Network cabling

Physical Transmission

Physical Transmission

Physical Transmission

Transmission Media Signaling Techniques

Wire Wireless

Coaxial cable

UTP

STP

Fiber Optic

Baseband

Transmission

Broadband

Transmission

Radio waves

Microwave

Infrared

Cable types

The primary cable types:

coaxial

Twisted-pair unshielded twisted-pair Shielded twisted-pair

Fiber optic

The coaxial cable

The most widely used network cabling. it is inexpensive. Light Flexible Easy to work with.

The coaxial cable

The coaxial cable consist of : Core consist of solid copper surrounded by

insulation, braided metal shielding and an outer cover for protection.

The coaxial cable

Shielding protects transmitted data by absorbing the noise.

The core of coaxial cable carries the electronic signals which make up data.

The core wire can be either solid or copper.

The coaxial cable

The core is surrounded by a dielectric insulation which separate it from the wire mesh.

The wire mesh protects the wire core from the noise and crosstalk.

Crosstalk is signal overflow from an adjacent wire. The entire cable is surrounded by a non-conducting

outer shield, made from rubber or plastic.

The coaxial cable

The coaxial cable is good for longer distances and for reliably supporting higher data rates with less sophisticated equipment.

Types of coaxial cable Thin (thinnet). Thick (thicknet).

Coaxial cable consideration

It is used when you need: A medium that will transmit voice, video and

data. To transmit data longer distances than less

expensive cabling can do Data security.

Twisted pair cable

It consists of two insulated strands of copper wire twisted around each other.

The twisting cancels out the electronic noise from adjacent pairs and from other sources .

Types of Twisted pair cable

Unshielded twisted pair cable (UTP). Shielded Twisted pair cable (STP).

Unshielded twisted pair cable (UTP)

It is the most popular type of twisted-pair and also the most popular one for LAN cabling.

The maximum cable length for this type is 100 meters.

It consist of two unshielded copper wires.

Shielded twisted pair cable (STP).

This type uses a jacket which is a higher-quality and more protective than UTP.

It uses a foil wrap between and around the wire pairs.

Therefore, STP is excellent in protecting data from outside interference.

Twisted pair cabling components

Hardware connection: RJ-45 RJ-11

RJ-45 differ from RJ-11 in that it is larger, and will not fit in the RJ-11 telephone jackt.

RJ-45 houses eight cable connections while RJ-11 houses only four .

RJ-11RJ-45

Twisted pair cabling consideration

Use Twisted pair if: Budget limitation. Easy installation is required.• Do not use it if : High data integrity is required with high speed

and long distance.

Fiber-optic cable

In this kind of cables, optical fibers carry digital data signals in a form of modulated

pulses of light. It is more safe than other kinds of cables,

because no electronic impulses are carried over the fiber-optic cable.

Therefore, data can’t be stolen.

Fiber-optic cable

It consist of : outer jacket Kevlar strands to strength the cable Plastic coating to cushion the fiber The fiber is at the center consist of cladding and core

Fiber-optic cable

Each glass strand passes signals in only one direction. Therefore, a cable consist of two strands one for sending and one for receiving data.

Fiber-optic consideration

Use fiber-optic if: Need to transmit data in a high speed over

long distance. In a very secure media .

Don’t use it if: tight budget. Don’t have the expertise available to install it

properly.

Wireless Transmission

Unguided Media: transport electromagnetic waves without the use of a physical conductor.

Transmission is sent and received through invisible waves

Less expensive than copper or fiber optic lines. Allows the user to move freely around the office or

campus and still remain connected to the network Fastest-growing segment of network media today

Wireless Transmission

1. Radio waves

Radio waves are omnidirectional. The radio wave band is under government regulation.

Radio waves are used for multicast communications, such as radio and television, and paging systems.

Frequencies range between 3 KHz and 1 GHz.

2. Microwaves

consist of number of dishes installed on high towers or high places

distance must be 50 kilometers or less. Its fast but it may have noise and

interference Microwaves are used for unicast

communication such as cellular telephones, satellite networks, and wireless LANs

3 .Infrared

Frequencies between 300 GHz to 400 Thz. Can not penetrate walls. Infrared signals can be used for short-range

communication in a closed area.

Signal Transmission

There are two techniques used to transmit the encoded signals over cable:

Baseband Broadband

I. Baseband Signaling Sends one data signal across the network media. Entire capacity of the media is used for the one data

signal Signals are transmitted in a digital format . Many devices can send and receive across the

medium, but only one at a time. Baseband:

Uses Digital Signaling Single Frequency Transmits Bi-directionally Uses Repeaters

I. Baseband Signaling

II. Broadband Signaling Divides the cable into several different channels. Signals are transmitted at different frequencies in an analog

mode. Allows many different signals to be sent simultaneously on a

single cable. Signal sent in only one direction. Used for computer network data transmissions. Broadband

Uses Analog Signaling Multiple Frequencies Transmits Uni-directionally Uses Amplifiers

II. Broadband Signaling

Factors Affecting Transmissions

The flow of a signal down the network media can become distorted.

Common types of distortions are:

a) attenuation

b) interference.

a) Attenuation Loss of signal power Measured by the decrease in decibels (db) over a

specific distance

b) Interference Interference is caused when a strong external signal

interferes with a signal. Radio frequency interference (RFI) - interference

caused by broadcast signals from a radio or television transmitter.

Electromagnetic interference (EMI) - motor or source of intense electrical activity creates an electromagnetic signal that interferes with a data signal.

Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from another data signal being transmitted on adjacent wire.