Introduction to the Satellite Communication Ground Segment
Ground segments of satellite communication systems employ a variety of node designs and network configurations in order to provide and manage services delivered to end users. The nodes in these networks range from the large earth stations used as gateways in a telephone network to very small aperture terminals (VSATs) that deliver data communication applications to remote business locations. Small aperture in this context refers to a reflector diameter in the range of 60 cm to 2.8m. We must also include low-cost end-user communication devices like desktop and handheld mobile telephones and direct broadcast satellite (DBS) home receivers.
This broad range of ground systems and devices employs many of the same hardware and software technologies found in other modern telecommunications and broadcastingnetworks that are the core of terrestrial wireless and Internet services.
As illustrated in Figure 1.1, the ground segment is that half of a satellite communication system which, quite naturally, resides on the ground. The space segment, consisting of orbiting communication satellites and a satellite control system used to operate and maintain the satellites, is that vital component which relays information between and among the various types of earth stations that make up the ground segment. In a previous work, we discuss in detail the design, operation, and management of the space segment, considering the technologies and physical principles that are key to its success.
In essence, the ground segment is useless without a properly operatingspace segment. Implementation of the space segment of geostationaryearth orbit (GEO) satellites represents many hundreds of millions of dollars;
a global nongeostationary (non-GEO) satellite system increases this levelto billions. Operators of GEO space segments include INTELSAT, SociétéEuropéene des Satéllites (SES), PanAmSat, GE American Communications(Americom), EUTELSAT, Japan Satellite Telecommunications (Jsat), andothers. Companies such as Globalstar LLC, ICO Teledesic, and OrbCommoperate non-GEO satellite constellations and systems. We will not discussthe space segment in detail in this book, but we will at times need to considerthe capabilities and constraints that it imposes as we work to provide theservice element of the overall system.
We use the term earth station to include classic fixed earth station facilitiesas well as mobile aeronautical, maritime, and handheld devices. In somecases, earth stations are individually owned and managed (e.g., the teleportoperated as a business), but this approach is being overtaken by the integratedtotal system that provides services to end users. Many readers alreadyown their own user terminals, which are technically small self-containedearth stations. But these terminals cannot operate without the ground segmentof the network operator. Examples of the latter include DIRECTV,British Sky Broadcasting (BSB), Measat Broadcasting Network Services(MBNS), operator of the Astra DBS service in Malaysia, COMSAT MobileServices, Telia of Sweden, Hong Kong Telecom, PT Indosat, and others.
The first two chapters of this text will lay the groundwork for thedetailed discussion of design and operating principles that follows. Theintention is to permit readers to devise their own approach to implementingand managing the earth stations and the overall ground segment. The materialpresented in this book should give readers a head start in the process,allowing them to prepare requirements, perform preliminary analyses, reviewdesigns provided by hardware suppliers, and manage the introduction of theoverall ground segment. We assume that readers have some level of familiaritywith the overall satellite system and the principles of RF engineering andtelecommunications networks, particularly those using satellites. We start with a chronological review of earth station technology, beginning in theearly twentieth century with the first introduction of radio (synonymouswith wireless at that point in time).
The long history of ground segment and earth station development andapplication dates back to the early 1900s, to the very beginnings of radiocommunications. Guglielmo Marconi successfully conducted the first transatlanticmessage transmission in 1901. The transmitters of the day produced aradio signal of around 1 MHz generated from a continuous spark. Radio wavesfrom this frequency and up to about 30 MHz can travel long distances on theground, since they can be reflected by the ionosphere (instead of an orbitingplatform). Later, commercial ships were equipped with these radios so thatland-based stations could handle messages sent with the international Morsecode. The 1997 movie Titanic dramatized how these simple mobile radio stationswere the lifelines of communication afforded the greatest ships at sea.
An overall timeline for the evolution of modern ground segments andearth stations is presented in Figure 1.2. It is impossible to present here everysignificant class of facility and application, since to do so would require anarea the size of a movie screen. However, we aim to show each major introductionof ground-based radio technology that contributed to how we usecommunication satellites in orbit. Other aspects of this history, particularlyfrom the space segment standpoint, can be found in our previous work.
Ground segments of satellite communication systems employ a variety of node designs and network configurations in order to provide and manage services delivered to end users. The nodes in these networks range from the large earth stations used as gateways in a telephone network to very small aperture terminals (VSATs) that deliver data communication applications to remote business locations. Small aperture in this context refers to a reflector diameter in the range of 60 cm to 2.8m. We must also include low-cost end-user communication devices like desktop and handheld mobile telephones and direct broadcast satellite (DBS) home receivers.
This broad range of ground systems and devices employs many of the same hardware and software technologies found in other modern telecommunications and broadcastingnetworks that are the core of terrestrial wireless and Internet services.
As illustrated in Figure 1.1, the ground segment is that half of a satellite communication system which, quite naturally, resides on the ground. The space segment, consisting of orbiting communication satellites and a satellite control system used to operate and maintain the satellites, is that vital component which relays information between and among the various types of earth stations that make up the ground segment. In a previous work, we discuss in detail the design, operation, and management of the space segment, considering the technologies and physical principles that are key to its success.
In essence, the ground segment is useless without a properly operatingspace segment. Implementation of the space segment of geostationaryearth orbit (GEO) satellites represents many hundreds of millions of dollars;a global nongeostationary (non-GEO) satellite system increases this levelto billions. Operators of GEO space segments include INTELSAT, SociétéEuropéene des Satéllites (SES), PanAmSat, GE American Communications(Americom), EUTELSAT, Japan Satellite Telecommunications (Jsat), andothers. Companies such as Globalstar LLC, ICO Teledesic, and OrbCommoperate non-GEO satellite constellations and systems. We will not discussthe space segment in detail in this book, but we will at times need to considerthe capabilities and constraints that it imposes as we work to provide theservice element of the overall system.
We use the term earth station to include classic fixed earth station facilitiesas well as mobile aeronautical, maritime, and handheld devices. In somecases, earth stations are individually owned and managed (e.g., the teleportoperated as a business), but this approach is being overtaken by the integratedtotal system that provides services to end users. Many readers alreadyown their own user terminals, which are technically small self-containedearth stations. But these terminals cannot operate without the ground segmentof the network operator. Examples of the latter include DIRECTV,British Sky Broadcasting (BSB), Measat Broadcasting Network Services(MBNS), operator of the Astra DBS service in Malaysia, COMSAT MobileServices, Telia of Sweden, Hong Kong Telecom, PT Indosat, and others.
The first two chapters of this text will lay the groundwork for thedetailed discussion of design and operating principles that follows. Theintention is to permit readers to devise their own approach to implementingand managing the earth stations and the overall ground segment. The materialpresented in this book should give readers a head start in the process,allowing them to prepare requirements, perform preliminary analyses, reviewdesigns provided by hardware suppliers, and manage the introduction of theoverall ground segment. We assume that readers have some level of familiaritywith the overall satellite system and the principles of RF engineering andtelecommunications networks, particularly those using satellites. We start with a chronological review of earth station technology, beginning in theearly twentieth century with the first introduction of radio (synonymouswith wireless at that point in time).
The long history of ground segment and earth station development andapplication dates back to the early 1900s, to the very beginnings of radiocommunications. Guglielmo Marconi successfully conducted the first transatlanticmessage transmission in 1901. The transmitters of the day produced aradio signal of around 1 MHz generated from a continuous spark. Radio wavesfrom this frequency and up to about 30 MHz can travel long distances on theground, since they can be reflected by the ionosphere (instead of an orbitingplatform). Later, commercial ships were equipped with these radios so thatland-based stations could handle messages sent with the international Morsecode. The 1997 movie Titanic dramatized how these simple mobile radio stationswere the lifelines of communication afforded the greatest ships at sea.
An overall timeline for the evolution of modern ground segments andearth stations is presented in Figure 1.2. It is impossible to present here everysignificant class of facility and application, since to do so would require anarea the size of a movie screen. However, we aim to show each major introductionof ground-based radio technology that contributed to how we usecommunication satellites in orbit. Other aspects of this history, particularlyfrom the space segment standpoint, can be found in our previous work.
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