TRANSMISSION MEDIA in computer networking

TRANSMISSION MEDIA

             transmission media is a pathway that carries the information from sender to receiver. we used different types of cables or waves to transmit data. data is transmitted normally through electrical or electromagnetic signals.

characteristics of cables:-

• SEGMENT LENGTH:- length of single wire.
• ATTENUATION:- indicate loss of single.
• BANDWIDTH:- amount of data carried by cable.
• NUMBER OF SEGMENT:- maximum number of segments in network.
• COST:- copper cables are cheapest, fiber optic cables are expensive.
• INTERFERENCE SUSCEPTIBILITY AND CROSSTALK:-  defines concept of electronic interference on cables.

TYPES OS CABLES

copper medum is the cheapest mode of data transfer.

• coaxial cable
• fiber optical cable
• twisted pair cable

TYPES OF TRANSMISSION MEDIA

there are two types of transmission media:-

1. GUIEDED MEDIA(WIRED)
2. UNGUIEDED MEDIA(WIRELESS)

1. COAXIAL CABLE:-

• consist of a solid copper core surround by an insulator mainly made up of poly vinly chloride (PVC) or teflon.
• coaxial cables are less prone to interference (both internal and external).

TYPES OF COAXIAL CABLE:-

coaxial cables are mainly devided into four categories.

• RG 58
• RG 8
• RG 6
• RG 59

              RG 58

• maximum segment length is 200 mtr.
• interference protection is better than twisted pair cables.
• offers resistance of 50 Ohms.
• BNC-T connector is used to connect this cable.
• used in thinnet (10BASe2)
• mostly used in changing enviroments.

THICKNET (10BASe5)

THINNET (10BASe2)

             10BASe5/2= 10 mb/s 500/200 mtr.

                                   RG 8

• maximum segment length is 500 mtrs.
• interference protection is good compare to any copper cables.
• offers resistance  of 50 Ohms.
• BNC-T or vampire tap connector is used to connect this cable.
• used in 10BASe5 network.

                                  RG 6

• broadband quad - shielded cable that offers an impedance of 75 Ohms.
• provides lower attenuation characteristics.
• useful in cable T.V, CCTV and satellite disantenna.

                                 RG 59

• solid conductor is surrounded by a foam polyethylene dielectric.
• offers impedance of 75Ohms.
• useful is secqurity camera cable TV and home theatre.

1. TWISTED PAIR CABLES

a pair of cables twisted around each other forms a twisted pair cable.

TYPES OF TWISTED PAIR CABLES

1. unshielded twisted pair cable (UTP)
2. shielded twisted pair cable (STP)

UTP (unshielded twisted cable):-

• pair of unshielded wires wound around each other.
• easily gets affected by EMI, RFI and crosstalk.
• cable offers resistance of 50 Ohms.
• maximum segment length is 100 mtrs.

EMI = electro magnetic inerference 

RFI = radio 

              UTP CABLES TYPES

• CAT 1
• CAT 2
• CAT 3
• CAT 4
• CAT 5
• CAT 5e
• CAT 6
• CAT 7

STP (shielded twisted pair cables)

• pair of wires wound around each other is place inside shield.
• better protection from EMI,RFI and crosstalk as compared to UTP.
• offers resistance of 50 Ohms.
• maxmimum segment length of 100 mtrs.

3. FIBER OPTIC CABLES/MEDIUM

• consist of center glass core surround by cledding.
• electrical signals are converted into light signals.
• a phenomenon called as total internal reflection is used for transmission.
• LED or laser is used to transmit signal.

FIBER OPTIC CABLE CHARACTERTIES

• BAND WIDTH:- carries large amount of data ranging from 100 mbps to 1 GBps.
• SEGMENT LENGTH:- transmit data signals over large distance.
• INTERFERENCE:- no electric signals pass through these types of cables thus providing security.

         FIBER OPTIC CABLE TYPES

fiber optic cables can carry signals in a single direction…

1. single mode
2. multi mode

1. SINGLE MODE:- 

• A type of cable that has only a single of glass fiber with a thin diameter.
• fiber optic cables that use lasers are known as single mode cable.

2.MULTI MODE:-

• A type of cable that contains a glass fiber with a larger diameter.
• it is a 62.5/125 micrometer fiber cable.

FIBER OPTIC CABLE CONNECTORS

• straigth tip (ST) :- joins individual fiber to optical devices.
• subscriber connector (SC) :- Attaches two fibers to send and receive signals.
• medium interface connector (MIC) :- joins fiber to FDDI controller.
• sub miniature type A (SMA):- uses individual connectors for each fiber stand.

FDDI= fiber distributed data interface

1. ferrule core connector (FC)
2. lucent connector (LC)

UNGUIEDED MEDIA (wireless media)

• unguieded form of transmission medium.
• transmitters and receivers are used to send and receive signals.
• involves use of electromagnatic waves such as microwave, infrared, radio waves etc.
• wireless medium is useful in connecting large geographical areas.

1. RADIO WAVES:-

• radio waves are the electromagnatic waves that are transmitted in all the directions of free space.
• radio waves are amnidirectional i.e. the signals are propagated in all the directions.

APPLICATIONS OF RADIO WAVES

• A radio wave is useful for multicasting when there is one sender and many receivers.
• an FM radio, T.V, cordless phones are EXP.. of a radio wave.

2. MICRO WAVE

• high frequency wave that is used for point to point communication.
• microwave categories:- terrestrial- relay towers are used to transmit radio signals between earth stations.
• SATELITE:- radio signals are transmitted between differenc base stations using satellites.

3. INFRARED TRANSMISSION (IRDA):-

• uses infrared lights for transmission and reception of signals.
• line of sight must be maintained between the devices.
• mainly used in LAN environments.
• LEDs or injection laser diode (ILD) is used to transmit information and photodiodes are used to receive the signals.