Very Long Baseline Interferometer

VLBI is an acronym for Very Long Baseline Inferometry, and can be roughly divided into two areas of application. The first area is in geodesy, which is covered in considerable detail in this book. The second area is in astrometry, or radio astronomy, which is only briefly treated in the book. Many people probably relate geodesy and land surveying more with geology and geography than with space-based measuring techniques; and at least through the first half of the 20th century, geodesy was largely based on knowledge in these fields. Surveyors were generally considered as technicians or craftsmen. Modern GPS (global positioning systems) is probably best known for its use in automobile navigation, but such space-based measuring systems have made tremendous advances in the field of geodesy as well. The most notable results obtained by VLBI so far has been the global-scale measuring of the movements of the tectonic plates which cover the surface of the earth. Details of this achievement are discussed in the book, but the primary focus of the material covered here remains an investigation of how VLBI can conduct these measurements with such high level of precision.
The book also explains how various aspects of system hardware, software and data analysis techniques can be effectively combined to yield a measurement accuracy that is four orders in magnitude better than conventional surveying techniques. VLBI requires knowledge in many areas of science and engineering.