Satelight Phone

7/30/2019 Satelight Phone

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NAME


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CELLULAR PHONE SYSTEM In cellular phone system the entire coverage area is

being divided into a number of hexagonal cells.

Each cell is provided with a BASE STATION.

Each mobile stationcommunicates directly with thebase station.

Base stations of all the cells are connected to theMOBILE SWITCHING CENTER.

The MSC is then connected to the PUBLIC SWITCHEDTELEPHONE NETWORKso that the land phone userscan also be connected to the mobile users.


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Contd

The voice transmission and controlsignal transmission takes place through

two channelsVOICE CHANNEL

CONTROL CHANNEL

each of which can either be forwardvoice channel (FVC) or reverse voicechannel (RVC) or FCC or RCC.


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The Radio Spectrum

The Radio spectrum is composed of many frequency bands

Communication systems have the ability to transmit signals atvarious frequencies, and the FCC (Federal Communications

Commission) regulates which frequencies to use. Satellites and cell phones work in ultra high frequency range.


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Satellite Telephones

A satellite telephone, satellite phone, or satphone is amobile phone that communicates directly withorbiting communications satellites and the coveragearea may include the entire earth.

The Satellite phones either make use of satellites ingeostationary orbit or they make use of satellites inlow earth orbit.

Satellite telephones are utilized in circumstances

where there is no access to a telephone or cellularnetwork

For example ships at sea


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GEOSTATIONARY ORBIT

A geostationary orbit (GEO) is an geosynchronous orbit

directly above the Earth's equator (0 latitude). Satellite

orbits in the direction of the Earth's rotation, at an altitude

of approximately 35,786 km above ground. This altitudeis significant because it produces an orbital period equal to

the Earth's period ofrotation

LOW EARTH ORBITA low Earth orbit (LEO) is generally defined as an orbit

within the locus extendi

ng from the Earths surface up to

an altitude of 2,000 km.
http://en.wikipedia.org/wiki/Geosynchronous_orbithttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/1_E7_mhttp://en.wikipedia.org/wiki/Orbital_periodhttp://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Orbithttp://en.wikipedia.org/wiki/Orbithttp://en.wikipedia.org/wiki/Rotationhttp://en.wikipedia.org/wiki/Orbital_periodhttp://en.wikipedia.org/wiki/1_E7_mhttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Geosynchronous_orbit


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GEOSTATIONARY SERVICES

These satellite phones use satellites in thegeostationary orbits. They can maintain near-continuous global coverage with only three or four

satellites, reducing the launch costs.DISADVANTAGE

The satellite is so far away (approx. 22,000 miles)that a comparatively large antenna system isrequired for signal transmission and reception.

EXAMPLES

Inmarsat satellite system


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LEO satellites orbit the earth at highspeed, low altitude orbits with an orbitaltime of 7090 minutes, an altitude of640 to 1120 kilometres and provide

coverage cells.Since the satellites are notgeosynchronous they mustfly complete orbits and thus furtherguarantee complete coverage over everyarea by at least one satellite at all times.EXAMPLEIridium satellite phone systemGlobalstar satellite phone system

LEO SERVICES
http://en.wikipedia.org/wiki/Speedhttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/Minutehttp://en.wikipedia.org/wiki/Minutehttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/Speed


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Inmarsat plc is an international

telecommunications companyfounded in 1979, originally asan intergovernmentalorganization.It operates a fleet of 11geosynchronous communicationsatellite.Inmarsat provides telephonyand data services to users

world-wide

INMARSAT SATELLITE PHONE SYSTEM
http://localhost/var/www/apps/conversion/tmp/scratch_1/wiki/Image:Satellite_phone.jpg


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Inmarsat technology

An Inmarsat terminal contacts the satellite

The satellites are digital transponders that

receive digital signals, reform the pulses, andthen retransmit them to ground stations. Theground stations perform billing and act asgateways to the public switched telephone

network. They are called gateways because they direct

the calls to the called party.


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SERVICE PROVIDED

Services include traditional voice calls , high-speed data services and facility like GPRS is

also provided at the rate of 492 kbps. Users are simply charged for the amount of

data they send and receive rather than thelength of time they are online .

The voice calls rate are the same wherever inthe world service is used.


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Iridium (satellite)

This system originally had 77 activesatellites and hence it iscalled IRIDIUM which is the name of a nelement whose atomic number is 77.Now it has a fleet of 66 activesatellites.

This service was launched innov1,1998. But it could notservive because of the high cost of callsand large size of the hand sets. It wasfinally bought by a group of investorsfor 25 million.

The satellites used are frequentlyvisible in the night sky as short-livedbright flashes, known asIRIDIUMFLARES.
http://localhost/var/www/apps/conversion/tmp/scratch_1/wiki/Image:9505A_Iridium_phone.jpg


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IRIDIUM TECHNOLOGY

Satellites are in low Earth orbit at a height ofapproximately 485 miles. Satellites communicate withneighbouring satellites via intersatellite links. Each

satellite can have four intersatellite links.

Because of this satellite to satellite link the callbetween two satellite phones is much cheaper.Because the call does not make use of groundstations at all. It is required only when a call is to bemade to a land line number or to a cellular phone


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Iridium System

The satellites orbit from pole to polewith an orbit

of roughly 100 minutes. This design means thatthere is excellent satellite visibility and servicecoverage at the North and South poles, wherethere are few customers.


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Opposed to the terrestrial cellular system, the cellsites in the Iridium system are overhead

and are moving !


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Global system

Globalstar satellite phoneservice is delivered through

48 Low-Earth-Orbitingsatellites providing both

voice and data services.

The Globalstar LEOconstellation is only 700

miles from earth whichallows for the highest qualityvoice clarity of any satellitephone in the industry.


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Globalstar satellite phone technology

When a call gets initiated it is picked up by 4satellites which combine the signals into onesignal. This combined signal is then

transmitted to one of several terrestrial"gateways." The gateways are the groundstations who direct the signal to the calldestination. These gateways process calls,they distribute them to an existing fixed and

cellular local network. This is done when acall is to get matured between a satellitephone and a mobile.


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ADVANTAGES

Since the call is being picked up by 4satellites the probability of call blocking

is greatly reduced. If buildings or terrain block the phone's

line-of-sight to a satellite, a "soft hand-

off" will take the place switching the callto an another satellite with nointerruption.


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http://outfittersatellite.com/globalstar.htmhttp://outfittersatellite.com/globalstar.htmhttp://outfittersatellite.com/globalstar.htmhttp://outfittersatellite.com/globalstar.htmhttp://outfittersatellite.com/globalstar.htm


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http://localhost/var/www/apps/conversion/tmp/scratch_1/wiki/Image:9505A_Iridium_phone.jpghttp://www.satellitephone.com.au/satellitephones.htmhttp://www.satellitephone.com.au/telitsat550.htm


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When we need two way real time videoconferencing in tough field situation,we can use this video rental equipment.It has a built in video screen and cameraso that we are ready to conference as soonas we open the case.


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The call path of the satellite phones is disaster free.

Provides global coverage.

But still satellite phones are not as popular as thecellular phones probably because of the high cost ofthe calls. Minimum call rate is slightly lesser than a $per minute. It is very famous in European countriesbut it has not become popular in the Asian countries.

Research is going on in order to decrease call costso that satellite phone becomes a common mansphone


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Documents

Satelight Phone