SEMINAR ON Presented By : Dusmant Sahu M C A 4 th Semester Regd. No

 INTRODUCTION  What is a satellite phone ?  Geostationary Orbit  LEO Orbit  SATELITE PHONE SERVICES  Global star System  How do satellite phones work?  Advantage  Disadvantage  Conclusion CONTENT

INTRODUCTION Probably the largest area of satellite usage is the telephone market. Satellite phones have become an essential part of communicating for businesses professionals, and even individuals. Sure cell coverage is found in most developed areas but not in more remote areas or undeveloped areas such as third world countries. That’s where satellite phones are needed. In fact you can communicate around the world with a Global satellite phone.

WHAT IS A SATELLITE PHONE ?  A satellite telephone, satellite phone, or satphone is a mobile phone that communicates directly with orbiting communications satellites and the coverage area may include the entire earth.  Satellite telephones are utilized in circumstances where there is no access to a telephone or cellular network.  The Satellite phones either make use of satellites in geostationary orbit or they make use of satellites in low earth orbit.

MAIN TOPIC

GEOSTATIONARY ORBIT A geostationary orbit (GEO) is an geosynchronous orbit directly above the Earth's equator (0º latitude). Satellite orbits in the direction of the Earth's rotation, at an altitude of approximately 35,786 km above ground. This altitude is significant because it produces an orbital period equal to the Earth's period of rotationgeosynchronous orbitEarthequatorlatitudealtitude35,786 kmorbital periodrotation

LOW EARTH ORBIT A low Earth orbit (LEO) is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km.orbit

SATELITE PHONE SERVICES GEOSTATIONARY SERVICES LEO SERVICES

These satellite phones use satellites in the geostationary 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 is required for signal transmission and reception.EXAMPLES  Inmarsat satellite system GEOSTATIONARY SERVICES

MAIN TOPIC  Inmarsat plc is an international telecommunications company founded in 1979, originally as an intergovernmental organization.  It operates a fleet of 11 geosynchronous communication satellite.  Inmarsat provides telephony and data services to users world-wide INMARSAT SATELLITE PHONE SYSTEM

SERVICE PROVIDED Services include traditional voice calls, high- speed data services and facility like GPRS is also provided at the rate of 492 kbps. The voice calls rate are the same wherever in the world service is used.

LEO SERVICES  LEO satellites orbit the earth at high speed, low altitude orbits with an orbital time of 70–90 minutes, an altitude of 640 to 1120 kilometres and provide coverage cells. speedaltitudeminutes EXAMPLE  Iridium satellite phone system  Globalstar satellite phone system

Iridium satellite Phone System  This system originally had 77 active satellites and hence it is called IRIDIUM which is the name of an element whose atomic number is 77.  Now it has a fleet of 66 active satellites.  This service was launched in nov1,1998. But it could not survive because of the high cost of calls and large size of the hand sets.

MAIN TOPIC Global system  Globalstar satellite phone service is delivered through 48 Low-Earth-Orbiting satellites providing both voice and data services.  The Globalstar LEO constellation is only 700 miles from earth which allows for the highest quality voice clarity of any satellite phone in the industry.

Globalstar satellite phone System When a call gets initiated it is picked up by 4 satellites which combine the signals into one signal. This combined signal is then transmitted to one of several terrestrial "gateways." The gateways are the ground stations who direct the signal to the call destination.

WORKING PROCESS OF A GLOBAL SATELITE PHONE

ADVANTAGES probability of call blocking is greatly reduced. Since the call is being picked up by 4 satellites the probability of call blocking is greatly reduced. no interruption. no interruption.

HOW DO SATELLITE PHONES WORK? Just like cellular phones, satellite phones use radio waves to send their signal. Because satellite phones use satellite signals, the antenna is a little larger, and they must be used in an area where there is unobstructed sky.

ADVANTAGES OF SATELITE PHONE  Use in disaster response  Reliability  Easier to use (similar to using a mobile phone)  No installation required  Easy for other people to call you

DISADVANTAGES  A disadvantage of a satellite phone is a noticeable delay in conversations. The signal must first travel to the satellite, then to an earthbound gateway before being routed to the receiver. The receiver's response will follow the same path in reverse, taking equally long to reach the caller.  Satellite phones are also more expensive than cellular phones.

The call path of the satellite phones is disaster free. Provides global coverage. But still satellite phones are not as popular as the cellular phones probably because of the high cost of the calls. It is very famous in European countries but it has not become popular in the Asian countries. Research is going on in order to decrease call cost so that satellite phone becomes a common man’s phone