Note: Descriptions are shown in the official language in which they were submitted.
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SUBMARINE OPTICAL CABLE JOINT WITH TERMINATING SOCKETS
Field of the Invention
The present invention relates to the field of submarine fiber-optic
communications systems and, in particular) to a device for connecting two
fiber-optic
cables together.
Background of the Invention
In our truly global society, more and more people are becoming interconnected
with one another through telecommunications systems. Although submarine fiber-
optic
cable communications systems are but one type of telecommunication system,
submarine
fiber-optic cables are capable of carrying a greater number of data and voice
transmissions than traditional submarine cable systems or modern satellite
communication systems.
Stretching thousands of miles across the oceans, submarine fiber-optic cables
lie
on the ocean's floor, thousands of feet below sea level. Because no one cable
could be
made that extended thousands of miles in length, submarine fiber-optic cable
. 20 communication systems are comprised of a series of submarine fiber-optic
cables that
are spliced together at cable joints. In this manner) many individual cables
can be
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connected to form a single cable of the required length.
If one were to cut open a standard "unarmored" fiber-optic cable, he would see
that each cable is comprised of a series of optic fibers clustered around a
steel "king"
wire. Together, these wires form the fiber-optic "core" of the cable. The
fiber-optic
core itself is surrounded by steel strength members and two watertight,
insulating jackets
(an inner copper jacket and an outer polyethylene jacket) encase the entire
assembly.
The function of the optic fibers is to carry the data and voice transmissions
sent over the
fiber-optic cable; the steel wires carry any loads placed upon the cable and,
in
conjunction with the insulating jackets, give the cable its rigidity.
A cable joint is used to connect two cables together. Traditionally, cable
joints
were formed by "terminating" the two cables in separate terminating sockets
and
securely connecting the two terminating sockets with a load-bearing fiber
storage tray or
cylinder. The individual optic fibers of the cables were then spliced together
and
secured in the storage tray and the entire subassembly was covered with a
steel jacket
and insulated with heat-shrink insulation to make the cable joint waterproof.
An
alternate cable joint design replaces the load-bearing fiber storage tray or
cylinder with a
"floating" (i.e., non-load-bearing) fiber storage tray. In this design,
because the fiber
storage tray is not securely connected to the terminating sockets, a11 loads
placed on the
individual cables are carried across the steel casing rather than through the
storage tray.
Cable terminating technology is well-known in the prior art. The idea behind
cable terminating is to secure the load-bearing steel members of the fiber
optic cable,
including both the steel strength members and the steel king wire, to a
terminating
socket so that any load placed on the steel members would be transferred to
the
terminating socket. The fragile optic fibers of the cable, however, would
completely
pass through the terminating socket.
Typically one terminates a fiber-optic cable by stripping off the cable's
insulating
jackets, separating the steel strength members from the fiber-optic core, and
slipping
both the strength members and the core through the center of the terminating
socket. A
copper jacket and a steel plug are then placed over the core and the steel
plug is firmly
wedged into the terminating socket. In this way, the steel strength members
are secured
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against the interior surface of the terminating socket) while the fiber-optic
core passes
freely through the socket. To terminate the steel king wire, one merely needs
to
separate the individual optic fibers from the king wire and to attach the king
wire to a
king wire clamp assembly. Because the king wire clamp assembly is also
connected to
the terminating socket, or is connected to a load-bearing fiber storage tray
that is itself
attached to the terminating socket, the end result is that all load-bearing
steel members
of the fiber-optic cable are secured to the terminating socket.
In a typical cable joint, the two cables to be joined are connected to
terminating
sockets (hereinaRer the "first" and "second" terminating sockets) that differ
in design
from one another. The reason the two terminating sockets are not identical is
because
the means for securing the first terminating socket to the steel casing and/or
to the fiber
storage tray usually differs from the means for securing the second
terminating socket to
the steel casing and/or to the fiber storage tray. Therefore, as a result, the
cable joint
has an "A" end and a "B" end; only "A"-type terminating sockets can connect to
the
"A" end of the cable joint and only "B"-type terminating sockets can connect
to the "B"
end of the cable joint.
For example, in some designs the first terminating socket is "connected" to
one
end {the "A" end) of a cylindrical steel casing by compressive force. To
accomplish this,
one first runs the cable longitudinally through the casing and then attaches
the cable to
the first terminating socket. Next, the cable and attached terminating socket
are pulled
back through the casing until the shoulder of the socket makes contact with
the end
plate of the casing. The second terminating socket, on the other hand, is
connected to
the casing at its other end (the "B" end) by mechanical means. This
terminating socket,
which is already connected to the first terminating socket by a fiber storage
tray, is
connected to the casing by a threaded assembly, locking rings, or some other
mechanical
device. As a result, the compressive force created by securing the second
terminating
socket to the steel casing forces the shoulder of the first terminating socket
up against
the end plate of the steel casing and holds it firmly in place. Thus, although
both
terminating sockets were attached to the storage tray in the same manner, the
means by
which they were attached to the steel casing differ greatly, thereby requiring
differing
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"A" and "B" terminating socket designs.
The disadvantage of this configuration is that it complicates the laying and
repairing of submarine fiber-optic cables. Because every section of cable has
an "A" end
and a "B" end (i.e., one end of the cable is terminated with an "A"-type
socket and the
S other end is terminated with a "B"-type socket), workers laying or repairing
submarine
cables must always be aware of which end of the cable they are working on
because an
"A" end can only connect to a "B" end with conventional cable joints.
Routinely,
however, a cable-laying ship will arrive at its destination only to find that
while the "B"
end of its spooled cable is ready to be laid out, the end of the cable to
which they wish
to connect is also a "B" end. In such a situation, workers must either replace
the
terminating socket of the spooled cable (turning a "B" end into an "A" end),
or make an
imperfect "B-to-B" (or "A-to-A") connection.
Summary of the Invention
In light of the above, it is an object of the present invention to provide a
universal submarine fiber-optic cable joint with universal terminating sockets
for use
with fiber-optic cables. In particular, this invention is designed to be used
with
unarmored fiber-optic cables, although it may readily be adapted for use with
armored
cables as well.
It is a further object of the present invention to provide a submarine fiber-
optic
cable joint wherein either end of the cable joint casing can connect to a
fiber-optic cable
that has been terminated in a universal terminating socket.
It is an additional object of the present invention to provide a submarine
fiber-
optic cable joint wherein either end of the cable joint casing can connect to
a fiber-optic
cable that has been terminated in a terminating socket that has a connection
interface
that is substantially similar to the connection interface of the universal
terminating
socket.
Accordingly, it is an embodiment of the invention to provide a universal
submarine fiber-optic cable joint with universal terminating sockets. The
device includes
first and second universal terminating sockets for terminating the strength
members of a
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first and second fiber-optic cable respectively. The optic fibers of the two
cables are
spliced together and are stored in a fiber storage tray that is positioned
between the two
terminating sockets. A cylindrical steel casing encloses the fiber storage
tray and
extends over a portion of the first and second terminating sockets. The first
terminating
socket is secured to the casing by pins that extend through apertures in the
casing and
are secured in pin chambers in the first terminating socket. A second set of
pins secure
the second terminating socket to the casing by passing through a second set of
apertures
in the casing and engaging pin chambers in the second terminating socket.
The first and second universal terminating sockets of the invention are
interchangeable; either socket can be secured to either end of the casing by
one or more
pins. It is this feature of the terminating sockets that make them
"universal." Although
in the preferred embodiment of the invention the two terminating sockets are
identical,
for the terminating sockets to be interchangeable, it is only necessary that
their
connection interfaces be substantially similar. Likewise, either end of the
casing can be
secured by one or more pins to any terminating socket that has a connection
interface
that is substantially similar to the connection interface of the universal
terminating
socket. This feature of the casing make it "universal" as well.
Additional objects, advantages, embodiments, and novel features of the
invention
will be set forth in part in the description that follows, and in part will
become apparent
to those skilled in the art upon examination of the following or may be
learned by
practice of the invention.
Brief Description of the Drawings
The invention will be more readily understood through the following detailed
description, with reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of the preferred embodiment of the invention;
FIG. 2 is the perspective view illustrated in Fig. 1 with the snap rivets and
pins
removed, and with portions of the interior structure illustrated by dashed
lines;
FIG. 3 is an expanded perspective view of the components used in a universal
terminating socket for terminating a fiber-optic cable;
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FIG. 4 is a perspective view of a universal terminating socket; and
FIG. 5 is a perspective view of the fiber storage tray.
In Fig. 2, the portion of the invention relating to the fiber storage tray is
illustrated with dashed lines. The dashed lines are used solely to show the
general
position of the fiber storage tray within the casing and is not intended to
illustrate how
the storage tray is connected to any other component. The fiber storage tray
is shown in
detail in Fig. 5.
Description of the Preferred Embodiment
The present invention is a universal submarine fiber-optic cable joint with
universal terminating sockets for use with fiber-optic cables. Although the
present
invention may be used with both armored and unarmored cables, the preferred
embodiment of the invention is for use with unarmored submarine fiber-optic
cables.
As seen in Fig. 1, the present invention will be described in connection with
unarmored submarine fiber-optic cables 1 and 2. In the preferred embodiment of
the
invention, the submarine fiber-optic cable joint is used to connect two 24-
fiber fiber-
optic cables for use in trans-oceanic cable operations. Before a cable is
connected to the
present invention, however, it is preferable that the insulating copper and
polyethylene
jackets 3 be stripped off, thereby revealing the cable's fiber-optic core 4
(including a
steel king wire 5 and steel strength members 6. Each stripped cable 7 is then
passed
through an anti-extrusion washer 8 and is inserted into the cable entrance 9
of a
terminating socket 10.
The universal terminating sockets 10 are partially encased by a cylindrical
steel
casing 12, as illustrated in Fig. 2. Each terminating socket 10 is secured to
the casing
12 by three steel pins 13. The thickness of the casing 12 must be sufficient
to withstand
the hydrostatic pressure it is exposed to when it is on the ocean floor, and
to resist any
loads placed on it by the terminating sockets 10 through the pins 13.
The pins 13 connect the casing 12 to the universal terminating sockets 10 by
passing through pin apertures 14 in the casing 12 and engaging cylindrical pin
chambers
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15 in the terminating sockets 10. The depth of the pin chambers 15 is designed
to
engage a su~cient volume of pins 13 to allow the pins 13 to restrain the
terminating
sockets 10 when any loads are placed on the terminating sockets 10. The pin
chambers
15, however, must not be made too deep; if there is insufficient structure
beneath the pin
chambers 15, the hydrostatic pressure exerted on the pins 13 might push them
through
the floor of the pin chambers 15 and into the terminating chamber 16 of the
terminating
sockets 10.
Once the pins 13 have been inserted into the casing 12 and the terminating
sockets 10, it is desirable that they stay there. Therefore, to ensure that
the pins 13 will
not fall out once they have been inserted, it is preferable that the pins 13
be knurled,
although a threaded access hole 17 should be provided to facilitate later pin
removal.
Because the length of a pin 13 is less than the combined depth of a pin
aperture 14 and a
pin chamber 15, snap rivets 18 are used to cover the pins 13 and to make the
snap
rivet/pin assembly lie flush with the outer surface of the casing 12.
1 S In the preferred embodiment of the invention, each pin aperture 14 and pin
chamber 15 is spaced I20 degrees apart from the next pin aperture 14 or pin
chamber
15. Furthermore, it is desirable that the pin apertures 14 on each end of the
casing 12 be
longitudinally aligned along the length of the casing 12.
The steel strength members 6 of the stripped cables 7 are secured to the
terminating sockets 10 along the surface of the terminating chamber 16 of each
terminating socket 10. The components used in conjunction with a universal
terminating
socket 10 for terminating a stripped fiber-optic cable 7 are shown in Fig. 3.
In Fig. 3,
however, the cable 7 has not yet been secured to the surface of the
terminating chamber
16. Likewise, Fig. 4 is a detailed perspective view of a terminating socket 10
before the
cable 7 has been secured. Cable terminating technology, however, is well-known
in the
prior art.
The idea behind cable terminating is to secure the load-bearing steel members
of
a stripped fiber optic cable 7, including both its steel strength members 6
and its steel
king wire 5, to a terminating socket 10 so that any load placed on the steel
members is
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transferred to the terminating socket 10. The fragile optic fibers 19,
however,
completely pass through the terminating socket 10.
With reference to Figs. 3 and 4, one typically terminates a fiber-optic cable
1 or
2 by stripping ofl'the cable's insulating jackets 3, separating the steel
strength members
6 from the fiber-optic core 4, and slipping both the strength members b and
the core 4
through the center of the terminating socket 10. A copper jacket 20 and a
steel plug 21
are then placed over the core 4 and the steel plug 21 is firmed wedged into
the
terminating chamber 16. In this way, the steel strength members 6 are secured
against
the surface of the terminating chamber 16, while the fiber-optic core 4 passes
freely
through the socket 10, the copper jacket 20, and the steel plug 21. To
terminate the
steel king wire 5, one merely needs to separate the individual optic fibers 19
from the
king wire 5, pass the optic fibers 19 through a king wire clamp assembly 22,
and attach
the king wire 5 to the king wire clamp assembly 22. Because the king wire
clamp
assembly 22 is also connected to the terminating socket 10 by screws (not
shown) the
end result of this process is that a11 load-bearing steel members of the fiber-
optic cable 1
or 2 are secured to the terminating socket 10.
After the fiber-optic cables 1 and 2 have been terminated in terminating
sockets
10, the individual optic fibers 19 of each cable 1 and 2 are connected in the
desired
combination. Methods of splicing optic fibers 19 together (such as recoating
or
mechanical splinting) are well known in the prior art. The spliced optic
fibers (not
shown) are then stored in a fiber storage tray 23. As shown in Fig. 2, the
fiber storage
tray 23 is positioned between the terminating sockets 10 and is completely
enclosed
within the casing 12. The fiber storage tray 23 may be firmly connected to the
king wire
clamp assemblies 22 and/or the terminating sockets 10 (a "load-bearing fiber
storage
tray"), or it may loosely connected to the king wire clamp assemblies 22
and/or the
terminating sockets 10 (a "floating fiber storage tray"). In the preferred
embodiment of
the invention, the fiber storage tray 23 is loosely connected to the king wire
clamp
assemblies 22.
Although a fiber storage tray 23 is used in conjunction with this invention,
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alternate embodiments of the invention may include using fiber storage
cylinders or
"loose-fit" storage means for storing the spliced optic fibers (not shown).
Likewise, the
cylindrical nature of the casing 12 is not an essential feature of this
device. The
cylindrical nature of the casing 12, however, is preferable because it makes
application
of heat-shrink insulation (not shown) over the casing 12 easier.
In the preferred embodiment of the invention, the terminating sockets 10, the
pins 13, and the casing 12 are all made out of high-strength steel. However,
because the
fiber storage tray 23 is not a load-bearing component in the preferred
embodiment of the
invention, this component is preferably made out of aluminum, although it can
be made
out of molded plastic as well.
The submarine fiber-optic cable joint that is the subject of the present
invention
has been designed to operate in conjunction with the disclosed universal
terminating
sockets I0. A unique feature of the invention, however, is that the connection
interface
of the casing i2 (i.e., the location of pin apertures 14) is designed to
operate with any
terminating socket (a "third-party terminating socket") whose connection
interface (i.e.,
the location of pin chambers 15) is similar to the connection interface of a
universal
terminating socket 10. The similarity between the connection interfaces of the
third-
party terminating socket and the universal terminating socket 10 need not be
exact; the
only requirement is that the third-party device have one or more pin chamber
15 that
matches up with a pin aperture 14 in the casing 12. If such a match can be
found, then
the casing 12 can be connected to the third-party terminating socket by one or
more pins
13.
This "universal" feature of the casing 12 ensures that either end of the
casing 12
can be connected to any terminating socket that has a connection interface
similar to that
of a universal terminating socket 10. Furthermore, as is readily apparent by
the figures
and the above disclosure, each terminating socket 10 of the present invention
is likewise
"universal" because it can be connected to either end of the casing 12.
Because of the
interchangeableness of terminating sockets 10 (or of any terminating sockets
that have
substantially similar connection interfaces), the present invention is not
subject to the
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"A-B" connection problems detailed earlier. Thus, the disclosed universal
submarine
fiber-optic cable joint is easier to use and is more versatile than currently-
existing cable
joints that require dissimilar "A" and "B" terminating sockets.
Still other objects and advantages of the present invention will become
readily
S apparent to those skilled in this art from the above-recited detailed
description, wherein
only the preferred embodiment of the invention has been shown and described.
The
description of the preferred embodiment is simply by way of illustration of
the best mode
contemplated for carrying out the invention. As will be realized, the
invention is capable
of other and di~'erent embodiments, and its several details are capable of
modification in
various respects, all without departing from the invention. Accordingly, the
drawings
and descriptions are to be regarded as illustrative in nature, and not as
restrictive.
to
