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PHYSICAL MEDIA

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Physical Media PHYSICAL MEDIA Physical Media Physical Media Physical Media Copper Coaxial Cable - Thick or Thin Unshielded Twisted Pair - CAT 3,4,5,5e&6 Optical Fiber ... – PowerPoint PPT presentation

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Date added: 20 February 2020
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Title: PHYSICAL MEDIA


1
Physical Media
  • PHYSICAL MEDIA

2
Physical Media
Physical Media
3
Physical Media
Physical Media
  • Copper
  • Coaxial Cable - Thick or Thin
  • Unshielded Twisted Pair - CAT 3,4,5,5e6
  • Optical Fiber
  • Multimode
  • Singlemode
  • Wireless
  • Short Range
  • Medium Range (Line of Sight)
  • Satellite

4
Copper Media Coaxial Cable
Physical Media
  • Coaxial cable is a copper-cored cable surrounded
    by a heavy shielding and is used to connect
    computers in a network.
  • Outer conductor shields the inner conductor from
    picking up stray signal from the air.
  • High bandwidth but lossy channel.
  • Repeater is used to regenerate the weakened
    signals.

Category Impedance Use
RG-59 75 ? Cable TV
RG-58 50 ? Thin Ethernet
RG-11 50 ? Thick Ethernet
5
Copper Media Twisted Pair
Physical Media
  • Twisted-pair is a type of cabling that is used
    for telephone communications and most modern
    Ethernet networks.
  • A pair of wires forms a circuit that can transmit
    data. The pairs are twisted to provide protection
    against crosstalk, the noise generated by
    adjacent pairs.
  • There are two basic types, shielded twisted-pair
    (STP) and unshielded twisted-pair (UTP).

6
Shielded Twisted Pair (STP)
Physical Media
7
Unshielded Twisted Pair (UTP)
Physical Media
8
Unshielded Twisted Pair (UTP)
Physical Media
  • Consists of 4 pairs (8 wires) of insulated copper
    wires typically about 1 mm thick.
  • The wires are twisted together in a helical form.
  • Twisting reduces the interference between pairs
    of wires.
  • High bandwidth and High attenuation channel.
  • Flexible and cheap cable.
  • Category rating based on number of twists per
    inch and the material used
  • CAT 3, CAT 4, CAT 5, Enhanced CAT 5 and now CAT
    6.

9
Categories of UTP
Physical Media
  • UTP comes in several categories that are based on
    the number of twists in the wires, the diameter
    of the wires and the material used in the wires.
  • Category 3 is the wiring used primarily for
    telephone connections.
  • Category 5e and Category 6 are currently the most
    common Ethernet cables used.

10
Categories of UTP CAT 3
Physical Media
  • Bandwidth 16 Mhz
  • 11.5 dB Attenuation
  • 100 ohms Impedance
  • Used in voice applications and 10baseT (10Mbps)
    Ethernet

11
Categories of UTP CAT 4
Physical Media
  • 20 MHz Bandwidth
  • 7.5 dB Attenuation
  • 100 ohms Impedance
  • Used in 10baseT (10Mbps) Ethernet

12
Categories of UTP CAT 5
Physical Media
  • 100 MHz Bandwidth
  • 24.0 dB Attenuation
  • 100 ohms Impedance
  • Used for high-speed data transmission
  • Used in 10BaseT (10 Mbps) Ethernet Fast
    Ethernet (100 Mbps)

13
Categories of UTP CAT 5e
Physical Media
  • 150 MHz Bandwidth
  • 24.0 dB Attenuation
  • 100 ohms Impedance
  • Transmits high-speed data
  • Used in Fast Ethernet (100 Mbps), Gigabit
    Ethernet (1000 Mbps) 155 Mbps ATM

14
Categories of UTP CAT 6
Physical Media
  • 250 MHz Bandwidth
  • 19.8 dB Attenuation
  • 100 ohms Impedance
  • Transmits high-speed data
  • Used in Gigabit Ethernet (1000 Mbps) 10 Gig
    Ethernet (10000 Mbps)

15
Fiber Media
Physical Media
  • Optical fibers use light to send information
    through the optical medium.
  • It uses the principal of total internal
    reflection.
  • Modulated light transmissions are used to
    transmit the signal.

16
Total Internal Reflection
Physical Media
17
Fiber Media
Physical Media
  • Light travels through the optical media by the
    way of total internal reflection.
  • Modulation scheme used is intensity modulation.
  • Two types of Fiber media
  • Multimode
  • Singlemode
  • Multimode Fiber can support less bandwidth than
    Singlemode Fiber.
  • Singlemode Fiber has a very small core and carry
    only one beam of light. It can support Gbps data
    rates over gt 100 Km without using repeaters.

18
Single and Multimode Fiber
Physical Media
  • Single-mode fiber
  • Carries light pulses along single path
  • Uses Laser Light Source
  • Multimode fiber
  • Many pulses of light generated by LED travel at
    different angles

19
Fiber Media
Physical Media
  • The bandwidth of the fiber is limited due to the
    dispersion effect.
  • Distance Bandwidth product of a fiber is almost a
    constant.
  • Fiber optic cables consist of multiple fibers
    packed inside protective covering.
  • 62.5/125 µm (850/1310 nm) multimode fiber
  • 50/125 µm (850/1310 nm) multimode fiber
  • 10 µm (1310 nm) single-mode fiber

20
Fiber-Optic Cable
Physical Media
  • Contains one or several glass fibers at its core
  • Surrounding the fibers is a layer called cladding

21
Fiber Optic Cable
Physical Media
  • FO Cable may have 1 to over 1000 fibers

22
Wireless Media
Physical Media
  • Very useful in difficult terrain where cable
    laying is not possible.
  • Provides mobility to communication nodes.
  • Right of way and cable laying costs can be
    reduced.
  • Susceptible to rain, atmospheric variations and
    Objects in transmission path.

23
Wireless Media
Physical Media
  • Indoor 10 50m BlueTooth, WLAN
  • Short range Outdoor 50 200m WLAN
  • Mid Range Outdoor 200m 5 Km GSM, CDMA, WLAN
    Point-to-Point, Wi-Max
  • Long Range Outdoor 5 Km 100 Km Microwave
    Point-to-Point
  • Long Distance Communication Across Continents
    Satellite Communication

24
Frequency Bands
Physical Media
Band Range Propagation Application
VLF 330 KHz Ground Long-range radio navigation
LF 30300 KHz Ground Radio beacons and navigational locators
MF 300 KHz3 MHz Sky AM radio
HF 330 MHz Sky Citizens band (CB), ship/aircraft communication
VHF 30300 MHz Sky and line-of-sight VHF TV, FM radio
UHF 300 MHz3 GHz Line-of-sight UHF TV, cellular phones, paging, satellite
SHF 330 GHz Line-of-sight Satellite communication
EHF 30300 GHz Line-of-sight Long-range radio navigation
25
Wireless LAN
Physical Media
PC
Access Point

Internet
Router
Switch
PC
Access Point
26
Terrestrial Microwave
Physical Media
  • Microwaves do not follow the curvature of earth
  • Line-of-Sight transmission
  • Height allows the signal to travel farther
  • Two frequencies for two way communication
  • Repeater is used to increase the distance
    Hop-by-Hop

27
Satellite Communication
Physical Media
28
ADVANTAGES Bandwidth - Fibre optic cables have a
much greater bandwidth than metal cables. The
amount of information that can be transmitted per
unit time of fibre over other transmission media
is its most significant advantage.  With the high
performance single mode cable used by telephone
industries for long distance telecommunication,
the bandwidth surpasses the needs of today's
applications and gives room for growth tomorrow. 
 Low Power Loss - An optical fibre offers low
power loss.  This allows for longer transmission
distances.  In comparison to copper in a
network, the longest recommended copper distance
is 100m while with fibre, it is 2000m. 
 Interference - Fibre optic cables are immune to
electromagnetic interference.  It can also be run
in electrically noisy environments without
concern as electrical noise will not affect
fibre.   Size - In comparison to copper, a fibre
optic cable has nearly 4.5 times as much capacity
as the wire cable has and a cross sectional area
that is 30 times less.   Weight - Fibre optic
cables are much thinner and lighter than metal
wires.  They also occupy less space with cables
of the same information capacity.  Lighter weight
makes fibre easier to install.   Safety - Since
the fibre is a dielectric, it does not present a
spark hazard.   Security - Optical fibres are
difficult to tap.  As they do not radiate
electromagnetic energy, emissions cannot be
intercepted.  As physically tapping the fibre
takes great skill to do undetected, fibre is the
most secure medium available for carrying
sensitive data.   Flexibility - An optical fibre
has greater tensile strength than copper or steel
fibres of the same diameter.  It is flexible,
bends easily and resists most corrosive elements
that attack copper cable. 
29
Disadvantage
Cost - Cables are expensive to install but last
longer than copper cables.  Transmission -
transmission on optical fibre requires repeating
at distance intervals.   Fragile - Fibres can be
broken or have transmission loses when wrapped
around curves of only a few centimetres radius. 
However by encasing fibres in a plastic sheath,
it is difficult to bend the cable into a small
enough radius to break the fibre.   Protection -
Optical fibres require more protection around the
cable compared to copper.
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