Comparison Between the Capabilities of the NAVSTAR GPS and Other Operational Radionavigation Systems; SSD 81-0177

[2], 17, [1] pages. Illustrations. Bibliography. Staplebound. Prepared for Presentation at EASCON '81 Washington, D.C. November 16, 1981. This paper compares the performance capabilities of six modern readionavigation techniques. Radionavigation employes triangulation methods to establish unknown position coordinates, usually by picking up precisely timed radio frequency transmissions from one or more known locations. This paper briefly describes the operating principles of the Navstar Global Positioning System (GPS) and of five other popular radionavigation systems. their capabilities are compared on the basis of such performance parameters as rang and accuracy, coverage, operation frequencies, and system status. 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. 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. Obstacles such as mountains and buildings block the relatively weak GPS signals. The GPS does not require the user to transmit any data, and it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver. The GPS project was started by the U.S. Department of Defense in 1973, with the first prototype spacecraft launched in 1978 and the full constellation of 24 satellites 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. 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). Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U.S. Congress authorized the modernization effort, GPS III.…