Satellites used for broadcasting DTH signals in India

April 21, 2016     noteshunt    

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.

Satellites-dth-india

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 22nd 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 29th 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. Tata Sky is now using GSAT 10 in addition to existing INSAT 4A to augment its transponder capacity and has already begun adding new channels from this satellite.

GSAT 15:

This is a satellite owned by ISRO which was launched on 10th 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 11th 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 20th 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 16th 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 17th 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 11th 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 SatelliteOwned & operated byLaunch DateMission Life (years)Geostationary positionNumber of Ku band Indian transpondersOperators using the satellite
INSAT 4AISRO22/12/20051283° East12Tata Sky
GSAT 10ISRO29/09/20121583° East12Tata Sky
GSAT 15ISRO10/11/20151293.5° East24DD free dish
MEASAT 3MEA Satellite systems11/12/20061591.5° East13Reliance digital TV and Sun direct
ST 2SingTel20/05/20111588° East10Videocon D2H
SES 7SES world skies16/05/200915108.2° East11Airtel digital TV
NSS 6SES world skies17/12/20021595° East11Dish TV
Asiasat 5Asiasat telecom11/08/200915100.5° East4Dish 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.

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