The characteristics and application of mobile satellite services
The growth of the Internet and improved wireless access has led existing MSS system operators to introduce new capabilities that include improved data and multimedia access.
This chapter addresses the history and evolution of the technology starting with the Marisat system in the s. This is relatively inexpensive.
Mobile satellite services ppt
These sets usually link into the standard cellular system. A telephone connection using MSS is similar to a cellular telephone link, except the repeaters are in orbit around the earth, rather than on the surface. Whalen, G. Since the satellite is so far above Earth, the radio signal is attenuated due to free-space path loss , so the signal received on Earth is very, very weak. The book presents current GMSC trends, mobile system concepts and network architecture using a simple mode of style with understandable technical information, characteristics, graphics, illustrations and mathematics equations. Telstar was the second active, direct relay communications satellite. Examples[ edit ] The first geostationary satellite was Syncom 3 , launched on August 19, , and used for communication across the Pacific starting with television coverage of the Summer Olympics.
However, it was not placed in orbit for the purpose of sending data from one point on earth to another. Please provide a Corporate E-mail Address. Therefore, to provide continuous communications capability with these lower orbits requires a larger number of satellites, so one will always be in the sky for transmission of communication signals.
In addition, there are important differences in the onboard and ground equipment needed to support the two types of missions. As satellites in MEO and LEO orbit the Earth faster, they do not remain visible in the sky to a fixed point on Earth continually like a geostationary satellite, but appear to a ground observer to cross the sky and "set" when they go behind the Earth.
Mobile satellite services pdf
Therefore, to provide continuous communications capability with these lower orbits requires a larger number of satellites, so one will always be in the sky for transmission of communication signals. The idea behind a communications satellite is simple: Send data up into space and beam it back down to another spot on the globe. Swearingen, D. As an example of how MSS can work, consider telephones in commercial airliners. A geostationary orbit is useful for communications because ground antennas can be aimed at the satellite without their having to track the satellite's motion. He has written three books on CNS engineering and systems for maritime, land and aeronautical applications and he has many projects and inventions in this field including DVB-RCS and Stratospheric Platforms. The world's first inflatable satellite — or "satelloon", as they were informally known — helped lay the foundation of today's satellite communications. Main article: Satellite constellation A group of satellites working in concert is known as a satellite constellation. I agree to my information being processed by TechTarget and its Partners to contact me via phone, email, or other means regarding information relevant to my professional interests. Geostationary orbit GEO [ edit ] Geostationary orbit To an observer on Earth, a satellite in a geostationary orbit appears motionless, in a fixed position in the sky. Like LEOs, these satellites do not maintain a stationary distance from the earth. The growth of the Internet and improved wireless access has led existing MSS system operators to introduce new capabilities that include improved data and multimedia access. This book presents global mobile satellite communications applications. LightSquared, www. This is because it revolves around the Earth at Earth's own angular velocity one revolution per sidereal day , in an equatorial orbit.
Telstar was the second active, direct relay communications satellite. Thus, Arthur C. The idea behind a communications satellite is simple: Send data up into space and beam it back down to another spot on the globe.
Sputnik 1 was launched as a major step in the exploration of space and rocket development. It covers how these enable connections between moving objects such as ships, road and rail vehicles and aircrafts on one hand, and ground telecommunications subscribers through the medium of communications satellites, ground earth stations, Terrestrial Telecommunication Networks TTNInternet Service Providers ISP and other wireless and landline telecommunications providers.
One disadvantage is that a MEO satellite's distance gives it a longer time delay and weaker signal than a LEO satellite, although these limitations are not as severe as those of a GEO satellite.
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