When selective availability was lifted in 2000, GPS had about a five-meter (16 ft) accuracy. As a result, several countries - including Russia, China, India, Japan, and the European Union - have developed or are in the process of setting up other global or regional satellite navigation systems. However, this practice was discontinued on May 1, 2000, in accordance with a bill signed into law by President Bill Clinton. Congress in 2000.įrom the early 1990s, GPS positional accuracy was degraded by the United States government by a program called Selective Availability, which could selectively degrade or deny access to the system at any time, as happened to the Indian military in 1999 during the Kargil War. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System (OCX). Originally limited to use by the United States military, civilian use was allowed from the 1980s following an executive order from President Ronald Reagan after the Korean Air Lines Flight 007 disaster.
The first prototype spacecraft was launched in 1978 and the full constellation of 24 satellites became operational in 1993. Although the United States government created, controls and maintains the GPS system, it is freely accessible to anyone with a GPS receiver. It provides critical positioning capabilities to military, civil, and commercial users around the world. It does not require the user to transmit any data, and operates independently of any telephonic or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.
The Global Positioning System ( GPS), originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. An Air Force Space Command Senior Airman runs through a checklist during Global Positioning System satellite operations.
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