Global Positioning Systems, Inertial Navigation, and Integration, Second Edition

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FUNDAMENTALS OF SATELLITEAND INERTIAL NAVIGATION

2.1 NAVIGATION SYSTEMS CONSIDERED

This book is about GNSS and INS and their integration. An inertial navigation system can be used anywhere on the globe, but it must be updated within hours of use by independent navigation sources such as GNSS or celestial navigation. Thousands of self-contained INS units are in continuous use on military vehicles, and an increasing number are being used in civilian applications.

2.1.1 Systems Other than GNSS

GNSS signals may be replaced by LORAN-C signals produced by three or more long-range navigation (LORAN) signal sources positioned at fixed, known locations for outside-the-building location determination. A LORAN-C system relies on a plurality of ground-based signal towers, preferably spaced 100–300 km apart, that transmit distinguishable electromagnetic signals that are received and processed by a LORAN signal antenna and LORAN signal receiver/ processor that are analogous to the Satellite Positioning System signal antenna and receiver/processor. A representative LORAN-C system is discussed in the U.S. DOT LORAN-C User Handbook [127]. LORAN-C signals use carrier frequencies of the order of 100 kHz and have maximum reception distances of hundreds of kilometers. The combined use of FM signals for location determination inside a building or similar structure can also provide a satisfactory location determination (LD) system in most urban and suburban communities.

There are other ground-based ...