A U.S. Department of Defense program to limit the accuracy of autonomous position fixes computed by civilian receivers. The error in position caused by S/A can be up to 100 meters.
S/A - The intentional degradation of GPS accuracy for civilian use (S/A has been deactivated indefinitely as of May 2, 2000). S/A limited the accuracy of civilian GPS systems to 300 feet or less 95% of the time.
A method of intentional accuracy degradation by the Department of Defense (DoD). With SA turned on GPS accuracy reduced to 100 meters. Selective availability has been turned off as of May 2, 2000. The DoD has no plans to turn SA on in the future. Instead other methods of GPS access will be employed.
Intentional degradation of the accuracy of the Global Positioning System.
A random error that was imposed on information from satellites relaying positional data; this error was rescinded in 2000 but may be reinstated by the USA military.
Procedure of intentionally introducing error into GPS signals thereby creating a pseudorange error. SA is used as a national security measure to keep non-military receivers from obtaining high-accuracy position information.
The system used by the U.S. Department of Defense to intentionally degrade the accuracy of satellite GPS signals being transmitted to civilian GPS receivers. All brands of civilian GPS receivers are equally affected by S/A. With random S/A on, the government has agreed that civilian GPS accuracy levels will consistently by 100 meters or less, 95% of the time. If S/A is turned off, those accuracy levels will improve to 10 to 15 meters consistently.
prior to May 2000, the US military intentionally degraded the accuracy of GPS signal data for civil and commercial purposes as a protective measure. The Department of Defense retains the right to restrict signal accuracy in the interest of US national defense.
a technique which is used to limit real-time accuracy achievable by civilian users and which consists of degradation of the broadcast orbit (i.e. the satellites' "known" position in space) and dithering of the satellite clocks
Intentional degradation of the Absolute Positioning performance capabilities of the NAVSTAR satellite system for civilian use (the Standard Positioning Service) by the U.S. military, accomplished by artificially "dithering" the clock error in the satellites. Has generally been mitigated through the use of Relative Positioning techniques. SA was activated on 25 March 1990, and was removed on the 1st May 2000 (midnight Washington D.C. time).
The system used by the U.S. Department of Defense prior to May 1, 2000 to intentionally degrade the accuracy of satellite GPS signals being transmitted to civilian GPS receivers. Until recently, all brands of civilian GPS receivers were equally affected by S/A. With random S/A on, the government had agreed that civilian GPS accuracy levels would consistently be 100 meters or less, 95% of the time. Now that S/A restrictions have been lifted, accuracy levels have improved to 20 meters or less.
The process whereby a GPS satellite clock is "dithered" and/or the satellite broadcasts erroneous ephemeris data to create a measurement error. This typically dilutes the horizontal precision to about 100 meters 95 percent of the time under current policy. (See Standard Positioning System.).
(SA) The random error which the government intentionally adds into GPS signals so that their accuracy, for civilian use, is degraded. The level of SA is subject to accuracy degradation to 100m 2DRMS.
A policy adopted by the Department of Defense to introduce some intentional clock noise into the GPS satellite signals thereby degrading their accuracy for civilian users.
A Department of Defense policy used to introduce some intentional clock noise into the GPS satellite signals, thereby intentionally degrading their accuracy for civilian users. This policy was discontinued as of May 1, 2000 and now SA is turned off (for now).
The random error, which the government can intentionally add to GPS signals, so that their accuracy for civilian use is degraded. SA is not currently in use. SOG See Speed Over Ground.
The system used by the U.S. Department of Defense to intentionally degrade the accuracy of satellite GPS signals being transmitted to civilian GPS receivers. With random S/A on, the government guaranteed that civilian GPS accuracy levels would be 100 meters or less, 95% of the time. S/A was eliminated May 2, 2000. Accuracy levels are now within 10 to 20 meters.
The introduction of errors in the satellite ephemeris parameters along with encrypted correction parameters which allow certain users to remove the effects of those errors.
Intentional degradation of GPS signal used for position fixing by the U.S. Department of Defense for purposes of national security. With selective availability turned on, positions can be fixed to about 300 meters. With selective availablity turned off, positions can be fixed to about 100 meters.
intentional pseudorange error in GPS signals created by the DOD as a measure of national security to prevent non-military receivers from obtaining high accuracy position information.
SA A DoD program to control the accuracy of pseudorange measurements, whereby the user receives a false pseudorange which is in error by a controlled amount. Differential and phase differencing techniques can reduce these effects for local applications.
A procedure by which the United States Department of Defense (USDoD) deliberately and intermittently interferes with the signals from GPS satellites so that civilian and other non-USDoD GPS receivers cannot calculate extremely precise locations, but their own units can. The errors thus introduced must be taken into account (and perhaps strategically minimized) by civilian GPS users. cale: The relationship between distance on a map and on the Earth's surface, usually represented as a ratio (for example, 1:10,000) or with a graph scale.
The random error, which the government can intentionally add to GPS signals, causes decreased position accuracy in civilian GPS receivers . SA is not currently in use.