Optical waveguides – Accessories – Splice box and surplus fiber storage/trays/organizers/ carriers
Reexamination Certificate
1999-02-12
2002-12-17
Negash, Kinfe-Michael (Department: 2633)
Optical waveguides
Accessories
Splice box and surplus fiber storage/trays/organizers/ carriers
C359S199200, C359S199200
Reexamination Certificate
active
06496639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatus for carrying on simultaneous communications over a single optical fiber by using two different operating frequencies, and more specifically to methods and apparatus for converting or upgrading a multiplicity of single optical fibers extending from a distribution cabinet to a multiplicity of user stations or first locations which individual optical fibers of said multiplicity initially provided a single communication channel to the multiplicity of remote locations and after upgrading those same optical fibers provide two communication channels operating at different frequencies.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 AND 1.98
The telecommunications industry is using more and more optical or light fibers in lieu of copper wire. Optical fibers have an extremely high bandwidth thereby allowing significantly more information than can be carried by a copper wire.
Of course, modern telephone systems require bidirectional communications where each station on a communication channel can both transmit and receive. This is true, of course, whether using electrical wiring or optical fibers as the transmission medium. Early telephone communication systems solved this need by simply providing separate copper wires for carrying the communications in each direction. Some early attempts at using optical fibers as a transmission medium followed this example and also used two different optical fibers such as optical fibers
10
and
10
A in the prior art
FIG. 1
for carrying the communications in each direction. As shown, in the prior art
FIG. 1
, fiber
10
is connected by an optical coupler
12
to an LED (light-emitting diode)
14
at one end and by optical coupler
16
to a PD (photodetection diode)
18
at the other end. Similarly, but in reverse, fiber
10
A is connected by an optical coupler
16
A to PD
18
at one end and by optical coupler
12
A to LED
14
at the other end.
However, because of extremely high bandwidths available for use by an optical fiber, a single fiber is quite capable of carrying communications in both directions. One technique is WDM (wavelength divisional multiplexing) which is shown in the prior art FIG.
2
and uses different wavelenghts for each direction of travel. Components in FIG.
2
and subsequent figures which operate the same as shown in
FIG. 1
carry the same reference numbers. In the embodiment shown in
FIG. 2
, a central office
20
is connected to an RT (remote terminal)
22
by a single optical fiber
10
B. As shown, the central office includes a light-emitting diode
14
optically connected to fiber optics
10
by optical coupler
12
for converting electrical signals to optical signals and a photodetection diode
18
optically connected to optical fiber
10
B by a coupler
16
B for converting optical signals to electrical signals. The fiber optics
10
and fiber optics
10
A are each connected to a wavelength division multiplexer
24
which in turn is connected by optical coupler
26
to optical fiber
10
B. This arrangement is duplicated at the RT
22
by light-emitting diode
14
A, photodetection diode
18
A, and wavelength division multiplexer
24
A. It will, of course, be appreciated that although the figure is shown as providing communications between a central office
20
(station
1
) and a remote terminal office
22
(station
2
), the communications system could be used for providing communications between any two types of stations such as, for example, two central offices, two remote terminal offices, or between a remote office and an individual user's location, etc. A typical communications system using an LED and a PD with a single optical fiber is disclosed in U.S. Pat. No. 5,075,791 entitled “Method and Apparatus for Achieving Two-Way Long-Range Communication Over an Optical Fiber”, issued to Mark W. Hastings, and incorporated in its entirety hereby by reference.
Yet another and simpler technique for using a single optical fiber
10
C for telephone systems is illustrated in the prior art FIG.
3
. The illustrated figure is referred to as TCM (time compression multiplexing) and is sometimes referred to as a “ping-pong” system. The system operates at a single frequency and uses a single optical fiber
10
and a single diode
30
and
30
A at each end connected by optical couplers
32
and
32
A, respectively, for both converting electrical signals to optical signals and for receiving optical signals and converting those optical signals to electrical signals. TCM systems have the obvious advantage of requiring fewer components.
However, as mentioned above, optical fibers have extremely high bandwidths and use of an optical fiber for a single ping-pong telephone channel is a very ineffective use of the fiber and, in fact, the available bandwidth of an optical fiber makes it possible to use a transmission technique such as TCM or ping-pong at one frequency and then by the use of WDM technology to use another technique at a second frequency. Of course, where optical transmission systems such as a ping-pong or TCM system has been installed, it would not be desirable to disrupt the operation of such systems. Further, once a ping-pong fiber-optic telephone system is installed, removal and replacement with a new system would normally be prohibitive from a cost point of view. Therefore, it would be advantageous to be able to upgrade the existing TCM or ping-pong fiber-optic telephone system to also carry a second communication channel at another frequency.
SUMMARY OF THE INVENTION
It is an object of this invention to provide methods and apparatus for upgrading a communication transmission system initially providing a communication channel operating at one frequency so that it can provide two communication channels operating at different frequencies.
It is another object of the invention to provide a method and apparatus to upgrade a communication transmission system without extensive rewiring of optical fibers.
It is still another object of the invention to provide methods and apparatus to upgrade a communication transmission system with minimal addition of new components.
It is yet another object of the invention to allow upgrading of a optical fiber communication transmission system to occur on an on-demand-basis.
The present invention accomplishes these and other objects in distribution apparatus of an optical fiber communication system for carrying information between a multiplicity of homes or first locations and a second location such as a remote terminal. The optical fiber communication system includes a multiplicity of optical fibers which extend one each between the multiplicity of homes or first locations and terminate at the distribution apparatus with a first Readily Releasable Optical Connector mounted at spaced locations on a first distribution panel. The communication system also includes a multiplicity of optical fibers extending between a second location and the distribution apparatus. This second multiplicity of optical fibers which extend between the distribution apparatus and the second location terminate at the distribution apparatus with a second Readily Releasable Optical Connector, and each one of the second Readily Releasable Optical Connectors being connected one each to one of the first Readily Releasable Optical Connectors on said first distribution panel. The upgrade according to the present invention comprises a multiplicity of combining units which combine the optical signals carrying information on two different optical fibers to produce an output on a single optical fiber which carries the two communication channels at different frequencies. Therefore, each one of a multiplicity of combining units is connected to an optical fiber carrying information at a first frequency, and an optical fiber carrying information at a second frequency as an output. From the combining unit, there is provided another optical fiber carrying information at both the first an
Jones Day Reavis & Pogue
Marconi Communications Inc.
Negash Kinfe-Michael
LandOfFree
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