December 8, 1993 GPS became publicly available

The history of GPS began with the satellite, the first artificial Earth satellite. On the night after its launch by the Soviet Union in 1957, researchers from the Massachusetts Institute of Technology were able to track the satellite’s orbit using the transmitted radio signal. And if you can track the position of Earth satellites, then you can find out the position of objects on Earth from the position of satellites.

The U.S. Navy experimented with a satellite navigation system for its submarines in the mid-1960s. The system used six satellites in near-polar orbits, and using the Doppler effect in the waves of their radio signals, determined the location.

It was originally called the Navstar Global Positioning System, but the contours of the present GPS were conceived at the Pentagon back in 1973. Testing began a year later, and the first working GPS satellite was launched in 1978. In 1979, it turned out that the originally planned 18 satellites would not be able to provide sufficient coverage of the Earth, so their number was increased to 24 (including 3 backup satellites).

Then the system was used only for military purposes: to launch missiles and maintain peace, by monitoring the testing of nuclear weapons, which were banned in 1963. But after the Korean airline’s 007 flight invaded Soviet territory in 1983 and was shot down, taking 269 lives with it, even the military realized what the benefits of using a GPS system by civilians could be.

On December 8, 1993, 20 years after the initial concept, US Secretary of Defense Les Aspin wrote to Secretary of Transportation Federico Peña that the system had reached “initial combat readiness,” as defined in 1992 by the federal radio navigation plan. Thus, the Department of Defense has opened access to the standard location services (SPS) GPS to the US Department of Transportation.

After further testing of the system by the military, the US Air Force command announced "full operational readiness" on April 27, 1995. The standard positioning system (SPS) used by civilians was initially limited to an accuracy of 100 meters. A more accurate system (PPS) was available only to authorized military users and offered accuracy of up to 22 meters.

In 1998, U.S. President Bill Clinton signed a decree whereby civilian location services became as accurate as military services since May 2000. This difference in accuracy was actually created artificially by introducing random errors into a public signal. These errors (so-called Selective Availability) are still used in war zones so that only friendly units can receive the most accurate signal.

GPS, supplemented by signal amplification and precise monitoring techniques, such as carrier phase amplification, differential GPS and relative kinematic positioning, now provide accuracy of up to 4 inches (about 10 centimeters). Currently, GPS receivers are integrated into a huge number of different devices, and have become as ubiquitous as mobile phones.

We use GPS constantly. For navigation in our trips by personal transport, in the management of the "army" of taxis, buses, trucks and rental cars. Rapid response and delivery systems are based on GPS. Airplanes fly with her help. Fishing boats find their way to rich waters using GPS. Scientists are watching wildlife, and people are watching themselves. Henry David Thoreau would definitely be amazed.