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Physical Transmission

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Presentation on theme: "Physical Transmission"— Presentation transcript:

1 Physical Transmission
Network cabling Physical Transmission

2 Physical Transmission

3 Cable types The primary cable types: coaxial Twisted-pair
unshielded twisted-pair Shielded twisted-pair Fiber optic

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

5 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.

6 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.

7 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.

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

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

10 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.

11 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 .

12 Types of Twisted pair cable
Unshielded twisted pair cable (UTP). Shielded Twisted pair cable (STP).

13 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.

14 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.

15 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 .

16 RJ-45 RJ-11

17 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.

18 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.

19 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

20 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.

21 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.

22 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

23 Wireless Transmission

24 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.

25 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

26 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.

27 Signal Transmission There are two techniques used to transmit the encoded signals over cable: Baseband Broadband

28 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

29 I. Baseband Signaling

30 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

31 II. Broadband Signaling

32 Factors Affecting Transmissions
The flow of a signal down the network media can become distorted. Common types of distortions are: attenuation interference.

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

34 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.

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