Satellite television is a system of delivering television programming
using signals relayed from communication satellites which orbit around
the earth at
35,786 KM above the equator in
geostationary orbits. The signals are received via an outdoor parabolic
reflector antenna usually referred to as a satellite dish and a
low-noise block down-converter
(LNB). A satellite receiver then decodes the desired television program for viewing on a television set
Receivers can be external set-top boxes, or a built-in television tuner.
Broadcast signals may or may not be encrypted, in India DD Free dish
broadcasts unencrypted signals which can be decoded by generic set top
boxes while commercial operators like Tata sky, Videocon DTH, Dish TV
etc. broadcast encrypted signals which are decrypted based on
information in the chip of your smart card.
Satellite Television signals are beamed in two types of bands:
- C band- This band is comprised of Analogue or
Digital signals in the 4 to 8 GHz frequency range used for Television
Receive Only (TVRO) broadcast and requires larger size of dish antenna
(6 to 8 feet) to receive the signals and is not effected by bad weather
conditions like rain.
- Ku band- This band is comprised of Digital signals
in the 12 to 18 GHz frequency range used for Direct to Home (DTH)
broadcast and requires much smaller dish antenna (2 to 4 feet) to
receive the more focused signals but is susceptible to outages during
bad weather conditions like heavy rains.
The compression standards used for broadcasting DTH signals are of two types:
- MPEG 2- This is the older standard of signal
compression which was used by incumbent DTH operators like Dish TV and
DD free dish where each transponder can carry approximately 20 SD
channels (Fewer in case of HD).
- MPEG 4- This is the newer standard of signal
compression introduced in 1999 and is being used in India by the newer
DTH operators like Airtel Digital, Videocon D2H, Reliance digital TV,
Sun DTH and now since October 2015 even Tata sky has completed switching
over from MPEG 2 to MPEG 4. With this compression standard each
transponder can carry approximately 40 SD channels (Fewer in case of HD)
Currently there are 6 private and 1 government DTH operators
providing service in India. The department of space (DOS) permits DTH
operators to only use satellites commissioned by Indian Space and
Research Organisation (ISRO) or in case there isn’t sufficient capacity
on ISRO satellites then they are permitted to use capacity leased by
ISRO from foreign satellites. ISRO is planning three GSAT launches in
the next two years related to communication and broadband satellites.
The main purpose of these launches are to replace the transponders
leased by foreign satellite players, other than those in the ‘C’ Band.
“We have launched the GSAT 16 offering 48 transponders in
November, and GSAT 15 will go up during this October with transponders.
We are coming up with a series of satellite launches to bridge the gap
as GSAT 17 and GSAT 18 will be launched during 2016.” Kiran Kumar,
Chairman, ISRO, said on the side-lines of the World Meteorology Day
Celebrations organised by Meteorology Society of India.
Satellites being used by Indian DTH operators:
INSAT 4A:
This is a satellite owned by ISRO which was launched on 22
nd
December 2005 with a mission life of 12 years. It’s geostationary
position is 83° East longitude. This satellite has 12 Ku band
transponders all of which are being used by
Tata Sky
for its SD and HD DTH broadcast using MPEG2 and MPEG4 compression. The
transponders have started to function with reduced power as the
satellite nears its end of mission life.
GSAT 10:
This is a satellite owned by ISRO which was launched on 29
th
September 2012 with a mission life of 15 years. It’s geostationary
position is 83° East longitude where it is co-located with INSAT 4A.
This satellite has 12 Ku band transponders and is planned as a
replacement for INSAT 4A which will reach its end of life in the next
two years.
Tata Sky will eventually be shifting its
operations from INSAT 4A to GSAT 10 and has already begun conducting
tests for signal transmission.
GSAT 15:
This is a satellite owned by ISRO which was launched on 10
th November
2015 with a mission life of 12 years. Its geostationary position is
93.5° East longitude. This satellite has 24 Ku band transponders of
which 5 are being used by
DD free dish for broadcasting
unencrypted SD channels using MPEG2 compression. DD will soon activate
more transponders on the satellite to add new encrypted channels with
MPEG4 compression.
MEASAT 3:
This is a satellite owned by Malaysia East Asia satellite systems, launched on 11
th
December 2006 with a mission life of 15 years. It’s geostationary
position is 91.5° East longitude. This satellite has 24 Ku band
transponders of which 13 have been leased by ISRO for making available
to Indian DTH operators.
Reliance digital TV uses 9 of the Ku band transponders for broadcasting SD and HD channels using MPEG4 compression,
Sun Direct
uses 4 Ku band transponders for broadcasting only SD channels using
MPEG4 compression and additionally shares 5 of Reliance’s transponders
for broadcasting free to air (FTA) encrypted channels.
ST 2:
This is a satellite owned by a joint venture between SingTel and Chunghwa telecom, launched on 20
th
May 2011 with a mission life of 15 years. It’s geostationary position
is 88° East longitude. This satellite has 41 Ku band transponders of
which 10 are leased by ISRO for making available to Indian DTH
operators.
Videocon D2H uses these 10 transponders to broadcast its SD and HD channels using MPEG4 compression.
SES 7:
This is a satellite owned by SES world skies, launched on 16
th
May 2009 with a mission life of 15 years. It’s geostationary position
is 108.2° East longitude. This satellite has 19 Ku band transponders of
which 11 have been leased by ISRO for making available to Indian DTH
operators.
Airtel Digital TV is using these 11 transponders for broadcasting its SD and HD channels using MPEG4 compression.
NSS 6:
This is a satellite owned by SES world skies, launched on 17
th
December 2002 with mission life of 15 years. It’s geostationary
position is 95° East longitude. This satellite has 50 Ku band
transponders out of which 11 have been leased by ISRO for making
available to Indian DTH operators.
Dish TV is using these 11 transponders to only broadcast it’s SD channels using MPEG2 compression.
Asiasat 5:
This is a satellite owned by Hong Kong based Asia satellite telecommunications company, launched on 11
th
August 2009 with a mission life of 15 years. It’s geostationary
position is 100.5° East longitude. This satellite has 14 Ku band
transponders of which 4 have been leased by ISRO for making available to
Indian DTH operators.
Dish TV is using these 4 transponders to only broadcast it’s HD channels using MPEG4 compression.
| Name of the Satellite |
Owned & operated by |
Launch Date |
Mission Life (years) |
Geostationary position |
Number of Ku band Indian transponders |
Operators using the satellite |
| INSAT 4A |
ISRO |
22/12/2005 |
12 |
83° East |
12 |
Tata Sky |
| GSAT 10 |
ISRO |
29/09/2012 |
15 |
83° East |
12 |
Tata Sky future use |
| GSAT 15 |
ISRO |
10/11/2015 |
12 |
93.5° East |
24 |
DD free dish |
| MEASAT 3 |
MEA Satellite systems |
11/12/2006 |
15 |
91.5° East |
13 |
Reliance digital TV and Sun direct |
| ST 2 |
SingTel |
20/05/2011 |
15 |
88° East |
10 |
Videocon D2H |
| SES 7 |
SES world skies |
16/05/2009 |
15 |
108.2° East |
11 |
Airtel digital TV |
| NSS 6 |
SES world skies |
17/12/2002 |
15 |
95° East |
11 |
Dish TV |
| Asiasat 5 |
Asiasat telecom |
11/08/2009 |
15 |
100.5° East |
4 |
Dish TV |
Also read: A handy guide to frequency bands used for telecommunication in India
Frequently asked questions:
Q1. Does using a larger dish size guarantee better picture quality for DTH service?
Ans. Bigger dish size does not improve clarity if
signal received by small dish is already at maximum level. Optimization
of signal strength is ensured during installation by the DTH company
engineer.
Q2. Does MPEG-4 have lower picture quality compared to MPEG-2 standard since the signal is more compressed?
Ans. MPEG-4 is a newer standard for signal
compression compared to MPEG-2 and allows more channels to be carried
per transponder but the decompression algorithm is also more advanced
and the end picture quality is the same as MPEG-2.
Q3. Is DTH signal reception affected or disrupted by environmental factors?
Ans. There are two main types of DTH signal
disruptions due to environmental factors which are intermittent in
nature, the first is ‘Rain outage’ where there is a temporary loss of
signal during heavy rains since water absorbs the high frequency
microwave radiations coming from the DTH satellite and the second is a
phenomenon called ‘Sun outage’ which occurs intermittently during the
period of February to March and September to October during Equinoxes
when the Sun’s radiation overpowers and interferes with the DTH signals
coming from satellites.
We hope this article has been useful in clearing all your
doubts regarding the various satellites used for broadcasting DTH
signals in India. If you still have any queries kindly post them in the
comments section below and we will do our best to resolve them. Keep
reading TT for the latest news in the Indian telecom Industry
