By :

Aniket R. Sangamwar

What is meant by satellite communication?

In satellite communication, signal transferring between the sender and receiver is done with the help of satellite.

In this process, the signal which is basically a beam of modulated microwaves is sent towards the satellite.

The satellite amplifies the signal and sent it back to the receiver’s antenna present on the earth’s surface. So, all the signal transferring is happening in space.

Thus this type of communication is known as space communication.

Keppler’s Law laws concerning the motions of planets formulated by German

astronomer Johannes Kepler

First Law

the orbit of a planet around the sun is ellipse

Second Law ( Law of areas)

-orbital velocity

Third Law (Law of Periods or Harminc Law)

revolution function of distance

Types of Satellite

Astronomical satellites

Communication satellites

Weather satellites

Navigation satellites

A spacecraft placed in orbit around the earth which carries on

board microwave transmitting and receiving equipment capable

of relaying signals from one point to another.

It uses microwave frequency (1-100 Ghz)

Communications Satellite

To penetrate the atmosphere

To handle wideband signals encountered in present day communications

To make practical use of high gain antennas aboard the spacecraft

Reasons for Using Microwave Frequency

Satellite Service Categories

1. Fixed Satellite Service (FSS) cover links between satellites and fixed (non moving earth stations)

2. Mobile Service (MSS) cover links to stations that maybe in motion (mobile) including ships (maritime mobile-MMSS), aircraft (aeronautical mobile-AMSS),and land vehicles (land mobile LMSS)

3. Broadcast Services include TV (DBS-TV) and audio (DBSA)

4. Intersatellite Service –satellite-to-satellite cross links

Space Segment It contains the satellite and all terrestrial

facilities for control and monitoring of the

satellite

This includes the tracking, telemetry, and

command stations(TT&C) with satellite

control center

Payload – It consists of the receiving and

transmitting antennas and all the electronic

equipment that supports the transmission of

carriers

Platform – It consists of all subsystems that

permits the payload to operate

Ground Segment

It consists of all the earth stations most often connected to the

end user’s equipment by a terrestrial network, or in case of

VSAT, directly connected to the end user’s equipment

Broad Categories of Satellites

Passive Satellite

Simply reflects a signal back to earth

No gain devices on board to amplify or repeat the signal

Otherwise called bent pipe satellite (frequency translating RF repeater)

Active Satellite

Receives, amplifies, retransmits the signal

Also called processing satellite (used in digital circuits where the signal is demodulated to baseband and regenerates the signal)

Satellite Orbits The trajectory followed by the satellite in equilibrium between

two opposing forces (gravitational force and inertial centrifugal

force)

Maximum extension at apogee and minimum at perigee

Satellite Orbits

By Altitude and Shape

What is GSAT?

The term "geosynchronous" refers to the satellite's orbital

period being exactly one sidereal day which enables it to be

synchronized with the rotation of the Earth ("geo-"). Along

with this orbital period requirement, to be geostationary as

well, the satellite must be placed in an orbit that puts it in the

vicinity over the equator.

These two requirements make the satellite appear in an

unchanging area of visibility when viewed from the Earth's

surface, enabling continuous operation from one point on the

ground. The special case of a geostationary orbit is the most

common type of orbit for communications satellites.

If a geosynchronous satellite's orbit is not exactly aligned with

the Earth's equator, the orbit is known as an inclined orbit. It will

appear (when viewed by someone on the ground) to oscillate

daily around a fixed point. As the angle between the orbit and the

equator decreases, the magnitude of this oscillation becomes

smaller; when the orbit lies entirely over the equator in a circular

orbit, the satellite remains stationary relative to the Earth's

surface – it is said to be geostationary.

GSAT HISTORY

The first geostationary communication satellite was Syncom 3, launched on

August 19, 1964 with a Delta D launch vehicle from Cape Canaveral. The

satellite, in orbit approximately above the International Date Line, was used to

telecast the 1964 Summer Olympics in Tokyo to the United States.

The GSAT series of geosynchronous satellites is a system developed by

ISRO with an objective to make India self-reliant in broadcasting

services.

●The concept was first proposed by Herman

Potočnik in 1928 and popularised by the science

fiction author Arthur C. Clarke in a paper in

Wireless World in 1945. Working prior to the

advent of solid-state electronics, Clarke

envisioned a trio of large, manned space

stations arranged in a triangle around the planet.

Modern satellites are numerous, unmanned, and

often no larger than an automobile.

GSAT-16

Design and development of the GSAT-16

communication satellite

The GSAT-16 satellite was designed, assembled and manufactured by

ISRO, based on theI-3K (I-3000) bus platform, which was developed by

ISRO in association with Antrix Corporation.

GSAT-16 will be the 11th among GSAT series of Indian communication

satellites, and will have estimated lifespan of 12 years. GSAT-16, an

advanced communication satellite, weighing 3181.6 kg at lift-off, is being

inducted into the INSAT-GSAT system. GSAT-16 is configured to carry a

total of 48 communication transponders.

GSAT-16 is cuboidal in shape and has external dimensions of 2.0m x 1.77m

x 3.1m. Its launch mass is 3,181.6kg and dry mass is 1457.7kg.

Its propulsion system includes 440 Newton Liquid Apogee Motor (LAM) with mono methyl hydrazine (MMH) as fuel and mixed oxides of nitrogen (MON-3) as oxidiser for orbit raising. It is fitted with a solar array, containing two 180 AH Lithium Ion batteries that can generate approximately 6,000W of power.

The largest number of transponders carried by a communication satellite developed by ISRO so far, in normal C-band, upper extended C-band and Ku-band. GSAT-16 carries a Ku-band beacon as well to help accurately point ground antennas towards the satellite.

The communication transponders on-board GSAT-16 together ensure continuity of various services currently provided by INSAT-GSAT system and serve as on-orbit spares to meet contingency requirements or for the augmentation of such services.

GSAT-16 satellite launch vehicle

Initially launch was planned for 4 December 2014, but was postponed due to inclement weather. GSAT-16 was finally launched on 6 December 2014 from the Guiana Space Centre, French Guiana, by an Ariane 5 rocket.

Ariane 5 is a European heavy lift launch vehicle that is part of the Ariane rocket family, an expendable launch system used to deliver payloads into geostationary transfer orbit (GTO) or low Earth orbit (LEO).

Ariane 5 rockets are manufactured under the authority of the European Space Agency (ESA) and the Centre National d'Etudes Spatiales. Airbus Defence and Space is the prime contractor for the vehicles, leading a consortium of sub-contractors.

Ariane 5 Vehicle Description Cryogenic main stage

Ariane 5’s cryogenic H173 main stage (H158 for Ariane 5 G, G+, and GS) is called the EPC (Étage Principal Cryotechnique — Cryotechnic Main Stage). It consists of a large tank 30.5 metres high with two compartments, one for liquid oxygen and one for liquid hydrogen, and a Vulcain 2 engine at the base with a vacuum thrust of 142 tonnes-force (1,390 kilonewtons). The H173 EPC weighs about 189 tonnes, including 175 tonnes of propellant.[4]

After the main cryogenic stage runs out of fuel, it can re-enter the atmosphere for an ocean splashdown.

● Solid boostersAttached to the sides are two P241 (P238 for Ariane 5 G and G+) solid rocket boosters

(SRBs or EAPs from the French Étages d’Accélération à Poudre), each weighing about 277

tonnes full and delivering a thrust of about 722 tonnes-force (7,080 kilonewtons). They are

fueled by a mix of ammonium perchlorate (68%) and aluminum fuel (18%) and

polybutadiene (14%). They each burn for 130 seconds before being dropped into the ocean.

Second stage

The second stage is on top of the main stage and below the payload. The

Ariane 5G used the EPS (Étage à Propergols Stockables—Storable

Propellant Stage), which is fueled by monomethylhydrazine (MMH) and

nitrogen tetroxide. It also has 10 tons of storable propellants. The EPS was

improved for use on the Ariane 5 G+, GS, and ES. Ariane 5 ECA uses the

ESC (Étage Supérieur Cryotechnique—Cryogenic Upper Stage), which is

fueled by liquid hydrogen and liquid oxygen.

Fairing

The payload and all upper stages are covered at launch by a fairing, which is

jettisoned once sufficient altitude has been reached (typically above

100 km). The Fairing is also used for aerodynamic stability and protection

from re-entry heating.

GSAT-16 ORBIT DETAILS

NORAD ID: 40332

Int'l Code: 2014-078A

Perigee: 35,772.6 km

Apogee: 35,814.2 km

Inclination: 0.1 °

Period: 1,436.1 minutes

Semi major axis: 42164 km

GSAT-16 was positioned at 55 deg East longitude in the Geostationary orbit and

co-located with GSAT-8, IRNSS-1A and IRNSS-1B satellites.

GSAT-16's communication capabilities

GSAT-16 communication spacecraft

has been planned for providing

continuity of Fixed Satellite Services

(FSS) in Normal C, Upper Extended C

and Ku-bands of the frequency

spectrum.

● The communication payloads provide a combination of total 48 transponders

across the three frequency bands (24-Normal C, 12-Extended-C and 12 in Ku-

band) along with a Ku-band beacon transmitter, which is the highest for an Indian

satellite. The spacecraft will be Co-located with GSAT-8 at 55 deg E.

The C-band coverage (IMS Coverage) will include Indian main land, Andaman-Nicobar, Lakshadweep, Sri Lanka, Maldives Islands along with the in-between Indian Ocean region.

The Ku-band coverage will include Indian main land and Andaman-Nicobar Islands. Again for the first time, the satellite Ku-band antenna will provide a minimum of 25 dB Co-polarization suppression over the 51 dBW EIRP contour of the YAMAL spacecraft.

●The C-Band payload will provide minimum 37 dB W EIRP over the coverage

with a minimum -4 dB/K G/T for a nominal antenna temperature of 300K.

The Ku-Band payload is estimated to provide minimum 52 dB W EIRP over Indian mainland and minimum 51 dB W EIRP over Andaman & Nicobar Islands. The G/T for Ku-Band payload is estimated to be better than +3 dB/K over mainland and +2 over the islands.

The communication payload consists of

• Normal C-band : 24 transponders

• Upper Extended C-Band : 12 transponders

• Ku-Band : 12 transponders

• Beacon Transmitter : 01

FREQUENCY BANDS

L-band(1-2GHz)

Global Positioning System (GPS) carriers and also satellite mobile

phones, such as Iridium; Inmarsat providing communications at sea, land

and air; WorldSpace satellite radio.

S-band (2–4 GHz)

Weather radar, surface ship radar, and some communications satellites,

especially those of NASA for communication with ISS and Space Shuttle.

In May 2009, Inmarsat and Solaris mobile (a joint venture between

Eutelsat and Astra) were awarded each a 2×15 MHz portion of the S-band

by the European Commission.

C-band(8-12GHz)

Primarily used for satellite communications, for full-time satellite TV networks or raw satellite feeds. Commonly used in areas that are subject to tropical rainfall, since it is less susceptible to rainfade than Ku band (the original Telstar satellite had a transponder operating in this band, used to relay the first live transatlantic TV signal in 1962).

X-band(8-12GHz)

Primarily used by the military. Used in radar applications including continuous-wave, pulsed, single-polarisation, dual- polarisation, synthetic aperture radar and phased arrays. X-band radar frequency sub-bands are used in civil, military and government institutions for weather monitoring, air traffic control, maritime vessel traffic control, defence tracking and vehicle speed detection for law enforcement.

Ku-band(12-18GHz)

Used for satellite communications. In Europe, Ku-band downlink is used from 10.7 GHz to 12.75 GHz for direct broadcast satellite services, such as Astra.

Ka-band(26-40GHz)

Communications satellites, uplink in either the 27.5 GHz and 31 GHz bands, and high-resolution, close-range targeting radars on military aircraft

Application

Communications

Television broadcasting

Weather forecasting,

A number of important defence and intelligence applications.

CostThe satellite was insured with an amount of ₹ 865 Crore.

Department of space had approved ₹ 800 Crore for the satellite

in financial year 2013-14.

SUMMERY OF GSAT-16

Launch Mass: 3181.6 kg

Dimension: 2.0 m x 1.77 m x 3.1 m cuboid

Launch Date: Sunday, December 7, 2014

Mission Life: 12 Years

Power: Solar array providing 6000 Watts and two 180 AH Lithium ion

batteries Ariane-5 VA-221

Type of Satellite: Communication

Manufacturer: ISRO

Owner: ISRO

Application: Communication

Orbit Type: GSO

GSAT-16 TEAM