This Report have all the information about communication section which we have came across during the Summer Training at Doordarshan Lucknow.

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Chapter-1
INTRODUCTION
Doordarshan is an autonomous Public Service Broadcaster
founded by the Government of India which is owned by
Broadcasting Ministry of India and is one of the two divisions of
Prasar Bharati. It is one of India's Largest broadcasting
organisation in terms of studio and transmitter infrastructure
established in 15 September 1959.It also broadcasts on digital
terrestrial transmitters. DD provides television, radio, online and
mobile services. Lucknow Doordarshan started functioning on
27th November 1975 with setup at 22,Ashok Marg, Lucknow.
Our training in Doordarshan Kendra Lucknow mainly focused
on these three divisions:-
1.1) STUDIO - Doordarshan is a leading broadcasting service
provider in India. DD Lucknow is full-flathead broadcast set up.
Many serials & program are being made here like "BIBI
NATIYON WALI", "NEEM KA PED" and "HATIM TAI" etc.
recorded in studio.
1.2) TRANSMITTER - Here the transmission of both audio and
video has been made. The transmission section does the function
of modulation of signal. Power amplification of the signal &
mixing of audio and video signal is done here.
1.3) EARTH STATION - The main function of earth station is
to make contact with satellite or communicate with it. The
signals from other transmitter are down linked here. Also the
signals here are uplinked to send it to larger distance.
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Chapter-2
EM SPECTRUM
The electromagnetic spectrum covers electromagnetic waves
with frequencies ranging from below one hertz to above
1025
hertz, corresponding to wavelengths from thousands
of kilometers down to a fraction of the size of an atomic
nucleus. This frequency range is divided into separate bands,
and the electromagnetic waves within each frequency band are
called by different names; beginning at the low frequency (long
wavelength)end of the spectrum these are: radio
waves, microwaves, THz waves, infrared, visible
light, ultraviolet, X-rays, and gamma rays at the high-frequency
(short wavelength) end.
Gamma rays, X-rays, and high ultraviolet are classified
as ionizing radiation as their photons have enough energy
to ionize atoms, causing chemical reactions. Exposure to these
rays can be a health hazard, causing radiation sickness, DNA
damage and cancer. Radiation of visible light wavelengths and
lower are called non-ionizing radiation as they cannot cause
these effects. In most of the frequency bands above, a technique
called spectroscopy. Electromagnetic waves are typically
described by any of the following three physical properties:
the frequency f, wavelength λ, or photon energy E. Frequencies
observed in astronomy range from 2.4×1023
Hz (1 GeV gamma
rays) down to the local plasma frequency of the ionized
interstellar medium (~1 kHz). Wavelength is inversely
proportional to the wave frequency, so gamma rays have very
short wavelengths that are fractions of the size of atoms,
whereas wavelengths on the opposite end of the spectrum can be
as long as the universe.
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Fig.1. Bands of EM Spectrum
Fig.2. Classification of Bands
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Chapter-3
FUNDAMENTALS OF TV SYSTEM
3.1 Picture Formation: - A picture can be considered to contain
a number of small elementary areas of light or shade which are
called PICTURE ELEMENTS. The elements thus contain the
visual image of the scene. In the case of a TV camera the scene
is focused on the photosensitive surface of pick up device and an
optical image is formed. The photoelectric properties of the
pickup device convert the optical image to a electric charge
image depending on the light and shade of the scene (picture
elements). Now it is necessary to pick up this information and
transmit it. The electron beam scans the image line by line and
field by field to provide signal variations in a successive order
then produces optical image. The scanning is both in horizontal
and vertical direction simultaneously. The horizontal scanning
frequency is 15,625 Hertz. The vertical scanning frequency is 50
Hz. The frame is divided in two fields. Odd lines which are
scanned first and then the even lines. The odd and even lines are
interlaced. Since the frame is divided into 2 fields the flicker
reduces. The field rate is 50 Hertz. The frame rate is 25 Hertz.
3.2 Number of TV lines per Frame: - If the number of TV
lines is high larger bandwidth of video and hence larger R.F.
channel width is required. If we go for larger RF channel width
the number of channels in the R.F. spectrum will be reduced.
However, with more no. of TV lines on the screen the clarity of
the picture i.e. resolution improves. With lesser number of TV
lines per frame the clarity (quality) is poor.
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3.3 Resolution:-The capability of the system to resolve
maximum number of picture elements along scanning lines
determines the horizontal resolution. It means how many
alternate black and white elements can be there in a line. The
vertical resolution depends on the number of scanning lines and
the resolution factor also known as Kell factor.
3.4 Grey Scale: - In black and white (monochrome) TV system
all the colors appear as gray on a 10- step gray scale chart. TV
white corresponds to a reflectance of 60% and TV black 3 %
giving rise to a Contrast Ratio of 20:1 (Film can handle more
than 30:1 and eyes capability is much more).
3.5 Brightness: - It reveals the average illumination of the
reproduced image on the TV screen. Brightness control in a TV
set adjusts the voltage between grid and cathode of the picture
tube (Bias voltage).
3.6 Contrast:- It is the relative difference between black and
white parts of the reproduced picture. In a TV set the contrast
control adjusts the level of video signal fed to the picture tube.
3.7 Viewing Distance: - Optimum viewing distance from TV
set is about 4 to 8 times the height of the TV screen. While
viewing TV screen one has to ensure that no direct light falls on
the TV screen.
3.8 Persistence of vision:- It refers to the optical
illusion whereby multiple discrete images blend into a single
image in the human mind and believed to be the explanation
for motion perception in cinema and animated films.
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Chapter-4
BROADCAST TV SYSTEM
Broadcast television systems are encoding or formatting
standards for the transmission and reception of terrestrial
television signals. It is categorized as Analog Television
Systems and Digital Television Systems.
4.1 Analog Television System:-
4.1.1 NTSC: -The first National Television System
Committee was developed in 1941 and had no
provision for color. In 1953 a second NTSC standard
was adopted, which allowed for color
television broadcasting which was compatible with
the existing stock of black-and-white receivers.
NTSC was the first widely adopted broadcast color
system and remained dominant until the 2000s, when
it started to be replaced with
different digital standards .
Fig.3. Analog television encoding system by nation; countries
using NTSC systems are shown in green.
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4.1.2 SECAM: - Development of SECAM began in 1956
by a team led by Henri de France working at Compagnie
Française de Télévision (later bought by Thomson,
now Technicolor). The first SECAM broadcast was made
in France in 1967, making it the second such standard to
go live in Europe. The system was also selected as the
standard for color in the Soviet Union, who began
broadcasts shortly after the French. The standard spread
from these two countries to many client states and former
colonies.
SECAM remained a major standard into the 2000s. It is in
the process of being phased out and replaced by DVB, the
new pan-European standard for digital television.
Just as with the other color standards adopted for broadcast
usage over the world, SECAM is a standard which permits
existing monochrome television receivers predating its
introduction to continue to be operated as monochrome
televisions. Because of this compatibility requirement,
color standards added a second signal to the basic
monochrome signal, which carries the color information.
The color information is called chrominance or C for short,
while the black-and-white information is called
the luminance or Y for short. Monochrome television
receivers only display the luminance, while color receivers
process both signals. In order to be able to separate the
color signal from the monochrome one in the receiver, a
fixed frequency sub carrier is used, this sub carrier being
modulated by the color signal. The color space is three-
dimensional by the nature of the human vision, so after
subtracting the luminance, which is carried by the base
signal, the color sub carrier still has to carry a two-
dimensional signal. Typically the red (R) and the blue (B)
information are carried because their signal difference with
luminance (R-Y and B-Y) is stronger than that of green
(G-Y).
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SECAM differs from the other color systems by the way
the R-Y and B-Y signals are carried. First, SECAM
uses frequency modulation to encode chrominance
information on the sub carrier. Second, instead of
transmitting the red and blue information together, it only
sends one of them at a time, and uses the information
about the other color from the preceding line. It uses
an analog delay line, a memory device, for storing one line
of color information. This justifies the "Sequential, With
Memory" name. Because SECAM transmits only one
color at a time, it is free of the color artifacts present
in NTSC and PAL resulting from the combined
transmission of both signals.
4.1.3 PAL :- Phase Alternating Line (PAL) is a color
encoding system for analogue television used in broadcast
television systems in most countries broadcasting at 625-
line / 50 field (25 frame) per second (576i).
All the countries using PAL are currently in process of
conversion or have already converted standards
to DVB, ISDB or DTMB.
The term PAL was often used informally and somewhat
imprecisely to refer to the 625-line/50 Hz (576i) television
system in general, to differentiate from the 525-line/60 Hz
(480i) system generally used with NTSC.
Accordingly, DVDs were labeled as PAL or NTSC
(referring to the line count and frame rate) even though
technically the discs carry neither PAL nor NTSC encoded
signal. CCIR 625/50 and EIA 525/60 are the proper names
for these (line count and field rate) standards; PAL and
NTSC on the other hand are methods of encoding color
information in the signal.
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4.2 Digital Television Standard:-
4.2.1 ATSC:- Advanced Television Systems
Committee (ATSC) standards are a set of standards
for digital television transmission over terrestrial, cable,
and satellite networks. It is largely a replacement for the
analog NTSC standard, and like that standard, used mostly
in the United States, Mexico and Canada.
The ATSC standards were developed in the early 1990s by
the Grand Alliance, a consortium of electronics and
telecommunications companies that assembled to develop
a specification for what is now known as HDTV.
ATSC includes two primary high definition video
formats, 1080i and 720p. It also includes standard-
definition formats, although initially only HDTV services
were launched in the digital format. ATSC can carry
multiple channels of information on a single stream, and it
is common for there to be a single high-definition signal
and several standard-definition signals carried on a single
(former) NTSC channel allocation.
4.2.2 DVB:- Digital Video Broadcasting (DVB) systems
distribute data using a variety of approaches, including:
 Satellite: DVB-S, DVB-S2 and DVB-SH
 DVB-SMATV for distribution via SMATV
 Cable: DVB-C, DVB-C2
 Terrestrial television: DVB-T, DVB-T2
 Digital terrestrial television for handhelds: DVB-H, DVB-SH
 Microwave: using DTT (DVB-MT), the MMDS (DVB-MC),
and/or MVDS standards (DVB-MS)
These standards define the physical layer and data link layer of
the distribution system. Devices interact with the physical layer
via a synchronous parallel interface (SPI), synchronous serial
interface (SSI), or asynchronous serial interface (ASI). All data
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is transmitted in MPEG transport streams with some additional
constraints (DVB-MPEG). These distribution systems differ
mainly in the modulation schemes used and error correcting
codes used.
4.2.3 ISDB:- The Integrated Services Digital Broadcasting is
a Japanese standard for digital television (DTV) and digital
radio used by the country's radio and television networks. ISDB
replaced NTSC-J analog television system and the previously
used MUSE Hi-vision analogue HDTV system in Japan, and will
be replacing NTSC, PAL-M and PAL-N in South America and
the Philippines. Digital Terrestrial Television Broadcasting
(DTTB) services using ISDB-T started in Japan in December
2003 and in Brazil in December 2007 as a trial. Since many
countries have adopted ISDB over other digital broadcasting
standards.
4.2.4 DTMB:- Digital Terrestrial Multimedia Broadcast is
the TV standard for mobile and fixed terminals used in
the People's Republic of China, Cuba, Hong Kong, and Macau.
Fig.4.DTT broadcasting systems. Countries using DTMB are shown in
purple.
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Chapter-5
VIDEO SIGNAL
What is Video Signal?
Video is nothing but a sequence of picture .The image we see is
maintained in our eye for a 1/16 sec so if we see image at the
rate more than 16 picture per sec our eyes cannot recognize the
difference and we see the continuous motion. In TV cameras
image is converted in electrical signal using photo sensitive
material. Whole image is divided into many micro particles
known as Pixels. These pixels small enough so that our eyes
cannot recognize pixel and we see continuous image ,thus at any
instant there are almost an infinite number of pixel that needs to
be converted in electrical signal simultaneously for transmitting
picture details. However this is not practicable because it is no
feasible to provide a separate path for each pixel in practice this
problem is solved by scanning method in which information is
converted in one by one pixel line by line and frame by frame .
Colour Composite Video Signal is formed with Video, sync
and blanking signals. The level is standardized to 1.0 V peak to
peak (0.7 volts of Video and 0.3 volts of sync pulse).
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Chapter-6
THE COLOUR TELEVISION
It is possible to obtain any desired colour by mixing three
primary colours i.e. Red, Blue and green in a suitable
proportion. The retina of human eye consists of very large
number of light- sensitive cells. These are of two types, rods and
cones. Rods are sensitive only to the intensity of the incident
light and cones are responsible for normal colour vision. The
small range of frequencies to which the human eye is responsive
is known as visible spectrum. This visible spectrum is from 780
mm (Red) to 380 mm(Violet). 3.7) ADDITIVE COLOUR
MIXING The figure shows the effect of projecting red, green,
blue beams of light so that they overlap on screen. Y= 0.3 Red +
0.59 Green + 0.11 Blue.
Fig.6. Additive Colour Mixing
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Chapter-7
SATELLITE COMMUNICATION
Satellite communication, in telecommunications, the use of
artificial satellites to provide communication links between
various points on Earth. Satellite communications play a vital
role in the global telecommunications system. Approximately
2,000 artificial satellites orbiting Earth relay analog and digital
signals carrying voice, video, and data to and from one or many
locations worldwide.
Satellite communication has two main components: the ground
segment, which consists of fixed or mobile transmission,
reception, and ancillary equipment, and the space segment,
which primarily is the satellite itself. A typical satellite link
involves the transmission or uplinking of a signal from an Earth
station to a satellite. The satellite then receives and amplifies the
signal and retransmits it back to Earth, where it is received and
reamplified by Earth stations and terminals. Satellite receivers
on the ground include direct-to-home (DTH) satellite
equipment, mobile reception equipment in aircraft, satellite
telephones, and handheld devices.
A satellite is basically a self-contained communications system
with the ability to receive signals from Earth and to retransmit
those signals back with the use of a transponder—
an integrated receiver and transmitter of radio signals. A satellite
has to withstand the shock of being accelerated during launch up
to the orbital velocity of 28,100 km (17,500 miles) an hour and a
hostile space environment where it can be subject
to radiation and extreme temperatures for its projected
operational life, which can last up to 20 years.
Satellites must be small and made of lightweight and durable
materials. They must operate at a very high reliability of more
than 99.9 percent in the vacuum of space with no prospect of
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maintenance or repair. The main components of a satellite
consist of the communications system, which includes
the antennas and transponders that receive and retransmit
signals, the power system, which includes the solar panels that
provide power, and the propulsion system, which includes
the rockets that propel the satellite.
Satellites operate in three different orbits: low Earth
orbit (LEO), medium Earth orbit (MEO), and geostationary or
geosynchronous orbit (GEO). LEO satellites are positioned at an
altitude between 160 km and 1,600 km (100 and 1,000 miles)
above Earth. MEO satellites operate from 10,000 to 20,000 km
(6,300 to 12,500 miles) from Earth. (Satellites do not operate
between LEO and MEO because of the inhospitable
environment for electronic components in that area, which is
caused by the Van Allen radiation belt.) GEO satellites are
positioned 35,786 km (22,236 miles) above Earth, where they
complete one orbit in 24 hours and thus remain fixed over one
spot. As mentioned above, it only takes three GEO satellites to
provide global coverage, while it takes 20 or more satellites to
cover the entire Earth from LEO and 10 or more in MEO.
Satellite communications use the very high-frequency range of
1–50 gigahertz (GHz; 1 gigahertz = 1,000,000,000 hertz) to
transmit and receive signals. The frequency ranges or bands are
identified by letters: (in order from low to high frequency) L-, S-
, C-, X-, Ku-, Ka-, and V-bands. Signals in the lower range (L-,
S-, and C-bands) of the satellite frequency spectrum are
transmitted with low power, and thus larger antennas are needed
to receive these signals. Signals in the higher end (X-, Ku-, Ka-,
and V-bands) of this spectrum have more power;
With the help of SATCOM Broadcasting services
include radio and television delivered directly to the consumer
and mobile broadcasting services. DTH, or satellite television,
services are received directly by households. Satellites also play
an important role in delivering programming to cell phones and
other mobile devices, such as personal digital assistants and
laptops. Satellite communications technology is often used
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during natural disasters and emergencies when land-based
communication services are down. Mobile satellite equipment
can be deployed to disaster areas to provide emergency
communication services.
The main advantage of satellites is that satellite technology is
ideal for “point-to-multipoint” communications such as
broadcasting.
Fig.7. Satellite Communication
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Chapter-8
EARTH STATION
A Ground station, Earth station or earth terminal is a terrestrial
radio station designed for extra planetary telecommunication
with spacecraft or reception of radio waves from astronomical
radio sources. Ground stations may be located either on the
surface of the Earth or in atmosphere. Earth stations
communicate with spacecraft by transmitting and receiving
radio waves in the super high frequency or extremely high
frequency bands (e.g., microwaves). When a ground station
successfully transmits radio waves to a spacecraft (or vice
versa), it establishes a telecommunications link. A principal
telecommunications device of the ground station is the parabolic
antenna.
Specialized satellite earth stations are used to telecommunicate
with satellites—chiefly communications satellites. Other ground
stations communicate with manned space stations or
unmanned space probes. A ground station that primarily
receives telemetry data, or that follows a satellite not
in geostationary orbit, is called a tracking station.
When a satellite is within a ground station's line of sight, the
station is said to have a view of the satellite. It is possible for a
satellite to communicate with more than one ground station at a
time. A pair of ground stations are said to have a satellite
in mutual view when the stations share simultaneous,
unobstructed, line-of-sight contact with the satellite.
In Earth Station Communication, a transponder can be used.
In air navigation or radio frequency identification, a flight
transponder is an automated transceiver in an aircraft that emits
a coded identifying signal in response to an interrogating
received signal. In a communications satellite, a satellite
transponder receives signals over a range of uplink frequencies,
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usually from a satellite ground station. The transponder
amplifies them, and re-transmits them on a different set of
downlink frequencies to receivers on Earth, often without
changing the content of the received signal or signals.
Fig.8.Earth Station
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Chapter-9
DIRECT-TO-HOME SATELLITE
BROADCASTING
Direct-to-Home satellite broadcasting (DTH) or Direct Satellite
Broadcasting (DBS) is the distribution of television signals from
high powered geo- stationary satellites to a small dish antenna
and satellite receivers in homes across the country. The cost of
DTH receiving equipment’s is now gradually declining and can
be afforded by common man. Since DTH services are fully
digital, it can offer value added services, video-on-demand,
Internet, e- mail and lot more in addition to entertainment. DTH
reception requires a small dish antenna (Dia60 cm), easily be
mounted on the roof top, feed along with Low Noise Block
Converter (LNBC), Set-up Box (Integrated Receiver Decoder,
IRD) with CAS (Conditional Access System). A bouquet of 40
to 50 video programs can simultaneously be received in DTH
mode.
Fig.9.DTH System
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DTH services were first proposed in India in 1996. The proposal
was not approved to due to concerns over national security and
negative cultural influence. In 1997, the Government of India
banned DTH services due to some security reasons but then on
some set parameters it is finally launched in India on 2 October
2003 by Dish TV.
Direct-to-Home (DTH) television is a method of receiving
satellite television by means of signals transmitted from direct-
broadcast satellites. The Government of India permitted the
reception and distribution of satellite television signals in
November 2000. The first DTH service in the country was
launched by Dish TV on 2 October 2003.
The Department of Space (DoS`) requires all DTH operators in
India to only use satellites commissioned by the Indian Space
Research Organisation (ISRO). DTH operators may use capacity
leased by ISRO from foreign satellites only if sufficient capacity
is not available on ISRO satellites.
The communication going from a satellite to ground is
called downlink, and when it is going from ground to a satellite
it is called uplink. When an uplink is being received by the
spacecraft at the same time a downlink is being received by
Earth, the communication is called two-way.
Generally frequency for uplink is kept higher than the
downlink. There is greater attenuation due to rain when the
signal frequency is high.
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Fig.10. Uplinking and Downlinking chain process
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CONCLUSION
Doordarshan is the oldest and the biggest Broadcasting media in
India. In my training session I learned a lot. Not only in
technical field but also in social field too. I got a great
experience of working in a Public Sector Company. I learned
about the recent trends in Broadcasting Media and also the
market strategies to maximize the profit using limited resources.
I would like to say that this training program was an excellent
opportunity for us to get to the ground level experiences. I
learned the way of work in an organization.
I have gained a lot of knowledge and experience required for
successful Communication Engineering.

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REFERENCES
1. http://www.ddlucknow.com
2. www.ddindia.gov.in/
3. https://en.wikipedia.org/wiki/Digital_terrestrial_television
4. https://en.wikipedia.org/w/index.php?title=Ground_station
&oldid=848823757
5. https://en.wikipedia.org/wiki/Satellite_television#Direct_b
roadcast_via_satellite