Check out the following information from the Office of Space Commercialization, on it's Satellite Navigation page. There are a lot of good links and information about satellite GPS navigation.
The use of satellites for positioning, navigation, and timing (PNT) has grown dramatically since the U.S. Government authorized civilian access to the Global Positioning System (GPS) in 1983. Thanks to the long-standing U.S. policy of making GPS freely available to the entire world, as well as a track record of highly dependable service, GPS has evolved from a neat gadget into a ubiquitous technology that is now fundamental to the global information infrastructure.
GPS is a constellation of over 24 U.S. government satellites providing PNT services to an unlimited number of civilian and military users on a continuous, worldwide basis -- free of direct user charges. Using the time and position data transmitted by the satellites, a GPS receiver can calculate its location on or above the surface of the Earth within a few meters. When used with an augmentation system, a receiver can attain much higher GPS accuracy -- within centimeters, or even millimeters.
Today, GPS technology is in everything from cars and airplanes to cell phones and wristwatches. Businesses use it to boost productivity in industries as diverse as farming, mining, construction, real estate, taxicab services, package delivery, and logistical supply chain management. GPS enhances public safety by preventing transportation accidents and reducing emergency response times. It helps further scientific aims such as weather forecasting, earthquake prediction, and environmental protection.
The precise GPS time signal, derived from atomic clocks on each satellite, has been harnessed to synchronize vast communications networks, electrical power grids, financial markets, and other systems that are critical to the U.S. economy.
The Commerce Department's use of GPS is extensive and far-ranging. NOAA navigates its vessel fleet and enforces fishery boundaries with GPS. The National Geodetic Survey uses GPS to survey the nation's coastlines, waterways, and airport approaches, and to define the National Spatial Reference System. The National Weather Service improves its forecasts by using the GPS radio signal to measure water vapor content in the atmosphere. The National Institute of Standards and Technology uses GPS to communicate its national time standard to other national laboratories. And the U.S. Census Bureau uses GPS to locate homes.
Through NOAA, the Commerce Department is also a PNT service provider, managing the national GPS augmentation known as the Continuously Operating Reference Station (CORS) network. CORS is a consortium of over 1,000 public and private sector tracking stations that enable high precision users to refine their GPS measurements to the centimeter level or better.
The Commerce Department is a key member of the National Executive Committee for Space-Based PNT, the senior body established by the President to advise and coordinate federal departments and agencies on matters concerning GPS and related systems. The Deputy Secretary of Commerce participates on the Executive Committee as a key representative of the commercial and civilian GPS community. The Commerce Department also hosts the National Executive Committee's meetings and its National Coordination Office, a permanent secretariat located at the Office of Space Commercialization.
Through the Office of Space Commercialization, the Commerce Department promotes the interests of commercial GPS users, manufacturers, and service providers. The Office conducts and disseminates economic studies related to GPS. The Office promotes GPS modernization efforts to improve future civilian capabilities. The Office participates in discussions with other nations to promote international use of and cooperation with GPS. The Office co-chairs the U.S.-European working group on GPS-Galileo trade and civil applications, which focuses on maintaining a level playing field as Europe's satellite navigation system enters the market.
Finally, the Commerce Department plays a regulatory role with regard to GPS. The National Telecommunications and Information Administration is responsible for co-managing (with FCC) the radio frequency spectrum used by GPS. The Bureau of Industry and Security sets guidelines for the export licensing of civilian GPS user equipment. And the Patent and Trademark Office processes applications for GPS-related technology patents.
In recent years, the Office of Space Commercialization has produced or contributed to the following materials related to GPS and satellite navigation:
- Joint Statement on GPS and Galileo Cooperation (Oct 2008)
- Request For Comments and Final Notice on Codeless/Semi-Codeless Access to GPS (May/Sept 2008)
- WGB Presentation from CGSIC Savannah (Sept 2008)
- GPS-Galileo Working Group B Meeting Summary (July 2008)
- Published Interview on Semi-Codeless GPS Transition Plan (July 2008)
- Presentation from Colombia GNSS Workshop (June 2008)
- U.S.-Australia Joint Delegation Statement on GPS Cooperation (April 2007)
- GPS-Related Testimony by Secretary of Commerce Carlos Gutierrez (March 2007)
- Presentation on Government's Role in Fostering Commercial Applications (March 2007)
- U.S.-E.U. Joint Statement on GPS-Galileo Trade and Civil Applications (January 2007)
- Presentation on Economic Benefits of Second Civilian GPS Signal (September 2006)
- Published Article on Economic Benefits of Second Civilian GPS Signal (July/August 2006)
- Presentations from GEOBrasil Summit 2006 (July 2006)
- Congressional Testimony on Space and National Power (June 2006)
- Public Media Event on Next-Generation GPS (January 2006)
- U.S.-Russia Joint Statement on GPS-GLONASS Cooperation (December 2004)
- U.S.-Japan Joint Statement on GPS Cooperation (November 2004)
- U.S.-EC Agreement on GPS-Galileo Cooperation (June 2004)
- Presentation on GPS for Students (March 2003)
For additional information about GPS and satellite navigation, please visit the following websites, which the Office helped develop: