The GPS Standard Positioning Service

June 2, 1995 - The Global Positioning System (GPS) is a space-based radionavigation system which is managed for the Government of the United States by the U.S. Air Force (USAF), the system operator. GPS was originally developed as a military force enhancement system and will continue to play this role.

However, GPS has also demonstrated a significant potential to benefit the civil community in an increasingly large variety of applications. In an effort to make this beneficial service available to the greatest number of users while ensuring that the national security interests of the United States are observed, two GPS services are provided.

The Precise Positioning Service (PPS) is available primarily to the military of the United States and its allies for users properly equipped with PPS receivers. The Standard Positioning Service (SPS) is designed to provide a less accurate positioning capability than PPS for civil and all other users throughout the world. Read more  [PDF]

May 1, 2000 - U.S. Commerce Secretary William M. Daley today praised the decision of President Clinton, Secretary of Defense Cohen, and the Interagency GPS Executive Board to improve the accuracy of the Global Positioning System (GPS) for civilian users by deactivating the Selective Availability (SA) feature.

Selective Availability (SA) is the deliberate introduction of error to the precise timekeeping of the GPS satellites, thereby reducing both positioning and timing accuracy for civilian users. It was designed to provide U.S. and Allied military forces with a navigational advantage in times of crisis or conflict.

With SA activated, civilians are only guaranteed to be within a 100 meter radius of where their GPS receivers say they are. The removal of SA will give civilian users a predicted error of approximately 20 meters. Depending upon the circumstances, some real-world users will experience far better accuracy. Read more  More  More  More

Video and Imagery

Camera onboard a Helicampro HCP-03 UAV helicopter. Read more . . .