Quote:
Originally Posted by Seahawk
BTW, the GPS system "dithered" the civilian GPS signal in those days, meaning it was not as accurate as the military GPS systems. I have no idea why.
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Paul, I watched a documentary on GPS a while back and remembered accuracy was enabled then disabled, and then enabled again. I'll reference the wiki below instead of summarizing:
https://en.wikipedia.org/wiki/Global_Positioning_System
The GPS project was started by the U.S. Department of Defense in 1973. The first prototype spacecraft was launched in 1978 and the full constellation of 24 satellites became operational in 1993. 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 incident.[6] 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).[7] which was authorized by the U.S. Congress in 2000.
From 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,[8] as happened to the Indian military in 1999 during the Kargil War. However, this practice was discontinued on May 1, 2000, in accordance with a bill signed into law by President Bill Clinton.[9] As a result, several countries have developed or are in the process of setting up other global or regional satellite navigation systems.