project report of tvro system

INSTITUTE OF ENGINEERING TECHNOLOGY

KATUNAYAKE

PROJECT REPORT OF

TVRO SYSTEM

ELECTRONICS & TELECOMMUNICATION

ENGINEERING

NATIONAL DIPLOMA IN ENGINEERING SCIENCES

[S.I.P. - PROJECT]

All Rights Reserved to Institute of Engineering Technology [NDES] Page 1

Preface

The satellite Communication is very important today’s world because of this globalization and most services are integrated also the service providers cost was tremendously went down during last few years. Therefore it is easy and cheap to take satellite link than getting optical fiber bandwidth. Therefore as an engineering students and today’s trends it is important to know how to align satellite receiver and this practical stuff was really helpful to understand the whole concept behind the satellite communication. In this report we highly concentrated with its practical aspect and we would use our practical experiences and we try to combine those practical scenarios with its real theoretical scenarios.


Acknowledgement

This Project Report is prepared to reflect a part of the subject Line & Radio Transmission. In our Specialized Instruction Program (SIP), This Report was so much valuable to get very good knowledge about TVRO System & Satellite Tracking. And also this provides a chance to improve our Report making skills as well. So, we would like to take this opportunity to thank those who support & encourage us to do this task. First of all we would like to give our very special thanks to Mr. K.A.S.S. Jayasinghe (HOD -Electrical) for his continuous support and guidance through Line & Radio Transmission subject and for giving confidence to do this Report.

Also we would like to thanks our senior NDES student Mr. Amila Niroshan who works at Dialog Axiata (pvt) Ltd. (Dialog TV) for giving us his maximum support & providing necessary equipment all the time. And numbers of times he visited our premises and inspects the project at times.

Finally we thank our colleague students of NDES 2010 batch for being with us and

helped us in so many ways.

2010th Batch

Electronics & Telecommunication Students

Department of Electrical Engineering

Institute of Engineering Technology

Katunayake.


Project Time Line


What is 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. Then 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.

Two satellites which are commonly used in satellite communication are Active and passive

satellites.

Passive satellites:-

It is just a plastic balloon having a metal coated over it. This sphere reflects the coming

microwave signals coming from one part of the earth to other part. This is also known as

passive sphere. Our earth also has a passive satellite i.e. moon.

Active satellites:-

It basically does the work of amplifying the microwave signals coming. In active satellites an

antenna system, transmitter, power supply and a receiver is used. These satellites are also

called as transponders. The transmitters fitted on the earth generate the microwaves. These

rays are received by the transponders attached to the satellite. Then after amplifying, these

signals are transmitted back to earth. This sending can be done at the same time or after

some delay. These amplified signals are stored in the memory of the satellites, when earth

properly faces the satellite. Then the satellite starts sending the signals to earth. Some

active satellites also have programming and recording features. Then these recording can be

easily played and watched. The first active satellite was launched by Russia in 1957. The

signals coming from the satellite when reach the earth, are of very low intensity. Their

amplification is done by the receivers themselves. After amplification these become

available for further use.


How Satellites Work

Orbit

First, as one would guess, satellites are launched into orbit. There are several types of orbit

for satellites to follow but the main three are Low Earth Orbit (LEO), Medium Earth Orbit

(MEO), and Geosynchronous Orbit (GEO). Satellites in a Low Earth Orbit are 100-300 miles

above the earth's surface, and it must travel around 17,500 mph, circling the planet in about

10 minutes, to avoid gravity pulling them back to earth. In a Medium Earth Orbit, a satellite

is 6,000–12,000 miles above the earth and will circle the planet 4 to 6 hours. The

Geosynchronous Orbit is a bit more complex, this orbit is 22,282 miles above the earth.

These satellites are positioned over the equator and rotate at the same speed as the earth.

This makes a satellite in a geosynchronous orbit remain in the same position above the

earth at all times (Boeing, 2002, p. 3).

Once a communication satellite is place in orbit, it receives signals and information from

earth. The signal being sent to the satellite is called the uplink. The satellite's transponder

then amplifies the signal, converts it to a different frequency, and sends it to another

satellite or to a ground station on earth. The signal sent back from the satellite is the

downlink (Boeing, 2002, p. 2).

Technology involved

There are many different types of technology involved with satellite communications. There

is technology used with the satellites themselves, to control the satellites and keep them

where they should be, as well as, the technology used for them relay signals back and forth

to earth. There are also numerous technologies used on the ground to interact with these

communication satellites to send and receive information.

The Satellite Technology

Communications satellites are comprised of many different subsystems to make a complete

system. Some of these subsystems are as follows:

● Propulsion subsystem is electric or chemical motors and thrusters used to reposition

the satellite or keep it in its proper orbit.

● Power subsystems comprised of solar panels that charge batteries to provide power

to the communications subsystem.

● The communications subsystem handles all transmit and receive functions. This

subsystem receives signals from earth, amplifies the signal received, and then

transmits the signal to another satellite or back to earth.

● Thermal control subsystem keeps active parts of a satellite cool enough function

properly by venting excessive heat into space.


● Attitude control subsystem interacts with the propulsion subsystem to keep a

satellite in its proper position. If a satellite falls out of position any data, television,

or telephone calls it is transmitting or receiving will be interrupted.

● Telemetry and Command subsystem allows operators to monitor and control the

satellite from the ground.

The Ground Technology

Different companies and organizations around the globe use communication satellites.

Governments, commercial entities, and individuals use satellite services. For example, we

have satellite television from companies like DirecTV, satellite phone service, global

positioning systems, imaging, and internet services. To have the ability to access the

satellites and services available requires specialized equipment to interact with the

satellites. The most important piece of equipment for any satellite service is an antenna,

you must have an uplink antenna to send anything to a satellite and a downlink antenna to

receive anything.

Future Trends

As with any technology that becomes available to everyone, there is always the chance that

it could be replaced by something superior or cheaper. This has a lot of effect on the way

that things are invented and if the item actually comes into production or not. With satellite

communications the major problem that is keeping it from blowing up in the industry is that

it is extremely expensive to set up. This can cause the private owned sector to balk at

obtaining satellite communications. As of now there are many different uses for satellites,

one of which is Direct TV, where satellites are used to program your TV and even get you

high speed internet(though this feature is not out yet).

One of the future technologies that is up and coming in the world today is laser technology.

Laser technology is extremely expensive and has many flaws in the current technology.

There are many different types of lasers out today, some can burn holes in objects, and

some can carry data and voice across a set distance. You can even see some by the naked

eye, and some are invisible. Below is a chart explaining which lasers you can see and which

lasers you cannot see.

The flaws of laser technology are that it can be very expensive to set up, and it has a short

distance LOS or Line of Sight. This can be very inconvenient when you are trying to use it to

get voice and data communications across the world. One of the good aspects of laser

technology is that a single laser diode can carry 10 gigahertz of data! This is an incredible

amount of data to cross one network. Even though a single beam of light can transfer a lot

of data, it is still limited on how far it can travel.


Internet Voice, also known as Voice over Internet Protocol (VoIP), is a technology that

allows you to make telephone calls using a broadband Internet connection instead of a

regular (or analog) phone line. Some services using VoIP may only allow you to call other

people using the same service, but others may allow you to call anyone who has a

telephone number - including local, long distance, mobile, and international numbers. Also,

while some services only work over your computer or a special VoIP phone, other services

allow you to use a traditional phone through an adaptor.

Because VoIP is digital, it may offer features and services that are not available with a

traditional phone. If you have a broadband internet connection, you need not maintain and

pay the additional cost for a line just to make telephone calls. With many VoIP plans you can

talk for as long as you want with any person in the world (the requirement is that the other

person has an Internet connection). You can also talk with many people at the same time

without any additional cost. If you're considering replacing your traditional telephone

service with VoIP, there are some possible differences:

● Some VoIP services do not work during power outages and the service provider may

not offer backup power.

● Not all VoIP services connect directly to emergency services through 9-1-1.

● VoIP providers may or may not offer directory assistance/white page listings.

Some of the examples of companies that use and buy satellite communications are the

military, private and commercial use. Of course the military has far more uses for satellites

than the citizens. Military uses can consist of satellite imagery and satellite phones, the

imagery part can help the C.I.A or any other intelligence agency find and pinpoint anyone in

the world (though we all know they can't find anyone useful).

Not only can it find people but also it can help them locate tanks, trucks, planes and other

avenues of mass destruction. Satellite phones are a great asset to the military and private

sectors because it will allow communications even when there are no land lines or they

have been taken out. Prime example of this is when hurricane Katrina hit land and New

Orleans was destroyed, we were able to use satellite communications because everything

else was destroyed.

Other company that use satellite are NASA and weather forecasters, these satellites allow

these companies to help predict and track the storms that come through the United States

and all over the world. If these were not in place, there would be a countless number of

people to have lost their lives in hurricane Katrina.

The last company that we would like to talk about is Direct TV. This company is a cable

service provider that uses satellites to feed the signal to the end user. This company is only

capable of sending a signal to a receiver at this time and not able to receive signals from

houses. DirecTV offers data services, however, their internet service has the same


restrictions, and they send high-speed data to the end user but cannot receive any uploaded

data. All data sent by the end users of DirecTV internet services have to use an alternate

source to upload data, such as, a phone line.

Satellite Communication Introduction & History

History of Satellite Communications

The first idea of satellite communication came from an article in 1945 named Wireless

World, where Author C. Clarke described the use of manned satellites in 24 hour orbits to

distribute television programs. However, the first person to carefully evaluate the technical

and financial aspects of such a venture was John R. Pierce of Bell Telephone Laboratories.

In a 1954 speech and 1955 article, Pierce described the usefulness of a communications

"mirror" in space, a medium-orbit "repeater" and a 24-hour-orbit "repeater." In comparing

the communications capacity of a satellite, which he estimated the capacity at 1,000

simultaneous telephone calls, and the capacity of the first trans-atlantic telephone cable,

which could carry 36 simultaneous telephone calls at a cost of 30-50 million dollars, Pierce

wondered if a satellite would be worth a billion dollars.

By the middle of 1961, RCA had a contract with NASA to build, a 4000 mile high, medium-

orbit, active communications satellite called RELAY, AT&T was working on its own medium-

orbit satellite called TELSTAR, and Hughes Aircraft Company had an exclusive contract to

build a 24-hour orbit, 20,000 mile high satellite, called SYNCOM. By 1964, two TELSTARs,

two RELAYs, and two SYNCOMs had operated successfully in space. The transponder

technology used by AT&T in the TELSTAR I satellite is current technology in use today.

On April 6, 1965, a new company called COMSAT launched its first satellite, EARLY BIRD,

from Cape Canaveral beginning Global satellite communications. The EARLY BIRD satellite

provided almost 10 times the capacity of submarine telephone cables for almost 1/10th the

price. Satellites are still competitive with cable for point-to-point communications, but the

future advantage may lie with fibre-optic cable.


Satellite Orbits

Satellites are launched into orbit, which is to say that they are shot up into the sky on

rockets to get them up above the atmosphere where there is no friction. The idea is to get

them flying so fast, that when they fall back to earth, they fall towards earth at the same

rate as the earth's surface falls away from them. When an object's path around the earth, its

"trajectory" matches the earth's curvature, the object is said to be "in orbit".

Orbital Distances

Any satellite can achieve orbit at any distance from the earth if its velocity is sufficient to

keep it from falling to earth and it is free of friction from earth's atmosphere, and gravity is

strong enough to pull it back towards earth. Distance from the earth can become a problem.

The farther the satellite is from the earth, the longer it takes for a radio or microwave

frequency transmission to reach the satellite. The altitudes at which satellites can orbit the

earth are split into three categories:

● Low Earth Orbit (LEO)

● Medium Earth Orbit (MEO)

● High Earth Orbit (HEO)

Satellites can orbit around the equator or the poles, though technically they can orbit the

earth on any elliptical or circular path.

● Equatorial Orbit

● Polar Orbit

When a satellite's orbit matches the rotation of the earth, and it's position over the earth

remains fixed, it's called Geostationary or geosynchronous orbit.


Orbit Distance Miles Km 1-way

Low Earth Orbit (LEO) 100-500 160 - 1,400 50 ms

Medium Earth Orbit (MEO) 6,000 - 12,000 10 -15,000 100 ms

Geostationary Earth Orbit (GEO) ~22,300 36,000 250 ms

High Earth Orbit (HEO) Above 22,300 Faster than 36,000 300 ms or more

Low Earth Orbit (LEO)

Typical Uses: Satellite phone, Military, Observation

Satellites in low earth orbit (LEO) satellites complete one orbit roughly every 90 minutes at a

height of between 100 and 500 miles above the earth's surface. This means that they are

fast moving ( >17,000mph) and sophisticated ground equipment must be used to track the

satellite. This makes for expensive antennas that must track the satellite and lock to the

signal while moving.

Satellites in this orbital range also have a very small 'footprint'--that is, the surface of the

earth that can be covered by the signal broadcast from the satellite is small. Thus, lots of

satellites (35 or more) are required to make worldwide communication possible. At several

million dollars per satellite, this is a very expensive satellite network to build and maintain.

Medium Earth Orbit (MEO)

Typical Uses: Weather Satellites, Observation, spy satellites

Most of the satellites in medium earth orbit circle the earth at approximately 6,000 to

12,000 miles above the earth in an elliptical orbit around the poles of the earth. Any orbit

that circles around the poles is referred to as a 'polar orbit'. Polar orbits have the advantage

of covering a different section of the earth's surface as they circle the earth. As the earth

rotates, satellites in polar orbits can cover the entire surface of the earth. Fewer satellites

are required to create coverage for the entire earth, as these satellites are higher and have a

larger footprint. Spy satellites typically use medium earth, polar orbits to cover as much of

the earth's surface as possible from one satellite.

High Earth Orbit (MEO)

Typical Uses: Space Observation, Weather Observation

High earth orbit places the satellite well outside the atmosphere and far enough away from

the earth and its radiation sources to minimize the earth's impact on measurements and

observations made by the satellites. However, at those altitudes the satellite cannot match

the rotation of the earth and so are not geostationary.


Geostationary and Geosynchronous (GEO)

Typical Uses for satellites in Geostationary Orbits: Television satellites, Long Distance

Communications satellites, Internet, Global Positioning Systems (GPS)

At 22,240 miles above the earth, craft inserted into orbit over the equator and travel at

approximately 6,880 miles per hour around the equator and which follow the earths

rotation are said to be in Geostationary orbit. Geostationary orbits allow these satellites to

maintain their relative position over the earth's surface. Since the satellite stays above the

same spot on earth's surface, geostationary orbits are also called geosynchronous.

Craft in geostationary orbit don't need to be tracked, reducing the cost of earth station

antennas. Geostationary craft also have the advantage of height, giving them the broadest

footprint (the signal broadcast covers the most earth surface), but this same height makes

them unsuitable for Voice, Voice over IP and other latency-sensitive services due to the

ground-satellite-ground propagation times (225 ms round trip or more). Additional power

and larger dishes are also required to boost the signal to the satellite and receive the signal

on the ground. Signals in geostationary systems also must pass through the entire

atmosphere and suffer the greatest dissipation of all three orbital systems.

Ground stations in the northern hemisphere point south to the equator to send and receive

to satellites. Ground stations in the southern hemisphere point north to communicate with

the same satellites. Geostationary satellites do have one small limitation. Ground stations

that are too far north or south (at the poles) cannot 'see' the geostationary satellite as the

curve of the earth is between the ground station and the satellite. Thus, satellites in other

orbits must be used.

Geostationary satellites are 'parked' in positions over the equator to maximize coverage

over the inhabited portions of the earth. This area in space forms a belt and is referred to as

the 'Clarke Belt' because it was noted science-fiction author Arthur C. Clarke that was the

first to propose the idea.

Polar Orbit

A satellite in this orbit flies over the earth from pole to pole. They are typically inserted at

lower orbits. Many polar orbits are elliptical in nature, and most polar craft are in the MEO

altitude. This orbit is most commonly used in surface mapping and observation satellites as

they allow a satellite which orbits the earth to take advantage of the earth's rotation to

cause the entire surface of the earth to pass below the satellite. Many of the pictures of the

earth's surface in applications such as Google Earth come from satellites in these polar

orbits.


Elliptical

An elliptical orbit is an oval shaped orbit used to place the orbit close to earth in specific

locations and to orbit at specific intervals. An elliptical orbit has two critical distances called

apogee and perigee. Perigee is when an orbital object is closest to the earth. Apogee is

when it is farthest away. Elliptical orbit satellites cover the polar regions where the

geostationary satellites cannot reach.

Azimuth and Elevation

Azimuth and elevation are angles used to define the apparent position of an object in the

sky, relative to a specific observation point. The observer is usually (but not necessarily)

located on the earth's surface.

The azimuth (az) angle is the compass bearing, relative to true (geographic) north, of a point

on the horizon directly beneath an observed object. The horizon is defined as a huge,

imaginary circle centered on the observer, equidistant from the zenith (point straight

overhead) and the nadir (point exactly opposite the zenith). As seen from above the

observer, compass bearings are measured clockwise in degrees from north. Azimuth angles

can thus range from 0 degrees (north) through 90 (east), 180 (south), 270 (west), and up to

360 (north again).

The elevation (el) angle, also called the altitude, of an observed object is determined by first

finding the compass bearing on the horizon relative to true north, and then measuring the

angle between that point and the object, from the reference frame of the observer.

Elevation angles for objects above the horizon range from 0 (on the horizon) up to 90

degrees (at the zenith). Sometimes the range of the elevation coordinate is extended

downward from the horizon to -90 degrees (the nadir). This is useful when the observer is

located at some distance above the surface, such as in an aircraft.

Azimuth and Elevation Calculations

All satellites today get into orbit by riding on a rocket. Many used to hitch a ride in the cargo

bay of the space shuttle. Several countries and businesses have rocket launch capabilities,

and satellites as large as several tons make it into orbit regularly and safely.

For most satellite launches, the scheduled launch rocket is aimed straight up at first. This

gets the rocket through the thickest part of the atmosphere most quickly and best

minimizes fuel consumption.


After a rocket launches straight up, the rocket control mechanism uses the inertial guidance

system (see sidebar) to calculate necessary adjustments to the rocket's nozzles to tilt the

rocket to the course described in the flight plan. In most cases, the flight plan calls for the

rocket to head east because Earth rotates to the east, giving the launch vehicle a free boost.

The strength of this boost depends on the rotational velocity of Earth at the launch location.

The boost is greatest at the equator, where the distance around Earth is greatest and so

rotation is fastest.

How big is the boost from an equatorial launch? To make a rough estimate, we can

determine Earth's circumference by multiplying its diameter by pi (3.1416). The diameter of

Earth is approximately 7,926 miles (12,753 kilometers). Multiplying by pi yields a

circumference of something like 24,900 miles (40,065 kilometers). To travel around that

circumference in 24 hours, a point on Earth's surface has to move at 1,038 mph (1,669

kmph). A launch from Florida's Cape Canaveral doesn't get as big a boost from Earth's

rotational speed. The Kennedy Space Center's Launch Complex 39-A is located at 28 degrees

36 minutes 29.7014 seconds north latitude. The Earth's rotational speed there is about 894

mph (1,440 kph). The difference in Earth's surface speed between the equator and Kennedy

Space Center, then, is about 144 mph (229 kph). (Note: The Earth is actually oblate -- fatter

around the middle -- not a perfect sphere. For that reason, our estimate of Earth's

circumference is a little small.)

Considering that rockets can go thousands of miles per hour, you may wonder why a

difference of only 144 mph would even matter. The answer is that rockets, together with

their fuel and their payloads, are very heavy. For example, the Feb. 11, 2000, liftoff of the

space shuttle Endeavour required launching a total weight of 4,520,415 pounds (2,050,447

kilograms) [source: NASA]. It takes a huge amount of energy to accelerate such a mass to

144 mph, and therefore a significant amount of fuel. Launching from the equator makes a

real difference.

Once the rocket reaches extremely thin air, at about 120 miles (193 kilometers) up, the

rocket's navigational system fires small rockets, just enough to turn the launch vehicle into a

horizontal position. The satellite is then released. At that point, rockets are fired again to

ensure some separation between the launch vehicle and the satellite itself.

Inertial Guidance Systems

A rocket must be controlled very precisely to insert a satellite into the desired orbit. An

inertial guidance system (IGS) inside the rocket makes this control possible. The IGS

determines a rocket's exact location and orientation by precisely measuring all of the

accelerations the rocket experiences, using gyroscopes and accelerometers. Mounted in

gimbals, the gyroscopes' axes stay pointing in the same direction. This gyroscopically stable

platform contains accelerometers that measure changes in acceleration on three different

axes. If it knows exactly where the rocket was at launch and the accelerations the rocket


experiences during flight, the IGS can calculate the rocket's position and orientation in

space.

Orbital Velocity and Altitude

A rocket must accelerate to at least 25,039 mph (40,320 kph) to completely escape Earth's

gravity and fly off into space (for more on escape velocity, visit this article at NASA).

Earth's escape velocity is much greater than what's required to place an Earth satellite in

orbit. With satellites, the object is not to escape Earth's gravity, but to balance it. Orbital

velocity is the velocity needed to achieve balance between gravity's pull on the satellite and

the inertia of the satellite's motion -- the satellite's tendency to keep going. This is

approximately 17,000 mph (27,359 kph) at an altitude of 150 miles (242 kilometers).

Without gravity, the satellite's inertia would carry it off into space. Even with gravity, if the

intended satellite goes too fast, it will eventually fly away. On the other hand, if the satellite

goes too slowly, gravity will pull it back to Earth. At the correct orbital velocity, gravity

exactly balances the satellite's inertia, pulling down toward Earth's center just enough to

keep the path of the satellite curving like Earth's curved surface, rather than flying off in a

straight line.

The orbital velocity of the satellite depends on its altitude above Earth. The nearer to Earth,

the faster the required orbital velocity. At an altitude of 124 miles (200 kilometers), the

required orbital velocity is a little more than 17,000 mph (about 27,400 kph). To maintain an

orbit that is 22,223 miles (35,786 kilometers) above Earth, the satellite must orbit at a speed

of about 7,000 mph (11,300 kph). That orbital speed and distance permit the satellite to

make one revolution in 24 hours. Since Earth also rotates once in 24 hours, a satellite at

22,223 miles altitude stays in a fixed position relative to a point on Earth's surface. Because

the satellite stays right over the same spot all the time, this kind of orbit is called

"geostationary." Geostationary orbits are ideal for weather satellites and communications

satellites.

In general, the higher the orbit, the longer the satellite can stay in orbit. At lower altitudes, a

satellite runs into traces of Earth's atmosphere, which creates drag. The drag causes the

orbit to decay until the satellite falls back into the atmosphere and burns up. At higher

altitudes, where the vacuum of space is nearly complete, there is almost no drag and a

satellite like the moon can stay in orbit for centuries.

Satellite Launch Window

Most people think that satellites can be launched from anywhere and at any time. The truth

is actually much more technically complicated than that. Satellite launches are carefully

planned and orchestrated events, not only because building satellites and shooting them off

to space requires a considerable amount of time, effort, money and manpower but also


because ill-timed launches can be downright dangerous. In order to successfully launch a

satellite, ground control and its engineers must carefully consider what's called the launch

window.

What is a satellite launch window?

The launch window refers to the specific time when a satellite can be shot and placed into

orbit the easiest. This time period is critical to the success of every launch because it

requires careful calculations to ensure that the satellite reaches the correct altitude and

speed so it can perform its specific function.

The launch window is also extremely important for the successful launching of the Space

Shuttle. It is also vital in ensuring that astronauts can be brought safely back to Earth in case

something goes awry during their flight. Astronauts have to land on an area that is not only

safe but also accessible to a rescue team. For other space flights such as interplanetary

exploration, it’s important to choose a launch window that will allow for the most fuel and

resource efficient course so the vehicle will be able to reach its destination.

Just how important is the launch window? In case of bad weather or if a glitch or

malfunction is discovered during this time period, the flight will have to be postponed or if

necessary, cancelled until the launch vehicle is deemed good to go during the next available

launch window. If the satellite is launched without paying any attention to the correct

launch window, there is a high likelihood it could enter the wrong orbit and fail its intended

purpose. When it comes to launching satellites, timing is key.

Satellite Frequency Bands Chart

Satellite Frequency Bands Chart is a chart and details and information showing the satellite

frequency bands as designated for international use.

Satellite technology is developing fast, and the applications for satellite technology are

increasing all the time. Not only can satellites be used for radio communications

applications, but they are also used for astronomy, weather forecasting, broadcasting,

mapping and very many more applications. In view of the variety of satellite frequency

bands that can be used, designations have been developed so that they can be referred to

easily.

The satellite frequency bands chart given below provides information about the most

commonly used designations for the satellite frequency bands.


Letter Designation for Satellite Frequency Band

Frequency Range (GHz)

L 1 - 2

S 2 - 4

C 4 - 8

X 8 - 12 ( 8 – 12.5 in North America )

Ku 12 – 18

K 18 – 27 ( 18 - 25.5 in North America )

Ka 27 - 40 ( 26.5 - 40 in North America )

O 40 - 50

V 50 - 75

Satellite Foot Prints

Satellite Footprint is the area of the earth visible to the satellite. Since the ability to

accurately view portions of the earth deteriorate as the edge of the footprint is reached,

satellite footprints overlap providing coverage for these areas. The best way to visualize a

satellite footprint is to view the full disk image from that satellite.


Online Resources

www.dishpointer.com provides us the all relevant details to be applied for the Receiver Antenna.

Elevation Angle, Azimuth, LNB skew ….. Etc.

http://www.dishpointer.com/


www.lyngsat.com provides us all the relevant details to be applied for the set top box interfaces

related to satellite parameters.

http://www.lyngsat.com/


Sat Finder android application on www.play.google.com will ease our stuff when finding directions

to receive satellite signals.

http://www.play.google.com/


ASIA SAT

Asia Satellite Telecommunications Company Limited (AsiaSat), which has been Asia's

premier regional satellite operator since established in 1988, is a dedicated pioneer in

advancing satellite communications in Asia. Asia Sat Telecommunications endeavor to

provide highly reliable satellite services and technical excellence for clients.

Being committed to offer customer-oriented, professional and proactive services, AsiaSat

has achieved the market leader position and enjoyed industry recognition over the years,

thus winning many sizable broadcasting and telecommunications enterprises, and

governments' confidence to be their professional partner. Through their four satellites,

AsiaSat 3S, AsiaSat 4, AsiaSat 5 and AsiaSat 7, AsiaSat enables billions of people around the

world to get access to information and communication channel.

AsiaSat's satellite fleet:

*is the gateway in space connecting to more than 50 countries in Asia Pacific

*bridges the communication of over two-thirds of the world's population

*serves over 150 public and private television and radio broadcasters worldwide, offering

more than 450 television and radio channels

*offers operators and end users telecommunications services such as voice networks,

private VSAT networks and broadband multimedia services

AsiaSat is ever-advancing to enable Asia Pacific-wide satellite connection. In November

2011, AsiaSat ordered two more satellites, AsiaSat 6 and AsiaSat 8, planned to be launched

in the second half of 2014. In December 2013, AsiaSat has also commissioned AsiaSat 9,

expected to be launched in 2017. Their proven expertise in satellite operation is fuelled

relentlessly with innovative management ideas, advanced and leading edge but proven

technologies to upgrade our space and ground network, and operational facilities and

apparatus


ASIA SAT 7

Selected Channel

Settings applied on Downlink

Frequency Set to receive Asia Sat 7 satellite TV signals is 3745 MHz.

Polarization selected is Vertical.

Symbol Rate applied is 2626.

Forward Error Correction set as ¾.

Various uses of Satellite Communication

Navigation

Communication

Weather

Earth Observation


Navigation

Navigation satellite is an artificial

satellite stationed in space for the

purposes of navigation. Satellite

navigation is a space-based radio

positioning system that includes one

or more satellite constellations,

augmented as necessary to support

the intended operation, and that

provides 24-hour three-dimensional

position, velocity and time information to suitably equipped users anywhere on, or near, the

surface of Earth. A satellite navigation system provides users with sufficient accuracy and

integrity of information to be useable for critical navigation applications. The GPS system is

the first core element of the satellite navigation system widely available to civilian users.

The Russian satellite navigation system, GLONASS, which is similar in operation, is another

satellite constellation element of GNSS.

The current constellation consists of 21 operational satellites and 3 active spares. Satellites

are in orbits with approximately 12-hour periods operating at an altitude of 20,200

kilometres. The orbital constellation consists of six orbital planes, each inclined with respect

to the equatorial plane by about 55 degrees. Such an arrangement ensures that at any time

there are at least four (and up to 12) satellites above the horizon available for simultaneous

measurements. GPS satellites transmit on two L-band frequencies: 1.57542 GHz (L1) and

1.22760 GHz (L2). The L1 signal has a sequence encoded on the carrier frequency by a

modulation technique which contains two codes, a precision (P) code and a

coarse/acquisition (C/A) code. The L2 carrier contains only P-code that is encrypted for

military and authorized civilian users. Most commercially available GPS receivers utilize the

L1 signal and the C/A code.

P-code users determine their geocentric positions instantly to about 5 metres with a single

hand-held satellite receiver. The C/A codes repeat every millisecond and are available to

every user. These codes are also usable for positioning but they provide only about 20- to

30-metre accuracy.

GPS-equipped balloons are monitoring holes in the ozone layer over the Polar Regions, and

air quality is being monitored using GNSS receivers. Buoys tracking major oil spills transmit

data using GNSS. Archaeologists and explorers are using the system.


Communication

A communications satellite is an artificial satellite stationed

in space for the purposes of telecommunications. Modern

communications satellites use geosynchronous orbits,

Molniya orbits or low Earth orbits.

Applications of communication satellite

Telephony

The first and still, arguably, most important application for communication satellites is in

international telephony. Fixed-point telephones relay calls to an earth station, where they

are then transmitted to a geostationary satellite. An analogous path is then followed on the

downlink. In contrast, mobile telephones (to and from ships and airplanes) must be directly

connected to equipment to uplink the signal to the satellite, as well as being able to ensure

satellite pointing in the presence of disturbances, such as waves onboard a ship.

Hand held telephony (cellular phones) used in urban areas do not make use of satellite

communications. Instead they have access to a ground based constellation of receiving and

retransmitting stations.

Televiosion and Radio

There are two types of satellites used for television and radio:

Direct Broadcast Satellite (DBS): DBS is a term used to refer to satellite television broadcasts

intended for home reception, also refered to as direct-to-home signals. It covers both

analogue and digital television and radio reception, and is often extended to other services

provided by modern digital television systems, including video-on-demand and interactive

features. A "DBS service" usually refers to either a commercial service, or a group of free

channels available from one orbital position targetting one country.

Fixed Service Satellite (FSS): FSS is the official classification for geostationary

communications satellites used chiefly for broadcast feeds for television and radio stations

and networks, as well as for telephony, data communications, and also for Direct-To-Home


(DTH) cable and satellite TV channels. Before the advent of direct broadcast satellite or DBS,

technology, FSS satellites were used for DTH satellite TV from the late 1970s into the 1980s,

up until the first DBS television system was launched in 1989 for Sky TV in the UK, with

DirecTV following suit in the USA in 1994. FSS satellites were the first geosynchronous

communications satellites launched in space (such as Intelsat 1 (Early Bird), Syncom 3, Anik

1, Westar 1, Satcom 1 and Ekran).

FSS satellites operate in either the C band (from 3.7 to 4.2 GHz) and the FSS K bands (from

11.45 to 11.7 and 12.5 to 12.75 GHz in Europe, and 11.7 to 12.2 GHZ in the United States).

FSS satellites operate at a lower power than DBS satellites, requiring a much larger dish than

a DBS system, usually 3 to 8 feet for K band, and 12 feet on up for C band (compared to 18

to 24 inches for DBS dishes). Also, unlike DBS satellites which use circular polarization on

their transponders, FSS satellite transponders use linear polarization.

Systems used to receive television channels and other feeds from FSS satellites are usually

referred to as TVRO (Television Receive Only) systems, as well as being referred to as big-

dish systems (due to the much larger dish size compared to systems for DBS satellite

reception), or, more pejoratively, BUD, or big ugly dish systems.

Mobile Satellite Technology

Initially available for broadcast to stationary TV receivers, popular mobile direct broadcast

applications made their appearance with that arrival of two satellite radio systems : Sirius

and XM Satellite Radio Holdings. Some manufacturers have also introduced special antennas

for mobile reception of DBS television. Using GPS technology as a reference, these antennas

automatically re-aim to the satellite no matter where or how the vehicle (that the antenna

is mounted on) is situated. These mobile satellite antennas are popular with some

recreational vehicle owners.

Amateur radio

Amateur operators have access to the OSCAR satellites that have been designed specifically

to carry amateur radio traffic. Most such satellites operate as spaceborne repeaters, and are

generally accessed by amateurs equipped with UHF or VHF radio equipment and highly

directional antennas such as Yagis or dish antennas. Due to the limitations of ground-based

amateur equipment, most amateur satellites are launched into fairly low Earth orbits, and

are designed to deal with only a limited number of brief contacts at any given time. Some

satellites also provide data-forwarding services using the AX.25 or similar protocols.


Satellite Broadband

In recent years, satellite communication technology has been used as a means to connect to

the internet via broadband data connections. This is very useful for users to test who are

located in very remote areas, and can't access a wireline broadband or dialup connection.

Weather.

Weather forecast use a variety of observations from which to

analyses the current state of the atmosphere. Since the launch

of the first weather satellite in 1960 global observations have

been possible, even in the remotest areas. Observation as

obtained from satellite used in Numerical Weather Prediction

(NWP) model.

During the 1970s and 1980s a wide range of satellite missions

have been launched from which many different meteorological

observations could be estimated. Some satellite instruments allowed improved estimation

of moisture, cloud and rainfall. Others allowed estimation of wind velocity by tracking

features (e.g. clouds) visible in the imagery or surface wind vectors from microwave

backscatter.

Satellite imagery (visible, infrared and microwave)

The most basic form of satellite imagery provides pictures of the current cloud conditions.

This is a familiar sight on TV weather forecasts. However, satellite imagery can also undergo

various types of quantitative processing to obtain information on important meteorological

variables such as wind speed and direction, cloud height, surface temperature, sea ice

cover, vegetation cover, precipitation, etc.

The first meteorological satellite was launched in 1960 by the USA and provided cloud cover

photography. Originally, satellite images were treated purely as qualitative pictures, which

were manually viewed and interpreted by meteorologists. Nowadays though, satellite

imagery undergoes a great deal of mathematical manipulation and can yield quantitative

analyses of atmospheric temperature, humidity, motion and many more meteorological

variables. The major advantage of satellites is their ability to produce near-global coverage,

which becomes especially important over oceans and remote, unpopulated land regions,

where other methods of observation are impracticable. Over large areas of the southern

hemisphere, satellites are the only means of Earth observation. As well as observing

changes in surface features such as vegetation and sea surface temperature, satellite

imagery can also capture the development of transient features such as clouds of water or

ice and plumes of ash or dust.


Two types of satellite having on board instruments used for earth weather images:

o Polar orbiters are positioned about 900 km above the surface of the Earth, in a

sunsynchronous orbit, which means they see the same part of the Earth at the same

time each day. Polar orbiters make about 14 orbits a day and can view all parts of

the atmosphere at least twice a day. Although their temporal resolution is limited,

they have high spatial resolution (typically around 1 km between pixels) since they

are relatively close to the Earth's surface.

o Geostationary satellites are positioned about 36,000 km above the equator in a

geostationary orbit, which means they are always fixed in position above one part of

the Earth. These satellites scan continuously (hence have high temporal resolution

15-30 minutes), but have limited spatial resolution (typically 3-10 km between

pixels).

Radiance is measured by the satellite instrumentation and stored as digital values in two-

dimensional arrays of pixels, which make up the image. Different instruments scan at

different wavelength bands, and provide different information about the atmosphere:

o Infrared radiation, particularly around 12.5 µm, tells us about the temperature of

emitting bodies, such as clouds or the surface in cloud-free regions. IR images are

particularly good for viewing clouds and images can be produced at night.

o Water vapour radiation, centred around 6.7 µm, measures radiation in the water-

vapour absorption band. WV images are good for viewing water vapour distributions

in cloud-free areas, and for viewing clouds. Most of the radiation sensed is from the

300-600 hPa layer.

o Visible radiation, produced in a wavelength band ~ 0.5-0.9 µm, shows clouds but

only by reflected sunlight, so no images are produced at night.

Earth Observation

Understand and analyzing global environmental conditions is an

essential element of guaranteeing our safety and quality of life.

Among other things, we need to be able to spot environmental

disasters in a timely manner, and to monitor and manage the

Earth’s natural resources. For this purpose, a number of Earth

Observation satellites are in orbit for Earth observations. Data

collected by these satellites allow us to understand the

processes and interactions among land masses, oceans, and

atmosphere. The utility of different data sets for different applications are agriculture,

forestry, geology, risk management, cartography, environment, and defence.


Agriculture

Agriculture is one of the most important application fields using Earth Observation data

from all missions, where other data sources are often too expensive, or too restricted in

scope.Typical applications include crop inventory, yield prediction, soil/crop condition

monitoring and subsidy control. The scale of products varies, but typical applications are

based on the recognition of individual agricultural parcels.

Forestry

EO data has assumed great importance in forest mapping and management, fire damage

monitoring and the increasingly important problem of illegal logging in many countries.

Typical applications include inventory & updating, Mapping, Change detection, Forest

Health Analyses, Fragmentation Analyses, Forest road maps, Digital Elevation Model.

Geology

Geology and related oil, mineral and gas exploration activities make up an application

segment that takes full advantage of satellite capabilities. The large-scale satellite view

allows the generation of Rock Unit Maps and Tectonic Structure Maps. Interferometry

allows the generation of Digital Elevation Models (DEMs) and the monitoring of mining

subsidence, while radar data are a powerful tool for off-shore oil seep detection and

monitoring. Alternative methodologies, such as the use of existing published maps, ground

survey mapping or aerial photography, when available, need be used only when very local

and detailed information is required.

Risk management

Risk management is one of the fields where EO data may play a primary role. Three different

risk situations may be considered:

o Pre-crisis

o During crisis

o Post-crisis

Products needed in the first situation are mainly related to the collection of land cover,

geological and hydrological information, while near-real time mapping and tracking of

events is required in crisis and post crisis situations.


Currently satellite data are commonly used for the management of risk situations, but very

demanding user requirements (particularly for better revisit times), prevent fully

operational use. There are unexploited opportunities in this field.

In the three possible risk management situations, crisis prevention is currently seen as the

main opportunity, much more than crisis monitoring and damage assessment. This is mainly

due to the fact that the coverage needs of crisis monitoring and damage assessment are less

than those required for prevention or for monitoring of an on-going crisis. In addition, the

number of crises occurring around the world in one year remains rather small. The

importance of post-crisis analysis could be improved if the insurance sector should start

operational use of satellite data for the assessment of damage due to natural disasters.

Cartography

Earth Observation data make an excellent basis for medium to large scale cartography.

Consequently, this segment makes extensive use of satellite data, especially in those

situations where the requirements for accuracy can be met, and alternative data sources

are too expensive or even unavailable. Satellite data, with different processing levels, are

used for the generation of cartography and digital elevation models.

Environment

Earth Observation data offer powerful solutions for environmental monitoring. The data can

be used mainly - Land Use / Land Cover maps, Hydrological / Watershed map, Wildlife

Habitat Maps, Land Unit Maps Soil Contamination Map, Surface Water Condition Maps,

Wetland Analyses, Quarries and Waste Identification, Desertification analysis.

Defence & Security

For the defence and security, EO information is a key information source, and it is handled

with more and more sophisticated Geological Information System instruments. The main

applications are the generation of maps, target monitoring and detection, and digital

elevation model generation.


During Dish Renovation

During Dish Renovation


Testing with Temporary Establishment

More helping hands from batch crew and seniors, juniors as well.


Big help attained from Amila Niroshan (Senior Student)

Testing done using Satellite Meter


Basement shifting to recognized new location

Cleaning the Dish


Excavating the Cable Path

More Co-operations by the Colleagues


Cable Laying Stage

Cable drawn through PVC pipe


Cable Pipe surrounded by Full of Sands

Tile Layer above the Sand Layer


Warning tape has been laid over the buried cable

Completion of cable route.


Vacuumed the laboratory

Yay..!! Here we Go! A.k.a. Asiasat3s


Paradigm Shifts we did during our project…….


Contribution to the Project

Project Supervised by

_______________________ _______________________

Mr. H.D.C. Asanga Mr. K.A.S.S. Jayasingha

Lecturer HOD – Electrical (A)

Institute of Engineering Technology Institute of Engineering Technology

Katunayake. Katunayake.

_______________________

Mr. C.A.L.J. Chandrasekara

Director / Principal

Institute of Engineering Technology

Katunayake.

Admission No: Name Admission No: Name

ET/10/7882 H.D.U.A.Ariyaratne EE/10/7069 C.A.B.Godagama

ET/10/7885 S.C.Gallage EE/10/7900 D.S.R.Dolawaththa

ET/10/7903 M.D.D.M.Mahawaththa EE/10/7902 W.N.P.Silva

ET/10/7910 B.M.K.T.Bellana EE/10/7920 D.T.H.Perera

ET/10/7911 W.P.C.Tissera EE/10/7926 S.D.A.T.Karunarathna

ET/10/7922 K.K.S.P.Perera EE/10/7930 W.A.Y.L.Wijesuriya

ET/10/7923 T.D.M.B.K.Ranasinghe EE/10/7958 P.M.S.S.Perera

ET/10/7929 E.M.P.M.Ekanayake EE/10/7965 B.K.H.Kanchana

ET/10/7935 H.M.G.R.Bandara EE/10/7973 M.M.Wanniarachchi

ET/10/7956 K.P.K.N.Somaratna EE/10/7989 G.M.G.Ishara

ET/10/7961 A.A.K.N.Amarasinghe EE/10/7994 W.L.P.Fernando

ET/10/7968 R.M.P.M.Rathnayake EE/10/8008 M.B.H.Dilan

ET/10/7980 I.C.Hettige EE/10/8022 R.M.S.S.Rathnayake

ET/10/7992 W.P.S.Fernando EE/10/8038 P.H.T.S.Hewage

ET/10/8004 H.K.Athapattu EE/10/8040 K.D.N.P.Perera

ET/10/8027 S.L.D.Kasun EE/10/8060 W.K.C.J.Weeratunge

ET/10/8050 T.Mauthar

ET/10/8159 K.A.J.C.Fernando


Remarks