A GPS receiver is one of the most accurate clocks in the world, if it has continual access to the satellites. The forte of a clock in a GPS receiver is short-term accuracy, not long-term consistency. People who really want to know exactly what time it is can set up a base station over a known point and analyze GPS signals for time instead of position. GPS time does differ from UTC time by an integer number of seconds, less than 20 for the near future. There are many applications for which coordinated time is vital. There will be an increasing number of applications in which smart tracker GPS signals control equipment directly, rather than going through a human “middle-man.” In such joint GPS/GIS uses as fertilizer or pesticide application, the automated system may steer the tractor while the farmer rides along simply for reasons of safety. Carving out roadways or laying pavement may be conducted in similar fashion. The Center for Mapping at Ohio State University boasts a system that can put a bulldozer blade in the correct position with an accuracy approaching one centimeter. While you might think that the maximum safeguards would be provided for a system designed to aid a warrior with a mortar or a nuclear-tipped ICBM, the fact is that GPS position data can suddenly disappear for periods of a few seconds to a few minutes.
That state of affairs is not going to be allowed for some important civilian applications. You will understand the need for reliability immediately if you imagine yourself as a passenger in a landing commercial aircraft. The plane is 50 feet above a runway in a blinding snowstorm. That’s no time for GPS to take a breather. It is going to be possible for ships to navigate in shallow water by knowing their vertical height and having an integrated survey of the bottom of the water body. On-the-fly marine navigation requires 3-D GPS decimeter accuracy. Again, everything has to work right and keep working. GPS tracker app will be vital to all sorts of civilian and commercial endeavors, so the systems built around it simply must be highly accurate and reliable.
Presidential Decision Directive 63, issued 29 March 1996 declared “A permanent interagency GPS Executive Board, jointly chaired by the Departments of Defense and Transportation, will manage GPS and U.S. Government augmentations.” In September 2000 the Civil GPS Service Interface Committee announced that DoD and DoT agreed to seek greater involvement from civilian federal agencies in the day-to-day management of GPS. Civil representation is to be sought throughout all stages of the DoD acquisition, requirements development, and planning, programming, and developing process. Once the civilians and the military agree on a few more issues related to GPS accuracy, coverage, and integrity, GPS will be the primary U.S. government radio-navigation system well into the next century. The satellites which will be launched to provide GPS information in 2015 and beyond are already being designed. Swords are being beaten into plowshares, but the changes will not come rapidly, for both political and security reasons. A real breakthrough would be the deployment of a way to jam GPS signals in a given geographic area, thus denying an enemy any use of the civilian Car GPS tracker device signal.