December 8, 1993 GPS became publicly available.

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

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

It was originally called the Navstar Global Positioning System, but the outlines of the current GPS were conceived in 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’s territory, therefore their number was increased to 24 (including 3 reserve satellites).

Then the system was used only for military purposes: for missile guidance and peacekeeping, with the help of monitoring tests of nuclear weapons, which were banned in 1963. But after flight 007 of the Korean airline lost its way into Soviet territory in 1983 and was shot down, taking 269 lives with them, even the military realized what the benefits of using the GPS system could be by civilians.
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On December 8, 1993, 20 years after the initial concept, US Secretary of Defense Les Aspin will write to the Minister of Transport Federico Peña that the system has reached “initial combat readiness,” as determined in 1992 by the federal radio navigation plan. Thus, the Department of Defense has opened access to the standard location services (SPS) of the GPS system 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 up to 22 meters.

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

GPS, supplemented by techniques of signal amplification and accurate monitoring, such as: carrier phase amplification, differential GPS and relative kinematic positioning, now allow up to 4 inches accuracy (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 travels 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. Aircraft fly with it. Fishing boats find their way to rich waters using GPS. Scientists watch the wildlife, and people follow themselves. Henry David Thoreau would definitely be amazed.