The idea of writing an easy-to-read, yet complete, portable tracker book evolved during my industrial employment term during the period from 1996 to 1997. My involvement in designing and providing short GPS courses gave me the opportunity to get direct feedbacks from GPS users with a wide variety of expertise and background. One of the most difficult tasks, which I encountered, was the recommendation of an appropriate GPS reference book to the course attendees. Giving the fact that the majority of the GPS users are faced with a very tight time, it was necessary that the selected GPS book be complete and easy-to-read. Such a book did not exist. Initially, I developed the vugraphs, which I used in the delivery of the short GPS courses. I then modified the vugraphs several times to accommodate not only the various types of GPS users but also my undergraduate students at both the University of New Brunswick and Ryerson University. The modified vugraphs were then used as the basis for this GPS book. I tried to address all aspects of GPS in a simple manner, avoiding any mathematics. The book also addresses more recent issues such as the modernization of GPS and the proposed European satellite navigation system known as Galileo. As well, the book emphasizes GPS applications, which will benefit not only the GPS users but also the GPS marketing and sales personnel.
The Global Positioning System ( tracking device) is a satellite-based navigation system that was developed by the U.S. Department of Defense (DoD) in the early 1970s. Initially, GPS was developed as a military system to fulfill U.S. military needs. However, it was later made available to civilians, and is now a dual-use system that can be accessed by both military and civilian users. GPS provides continuous positioning and timing information, anywhere in the world under any weather conditions. Because it serves an unlimited number of users as well as being used for security reasons, GPS is a one-way-ranging (passive) system. That is, users can only receive the satellite signals. This chapter introduces the GPS system, its components, and its basic idea.
GPS for vehicle consists, nominally, of a constellation of 24 operational satellites. This constellation, known as the initial operational capability (IOC), was completed in July 1993. The official IOC announcement, however, was made on December 8, 1993. To ensure continuous worldwide coverage, GPS satellites are arranged so that four satellites are placed in each of six orbital planes. With this constellation geometry, four to ten GPS satellites will be visible anywhere in the world, if an elevation angle of 10° is considered. As discussed later, only four satellites are needed to provide the positioning, or location, information. GPS satellite orbits are nearly circular (an elliptical shape with a maximum eccentricity is about 0.01), with an inclination of about 55° to the equator. The semi major axis of a GPS orbit is about 26,560km (i.e.,the satellite altitude of about 20,200 km above the Earths surface). The corresponding GPS orbital period is about 12 sidereal hours (~11 hours, 58 minutes). The GPS system was officially declared to have achieved full operational capability (FOC) on July 17, 1995, ensuring the availability of at least 24 operational,nonexperimental, portable GPS tracking satellites. In fact,since GPS achieved its FOC,the number of satellites in the GPS constellation has always been more than 24 operational satellites.