satellite and optical communication module 3 ppt.ppt

bec515d soc module 3

1. BEC515D - Satellite and Optical
Communication(Scheme 2022)
Module – 3

2. Communication Satellites
•Introduction
•Since the launch of Sputnik-1 in the year 1957, over 8000 satellites have
been launched till date for a variety of applications like communication,
navigation, weather forecasting, Earth observation, scientific and military
services
•The term ‘satellite’ has become a household word today as the horizon of
its applications has touched the life of everyone, whether it be talking to
someone thousands of kilometres away within the comforts of one’s own
house in a matter of a few seconds, watching a variety of TV programmes
or having access to the world news and weather forecast on a routine
basis

3. Communication Satellites

4. Communication Satellites
•The application areas of communication satellites mainly include
television broadcasting, international telephony and data communication
services.
•Communication satellites act as repeater stations that provide either
point-to-point, point-to-multipoint or multipoint interactive services.
•Communication-related Applications of Satellites
•Communication-related Applications of Satellites
•Traditionally, satellite applications included television broadcasting and
fixed and mobile telephony services
•But now newer dimensions are being added to the spectrum of the
satellite applications with the advent of services like the internet and
multimedia.
•However, satellites are facing tough competition from terrestrial networks
in general, with fibre optics in particular.

5. Communication Satellites
•Satellite TV refers to the use of satellites for relaying TV programmes from
a point where they originate to a large geographical area. GEO satellites in
point-to-multipoint configuration are employed for satellite TV
applications.
•There are primarily two types of satellite television distribution systems,
namely the television receive-only (TVRO) and the direct broadcasting
satellite (DBS) systems.
•In satellite telephony, satellites provide both long distance (especially
intercontinental) pointto-point or trunk telephony services as well as
mobile telephony services.
•They are particularly advantageous when the distances involved are large
or when the region to be covered is sparsely populated or has a difficult
geographical terrain

6. Communication Satellites
•Satellites also provide data communication services including data,
broadcast and multimedia services such as data collection and
broadcasting, image and video transfer, voice, internet, two-way
computer interaction
•Communication satellites can be GEO satellites or a constellation of LEO,
MEO or HEO (highly elliptical orbit) satellites.

7. Communication Satellites
•GEO satellites maintain a key role in distributing traditional services such
as television or more novel services such as access to the internet.
• New trends in mobile communication have led to the development of
constellations of non-GEO satellites in the LEO, MEO and HEO.
•These constellations guarantee flexible links to users, without requiring
Earth-based installations at all points on the globe.
• Hence, broadcasting services like TV, radio and telephony communication
services mainly remain in the domain of GEO satellites while the newer
services like messaging, voice, fax, data and video conferencing facilities
are well suited to LEO, MEO or HEO satellite constellations.

8. Communication Satellites
•Geostationary Satellite Communication Systems
• The geostationary orbit has been the preferred orbit for satellite
communication systems and provides most of the revenue for satellite
system operators.
• The first geostationary communication satellite, named Early Bird
(Intelsat 1) was launched by INTELSAT in 1965. Commercial satellites
launched in the 1970s and 1980s were all geostationary satellites.
• These satellites were used for international, regional and domestic
telephone and video distribution services.
• Some of the important geostationary satellite missions include Intelsat,
Inmarsat, Telstar, Asiasat, Arabsat, Galaxy, GE, Superbird, Eutelsat, Astra,
Palapa and so on

9. Communication Satellites
•Non-geostationary Satellite Communication Systems
• Non-geostationary satellite communication systems are emerging to
provide mobile communication services as well as other services like
messaging, video, fax and data communication.
•Constellations of satellites orbiting in LEO or MEO orbits can provide
global mobile communication services.
•However, the cost of building such a constellation of satellites is huge as
compared to having a geostationary satellite.
•Therefore, these systems have not made great progress and are still in the
developmental stage. IRIDIUM, Orbcomm, Globalstar and ICO systems are
some of the non-geostationary satellite communication systems.

10. Communication Satellites
•Frequency Bands
•Satellite communication employs electromagnetic waves for transmission
of information between Earth and space.
•The bands of interest for satellite communications lie above 100 MHz
including the VHF, UHF, L, S, C, X, Ku and Ka bands

11. Communication Satellites
•Payloads
• Transponder is the key payload of any communication satellite.
•Basic elements of a satellite communication system (Figure) include the
ground segment and the space segment.
• The ground segment comprises the transmitting and the receiving Earth
stations together with their associated instruments, antennae, electronic
circuits, etc.
• These Earth stations provide access to the space segment by transmitting
and receiving information from the satellite, interconnect users with one
another and with the terrestrial network.
• The space segment comprises one or more satellites, which act as
repeater stations providing point-to-point, point-to-multipoint or
multipoint interactive services

12. Communication Satellites

13. Communication Satellites
•Types of Transponders
1. Transparent or bent pipe transponders
2. Regenerative transponders
1.Transparent or Bent Pipe Transponders
•Amplitude and the frequency are altered
•The modulation and the spectral shape of the signal are not affected.
•They are also referred to as ‘bent pipe’ transponders as they simply
transmit the information back to Earth.

14. Communication Satellites

15. Communication Satellites
•The uplink section of the transponder, comprising the input filter,
LNA and the down converter is common to all the channels and is
shared by all the transponders.
•The down converter is basically a mixer which provides a fixed
frequency translation corresponding to the exact frequency
difference between the centre of the uplink and the downlink
frequency bands.
•For example, the down converter for a C band transponder
provides a frequency translation of 2.225 GHz as the difference
between the centre of the uplink frequency band (5.925–6.425
GHz) and the downlink frequency band (3.7–4.2 GHz) in this case is
2.225 GHz

16. Communication Satellites
•The full bandwidth is separated into individual transponder
channels by a bank of RF filters called the input multiplexer
(IMUX)
•Each filter being tuned to pass the full bandwidth of a
particular channel and reject all other channels.
•The output of each IMUX filter is then amplified by separate
power amplifiers.
•The power amplifiers employed are travelling wave tube
amplifiers (TWTA) for higher power levels (50 W or more) and
at higher frequency bands (Ku and Ka bands) and solid state
power amplifiers (SSPAs) for lower power applications

17. Communication Satellites
•The output of all the transponder channels is then combined
in an output de-multiplexer.
•Then fed to a common transmitting antenna for down-
beaming the signal on to Earth.
•2. Regenerative Transponders
•Regenerative transponders are those in which some onboard
processing is done and the received signal is altered before
retransmission.
•This onboard processing helps to improve the throughput and
error performance by restoring the signal quality prior to
retransmission to the Earth.
•These repeaters are also called digital processing repeaters

18. Communication Satellites
•Transparent transponders, although they are simplest to
design and can handle all three multiple-access methods, i.e.
FDMA, TDMA and CDMA.
•Types of regenerative transponders.
•(i)Satellite-switched Tdma Transponders employing wideband
RF and IF switching
•(ii)Narrowband Digital Processing Transponders with channel
routing (Routing
 is the process of finding the best path for
traffic in a network, or across multiple networks)and digital
beam forming (sum constructively at a desired angle, while
summing destructively at other angles)
•(iii)Demod-remod Transponders, which demodulate the
received signal and completely restore the information before
retransmission

19. Communication Satellites
•Transponder Performance Parameters
•(i)EIRP (ii) G/T
•(i)EIRP The product of the transmit antenna gain and the
maximum RF power per transponder defines effective isotropic
radiated power (EIRP)
•EIRP values for the C band and Ku band satellites are around 40
dBW and 55 dBW respectively.
•EIRP defines the downlink performance of a transponder and
specifies the coverage area of a satellite.
•(ii)G/T The uplink performance of a satellite is defined by the
parameter called the relative gain-to-noise temperature (G/T)
ratio.
•It is the ratio of the receive antenna gain and the noise
temperature of the satellite receiving system.

20. Communication Satellites
•Satellite versus Terrestrial Networks

21. Communication Satellites
•Satellite versus Terrestrial Networks
•Advantages of Satellites Over Terrestrial Networks
i.Broadcast property – wide coverage area
ii.Wide bandwidth – high transmission speeds and large
transmission capacity
iii.Geographical flexibility – independence of location. (infinite
choice of routes and hence they can reach remote locations)
iv.Easy installation of ground stations.
Once the satellite has been launched, installation and
maintenance of satellite Earth stations is much simpler than
establishing a terrestrial infrastructure, which requires an
extensive ground construction plan

22. Communication Satellites
(iv)Immunity to natural disaster.
Satellites are more immune to natural disaster such as
floods, earthquakes, storms, etc., as compared to Earth-
based terrestrial networks
(v)Independence from terrestrial infrastructure.
Satellites can render services directly to the users, without
requiring a terrestrial interface.
Direct-to-home television services, mobile satellite services
and certain configurations of VSAT networks are examples
of such services

23. Communication Satellites
•Disadvantages of Satellites with Respect to Terrestrial
Networks
i.Transmission delay
ii.Echo effects.
•The echo effect, in which the speaker hears his or her own
voice, is more predominant in satellite-based telephone
networks as compared to terrestrial networks.
•This is due to larger transmission delays .
• with the development of new echo suppressors, satisfactory
link quality has been provided in the case of single-hop GEO.
iii . Launch cost of a satellite

24. Communication Satellites
•Satellite Telephony
•long distance point-to-point trunk telephony services &
mobile telephony services
•Potential users of these services include international
business travellers and people living in remote areas.
•Satellite telephony networks employ point-to-point duplex
satellite links enabling simultaneous communication in both
the directions.
•Single GEO satellites or a constellation of LEO, MEO and GEO
satellites are used for providing telephony services.
•Telephone satellite links generally employ circuit-switched
systems offering a constant bit rate services

25. Communication Satellites
S.N
o
Parameter Circuit switching Network Packet switching Network
1Path
In circuit switched network a
dedicated path is created
between two points by setting
the switches.
In packet switched network no dedicated path
is created between two points. Only the
virtual circuit exists.
2
Availability of
Bandwidth
In circuit switching, bandwidth is
fixed because it is reserved in
advance.
In the virtual circuit network, require
bandwidth is dynamic because it can be
released as it is needed.
3
Wastage of
Bandwidth
In circuit switching, bandwidth is
fixed, unused bandwidth on an
allocated circuit is wasted.
Other packets from an unrelated source may
utilize unused bandwidth.
4Charging
In circuit switching, users are
charged based on time and the
basis of distance.
In packet switching, users are charged based
on time and number of bytes carried & not
based on distance.
5End Terminal
In this telephone and modem is
used as end terminal.
In this computer is used as end terminal.
6Information type
In this information type is
Analog voice or PCM digital
voices.
In this information type is binary information.

26. Communication Satellites

27. Communication Satellites
Various steps in making a call through a satellite network
1. The user lifts the receiver when he or she wants to make a call. This sends
a request to the local Earth station, which in turn sends a service request
to the master station.
2. If the master station is able to provide the satellite capacity, it sends a
confirmation signal to the local Earth station, resulting in a dial tone in the
telephone instrument.
3. The user then dials the destination number, which is transferred to the
control station, which determines the destination Earth station and
signals it that a connection needs to be established.
4. The destination Earth station then signals the called party of the incoming
call by ringing that telephone instrument.
5. The satellite capacity is allocated to the connection and the telephone link
is established once the called party lifts the handset.
6. Once the conversation is over, the calling party hangs up the receiver,
hence indicating to the local Earth station to terminate the call

28. Communication Satellites
Point-to-Point Trunk Telephone Networks
• One of the traditional applications of satellites includes intercontinental
trunk telephony services.
• Thin route services are used in those regions where installation of
terrestrial networks is not feasible either due to low density of population
or because of difficult geographical terrain.
•These services are particularly useful for establishing connections
between the company’s headquarters and its remote offices
•Trunk telephony services come under the domain of fixed satellite
services (FSS), mainly utilizing C and Ku bands.
• Generally, GEO satellites are utilized for providing these services.
•Intelsat, Europestar, Eutelsat, PamAmSat are examples of some of the
satellites used for the purpose

29. Communication Satellites
2. Mobile Satellite Telephony
•One of the important services provided by mobile satellite services (MSS)
is the interactive voice communication to mobile users.
•This service is referred to as mobile satellite telephony.
•The satellite phones target two specific markets.
•The first is that of international business users requiring global mobile
coverage.
•Satellites provide them with truly global mobile services with a single
mobile phone, which is impossible with terrestrial systems due to the
difference in cellular mobile phone standards from region to region

30. Communication Satellites
Satellite Television
•75 % of the satellite market for communication services
•Satellite television basically refers to the use of satellites for relaying TV
programmes from a central broadcasting centre to a large geographical
area.
•Satellites, by their very nature of covering a large geographical area, are
perfectly suited for TV broadcasting applications.
•As an example, satellites like GE and Galaxy in the US, Astra and Hot Bird
in Europe, INSAT in India and JCSAT (Japanese communications satellite)
and Superbird in Japan are used for TV broadcasting applications.

31. Communication Satellites
Satellite Television
•The five Hot Bird satellites provide 900 TV channels and 560 radio stations
to 24 million users in Europe.
•Other means of television broadcasting include terrestrial TV broadcasting
and cable TV services

32. Communication Satellites
Satellite Television
•A Typical Satellite TV Network
•Satellite television employs GEO satellites acting as point-to-multipoint
repeaters receiving a certain telecast from the transmission broadcasting
centre and retransmitting the same after frequency translation to the
cable TV operators, home dishes, etc., lying within the footprint of the
satellite.
•Satellites can provide TV programmes either directly to the users (direct-
to-home television) or indirectly with the help of cable networks or
terrestrial broadcasting networks, where the satellite feeds the signal to a
central operator who in turn transmits the programmes to the users
either using cable networks or through terrestrial broadcasting.
• A typical satellite TV network, like any other satellite network, can be
divided into two sections:
i.Uplink section
ii.Downlink section.

33. Communication Satellites
Satellite Television
•A Typical Satellite TV Network

34. Communication Satellites
Satellite Television
•The Uplink Section
•comprises three main components:
1.The programming source
2.The broadcasting centre
3.Main broadcasting satellite
1. The programming source
•Provide various TV programming signals, like TV channels, sports
coverage, news coverage or local recorded TV programmes, to the
broadcasting centre
•Through terrestrial means, like using the line-of-sight microwave
communication
•Fibre optic cable, or using satellites referred to as back-haul satellites

35. Communication Satellites
•One-time events like various news events, a vehicle-mounted Earth
station generally operating in the Ku band is driven to the site
•Then the programmes are transmitted to the main broadcast centre
using a back-haul satellite on a point-to-point connectivity basis [known
as satellite news gathering (SNG)]
2. The broadcasting centre & 3.Main Broadcasting centre
•The broadcasting centre is the hub of the satellite TV system and it
processes and beams the signal to the main broadcasting satellite.
• It also adds commentary or advertisements to the signals from the
various programming sources.
•Generally, the signals are transmitted using analogue techniques in the C
band or using a digital format employing various compression techniques
in the Ku band.
•The signals are also generally encrypted before transmission to prevent
unauthorized viewing.

36. Communication Satellites
Downlink
•The satellite downlink comprises
i. The main broadcasting satellite
ii.The TV receiving network
•Satellites distributing programmes to the terrestrial broadcast network
comprise various terrestrial broadcasting centres that receive the
satellite signal and transmit them to the users in the VHF and the UHF
bands using terrestrial broadcasting.
•The user end has directional yagi antennas to pick up these signals
•In the case of satellite distributing programmes to a cable operator, the
downlink section comprises the cable–TV head ends and the cable
distribution network
•For DTH services, receive-only satellite dishes are mounted at the user’s
premises to receive the TV programmes directly from the satellite.

37. Communication Satellites
SATELLITE–CABLE TELEVISION
•cable TV refers to the use of coaxial and fibre optic cables to connect
each house through a point-to-multipoint distribution network
•Cable TV, originally referred to as CATV (community antenna television)
stood for a single head end serving a particular community, like various
houses in a residential area
•The head ends receive programming channels from either a local
broadcasting link or through satellites.
•The use of satellites to carry the programming channels to the cable
systems head ends is referred to as satellite–cable television

38. Communication Satellites
Satellite–Cable Television

39. Communication Satellites
Satellite–Cable Television
•The head end in this case consists of various receive-only Earth stations
with the capability of receiving telecast from two to six satellites.
•These Earth stations either have multiple receiving antennas or, a single
dish antenna with multiple feeds, with each feed so aligned as to receive
telecast from a different satellite

40. Communication Satellites
Satellite–Local Broadcast TV Network

41. Communication Satellites
Satellite–Local Broadcast TV Network
• It is the same as the satellite–cable TV network except for the fact that
here the satellite distributes programming to local terrestrial
broadcasting stations instead of distributing it to the cable head end
stations.
•The broadcasting stations use powerful antennas to transmit the
received signals to various users within the line-of-sight (50–150 km)
using UHF and VHF microwave bands.
•The users receive these TV signals using directional antennas like yagi
antennas, reflector antennas or dipole antennas

42. Communication Satellites
Direct-to-Home Satellite Television
• Direct-to-home (DTH) satellite television refers to the direct reception of
satellite TV programmes by the end users from the satellite through their
own receiving antennas

43. Communication Satellites
Satellite Radio
• A satellite providing high fidelity audio broadcast services to
the broadcast radio stations is referred to as a satellite radio
•Sound quality is excellent in this case due to a wide audio
bandwidth of 5–15 kHz and low noise provided over the
satellite link. Satellite radio like the satellite TV employ GEO
satellites
•Using point-to-multipoint connectivity, the audio signals
from various music channels, news and sports centres are
transmitted by the satellite to a conventional AM or FM
radio station.
•The signal is then de-multiplexed and the local commercials
and other information is added here in the same way as in a
TV network

44. Communication Satellites
Satellite Radio
•The satellite can also transmit the signal directly to the user’s
radio sets.
•Some of the major providers of satellite radio services
include Sirius and XM Radio of the USA

45. Communication Satellites
Important Missions
• Various satellite missions are broadly classified into three
categories namely,
i.International
ii.Regional
iii.Domestic systems
•As the name suggests, international systems provide global
coverage, regional systems provide services to a particular
region, continent or to a group of countries and national
systems provide coverage to a particular country that owns
the satellite .

46. Communication Satellites
International Satellite Systems
•Provide international communication services.
•Initially all international satellites were GEO satellites but
now certain non-GEO satellite constellations that provide
global coverage have come to the market.
•Some of the international satellite missions include Intelsat,
PamAmSat, Orion, Intersputnik, Inmarsat, etc., in the
category of GEO systems and the Iridium and Globalstar
constellations in the nonGEO category

47. Communication Satellites
Regional Satellite Systems
• One of the drawbacks of international satellite systems is
that they are not optimized to the needs of the individual
countries.
•The first step to meet the focused needs of the countries
was to have a regional system that provided services to
countries on a regional basis rather than on a global basis

48. Communication Satellites
Regional Satellite Systems
• established with the aim of strengthening the
communication resources of the countries belonging to the
same geographical area.
• Some of the regional satellite systems include Eutelsat,
Arabsat, AsiaSat, Measat, ACeS (Asia cellular satellite),
Thuraya, etc. EUTELSAT operates a fleet of satellites that
provide communication services to Europe, the Middle East,
Africa and large parts of the Asian and American continents.
•Arabsat satellites provide satellite communication services to
the Middle East, Africa and large parts of Europe.
•The Asia Satellite Telecommunications Company Limited
(AsiaSat) and Measat systems are Asia’s regional satellite
operators, providing satellite services to the Asia Pacific
region.

49. Communication Satellites
Regional Satellite Systems
• ACeS is another satellite-based regional communication
system providing services to Asia.
• It provides fully digital video, voice and data services
throughout Asia.
•The Thuraya system provides mobile communication
services to the Middle East, North and Central Africa,
Europe, Central Asia and the Indian subcontinent

50. Communication Satellites
EUTELSAT (European Telecommunication Satellite Organization)
•The EUTELSAT organization was formed in the year 1977 in
Europe
• to design and construction of satellites and to manage the
operation of regional satellite communication services in
Europe.
•The first communication satellite to be launched by EUTELSAT
was the orbital test satellite (OTS) in the year 1978, which
carried out link tests with small Earth stations with the help of
a powerful antenna on board the satellite
•Link Test :
i.Carrier-to-noise ratio
ii.energy per bit-to-noise power density (Eb/No)
iii. carrier-to-interference (C/I)

51. Communication Satellites
EUTELSAT (European Telecommunication Satellite
Organization)
• OTS was the first
 
three-axis-stabilised Ku-band 
satellite
• OTS 1 - was launched on 13 September 1977 and it was
destroyed 54 seconds later due to its United States
 
Delta
 
launcher exploding – crack in the fuel tank.
•OTS 2 
was successfully launched on 11 May 1978 using the
same Delta
 
launch vehicle

52. Communication Satellites
EUTELSAT (European Telecommunication Satellite
Organization)
•Currently, 24 satellites of the organization are operational
over various locations from 15◦ W and 70.5◦ E on the GEO
orbit(latitude and longitude), serving more than 150
countries and up to 90 % of the world’s population.
•Out of these 24 satellites, 20 satellites are fully operated by
EUTELSAT and the remaining four, including the Telecom-2D,
Telstar-12, Ek spress-A3 and Ekspress-AM22, are leased
satellites from other organizations.

53. Communication Satellites
ECS-1
•Used to provide communication services to post office and
telecommunication administration and to broadcast TV
programmes
•television, telephony and data transmission services on a
regional basis and mobile communication
•Hot Bird, Eurobird and Atlantic Bird series were also
launched under EUTELSAT

54. Communication Satellites
Atlantic Bird satellites.
•provide video, IP (Internet Protocol) and data
communication services to Europe, the Middle East and
North African markets

55. Communication Satellites
Eurobird satellites.
•Eurobird satellites provide broadcasting and
telecommunication services primarily to the Western and
Central European region

56. Communication Satellites
Hot Bird satellites.
•The Hot Bird satellite family provides television services,
radio and multimedia services over a wide coverage area
•Europe, North Africa and large parts of the Middle East.

57. Communication Satellites
SESAT satellites.
•The SESAT (Siberia–Europe satellites) satellites provide a
wide range of telecommunication services over a very large
geographical coverage area that extends from the Atlantic
Ocean to Eastern Russia, including a large part of Siberia

58. Communication Satellites
NATIONAL SATELLITE SYSTEMS
•National satellite systems, - domestic satellite systems,
provide services to a particular country.
•Established by developed countries like the USA,
USSR(United Soviet Socialist Republics) and Canada to serve
their country’s population according to their specific needs.
•The Soviet Union was composed of 15 constituent soviet socialist republics.
Those were Russia, Ukraine, Belarus, Moldova, Lithuania, Latvia, Estonia, Georgia,
Armenia, Azerbaijan, Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, and
Turkmenistan.
•Developing nations like India, China, Japan, etc., also have
their own national satellite systems.
•Some of the domestic satellite systems include Galaxy,
Satcom, EchoStar and Telestar of the USA, Brasilsat of Brazil,
INSAT of India, Optus of Australia and Sinosat of China

59. Communication Satellites
National Satellite Systems
•INSAT (Indian National Satellite)
•Owned by the Indian Department of Space, named the
Indian Space Research Organization (ISRO)
• INSAT is one of the largest domestic communication satellite
networks in the world,
• providing services in the areas of telecommunications,
television broadcasting, mobile satellite services and
meteorology including disaster warning
•INSAT is a joint venture of the Department of Space (DOS),
Department of Telecommunications (DOT), Indian
Meteorological Department (IMD), All India Radio (AIR) and
Doordarshan.

60. Communication Satellites
National Satellite Systems
•INSAT (Indian National Satellite)
•Beginning with the launch of INSAT-1A in 1982, the INSAT
satellite programme has come a long way today.
• INSAT-1A belonged to the INSAT-1 series, further comprising
INSAT-1B, 1C and 1D satellites.
• The INSAT-1 series was followed by INSAT-2 and INSAT-3
series of satellites