Very Small Aperture Terminal (VSAT) | UPSC

Very Small Aperture Terminal (VSAT): Applications, Advantages and Challenges | UPSC

  • Context: The Tribal Affairs Ministry is planning to collaborate with the Indian Space Research Organisation (ISRO) to deploy VSAT (very small aperture terminal) stations on a pilot basis for around 80 remote and isolated tribal villages to bring Internet services there.

Very Small Aperture Terminal


  • A very small aperture terminal (VSAT) is a ground station that transmits and receives data from satellites in real-time.
  • It utilizes small, compact antennas (usually less than 3 meters in diameter) for transmitting and receiving such data signals.
  • This technology has become increasingly popular due to its ability to provide coverage in remote areas where terrestrial networks may not be available.

Characteristics of VSAT

  • VSATs exclusively utilize geostationary satellites for communication purposes.
    • Satellites in geostationary orbit (GEO) circle Earth above the equator from west to east following Earth’s rotation – taking 23 hours 56 minutes and 4 seconds – by travelling at exactly the same rate as Earth.
    • This makes satellites in GEO appear to be ‘stationary’ over a fixed position.
    • GEO is used by satellites that need to stay constantly above one particular place over Earth, such as telecommunication satellites.
    • This way, an antenna on Earth can be fixed to always stay pointed towards that satellite without moving.
    • VSAT internet is usually capable of and suitable for supporting multiple connected computers concurrently.

Mobile VSATs

  • Recently, many emergency responders have moved towards more advanced mobile VSAT technology.
  • In mobile VSATs, the underlying technology is the same as regular VSATs: relatively large, specially made dishes that work off geostationary satellites.


  • Because the ground station is communicating with satellites, there is less infrastructure required to service remote locations.
  • VSAT is also independent of local telecommunications networks, making it an ideal system to back up wired systems and reduce business recovery risk.
      • If the wired network goes down, a business can still go on using the VSAT network.
  • A VSAT can provide reliable internet connectivity for natural disasters, which would typically take down traditional terrestrial infrastructure.


  • Large banks use VSATs to support automated teller machines (ATMs) and to serve as backup to wired networks.
  • The National Stock Exchange (NSE) of India has one of the largest VSAT networks in the world, supporting NSE transactions in areas where wired options are limited or unavailable.
  • VSAT networks have a number of commercial applications, including, perhaps most notably, enterprise resource planning (ERP).
      • The use of VSAT to track inventory was one of the many innovations Walmart pioneered in retail to effectively manage its vast inventory in real-time and reduce delivery costs between the warehouse and stores.

Challenges in VAST Communication

Latency •  Network latency (sometimes referred to as lag) is best described as the delay in the time that data takes to transfer across a network.

• Due to the long distances that signals must travel between satellites and ground terminals, latency is an inherent challenge in communications via VAST.

Spectrum availability and management • Access to sufficient and appropriate spectrum is crucial for VSAT service providers.

• They must compete with other satellite operators and terrestrial communication services for limited bandwidth.

Bad Weather • The bands used by VSATs – C and Ku – can be adversely impacted by bad weather, including heavy rain, thunderstorms, sandstorms and even thick fog.

• Any tiny particles suspended in the atmosphere can and will impact the radio signals coming to and from a satellite.

• The occasional sun outage due to solar radiation can also distort signals from the satellite.

Blocked Signals • Satellite dishes used for VSATs should have a direct line of sight to sky to properly function.

•Buildings and structures, trees, hills, vehicles and even people can block signals if placed in front of satellite dishes.

Less Speed • The upload and download speeds are lesser to most terrestrial based connections.


Practice Questions:

Q. Discuss the key applications of Very Small Aperture Terminal (VSAT) technology in disaster management in India, along with its advantages and challenges. (Answer in 250 words)

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