This document provides an overview of VSAT (Very Small Aperture Terminal) technology. It discusses VSAT components, installation, advantages, applications including distance learning, network architecture, and multiple access techniques. A VSAT consists of an outdoor transceiver and indoor data processing unit. Information is sent to satellites and transmitted to remote VSAT sites. VSATs offer flexible, low-cost networks for applications such as corporate networks, internet access, and distance education. Distance learning uses VSATs to transmit educational content from hub to remote areas.

1. FET(FACULTY OF ENGINEERING AND
TECHNOLOGY )
GOMAL UNIVERSITY D I KHAN
SEMESTER 8TH (2012-2016)
DATE 08/12/2015
1
By Engr Mateeullah
shahid

2. OVERVIEW
VSAT
 Introduction
 Advantages
 Applications
 Network Architecture
 Multiple Access Techniques
Distance Learning: an application
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M- Shahid

3. Introduction To VSAT
A Very Small Aperture Terminal (VSAT) is a
device known as a small private earth station
- that is used to transmit & receive data signal
through a satellite.
VSAT stands for Very Small Aperture Terminal
and refers to receive/transmit terminals
installed at dispersed sites connecting to a
central hub via satellite using small diameter
antenna dishes (0.6 to 3.8 meter). 3

4. INTRODUCTION (CONTD.)
• VSAT is used for both broadcast & interactive
applications of effective data, voice and
video transfer.
• It requires no staff or additional technology
to operate it.
• It simply plugs into existing terminal equipment
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5. VSAT INSTALLATION
Information is produced at the hub having a
very large 15 to 36 foot antenna. The hub
controls and monitors the network through
a network management system (NMS).
Information is sent up to the communication
satellite which receives, amplifies and
beams it back to earth for reception by the
remote VSATs.
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6. VSAT SITE INSTALLATION
• Ground Mount
This involves a tube lowered into a hole
which is then filled in with concrete. The pole
should be accurately vertical so that when you
swing the dish around to find the satellite the
elevation angle stays the same all the time.
The indoor data processing unit (DPU)
The indoor data processing unit (DPU)
should be located in a dry, cool and clean place.
The antenna needs to be mounted where it can 'see' the
satellite and where it is safe from unauthorized access.
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7. SAFETY
Installing a dish is normally dangerous. Take care
not to fall down and not to drop tools on others
below. Be careful with ladders - always tie off
the top to some secure point. A small electric
shock may make you fall off a ladder so be extra
careful.
TIPS : ---- If you are a beginner, practice
the complete installation at ground level before
moving everything to the roof.
 Accuracy
The dish pointing needs to be near
perfect as the transmit beam is narrower then
7

8. WHY VSAT?
The dish is small, easily transportable and
installation lead-time is much shorter if
compared to terrestrial links.
VSAT network allows rapid, low-cost network
re-configuration and expansion to meet new
or unexpected business requirements.
Cost effective transmission and network
operations are made possible by use of the
Ex-C band satellite frequency and frequency
times division multiple access (FTDMA),
Frequency division multiple access (FDMA) or
Time division multiple access (TDMA)
transmission techniques.
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9. PARTS OF VSAT
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10. A VSAT SHOULD CONSISTS
OF TWO PARTS
VSAT
Transceiver
Device such as
Personal Computer
(PC)
Short for “Small Aperture Terminal, an earthbound station used
in satellite communications of data, voice and video signals,
excluding broadcast television.
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11. CONT….
• A VSAT consists of two parts, a transceiver that is
placed outdoors in direct line of sight to the satellite
and a device that is placed indoors to interface the
transceiver with the end user's communications
device, such as a PC .
• The transceiver receives or sends a signal to a
satellite transponder in the sky.
• The satellite sends and receives signals from a
ground station computer that acts as a hub for the
system. 11

12. WORKING OF HUB STATION
• Each end user is interconnected with the hub
station via the satellite, forming a star topology.
• The hub controls the entire operation of the network
.
• For one end user to communicate with another,
each transmission has to first go to the hub station
that then retransmits it via the satellite to the other
end user's VSAT.
• VSAT can handle up to 56 Kbps.
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13. ADVANTAGES OF VSAT
Offer flexibility as adding a site is quick and
easy.
Service charges depend on the bandwidth,
which is allocated to network in line with
your requirements.
VSAT terminals prices are falling.
No last mile issues.
There are many advantages that VSAT offers, some of them
are as follows:
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14. CONTD….
• Easy access to remote locations—Where
it would be difficult to facilitate a
• wire line arrangement, such as on an oil rig,
a VSAT can easily be set up.
As it is mobile, so be used for short term or
emergency communications.
Excellent for broadcast transmission.
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15. DISADVANTAGES OF VSATS
• Transmission quality subject to weather
conditions—Stormy weather can
• cause disruptions. Most large users of VSAT networks have
some leased
• lines available to use as backup when disruptions occur.
• ■ Potentially high startup costs for small
installations—A small company
• may face a high startup cost if it does not have many nodes.
(If VSAT is the
• only available recourse—if there is no way to communicate
without it—
• then the installation cost is a moot point.)
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16. APPLICATIONS OF VSAT
• VSAT is an ideal satellite network that
provides
communications support for a wide range of
applications:
Distance Education
Retail Networks
• • Point-of-Sale(PoS) transaction, banking,
inventory, reservation system.
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17. CONTD….
Corporate Networks
• • Internet/Intranet access, corporate voice,
file transfer, video-conferencing.
High-speed Internet access
• • Browsing, E-mail, E-commerce .
Financial Management
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18. DISTANCE LEARNING USING VSAT
Distance education is an innovation that
allows educational content to be transmitted
from area to area and provides students in
rural areas also an opportunity to get
education.
Due to the need for high speed and high
quality educational messages,
communication satellites are often used
more for efficient transmission.
The main purpose of distance education is to
provide people greater access to education
without the limitations of distance and
boundaries.
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19. PROCESS OF DISTANCE LEARNING
At the teacher end the audio and video input is fed to
the Hub . A dummy student is also placed there to
see whether the information is sent correctly and in
order. Data from the hub is passed through the router
to the central hub, wherefrom it is transmitted to the
satellite.
At the user end, the user is given a particular IP
address and a login ID. Using this can access the
remote earth station which receives the data from the
central Hub via satellite.
Distance education requires a network, which has
broadband capability, so that the network is able to
carry large amount of video and audio data. Satellite
distribution can facilitate two-way transmission of
dense data traffic at speeds equal to or faster than
most wire-based systems.
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20. NETWORK ARCHITECTURE
• VSAT network can be of following two types:
•
1.Hub type (VSAT Star Net with Star network topology)
2.Hub less type (VSAT Dial Net and VSAT Direct with
point-to-point or meshed network topology)
Most VSAT networks use a star configuration, which
composes a single Hub communicating with
remote VSATs. A VSAT Hub is a huge earth station
that is responsible for controlling & monitoring all the
activities of the geographical spread of VSATs. In
some cases all the remote VSATs communicate to one
central site, this central site is connected to the hub,
as hub is the switching element. This service supports
transmission bandwidth ranging from 9.6 kbps to 2
Mbps duplex.
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21. VSAT HUB NETWORK
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M- Shahid

22. • [1] Ha, Tri T., Digital Satellite Communications, 2nd ed., TMH,
2009.
• [2]http://en.wikipedia.org/wiki/Very-small-aperture_terminal
[accessed on 25/09/2013].
• [3]http://www.cse.iitb.ac.in/synerg/lib/exe/fetch.php?id=public%3ast
udents%3azahirk%3adm%3ainterfacing_to_pc&cache=cache&medi
a=public:students:zahirk:dm:vsat_doc.pdf [accessed on 29/10/2013]
• [4] http://novastars.com/vsat [accessed on 28/10/2013].
• [5] Rao, K.N. Raja, Fundamentals of satellite communication, PHI
pvt. Ltd., 2004.
• [6] Tseng, Yuh M., Cryptanalysis and Improvement of Key
Distribution System for VSAT Satellite Communications,
INFORMATICA, 2002, Vol. 13, No. 3, P 369–376.
REFERENCES
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