Satellites FJHJnal

8/13/2019 Satellites FJHJnal

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OVERVIEW

Satellite technology has progressed tremendously over the last 5

since Arthur C. Clarke first proposed its idea in 1945 in his ar

Wireless World.

Today, satellite systems can provide a variety of services in

broadband communications, audio/video distribution networks, mnavigation, worldwide customer service and support as well as m

command and control.


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WHAT IS A SATELLITE?

A satellite is something that orbits

Moon is a natural satellite

satellites are made by scientists and technologists


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WHAT DOES A SATELLITE DO..?

A satellite orbits Earthit helps people communicate and learn more about our planet.

Camera maps

weather

Communications TV

Internet

Telephone, Mobile, Faxetc.


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HISTORY

Satellite communications began in October 1957 with the launch by the USSR a small satellite called Sputnik 1 Beacon transmitter, no communications capability

3.11.1957 Sputnik 2

12.4.1961 Vostok 1

First true communication satellites (Telstra I & II) were launched in July 1962 & May 1963

10/1964 Syncom 2: First GEO satellite, 7.4/1.8 GHz (one TV-channel or several 2-way telephone connections

1987 TVSAT: First DBS-satellite (Direct Broadcast Satellite, Television-broadcasts directly to home)


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KINDS OF SATELLITE

| LEO or Low Earth Orbit 100 to 300 miles, very fast, travel about 17,500 m/h

2| MEO or Medium Earth Orbit Oval orbit, travel about 17,500 m/h, largerthan LEOs, stay a longer time, orbit 6,000 to12,000 miles.

3| GEO or Geostationary Earth Orbit distance 22,282 miles ,circle the Earth in 24hours

cover a large part of the planet,

three satellites can cover the globe .


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(LEO)LOW EARTH ORBITING SATELLITE

LEO satellites are much closer to the earth than GEO satellites,

ranging from 500 to 1,500 km above the surface.

LEO satellites dont stay in fixed position relative to the

surface, and are only visible for 15 to 20 minutes each pass.

A network of LEO satellites is necessary for LEO satellites to

be useful


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Disadvantages:

A network of LEO satellites

which can be costly

LEO satellites have to comp

Doppler shifts cause by thmovement.

Atmospheric drag effects

satellites, causing gradua

deterioration.

Advantages:

A LEO satellites proximity to earth

compared to a GEO satellite gives it a

better signal strength and less of a

time delay, which makes it better forpoint to point communication.

A LEO satellites smaller area of

coverage is less of a waste of

bandwidth.


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Applications: It providing mainly

mobile data services.


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(MEO)MEDIUM EARTH ORBITING SATELLITE

A MEO satellite is in orbit somewhere between 8,000 km and

18,000 km above the earths surface.

MEO satellites are similar to LEO satellites in functionality.

MEO satellites are visible for much longer periods of time than

LEO satellites, usually between 2 to 8 hours.

MEO satellites have a larger coverage area than LEO satellites.


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Disadvantages:

A MEO satellites distanc

a longer time delay and

signal than a LEO satellthough not as bad as a G

satellite.

Advantages:

A MEO satellites longer

duration of visibility and

wider footprint means fewersatellites are needed in a MEO

network than a LEO network.


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Applications: Again providing mobile

telephony services


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GEOSTATIONARY ORBITS

These satellites are in orbit 35,863 kmabove the earths surface along theequator.

Objects in Geostationary orbit revolve

around the earth at the same speed asthe earth rotates. This means GEOsatellites remain in the same positionrelative to the surface of earth.


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Disadvantages:

A GEO satellites distance also

have both a comparatively wea

time delay in the signal, which

point to point communication. GEO satellites, centered above t

have difficulty broadcasting s

polar regions

Advantages:

A GEO satellites distance fromearth gives it a large coveragearea, almost a fourth of theearths surface.

GEO satellites have a 24 hour viewof a particular area.

These factors make it ideal forsatellite broadcast and othermultipoint applications..


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Applications: TV

Radio

telecommunications

broadcasting


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OTHER ORBITS

Molniya Orbit Satellites: Used by Russia for decades.

Molniya Orbit is an elliptical orbit. The

satellite remains in a nearly fixed position

relative to earth for eight hours.

A series of three Molniya satellites can act

like a GEO satellite.

Useful in near polar regions.


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OTHER ORBITS

High Altitude Platform (HAP): One of the newest ideas in satellite communication.

A blimp or plane around 20 km above the earths

surface is used as a satellite.

HAPs would have very small coverage area, butwould have a comparatively strong signal.

Cheaper to put in position, but would require a lot

of them in a network.


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THE FIXED PLACE


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FIGURE FOR REAL SATELLITE


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WHAT'S INSIDE A SATELLITE?

1. The propulsion subsystem.2. The power subsystem generates electricity

3.The communications subsystem

4.The thermal control subsystem:

5. Operators at the ground station :


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The Anatomy of a

Satellite

basic parts


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SATELLITE FREQUENCY BANDS

There are three most commonly used satellite frequency 1. C-band : transmissions between 4 to 8 GHz frequency range size of anmeters in diameter.2. Ku-band : transmissions between 11 to 17 GHz frequency range antenna

small as 18 inches in diameter.3. Ka-band: transmissions between 20 to 30 GHz frequency range. These vfrequency and very small antennas.


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ADVANTAGES& DISADVANTAGESSATELLITES

Disadvantages:

Launching satellites into o

costly.

Satellite bandwidth is gra

becoming used up.

There is a larger propagat

in satellite communication

terrestrial communicatio

Advantages:

The coverage area of a satellitegreatly exceeds that of a terrestrialsystem.

Transmission cost of a satellite isindependent of the distance from the

center of the coverage area. Satellite to Satellite communication is

very precise.

Higher Bandwidths are available foruse.


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APPLICATIONS OF A SATELLITE

Uses in the Wars .

Uses in the geologic and ceremonial .

Uses in the Communications .

Uses in the system GPS .

Uses in the espial .

Uses in the transmission of the television.

And a lot of applications .


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ENDLORILLA X MATANGCOY X MORALDA X MAXINOEND

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