Satelite presentation (n.singh)

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Satellite

A

presentation

on

By Mr. N. SINGH

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OVERVIEW

• Satellite technology has progressed tremendously over the last 50

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

article in Wireless World.

• Today, satellite systems can provide a variety of services including

broadband communications, audio/video distribution networks,

maritime navigation, worldwide customer service and support as

well as military command and control.

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OVERVIEW

• Satellite systems are also expected to play

an important role in the emerging 4G

global infrastructure providing the wide

area coverage necessary for the

realization of the “Optimally Connected

Anywhere, Anytime” vision that drives the

growth of modern telecom industry.

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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 Earth•it helps people communicate and learn more about our planet. • Camera

maps weather

•Communications TVInternetTelephone, Mobile, Fax…etc.

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History of Satellite CommunicationsHistory of Satellite Communications

•Satellite communications began in October 1957 with the launch by the USSR a small satellite called Sputnik 1 (4.10.1957)

•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 a Satellite

1) 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, larger than LEOs, stay a

longer time, orbit 6,000 to 12,000 miles.

3) GEO, or Geostationary Earth Orbit distance 22,282 miles ,circle the Earth in 24 hours cover a large part of the planet, three satellites can cover the globe .

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GEO MEO LEO

Orbit T ypes

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Low-Earth-orbiting SatellitesLow-Earth-orbiting Satellites

• LEO satellites are much closer to the earth than GEO satellites, ranging from 500 to 1,500 km above the surface.

• LEO satellites don’t 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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A LEO satellite’s proximity to earth compared to a GEO satellite gives it a better signal strength and less of a time delay, which makes it better for point to point communication.

A LEO satellite’s smaller area of coverage is less of a waste of bandwidth.

Advantages:

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A network of LEO satellites is needed, which can be costly

LEO satellites have to compensate for Doppler shifts cause by their relative movement.

Atmospheric drag effects LEO satellites, causing gradual orbital deterioration.

disadvantages:

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• It providing mainly mobile data services.

APPLICATION:

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MEDIUM-Earth-orbiting MEDIUM-Earth-orbiting SatellitesSatellites

•A MEO satellite is in orbit somewhere between

8,000 km and 18,000 km above the earth’s 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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A MEO satellite’s longer duration of visibility and wider footprint means fewer satellites are needed in a MEO network than a LEO network.

Advantage:

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• A MEO satellite’s distance gives it a longer time delay and weaker signal than a LEO satellite, though not as bad as a GEO satellite.

disadvantage:

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• Again providing mobile telephony services

APPLICATION:

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Geostationary orbitsGeostationary orbits

•These satellites are in orbit

35,863 km above the earth’s

surface along the equator.•Objects in Geostationary orbit

revolve around the earth at the

same speed as the earth

rotates. This means GEO

satellites remain in the same

position relative to the surface of

earth.

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Advantages:

A GEO satellite’s distance from earth gives it a large coverage area, almost a fourth of the earth’s surface.

GEO satellites have a 24 hour view of a particular area.

These factors make it ideal for satellite broadcast and other multipoint applications.

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A GEO satellite’s distance also cause it to have both a comparatively weak signal and a time delay in the signal, which is bad for point to point communication.

GEO satellites, centered above the equator, have difficulty broadcasting signals to near polar regions

disadvantages:

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APPLICATION:

• telecommunications

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APPLICATION:

•broadcasting

•TV

•Radio

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Other Orbits

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.

Molniya Orbit Satellites:

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Other Orbits

One of the newest ideas in satellite communication.

A blimp or plane around 20 km above the earth’s surface is used as a satellite.

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

Cheaper to put in position, but would require a lot of them in a network.

High Altitude Platform (HAP):

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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

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What's Inside a Satellite?

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 bands:

1. C-band : transmissions between 4 to 8 GHz frequency range , size of an antenna 2-3 meters in diameter.

2. Ku-band : transmissions between 11 to 17 GHz frequency range, antennas can be as small as 18 inches in diameter.

3. Ka-band: transmissions between 20 to 30 GHz frequency range. These very high frequency and very small antennas.

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Advantages of Satellites

• The advantages of satellite communication over terrestrial communication are: The coverage area of a satellite greatly

exceeds that of a terrestrial system. Transmission cost of a satellite is independent

of the distance from the center of the coverage area.

Satellite to Satellite communication is very precise.

Higher Bandwidths are available for use.

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Disadvantages of Satellites

• The disadvantages of satellite communication: Launching satellites into orbit is costly. Satellite bandwidth is gradually becoming

used up. There is a larger propagation delay in satellite

communication than in terrestrial communication.

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Applications of a Satellite

1) Uses in the Wars .

2) Uses in the geologic and ceremonial .

3) Uses in the Communications .

4) Uses in the system GPS .

5) Uses in the espial .

6) Uses in the transmission of the television.

And a lot of applications .

Satelite presentation (n.singh)

Education

Transcript of Satelite presentation (n.singh)