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In keeping with the objectives of the previous editions, the third edition is intended to provide broad coverage of satellite communications systems, while maintaining sufficient depth to lay the foundations for more advanced studies. Mathematics is used as a tool to illustrate physical situations and obtain quantitative results, but lengthy mathematical derivations are avoided. Numerical problems and examples can be worked out using a good calculator or any of the excellent mathematical computer packages readily available. MathcadTM is an excellent tool for this purpose and is used in many of the text examples.
The basic Mathcad notation and operations are explained in Appendix H. In calculating satellite link performance, extensive use is made of decibels and related units. The reader who is not familiar with some of the more specialized of these units will find them explained in Appendix G The main additions to the third edition relate to digital satellite services.
These have expanded rapidly, especially in the areas of Direct Broadcast Satellite Services (mainly television), and the Internet; new chapters have been introduced on these topics. Error detection and correction is an essential feature of digital transmission, and a separate chapter is given to this topic as well. The section on code-division multiple access, another digital transmission method, has been expanded. As in the previous editions, the basic ideas of orbital mechanics are covered in Chap. 2.
However, because of the unique position and requirements of the geostationary orbit, this subject has been presented in a chapter of its own. Use of non-geostationary satellites has increased significantly, and some of the newer systems utilizing louearth orbits (LEOs) and medium earth orbits (MEOs), as proposed for Internet use, are described. Iridium, a 66 LEO system that had been designed to provide mobile communications services on a global scale declared bankruptcy in 2000 and the service was discontinued.
For this reason, the description of Iridium was not carried through into the new edition. In December 2000 a new company, Iridium Satellite LLC was formed. Details of the company and the services offered or pro- posed will be found at http:/www.iridium.com/. Considerable use has been made of the World Wide Web in updating the previous edition, and the web sites are referenced in the text.
Listings of artificial satellites, previously appended in tabular form, can now be found at the web sites referenced in Appendix D; these listings have the advantage of being kept current. Much of the information in a book of this nature has to be obtained from companies, professional organizations, and government departments. These sources are acknowledged in the text, and the author would like to thank the personnel who responded to his requests for information.
Thanks go to the students at Lakehead University who suggested improvements and provided corrections to the drafts used in classroom teaching; to Dr. Henry Driver of Computer Sciences Corporation who sent in comprehensive corrections and references readers’ comments and suggestions and he can be reached by email at [email protected]
Thanks also go to Carol Levine for the friendly way in which she kept the editorial process on schedule, and to Steve Chapman, the sponsoring editor, for providing the impetus to work on the third edition.