Fiber Optic Cable Facts

Coaxial cable is commonly used to convey data, video, and voice signals in radio, television, and broadband internet applications.

This lesson covers the following topics:

  • Coaxial cable components

  • Comparison

  • Cable grade

  • Connectors

Coaxial Cable Components

Coaxial cable is built with the following components:

  • The inner conductor is made of a copper core. It carries the data signals.

  • The insulator surrounds the inner conductor and keeps the signal separated from the mesh conductor. It is made of PVC plastic.

  • The braided mesh conductor is a second physical channel and also functions as a ground. It is made of aluminum or tin-coated copper.

  • The sheath is made of PVC plastic and encases the cable, protecting it from external elements.

Comparison

Coaxial cable has the following advantages and disadvantages compared to other cable types:

Advantages

Disadvantages

Advantages compared to other cable types include:

  • Less susceptible to electromagnetic Interference (EMI)

  • Resistant to physical damage

  • Large existing infrastructure

Disadvantages compared to other cable types include:

  • Expensive

  • Not very flexible (difficult to bend around corners)

  • Multiple splitters degrade signal quality

Cable Grade

The table below describes the grade specifications of common coaxial cable.

Grade

Uses

Resistance Rating

RG-59

CCTV video systems; short cable lengths (less than 3 meters) are sometimes used for cable TV

75 ohms

RG-6

Cable TV, satellite TV, and broadband cable internet

75 ohms

Because RG-6 can carry a higher-quality signal with much lower signal loss than RG-59, you should always use RG-6 cabling for coaxial cable implementations.

Connectors

The following table describes the most common type of connectors used with coaxial cable:

Connector

Description

BNC
(Bayonet Neill-Concelman)

The BNC connector is molded onto the cable. It is used:

  • In legacy 10Base2 Ethernet networks

  • In specialized industries

  • To connect composite video displays on commercial video devices

F-Type

The F-Type connector is crimped onto the cable using a special tool. It is used to:

  • Create cable and satellite TV connections

  • Connect a cable modem to a broadband cable connection

    Some F-Type connectors can be twisted onto a cable without a special tool. However, these types of connectors can cause signal leakage.

Twisted pair cabling reduces interference when transmitting signals. It supports a wide range of fast, modern network standards.

This lesson covers the following topics:

  • Twisted pair cable components

  • Comparison

  • Categories

  • Rating

Twisted Pair Cable Components

Twisted pair cabling is composed of the following components.

  • Four pairs of copper wires carry the data signals. One wire in the pair carries a positive signal; the other carries a negative signal. Wires are twisted into pairs to reduce the effects of electromagnetic interference (EMI) and crosstalk.

  • Polyvinyl chloride (PVC) plastic insulation surrounds each copper wire.

  • An outer plastic sheath bundles the wires together and protects them.

    • Unshielded twisted pair (UTP) has only an outer plastic sheath. UTP cables are easier to work with and are less expensive than shielded cables.

    • Shielded twisted pair (STP) has a grounded outer copper shield around the entire wire bundle or around each wire pair. STP provides additional EMI protection, but costs considerably more than UTP.

  • T568A and T568B are two major wiring standards used in the networking industry. The Telecommunications Industry Association (TIA) /Electronic Industries Alliance (EIA) developed these standards that determine the order of the twisted pair wires placed in the RJ45 connectors when you are terminating a connection.

Comparison

Twisted pair cable has the following advantages and disadvantages compared to other cable types:

Advantages

Disadvantages

  • Inexpensive compared to other media types.

  • Easy to install, flexible, and light weight.

  • Very common media and tools are easy to obtain.

  • The most common and most supported network medium.

  • Is susceptible to interference.

  • Is vulnerable to cable damage.

  • Is vulnerable to eavesdropping.

  • Has low bandwidth.

Categories

The following table describes the unshielded twisted pair (UTP) cable categories and their specifications.

Even though cable categories may look physically similar, they are electrically different. Higher numbered cable categories have much faster transmission speeds because they use different wire gauges and have more wire twists per inch than lower numbered cable categories.

Category

Connector

Speed

Frequency

Description

Phone cable

RJ11

10 Mbps

N/A

Used to connect a modem to a phone jack in a wall outlet to establish a dial-up internet connection.
Has two pairs of cable (a total of 4 wires).

Cat 5

RJ45

100 Mbps

100 MHz

Supports up to 100 Mbps Ethernet.

Cat 5e

RJ45

1000 Mbps

100 MHz

Is similar to Cat 5 but provides better EMI protection. Supports gigabit Ethernet (gigabit connections require the use of all four twisted pairs).

Cat 6

RJ45

10 Gbps

250 MHz

Limits 10 Gbps speeds to cable lengths less than 55 meters.

Cat 6a

RJ45

10 Gbps

500 MHz

Limits 10 Gbps speeds to cable lengths less than 100 meters. Provides additional shielding and tighter cable twists than standard Cat 6, which reduces (alien) crosstalk and makes it less susceptible to EMI.

Cat 7

RJ45

10 Gbps

600 MHz

Has the strictest specifications for crosstalk and noise. In shielded only.

Cat 7a

RJ45

10 Gbps

1000 MHz

Offers exceptional noise immunity in addition to the strictest specifications for crosstalk and noise. In shielded only.

Cat 8.1

Class I: RJ45
Class II: non-RJ45

25 Gbps

2000 MHz

Rated for data transfers 250 times faster than Cat5. Is not compatible with Cat5e and Cat6 cables due to different connectors. In shielded only.

Cat 8.2

Class I: RJ45
Class II: non-RJ45

40 Gbps

2000 MHz

Rated for data transfers 400 times faster than Cat5. Is not compatible with Cat5e and Cat6 cables due to different connectors. In shielded only.

Always use a special crimping tool to attach connectors to UTP cable.

Keep the following in mind when working with twisted pair cables:

  • Each type of UTP cable can be substituted for any category below it, but never for a category above. For example, Cat 6 can be substituted for a task requiring Cat 5e; however, neither Cat 5 nor Cat 3 should be used for the task.

  • Cat 5/5e/6/6a cables come with wires that have solid cores or stranded cores. Use solid core cables for longer runs inside walls or the ceiling; use stranded wires for drop cables where flexibility and frequent movement occurs.

Rating

Twisted pair cable can be rated differently for specific purposes in various construction applications.

Rating

Description

Direct burial

Direct burial cable is designed to be buried directly in the ground.

  • Needs no additional protection of piping or sheathing.

  • Built to tolerate heat, moisture, and other hazards.

General

Cables with general purpose rating are the minimum requirement in commercial installations including network patch cables.

  • Complies with UL-1518 testing and vertical flame test.

  • High toxicity when burned and gives off toxic and corrosive gasses.

Plenum

Plenum rated cable is laid in the plenum spaces of buildings and must meet rigorous fire safety standards. Air plenum spaces are the open areas above drop ceilings or below raised floors used for air circulation. Plenum cables are:

  • Coated with flame retardant and use non-toxic plastics that don't smoke much.

  • Regulated under the National Fire Protection Association standard NFPA-262 and 90A.

Riser

Riser rated cable is run between floors through open vertical shafts.

  • Suited for areas not defined as plenum but may conduct fire from one floor to another.

  • Is industry standard UL-1666 tested for flame propagation.

  • Requires tests to be conducted with mounted vertically cable.

Twisted pair cables remain one of the primary ways that computers connect to a network.

This lesson covers the following topics:

  • Twisted pair cable connectors

  • Wiring standards

  • Ethernet pin specifications

  • Cable tips

Twisted Pair Cable Connectors

The table below describes the two types of connectors used with twisted pair cables.

Connector

Description

RJ11

The RJ11 connector:

  • Has 4 or 6 connectors

  • Conforms to the RJ-11 wiring standard which supports up to 2 pairs of wires (one phone and one power).

  • Uses a locking tab to keep a connector secure in an outlet.

  • Is used primarily for telephone wiring.

  • Conforms to the RJ-14 and RJ-25 wiring standards which support additional phone lines using the same jack.

RJ45

The RJ45 connector:

  • Has 8 connectors.

  • Supports up to 4 pairs of wires.

  • Uses a locking tab to keep a connector secure in an outlet.

  • Is used for Ethernet networks.

Wiring Standards

The table below illustrates patch (also called straight through) and crossover cable wiring using T568A and T568B standards. These are the termination standards used by the internet backbone infrastructure, internet providers, and businesses.

Wiring

Description

Patch cable wiring configuration


Patch

Computers connect to the network through a hub or switch with a patch cable. Patch cables use the same wire configuration on each connector end. The most commonly used wiring configurations are:

  • T568A Wires are arranged from pins 1 to 8 in each connector in the following order: GW, G, OW, B, BW, O, BrW, Br.

  • T568B Wires are arranged from pins 1 to 8 in each connector in the following order: OW, O, GW, B, BW, G, BrW, Br.

It doesn't matter which standard you use as long as all cables use the same standard. This helps prevent confusion during troubleshooting.

Crossover cable wiring configuration


Crossover

Computers can connect directly to one another using a crossover cable.

The easiest way to create a crossover cable is to arrange the wires in the first connector using the T568A standard and arrange the wires in the second connector using the T568B standard.

Ethernet Pin Specifications

Ethernet specifications use the following pins for communication:

  • Cat 5 Ethernet (100BASE-T) and below. (Tx is a pin used for transmitting and Rx is a pin used for receiving).

    • Pin 1: Tx+

    • Pin 2: Tx-

    • Pin 3: Rx+

    • Pin 4: Unused

    • Pin 5: Unused

    • Pin 6: Rx-

    • Pin 7: Unused

    • Pin 8: Unused

  • Cat 5e (1000BASE-T) and above. (Bi indicates the pin is used for both transmitting and receiving).

    • Pin 1: Bi+ D0

    • Pin 2: Bi- D0

    • Pin 3: Bi+ D1

    • Pin 4: Bi+ D2

    • Pin 5: Bi- D2

    • Pin 6: Bi- D1

    • Pin 7: Bi+ D3

    • Pin 8: Bi- D3

Cable Tips

Be aware of the following when making cables for Ethernet:

  • Use a crimping tool designed for RJ45 connectors to attach connectors to UTP cable. Most crimping tools include an integrated wire stripper that you can use to remove the outer sheath from the cable. This allows you to access the individual wires.

  • Use the appropriate punch-down tool when connecting UTP cabling to a punch-down block. To use a punch-down tool, position the UTP wire into a slotted post in the punch-down block. With the punch-down tool, press down on the top of the wire over the post.

  • Be sure to use the correct connector type. There are different connectors rated for solid or stranded core wires.

  • Keep the pairs twisted as much as possible up to the connector. This helps reduce crosstalk.

  • Be aware that making Cat 6 compliant cables is difficult. If you do not add the connectors exactly right, the cable will be capable of only 100 Mbps speeds. In most cases, it is easier to buy cables of the correct length than to try and make your own.

Fiber-optic cables deliver data, video, and voice services faster and more reliably than other cable systems.

This lesson covers the following topics:

  • Fiber-optic cable components

  • Comparison

  • Mode

  • Connectors

Fiber-optic Cable Components

A fiber-optic cable, also called an optical-fiber cable, is composed of the following components:

  • The central core carries the signal. It is made of plastic or glass.

  • The cladding maintains the signal in the center of the core as the cable bends.

  • The protective layer provides a stiff structure to prevent the cladding and central core from breaking.

  • The plastic sheath encases everything and protects the cable.

Comparison

Fiber-optic cabling offers the following advantages and disadvantages as compared to other cable types:

Advantages

Disadvantages

Advantages of fiber-optic cable:

  • Completely immune to EMI

  • Highly resistant to eavesdropping

  • Fastest available transmission rates

  • Greater cable distances without a repeater

Disadvantages of fiber-optic cable:

  • Very expensive

  • Difficult to work with

  • Special training required to attach connectors to cables

Mode

Multi-mode and single-mode fiber cables are distinct from each other and not interchangeable. The following table describes multi-mode and single-mode fiber cables.

Mode

Description

Single-mode

Single-mode fiber-optic cable:

  • Transfers data through the core using a single light ray (the ray is also called a mode).

  • Has a core diameter of around 10 microns.

  • Supports a large amount of data.

  • Allows cable lengths to extend a great distance.

Multi-mode

Multi-mode fiber-optic cable:

  • Transfers data through the core using multiple light rays.

  • Has a core diameter of around 50 to 100 microns.

  • Limits the distance of cable lengths.

Connectors

To connect computers using fiber optic cables, you need two fiber strands: one for transmitting and the other for receiving. Fiber optic cabling uses the following connectors:

Connector

Description

ST Connector

Fiber optic ST connector

An ST connector:

  • Is used with single mode and multi-mode cabling.

  • Is a keyed, bayonet-type connector.

  • Is also called a push in and twist connector.

  • Has a separate connector for each wire.

  • Is nickel plated with a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.

  • Requires the exposed fiber tip to be polished as part of the assembly process. This ensures that light is passed from one cable to the next with no dispersion.

SC Connector

Fiber optic SC connector

An SC connector:

  • Is used with single-mode and multi-mode cabling.

  • Is a push on, pull off connector type that uses a locking tab to maintain connection.

  • Has a separate connector for each wire.

  • Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.

  • Requires the exposed fiber tip to be polished as part of the assembly process.

LC Connector

Fiber optic LC connector

An LC connector:

  • Is used with single-mode and multi-mode cabling.

  • Is composed of a plastic connector with a locking tab, similar to an RJ45 connector.

  • Is a single connector with two ends to keep the two cables in place.

  • Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.

  • Is half the size of other fiber optic connectors.

MT-RJ Connector

Fiber optic MT-RJ connector

An MT-RJ connector:

  • Is used with single mode and multi-mode cabling.

  • Is composed of a plastic connector with a locking tab.

  • Uses metal guide pins to ensure it is properly aligned.

  • Is a single connector with one end that holds both cables.

  • Uses a ceramic ferrule to ensure proper core alignment and prevent light ray deflection.