8. The Global Positioning System is commonly known as $\qquad$. It is a system that can perform real-time positioning and navigation globally, consisting of GPS satellites, ground control systems, and users.
A. ABS
B. ADS
C. GES
D. GPS
【Answer】D
【Analysis】The Global Positioning System (GPS) is a high-precision radio navigation and positioning system based on artificial Earth satellites. It can provide accurate geographical location, vehicle speed, and precise time information anywhere in the world and in near-Earth space. Since its inception, GPS has attracted many users with its high precision, all-weather, global coverage, and convenient flexibility. The global positioning system was originally invented by the United States. In the 1970s, the U.S. Department of Defense began to develop the "Navigation Satellite Timing and Ranging Global Positioning System" for the purpose of providing real-time, all-weather, and global navigation services to the land, sea, and air domains, as well as for intelligence collection, nuclear explosion monitoring, and emergency communications, among other military purposes. In 1973, the U.S. Department of Defense began designing and testing. On February 4, 1989, the first GPS satellite was successfully launched. By the end of 1993, a practical GPS network, i.e., the (21+3 GPS) constellation, was built and began commercial operations. After more than 20 years of research and experimentation, costing $30 billion, by March 1994, a 24-satellite GPS constellation with a global coverage rate of 98% had been completed. GPS mainly consists of three parts: the space segment (GPS satellites), the ground control segment, and the user equipment segment.

It should be noted that GPS is the abbreviation for Global Positioning System, a general term, and does not specifically refer to the "U.S. Global Satellite Navigation System." However, the U.S. got there first and used the name "GPS." Currently, there are four major navigation systems worldwide: the U.S. Global Positioning System (GPS), which is still the most precise and widely covered navigation and positioning system globally; the European Union's "Galileo" system, the world's first global satellite navigation and positioning system based on civilian use, developed by the EU to break the U.S. GPS monopoly in the satellite navigation and positioning field, known as the European version of "GPS"; the Russian "GLONASS" system, originally developed during the Soviet era, using Frequency Division Multiple Access (FDMA) technology, which broadcasts navigation signals using the same code on different carrier frequencies, and when fully built, will be among the world's leading in terms of precision; and China's BeiDou Navigation Satellite System (BDS), an independently developed and operated global satellite navigation and communication system, ranking among the world's top four satellite navigation systems alongside the U.S. GPS, Russian GLONASS, and EU Galileo systems. The BeiDou Navigation Satellite System can provide high-precision, high-reliability positioning, navigation, and timing services to various users globally, 24/7, and also has short message communication capabilities.