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Communication systems
1. Submitted to :
Mr. Tarun Verma
Submitted by :
Sagar Bissa(2011uec1298)
Ramniwas Jat (2011uec1296)
Sandeep Kr. Mahawar(2011uec1303)
Rakesh Mehra(2011uec1293)
Sitaram Choudhary(2011uec1312)
2. Outline
⢠Communication Systems
⢠Wireless Communications
⢠Radio
⢠Radar
⢠History of wireless communication
⢠Current Wireless Systems
⢠Cellular systems
⢠Wireless LANs
⢠Satellite Systems
⢠Paging Systems
⢠Bluetooth
⢠Sixth sense Technology
⢠Design challenges
3. COMMUNICATION SYSTEMS
⢠Provide electronic exchange of multimedia data,
Voice, data, video, music, email, web pages, etc.
⢠Communication Systems of today Radio and TV
broadcasting, Public Switched Telephone Network
(voice, fax, modem)
⢠Cellular Phones
⢠Computer networks (LANs, WANs, and the
Internet)
⢠Satellite systems (pagers, voice/data, movie
broadcasts)
⢠Bluetooth
4. Block diagram of a Communication Systems
Transmitter
Carrier
Information to
be transmitted
(Baseband signal)
Transmitted
signal
Channel
Received
signal
Receiver
Recovery of
information
5. Objectives
⢠Provide electronic exchange of multimedia
information
⢠The information to be transmitted is electromagnetic
wave or electrical signal may represent: multimedia
data, Voice, data, video, music, email, web pages, etc.
⢠The frequency bandwidth occupied by the
information signal is called the baseband, and the
signal is often referred to as the baseband signal.
⢠Channel â is the medium by which the transmitted
signal is propagated:
⢠Various layers of atmosphere, cable for telephone or
date link, cable TV or
⢠Electrical signals are converted to a corresponding
light signal that is propagated through a fiber optic
channel
6. What is Wireless Communication ?
ďą Transmitting voice and data using electromagnetic
waves in open space (atmosphere)
ďąElectromagnetic wave
ďTravel at speed of light (c = 3x108 m/s)
ďHas a frequency (f) and wavelength (Îť)
ďc=fx Îť
ď§Higher frequency means higher energy photons
ď§The higher the energy photon the more
penetrating is the radiation
7. Wireless Communications
⢠Multimedia wireless Communications at any Time
and Anywhere
⢠Brief history
⢠Ancient Systems: Smoke Signals, Carrier Pigeons
⢠Radio invented in the 1880s by Marconi
⢠Many sophisticated military radio systems were developed
during and after WW2
⢠Cellular has enjoyed exponential growth since 1988, with
more than 2 billion users worldwide today
⢠Ignited the recent wireless revolution, 1980-2003
⢠Growth rate tapering off
⢠Is there a future for wireless?
10. An inventor named James Clerk
Maxwell was accredited for the initial
discovery of the uses of radio signals.
Although he did not invent the radio.
Nikola Tesla was the first to talk about
utilizing these signals for the use of
communication.
11. Another inventor named Guglielmo
Marconi built a radio system around
the same period capable of spanning
long distances . Many others
experimented and contributed to the
invention of radio including; Faraday,
Bose, and Popov.
12.
13.
14.
15.
16. ďradio waves are generated by an antenna and
they propagate in all directions as a straight line
ďradio waves travel at a velocity of 186.000 miles
per second
ďradio waves become weaker as they travel a long
distance
17. ďthere are 3 modes of propagation:
ď§ surface mode â for low frequency
waves
ď§ direct mode â for high frequency
waves
ď§ ionospheric mode â long distance
high frequency waves
18. ENCODING INFORMATION ON RADIO
WAVES
⢠What quantities characterize a radio
wave? â sort of info it carries,
frequency or type of encoding done..
⢠Two common ways to carry analog
information with
radio waves
â Amplitude Modulation (AM)
â Frequency Modulation (FM): âstatic
freeâ
19.
20.
21. Radar
⢠RADAR is a method of using electromagnetic waves to remote-
sense the position, velocity and identifying characteristics of
targets.
Two Basic Radar Types
⢠Pulse Transmission
⢠Continuous Wave
22.
23. Types of radar
1 Primary radar 2 secondary radar
Pulse
radar
Continues
radar
Intra pulse
modulated
Pulse
modulated
modulate
d
Un
modulated
ďImaging Radar
ďNon-Imaging Radar
25. Frequency modulation looks like
On the above diagram, the frequency of the wave is low on the left
and it slowly increases as you look right. The different frequencies of
the wave will lie in a range called bandwidth. Radars use bandwidth
for several reasons regarding the resolution of a data image, memory
of the radar and overuse of the transmitter. For instance, a high
bandwidth can yield a finer resolution but take up more memory.
26. Continuous- Wave Radar
CW radar sets transmit a high-frequency signal
continuously. The echo signal is received and
processed. The receiver need not to be mounted at
the same place as the transmitter. Every firm civil radio
transmitter can work as a radar transmitter at the
same time, if a remote receiver compares the
propagation times of the direct signal with the reflected
one. Tests are known that the correct location of an
airplane can be calculated from the evaluation of the
signals by three different television stations.
27. Frequency
Wavelength 1 mm1 km 1 m 1 Âľm 1 nm
1 MHz 1 GHz
IR UV
109
Hz
0 1 2 3 4 5 6 7 8 9 10 11 12
30 20 10 8 6 5 4 39 7
Allocated Frequency (GHz)
Wavelength (cm)
X-BandC-BandS-BandL-BandUHF
VHF
Visible
1012
Hz
Ku
K
Ka
W
30. Use of radar
ďą Detection and search radar
ďą missile guidance systems
ďą Radar for biological research
ďą Air traffic control and navigation radar
ďą Weather-sensing radar systems
ďą Parking of vehicles
ďą military purpose
ďą electron pressure
ďą Temperature measurement
33. Radar Can Measure Temperature
ďSome electrons are
moving due to heat - In
this case the echo is
scattered
ďThe echo will contain a
range of frequencies close
to the transmitter
frequency
ďAs the temperature
increases, the electrons
move faster
ďSo radar can act like a
thermometer and measure
the temperature of the
ionosphere
34. ⢠Atmospheric attenuation
⢠Reflection off of earthâs
surface
⢠Over-the-horizon
diffraction
⢠Atmospheric refraction
Radar beams can be attenuated, reflected and
bent by the environment
Radar beams can be attenuated, reflected and
bent by the environment
36. The AN/TPS-43 radar
system, with a 200 mile
range, was the only Air
Force tactical ground based
long range search and
warning radar for nearly two
decades. Most of the
AN/TPS-43 radars are being
modified to the AN/TPS-75
configuration.
3-D Air Search Radar
37. History of wireless communication
⢠Guglielmo Marconi invented the wireless telegraph in 1896
ďą Communication by encoding alphanumeric characters in
analog signal
ďą Sent telegraphic signals across the Atlantic Ocean
⢠1914 first voice communication over radio waves
⢠Communications satellites launched in 1960s
⢠Advances in wireless technology
⢠More recently
ďą Radio, television, mobile telephone, communication
satellites
ďą Satellite communications, wireless networking, cellular
technology
38. Early uses
ď It was very much for entertainment
often playing popular music.
ď It was also the fastest medium to
release news.
ď Unlike previous publications such as
newspapers the radio was instant .
Radio was reserved for military uses
during the first part of the 20th
century.
39.
40. Advantages and disadvantages of
wireless communication
ďadvantages:
ď§ mobility
ď§ a wireless communication network is a solution in
areas where cables are impossible to install (e.g.
hazardous areas, long distances etc.)
ď§ easier to maintain
ďdisadvantages:
ď§ has security vulnerabilities
ď§high costs for setting the infrastructure
ď§unlike wired comm., wireless comm. is influenced by
physical obstructions, climatic conditions, interference
from other wireless devices
42. Cellular Systems:
Reuse channels to maximize capacity
⢠Geographic region divided into cells
⢠Frequencies/timeslots/codes reused at spatially-
separated
locations.
⢠Co-channel interference between same color cells.
⢠Base stations/MTSOs coordinate handoff and
control functions
⢠Shrinking cell size increases capacity, as well as
networking burden
BASE
STATIO
N MTS
O
44. Type of Cells
⢠Cell radii can be vary from 10âs of meters in
buildings to 100âs of meters in the cities, up to
several kmâs in the countryside.
⢠Macrocells, provide overall area coverage
⢠Microcells, Microcell will focus on slow
moving subscribers moving between
buildings.
⢠Picocells, Would focus on the foyer of a
theater, or exhibition centre.
45. The Wireless Revolution
Cellular is the fastest growing sector of communication
industry (exponential growth since 1982, with over 2 billion
users worldwide today)
⢠Three generations of wireless
⢠First Generation (1G): Analog 25 or 30 KHz FM, voice only, mostly
vehicular communication
⢠Second Generation (2G): Narrowband TDMA and CDMA, voice
and low bit-rate data, portable units.
2.5G increased data transmission capabilities
⢠Third Generation (3G): Wideband TDMA and CDMA, voice and
high bit-rate data, portable units
46. 0G (Zero Generation Mobile System)
ďAt the end of the 1940âs, the first radio telephone
service was introduced, and was designed to users in
cars to the public land-line based telephone
network.
ďIn the 1960âs, a system launched by Bell Systems,
called, Improved Mobile Telephone Service (IMTS),
brought quite a few improvements such as direct
dialing and more bandwidth. The very first analog
systems were based upon IMTS and were created in
the late 60s and early 70s.
47. 1G Technology
ď1G refers to the first-generation of
wireless telephone technology was
developed in 1970âs.
ď1G had two major improvements:
ďthe invention of the microprocessor
ďthe digital transform of the control link between
the phone and the cell site.
ďAnalog signal
50. Previous Technology - 2G
ďDigital data can be compressed and multiplexed
much more effectively than analog voice
encodings
ďMultiplexing -multiple analog message signals
or digital data streams are combined into one
signal
ďFor 1 and 2G standards, bandwidth maximum is
9.6 Kbit/sec, (I.E) approximately 6 times slower
than an ISDN
51. Previous Technology - 2G
ďAllows for lower powered radio signals that
require less battery
ďPowerâCODEC introduction -program that
encodes and decodes digital data stream or signal
ďTranslates data from digital to analog and vice
versa
53. Advantages in Previous Technology
- 2G
ďThe digital voice encoding allows digital error
checking
ďincrease sound quality
ďlowers the noise level
ďGoing all-digital allowed for the introduction of
digital data transfer
ďSMS ââshort message serviceâ
ďE-mail
54. Disadvantages in Previous
Technology - 2G
ďCell towers had a limited coverage area
ďJagged Decay curve
ď Abrupt dropped calls
ď Analog âgradual sound reduction
ďâSpottyâ coverage
55. 3G Technology
ďLarge capacity and broadband capabilities
ďAllows the transmission of 384kbps for mobile
systems and up to 2Mbps
ďIncreased spectrum efficiency â5Mhz
ďA greater number of users that can be simultaneously
supported by a radio frequency bandwidth
ďHigh data rates at lower incremental cost than 2Gâ
Global roaming
56. Previous Technology - 3G
ďCDMA âCode Division Multiple Access
ďForm of multiplexing
ďDoes not divide up the channel by time or frequency
ďEncodes data with a special code associated with each
channel
58. Types of Multiplexing
ďFDMA â Frequency Division Multiple Access
ďEach phone call is allocated one frequency for the entire
duration of the call
59. Types of Multiplexing
ďTDMA - Time Division Multiple Access
ďEach phone call is allocated a spot in the frequency for a
small amount of time, and "takes turns" being transmitted
60. Types of Multiplexing
ďCDMA - Code Division Multiple Access
ďEach phone call is uniquely encoded and transmitted across
the entire spectrum, in a manner known as spread spectrum
transmission
61. Reasons for New Research
ďEven though 3G has successfully been introduced
to mobile users, there are some issues that are
debated by 3G providers and users.
ďHigh input fees for the 3G service licenses
ďGreat differences in the licensing terms
ď3G phones are expensive
63. What is 4G?
ďFourth Generation Technology
ďFaster and more reliable
ď100 Mb/s
ďLower cost than previous generations
ďMulti-standard wireless system
ďBluetooth, Wired, Wireless
ďAd Hoc Networking
ďIPv6 Core
ďOFDM used instead of CDMA
ďPotentially IEEE standard 802.11n
ďMost information is proprietary
65. Communications Architecture
ďPersonal Layer Gateway:
ďdevices that connect to upper layers; cell phone, fax,
voice, data modem, MP3 players, PDAs
ďInfo-Sensor layer:
ďenvironmental sensors
ďFiber-optic wire layer:
ďhigh speed subterranean labyrinth of fiber optic cables
and repeaters
66. Ad Hoc Networks
ď Spontaneous self
organization of networks of
devices
ď Not necessarily connected to
internet
ď 4G will create hybrid wireless
networks using Ad Hoc
networks
ď Form of mesh networkingâ
Very reliable
67. Enhance Mobile Gaming
ďExperience enhance wireless capabilities that
deliver mobile gaming interaction with less
than five seconds
ďPlay online multi player games while traveling
at high speeds or sitting outside
68. Broadband access in Remote
location
ď4G will provide a wireless alternative for broadband access
ďI will provide first opportunity for broadband access in
remote locations without an infrastructure to support
cable or DSL access.
69. Wireless Local Area
Networks (WLANs)
ďŹ WLANs connect âlocalâ computers (100m range)
ďŹ Breaks data into packets
ďŹ Channel access is shared (random access)
ďŹ Backbone Internet provides best-effort service
ďŹ Poor performance in some apps (e.g. video)
01011011
Internet
Access
Point
0101 1011
70. Wireless LAN Standards
⢠802.11b (Current Generation)
⢠Standard for 2.4GHz ISM band (80 MHz)
⢠Frequency hopped spread spectrum
⢠1.6-10 Mbps, 500 ft range
⢠802.11a (Emerging Generation)
⢠Standard for 5GHz NII band (300 MHz)
⢠OFDM with time division
⢠20-70 Mbps, variable range
⢠Similar to HiperLAN in Europe
⢠802.11g (New Standard)
⢠Standard in 2.4 GHz and 5 GHz bands
⢠OFDM
⢠Speeds up to 54 Mbps
In 200?,
all WLAN
cards will
have all 3
standards
71. Satellite Systems
⢠Cover very large areas
⢠Different orbit heights
⢠GEOs (39000 Km) versus LEOs (2000 Km)
⢠Optimized for one-way transmission
⢠Radio (XM, DAB) and movie (SatTV) broadcasting
⢠Most two-way systems struggling or bankrupt
⢠Expensive alternative to terrestrial system
⢠A few ambitious systems on the horizon
72. Paging Systems
⢠Broad coverage for short messaging
⢠Message broadcast from all base stations
⢠Simple terminals
⢠Optimized for 1-way transmission
⢠Answer-back hard
⢠Overtaken by cellular
73. Bluetooth
⢠Cable replacement RF technology (low cost)
⢠Short range (10m, extendable to 100m)
⢠2.4 GHz band (crowded)
⢠1 Data (700 Kbps) and 3 voice channels
⢠Widely supported by telecommunications, PC,
and consumer electronics companies
⢠Few applications beyond cable replacement
76. SOME OF INTERACTIVE
TECHNOLOGIES
â˘Multi touch Systems
â˘Flexible screens
â˘Multi touch IWB (Interactive White Boards)
â˘Smart interactive Tables & multi touch
desks
â˘Microsoft Surface
â˘SIXTH SENSE TECHNOLOGY
77. INTRODUCTION
â˘SixthSense is a wearable gestural interface that
augments the physical world around us with digital
information.
â˘Technology that plays with Human gestures to
make the world more interactive and workflow
much easier.
â˘Pranav Mistry, of Indian origin, a PhD student in
the Fluid Interfaces Group at the MIT Media Lab is
the mastermind behind the sixth sense technology.
79. SO WHY SIXTH
SENSE??
â˘Hereby Physical world is painted with the
digital information.
â˘You can carry your digital world with you
wherever you go.
â˘You can start with any wall or any surface
as an interface even your palm.
81. CAMERA
â˘Also called as digital
eye as it analyses the
digital pixels.
â˘It captures the object
in view and tracks the
gestures.
82. PROJECTOR
â˘The projector projects
visual information
enabling surfaces and
physical objects to be
used as interfaces.
â˘It displays data sent
from the smart phone
on any surface in
viewâobject, wall, or
person.
83. SMART PHONE
â˘A web enabled smart
phone in the userâs
pocket processes the
video data.
â˘Other software
searches the web and
interprets the hand
gestures.
84. COLOR MARKERS
â˘At the tip of the userâs
fingers.
â˘Helps the webcam to
recognize the
gestures.
â˘The movements and
arrangements of these
makers are interpreted
into gestures.
94. â˘Organize, sort & resize pictures by
projecting them on a surface.
â˘Call up the map and use
thumbs & index fingers to
navigate through.
95. â˘Zoom in & zoom out
using intuitive hand
movements.
â˘Drawing application by
tracking fingertip
movements.
96. CONCLUSION
â˘Integrating information to everyday objects
will not only help us to get rid of the digital
divide, but will also help us in some way to
stay human, to be more connected to our
physical world.
â˘IT WILL NOT END UP IN MAKING US
MACHINES SITTING IN FRONT OF
OTHER MACHINES!!
98. Design Challenges
⢠Hardware Design
⢠Precise components
⢠Small, lightweight, low power
⢠Cheap
⢠High frequency operations
⢠System Design
⢠Converting and transferring information
⢠High data rates
⢠Robust to noise and interference
⢠Supports many users
⢠Network Design
⢠Connectivity and high speed
⢠Energy and delay constrains
The Radar Set AN/SPS-49 is an L-band, long-range, two-dimensional, air-search radar system that provides automatic detection and reporting of targets within its surveillance volume. The AN/SPS-49(V) radar operates in the frequency range of 850 - 942 MHZ. It shows the elevation coverage of a typical air search radar.
1 1
http://www.fas.org/man/dod-101/sys/ac/equip/an-tps-43.htm It resolves in elevation as well as azimuth. It uses multiple feeds and switches between feeds for different elevation angles. It has six stacked beams.
Q1. Can you think of a system whose range of communication is more than satellite links? Q2. Give an example of a system whose range of communication is shorter than IR links. Point to ponder: Why does range of communication increase on logarithm scale?