damaging the tether and connectors during installation of the distribution cable. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.