A handy guide to Satellites used for broadcasting DTH signals in India

 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 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. Tata Sky is now using all GSAT 10 transponders in addition to existing INSAT 4A to augment its transponder capacity and has already begun adding new channels from this satellite using MPEG4 compression.

ST 2:

This is a satellite owned by a joint venture between SingTel and Chunghwa telecom, which was 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 12 are leased by ISRO for making available to Indian DTH operators. Videocon D2H uses these 12 transponders to broadcast its SD and HD channels using MPEG4 compression.

MEASAT 3:

This is a satellite owned by Malaysia East Asia satellite systems, which was 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.

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 and 1 for broadcasting encrypted SD channels using MPEG4 compression. Additionally 1 transponder is being used by Sun Direct for broadcasting only HD channels using HEVC compression.

NSS 6:

This is a satellite owned by SES world skies, which was 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 12 have been leased by ISRO for making available to Indian DTH operators. Dish TV is using these 12 transponders to broadcast it’s SD channels using MPEG2 compression and HD channels using MPEG4 compression.

Asiasat 5:

This is a satellite owned by Hong Kong based Asia satellite telecommunications company, which was 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.

SES 7:

This is a satellite owned by SES world skies, which was 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 12 have been leased by ISRO for making available to Indian DTH operators. Airtel Digital TV is using these 12 transponders for broadcasting its SD and HD channels using MPEG4 compression.

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 technician.

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.