GPS Presidential Policy
- National PNT Engineering Forum
- GPS Directorate
- GPS Modernization
- GPS Evolutionary Architecture Study (GEAS)
- Selective Availability
- Presidential Policy
As GPS has gained in popularity, several policy documents have been issued to govern the use of GPS.
Today, I am pleased to announce that the United States will stop the intentional degradation of the Global Positioning System (GPS) signals available to the public beginning at midnight tonight. We call this degradation feature Selective Availability (SA). This will mean that civilian users of GPS will be able to pinpoint locations up to ten times more accurately than they do now. GPS is a dual-use, satellite-based system that provides accurate location and timing data to users worldwide. My March 1996 Presidential Decision Directive included in the goals for GPS to: encourage acceptance and integration of GPS into peaceful civil, commercial and scientific applications worldwide; and to encourage private sector investment in and use of U.S. GPS technologies and services. To meet these goals, I committed the U.S. to discontinuing the use of SA by 2006 with an annual assessment of its continued use beginning this year.
The decision to discontinue SA is the latest measure in an on-going effort to make GPS more responsive to civil and commercial users worldwide. Last year, Vice President Gore announced our plans to modernize GPS by adding two new civilian signals to enhance the civil and commercial service. This initiative is on-track and the budget further advances modernization by incorporating some of the new features on up to 18 additional satellites that are already awaiting launch or are in production. We will continue to provide all of these capabilities to worldwide users free of charge.
My decision to discontinue SA was based upon a recommendation by the Secretary of Defense in coordination with the Departments of State, Transportation, Commerce, the Director of Central Intelligence, and other Executive Branch Departments and Agencies. They realized that worldwide transportation safety, scientific, and commercial interests could best be served by discontinuation of SA. Along with our commitment to enhance GPS for peaceful applications, my administration is committed to preserving fully the military utility of GPS. The decision to discontinue SA is coupled with our continuing efforts to upgrade the military utility of our systems that use GPS, and is supported by threat assessments which conclude that setting SA to zero at this time would have minimal impact on national security. Additionally, we have demonstrated the capability to selectively deny GPS signals on a regional basis when our national security is threatened. This regional approach to denying navigation services is consistent with the 1996 plan to discontinue the degradation of civil and commercial GPS service globally through the SA technique.
Originally developed by the Department of Defense as a military system,
GPS has become a global utility. It benefits users around the world
in many different applications, including air, road, marine, and rail
navigation, telecommunications, emergency response, oil exploration,
mining, and many more. Civilian users will realize a dramatic improvement
in GPS accuracy with the discontinuation of SA. For example, emergency
teams responding to a cry for help can now determine what side of
the highway they must respond to, thereby saving precious minutes.
This increase in accuracy will allow new GPS applications to emerge
and continue to enhance the lives of people around the world.
March 30, 1998
VICE PRESIDENT GORE ANNOUNCES ENHANCEMENTS TO THE GLOBAL POSITIONING SYSTEM THAT WILL BENEFIT CIVILIAN USERS WORLDWIDE
Washington DC Vice President Gore today announced that a second civilian signal will be provided by the U.S. Global Positioning System.
"This new civilian signal will mean significant improvements in navigation, positioning and timing services to millions of users worldwide -- from backpackers and fishermen to farmers, airline pilots, and scientists," the Vice President said.
The addition of a second civil signal represents a strong commitment by the United States to civil GPS users worldwide and is a major step in the evolution of GPS as a global information utility. Much like the Internet, GPS is becoming increasingly indispensable for navigation, positioning, and timing by users around the world. Also like the Internet, GPS has become an engine of economic growth and efficiency as businesses and consumers continue to develop new and creative applications of this technology.
The addition of a second frequency will greatly enhance the accuracy, reliability and robustness of civilian GPS receivers by enabling them to make more effective corrections for the distorting effects of the Earth's atmosphere on the signals from space. GPS has always provided signals on two frequencies for military users for this purpose. Today's announcement marks a new era in which civilians will have access to the same type of capability.
"The decision announced today demonstrates that we can successfully balance the needs of civilian users with the demands of national security," Vice President Gore said. "GPS civil signals are, and will continue to be, provided free of charge to consumers, businesses, and scientists around the world. We will continue to do everything we can to protect these GPS signals and to promote GPS applications for commercial, public safety, and national security purposes."
The addition of a second civil signal has been recommended by a number of expert panels, the most recent of which was the White House Commission on Aviation Safety and Security, chaired by the Vice President. Today's announcement fulfills a pledge made last March by the Departments of Defense and Transportation to reach a decision on a second civil frequency within a year. The Departments of Defense and Transportation co-chair an Interagency GPS Executive Board, created by President Clinton in 1996 to manage GPS and its U.S. government augmentations.
"This new civilian signal will mean significant improvements in navigation, positioning and timing services to millions of users worldwide -- from backpackers and fishermen to farmers, airline pilots, and scientists," Vice President Gore said.
The NAVSTAR Global Positioning System (GPS) is a constellation of 24 satellites developed, launched, and maintained by the U.S. Air Force that provides positioning, timing, and navigation signals free-of-charge to both military and civilian users worldwide.
A second civil frequency will allow receivers to measure the time of arrival for two signals that have passed through the Earth's atmosphere and correct for the distortion introduced by passage from space to earth.
An improved location calculation will allow safety-critical users requiring dynamic, reliable capability to be more reliant on the GPS signal, improve the overall accuracy of the system for the average user, and allow the high-accuracy users (surveying, geodesy, weather forecasters, etc.) to determine their data in a faster, more reliable manner. In addition, the second civil signal will allow the safety-critical users to have a backup signal in the event of inadvertent disruption of the current civil signal.
The Interagency GPS Executive Board (IGEB) has selected the 1227.6 MHZ band (currently known as the L2 signal) for the addition of new civil capability. A third civil signal will also be added with a decision on the frequency to be made in August of this year. The decision on which of these two new signals the Government will pursue to become the safety-of-life service signal will also be made in August.
One of the key factors in deciding which frequency to pursue as the safety-of-life signal is a commitment by all members of the IGEB to have a safety-of-life service signal available by 2005.
The new signals are intended to be added to the GPS Block IIF satellites.
The new signals will be available to all civil users worldwide. Internationally, interest has been expressed via the International Civil Aviation Organization (ICAO) in the use of a second GPS civil signal in conjunction with the Japanese MSAS and the European EGNOS augmentation programs.
Currently the GPS system is used by a wide range of users: from cars and trucks on the nation's highways to ships at sea and on inland waterways; from civil aviation to satellites in space, from earthquake monitoring equipment to surveyors to backpackers; new industries such as precision farming; and the electrical power companies and long-distance phone systems which derive timing and synchronization from the signals.
U.S. GLOBAL POSITIONING SYSTEM POLICY
The President has approved a comprehensive national policy on the future management and use of the U.S. Global Positioning System (GPS) and related U.S. Government augmentations.
The Global Positioning System (GPS) was designed as a dual-use system with the primary purpose of enhancing the effectiveness of U.S. and allied military forces. GPS provides a substantial military advantage and is now being integrated into virtually every facet of our military operations. GPS is also rapidly becoming an integral component of the emerging Global Information Infrastructure, with applications ranging from mapping and surveying to international air traffic management and global change research. The growing demand from military, civil, commercial, and scientific users has generated a U.S. commercial GPS equipment and service industry that leads the world. Augmentations to enhance basic GPS services could further expand these civil and commercial markets.
The basic GPS is defined as the constellation of satellites, the navigation payloads which produce the GPS signals, ground stations, data links, and associated command and control facilities which are operated and maintained by the Department of Defense; the Standard Positioning Service (SPS) as the civil and commercial service provided by the basic GPS; and augmentations as those systems based on the GPS that provide real-time accuracy greater than the SPS.
This policy presents a strategic vision for the future management and use of GPS, addressing a broad range of military, civil, commercial, and scientific interests, both national and international.
In the management and use of GPS, we seek to support and enhance our economic competitiveness and productivity while protecting U.S. national security and foreign policy interests.
Our goals are to: