Outside plant

In telecommunication, the term outside plant has the following meanings:

• In civilian telecommunications, all cables, conduits, ducts, poles, towers, repeaters, repeater huts, and other equipment located between a demarcation point in a switching facility and a demarcation point in another switching center or customer premises.

Note: The demarcation point may be at a distribution frame, cable head, or microwave transmitter.

• In DOD communications, the portion of intrabase communications equipment between the main distribution frame (MDF) and a user end instrument or the terminal connection for a user instrument.

Context

It takes a lot to connect dozens or millions of telephones together, including people and hardware. Hardware that stays in place (not trucks or screwdrivers) is called "plant." Some items of plant can be centralized and kept indoors in the telephone exchange. This is called Inside plant. Other equipment, such as wires to connect a phone to its exchange, or optical fibers to connect exchanges to each other, must be outdoors, hence is called outside plant. Outside plant is made to be rugged. Core network plant is often arranged in diversity schemes including SONET rings to avoid single failure points.

The CATV industry also divides its fixed assets between Head end or inside plant, and outside plant. The electric power industry sometimes uses the term "outside plant" to refer to electric power distribution systems.

Copper access network

In civilian telecommunications, the copper access network (also known as the local loop) typically consists of the following elements:

• In-house wiring that connects customer premises equipment to the demarcation point.
• One or more twisted pairs connect the demarcation point to a streetside cabinet or Serving area interface.
• The streetside cabinet contains a distribution frame.
• The streetside cabinet is connected to the main distribution frame, located at the central office, by one or more cables which together contain hundreds of copper twisted pairs or by optical fiber.
• Jumper cables are installed on both the MDF and the streetside distribution frame.
• Active equipment (such as a POTS or DSL line circuit) can then be connected to the line in order to provide service, but this is not considered part of outside plant.

How It's Made

Copper Rod Breakdown

The first step in low voltage cable production is copper rod breakdown. Copper is sent to the factory in 5,000lb coils. These copper coils are continuously drawn through diamond dies that drastically reduce the diameter of the copper to 10 or 12 gauge. Lubrication is used during this process to reduce the amount of friction and heat on the copper cable. Once completed, the copper is stacked in vertical coils, called Stem Packs. These stem packs are then transferred to another drawling operation that further reduces the gauge of the copper. During this stage, the copper is also charged with an electrical current. This anneals the copper, which is a softening process. Once annealed and cooled off, the copper runs through a laser measurement system, to verify it is within manufacturing specifications.

Copper Insulation Process

The copper insulation process is continually monitored and controlled up to +/- .0001". Once the copper is insulated, it runs through a water cooling trough, allowing the wire jacket to properly harden.

Copper Twisting

Twisting helps reduce crosstalk between the individual pairs of wire. Some Cat6 premise cables include a center spline, or wire separator, to further reduce crosstalk and increase performance. Copper twisting is accomplished by running each individual wire through multiple faceplates. This helps control pair position. Once twisted, we have what's called a Cable Unit.

Jacketing

The cable unit then goes through the jacketing process. This step varies, depending on what type of cable your manufacturing. OSP cable typically uses a black polyethylene or UV rated Polyvinyl chloride (PVC). For Cat3, Cat5e and Cat6 Premise cable, varying grades of PVC are used, depending on flame safety rating requirements. This steps starts off with molten plastic being extruded at high pressure and formed around the moving cable core. Shielding, ripcords, armoring and water blocking compound may also be applied at this step. Cables that require dual shielding or double armor will need to repeat this process. Once completed, the cable passed through a long cooling bath, then through a laser micrometer to verify the final diameter.

Printing

Printing is done just before the cable is put in its final packaging. For OSP cable, a hot foil printing process is used, that leaves an indented print in the cable jacket. For Premise cable, a high speed ink jet printer is used. Some cable manufacturers print footage marking from 1000-0ft, making it very easy to determine how much cable you have left in the box, or measuring out cable runs. Other manufacturers use a 6 digit footage mark, making the process a little harder.

Coiling

The completed cable is then wound onto a reel or coil. the coiling process requires very precise tension controls to insure the cable won't tangle when being pulled out of the box.

Final Testing

Once the cable is printed and coiled, it goes through one last set of tests. The manufacturer will test it against a large set of mechanical and electrical performance specifications. Once tested, the cable is ready for shipment. ^[1]

See also

• Inside plant

References

•  This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).