2.  What is transmission Media ?
 Types of Transmission Media
1) Guided Media :
What is guided Media & It’s types
A) Twisted Pair Cable
B) Coaxial Cable
C) Fiber optics Cable

3. 2) Unguided (Wireless) Media :
 What is unguided Media ,
 Reasons for Unguided Media ?
 Types of Unguided Media
A) Bluetooth
B) Wi-Fi
C) Mobile Computing
D) Infrared
E) Microwave

4. TRANSMISSION MEDIA:
 Enables computer to Send &Receive
messages but do not guarantee that the
message will be understood or not.
 Guided ( Wired ) The medium itself is more
important in determining the limitations of
transmission. The transmission capacity, in
terms of either data rate or bandwidth,
depends critically on the distance and on
whether the medium is point-to-point or
multipoint.
 Now we see one by one of them as follows:-

5. 1) Twisted
Pair Cable
 A basic twisted pair cable consist of two strands of copper wire
twisted together, this twisting reduces sensitivity of cable.
 The twisted pair cable are most significant because of it’s low
cost . It is inexpensive to install and offers the lowest cost per
foot of any cable.
 The figure shows the twisted pair cable with insulating jackets
and conductors.
 There are two types of twisted pair cable as follows :--
1) Shielded
2) Unshielded

6. Shielded
twisted
cable
 Shielded twisted pair cable consist of one or more twisted pairs
of cables enclosed in a foil wrap & woven copper shielding. The
shield is connected to the ground portion of the electronic device
to which the cable is connected.
 STP(Shielded twisted cable) is less costly ,than coaxial cable or
optical fiber cable.
 STP cable has theoretical capacity of 500Mbps , although exceeds
155Mbps But, Most common data rate for STP is 16Mbps.
 The shield in STP results in Good EMI characteristics.

7. 1) Requires amplifiers every 5 to 6Kms for analog
signals.
2) Limited in terms of data rate and distance.
3) Requires repeaters for every 2 to 3Kms for digital
signals.
4) Autonuation is strong function of frequency.
5) Twisting reduces low frequency interference.
6) susceptible to interference and noise.

8. Unshielded
twisted
cable
 Unshielded twisted cable doesn’t incorporate a braided
shield into it’s structure.
 Several twisted pairs can be bundled together in a single
cable. These pairs are typically differentiated by colour .
 UTP cable is less costly as compare to any other although
category 5 type to be more costly.
 UTP cable is easy to install & have attenuation characteristic
that limit the length of cable runs to a 100 Mtrs limit .

9. 2) Coaxial
Cable
 It consist of center conductor usually consist of sold copper wire.
 an outer conductor forms a tube surrounding the center conductor
this consist of Braided wires , metallic foils or both .
 And insulation layer keeps the outer conductor spaced from the
inner conductor.
 A plastic encasement (jacket) protects the cable from damage.
 There are two types of coaxial cable as:
1) Thinnet
2) Thicknet

10. 1) Requires amplifiers every 5th kms. For long distance.
2) Useable spectrum for analog signalling upto 500Mhz.
3) Requires repeaters for every 5th kms for digital
signalling.
4) Most commonly used in T.V.
5) Can carrying more than 10,000 voice channel .
6) Short range connection between devices.

11. Bundle of
1) Optical Optical
fiber
fiber Cable
 The centre conductor of fiber cable is the ideal cable for data
transmission. The centre conductor is consist of highly
refined glass or plastic designed.
 A glass core supports a longer cabling distance, but a plastic
core is typically easier to work with.
 A fiber is coated with a cladding that reflects signals back into
the fiber to reduce the signal loss .
 A plastic sheath protects the fiber.

12.  The cost of the fiber cable and connectors has significantly
fallen in recent years .
 But fiber-optic cable is also the most expensive cable type.
 Greater skill is required to install fiber –optic cable than to
install most copper cables.
 Fiber-optic cable can support high data rates (as high as
200,000Mbps) even with long cable runs.
 Normally fiber –optic cable can transmit 100Mbps signals
for several kms .
 Attenuation is much lower in fiber than copper cables.
 Fiber optic cable doesn’t use electric signals for data
transmission hence ,they are totally immune to EMI.

13.  The extraordinary convenience of wireless
communication has placed an increased emphasis on
wireless networks in recent years.
 Wireless networks are especially useful for Spaces
where cabling would be impossible or inconvenient
Eg:open lobbies. and people who move around a lot
within their work environment
 Temporary installation & people who travel outside
of the work environment uses wireless networks.
 These are classified into following types as :

14. 1) Bluetooth
2) Wi-Fi
3) Satellite Microwave
4) Infrared

15.  Bluetooth is a low-cost, low power, short range wireless
communication technology used in. networking, mobile
phones and other portable device.
 Bluetooth wireless technology also enables devices to
communicate with each other as soon as-they come within
range. no need to connect, plug into, install, enable or
configure anything.”

16.  Wi-Fi or Wireless Fidelity refers to the technology
surrounding the radio transmission of internet protocol data
from an internet connection wirelessly to a host computer.
 Most often the internet connection is a higher speed one such
as satellite, DSL or cable rather than slower dial-up
connections.
 A Wi-Fi Network Works Basic concept is same as Walkie-
talkies. A Wi-Fi hotspot is created by installing an access
point to an internet connection. An access point acts as a base
station. When Wi-Fi enabled device encounters a hotspot the
device can then connect to that network wirelessly. A single
access point can support up to 30 users and can function
within a range of 100 – 150 feet indoors and up to 300 feet
outdoors.

17.  Satellite Microwave: Satellite is relay station Receives on one
frequency, amplifies or repeats signal and transmits on
another frequency Eg. Uplink 5.925-6.425 ghz & downlink
3.7-4.2 ghz
 Typically requires geo-stationary orbit Height of 35,784km
Spaced at least 3-4° apart
 Typical uses Television Long distance telephone Private
business networks Global positioning

18.  Infrared technology allows computing devices to
communicate via short-range wireless signals.
 With infrared, computers can transfer files and other digital
data bidirectionally.
 The infrared transmission technology used in computers is
similar to that used in consumer product remote control
units.
 Modulate noncoherent infrared light End line of sight (or
reflection) Are blocked by walls No licenses required Typical
uses TV remote control IRD port