Presentation on theme: "Communication channels and transmission media"— Presentation transcript:
1 Communication channels and transmission media A communication channel is simply a medium through which a message is transmitted to its intended audience, such as print meida or broadcast (electronic) media.Transmission media describes the types of physical system used to carry a communication signal from one system to another.These can be Physical or Wireless
2 Physical transmission media These include wires, cables and any other tangible (touchable) materials used to send communication signals.These include;1 – Twisted Pair cablesA type of cable that has two independently insulated wires twisted around each other.The oldest, simplest, andmost common type ofconducted media is twistedpair wires.Twisted pair cable comes in twovarieties:Shielded andUnshielded Twisted Pair (UTP).
3 Unshielded twisted cable (UTP) ApplicabilityGenerally used as phone cablesThese are the most popular type of cable around the world.They come in 6 different types, and depending on what you want to achieve, you will need to employee the appropriate type of cable.
4 UTP (UNSHIELDED TWISTED CABLE) Note:InexpensiveCan be affected by interference as there is no protective metal shield
5 Shielded twisted pair (STPs) Note:They are more expensive compared to UTPsCan’t be affected by interference as they have a protective metal shieldA device known as a Registered Jack (RJ) connectors are used to interface between UTP and the interface cards of a computer.RJ-45 is an 8-position connector used for network cabling usually on Ethernet connections.Twisted pair cables have data transfer rates ranging from 10Mbps 1 Gigabyte.
6 It is the most popular and generally the best for schools. generally speaking, the advantages of STP cables include;They are CheapEasily available on marketsmall in sizeeasy to installIt is the most popular and generally the best for schools.
7 Coaxial CablesCOAXIAL CABLEA CABLE that consist of two conductors that share a common axis. The inner conductor is made up of a solid copper wire (called a core) surrounded by an insulator, or a metal shield.The core, which actually transports the data, consists of a single copper strand or of several braided strands.The insulator surrounding the central core is made of a dielectric material that prevents any contact with the shield that could cause electrical interactions (short circuit).
8 Because of its good shielding properties, coaxial cable is very good at carrying analog signals with a wide range of frequencies. Coaxial cables are used to carry radio, video, measurement and data signals.
9 BNC connectors are used to connect coaxial cables on the network Coaxial cable also comes in two primary physical types:thin coaxial cable (that come in a diameter of 0.25 inches and are used to connect workstations in the same office)thick coaxial cable (come with a diameter of 0.5 inches and are used to interconnect workstations in different rooms)BNC connectors are used to connect coaxial cables on the networkBNC refers to Bayonne – Neill CouncilmanBNC ConnectorThese connectors are mostly used in networks and video connections were shielding against electromagnetic interference is important
10 Advantages of using Coaxial Cables as a Transmission Medium VersatilityCoaxial cables can be used for a number ofdifferent functions. When you hook up your DVDplayer to your television, you may use a coaxialcable.
11 These cables are also often used to connect Your television or computer to a satellitedish or cable connection. Coaxial cables arecapable of carrying anything from radiotransmissions to video to data signals.
12 CapacityBecause Coaxial cables are capable of transmitting so manydifferent types of signals, their capacity is important.These cables consist of a large number of copper wires that arebanded together within the rubber outer coating of the cable.These cables are capable of transmitting large amounts of dataat a high rate of speed, up to 100 megabytes per second.This makes a coaxial cable the ideal type to use for broadbandInternet connection, as well as television service to avoid adelay.
13 3 – Frequency RangeDifferent kinds of data require various frequencies to transmitthe information from one place to another.Coaxial cables are capable of transmitting variousfrequencies, even at the same time, making the cables agood choice for running multiple connections on the sameline, such as both Internet and cable through the same line.
14 4- ProtectionCoaxial cables are typically protected by thick layers ofrubber. This not only protects the delicate wires insidefrom breaking or starting a fire; it also helps to keepoutside interference from the wires.The lack of interference means that the cables are ableto transmit information more quickly and efficiently. Italso creates a low occurrence of errors in the data that istransmitted through the cable. The signal is also capableof travelling over longer distances when encased within acoaxial cable.
15 DISADVANTAGES OOF USING COAXIAL CABLES Heavy and bulky to carryMore expensive compared to the Twisted Pair Cable to buyDifficult to work (difficult to install….. The more complex the network, the more difficult to use)
16 FIBRE OPTIC CABLESIt’s a network cable that contains strands of glass fibre inside an insulated casing.It consists of a centre glass core surrounded by several layers of protective materials. They are designed to carry data for long distances and at very high bandwidth (gigabit speed)They carry communications signalsusing pulses of light rather than electronicsignals (thereby eliminating the problem of electrical interference)
17 Advantages of Fibre Optic Cables Carry significantly more signals than other cables.Faster data transmission (because of no external & internal noise)Early detection of cable damage and secure transmissionSecure data transfers since data is sent as beams of light.Not affected by electromagnetic interference, crosstalk and radio frequenciesBetter security for signals during transmission.Since it carries no electrical signals, these cables can be used to connect buildings with different electrical grounds.
18 Disadvantages of Optical Fibre Cables Expensive as compared to other mediaBuying and installation2. Harder to install and modify.Special equipment requiredPhysical DamageTHINK!!! HAVE YOU SEEN FIBRE OPTIC CABLES BEING INSTALLED?