Today it is difficult to surprise somebody that during one minute you can make a call from you home or cell phone, for example, to Australia and an audibility will be like you talk with your neighbour. Or you can visit the Library of the USA Congress using the Internet service at home. But not every man knows that these and many other services are possible just due to satellite communication systems.

     Satellite communication is one of the most "young" types of communication. However, after its appearance in the 60-es, due to the intensive development of rocket-space systems and complexes, this form of communication was progressing so stormily that today it helps to solve the enormous range of problems. They are as follows: long-distance transfer and reception of analog and digital signals; television and broadcasting programs translation; telephone, telegraphic and teletype communication; personal communication; objects safe motion measures in the sea and air; rescue service; solution of the Earth and the outer space investigation problems; solution of the navigation and united time service problems; and many others.

     The satellite communication systems and their technologies have collected all up-to-date achievements of scientific and technical progresses. Almost all the discoveries and achievements of modern radio electronics and computer technology are used in creating the satellite communication means. A necessity to receive and to transfer the vast flows of different information (speech, fax, telex, packets of numerical data, multimedia which includes computer graphics, video, text information and sonic effects), a process of introduction of personal computer engineering every-where, an extremely fast growth of demands for the Internet services result in the fact that almost all satellite communication systems that are constructed on the digital principles and are the highly intellectual systems which combine naturally analog, microprocessor and computer means of signal processing.

     The satellite communication systems are not only spacecrafts where onboard equipment for signal reception, transfer and processing is allocated. Also they represent enormous ground-based infrastructure including special ground-based stations for system control and data acquisition, analysis, coding and decoding, user integration and their adaptation into one or another communication system, and also temporal and territorial service distribution. It is vast sphere of activity, the huge number of interesting and significant problems.