cabling

TWISTED-PAIR CABLE 

Unshielded

• its frequency range is suitable for transmitting both data and voice.
• it consists of two conductor, each with its owwn coloured plastic insulation
• actually, colours are used both to identify the specific conductors in a cable

• two wires are twisted around each other at regular interval, make the cumulative effect of the interference is equal on both wires, resulting the total effect of the noise at the reciever is therefore 0.
• UTP has a lot of advantage like more cheaper, flexible and easy to install
• Electronic Industries Association has developed standards to grade UTP cables by quality, with 1 to 5.

1. fine for voice but inadequate for all but low-speed date communication.
2. suitable for voice and for digital data transmission of up to 4Mbps
3. can be used for data transmission of up to 10Mbs. its standard cable for most telephone systems.
4. can bring the possible transmission rate to 16Mbs
5. used for data transmission up to 100Mbs

Shield

• it has a metal foil or braided-mesh covering that encases each pair of insulated conductors.
• the function of metal casing is prevents the penetration of electromagnetic noise and eleminate crosstalk.
• it also uses the same connectors as UTP.

COAXIAL CABLE

• it carries signals of higer frequency ranges than twisted-pair cable.
• it has central core conductor of solid or standaed wire, encased in an outer conductor of metal foil, braid, or a combination of the two.
• the outer metallic wrapping serves both as a shield against noise and as a second conductor to completes the curcuit.
• the outer also can enclosed in an insulating sheath and the whole cable is protected by a plastic cover

 

 

OPTICAL FIBRE

 

Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world.
The process of communicating using fiber-optics involves the following basic steps: Creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal.