History of GPS

Global Positioning System (GPS) is a satellite-based navigation system which was developed by the United States Department of Defense. Originally, developed for military use, it was made available for civilians in the 1980s. This technology is operated with the help of twenty-four satellites placed in orbit, and programmed to work 24 hours a day, in any weather, and in any part of the world.

The twenty-four satellites circle the Earth, twice a day, and transmit signal information to the planet. GPS receivers located on Earth use triangulation, a trigonometric method of determining position, to ascertain the user's exact location. In this process, the time taken for the signal to be transmitted, and the time taken for the signal to be received is calculated. After analyzing the time taken, with the distance measurement from a few more satellites, the user's position is displayed on an electronic map. A GPS receiver needs to be locked with the signal of at least three satellites to obtain a 2D position, and four or more satellites to obtain a 3D position. It can also calculate speed, distance and time.

History of GPS

The Global Positioning System was built by the U.S. Department of Defense, in collaboration with the Massachusetts Institute of Technology. In 1951, the U.S. Air Force wanted a guidance system, for the proposed ICBM, that was to travel by railroad. In order to cater to this need, Dr. Ivan Getting, an American physicist and electrical engineer, developed a 3D positioning system which could determine location based on time difference of arrival. This system, eventually, became the platform for the Global Positioning System or GPS, we use in our daily life.

The decision to develop an advanced satellite navigation system, based on the existing technology of the U.S. Air Force and the U.S. Navy, gave rise to the GPS in 1973. It went through extensive testing for the next few years. Although, the satellites were yet to be launched, the first transmitters were installed, and successfully tested with the help of Pseudolites (or pseudo-satellites) in 1977. Eventually, by the year 1985, eleven satellites were launched into space.

The first Block I satellite, with special sensors to detect atomic explosions, was launched by the United States in 1980, with the sole aim to monitor the Soviet Union's compliance to refrain from nuclear testing. In the same year, the on-board atomic clocks, accurate to one-billionth of a second, were activated. These clocks used change in the energy levels of electrons to measure time.

Initially developed for the military, GPS was made available for public use in 1983. The Korean Airline Flight 007 tragedy, in which, Soviet fighters shot down a Korean civilian aircraft lost over Soviet territory, led to the removal of security classifications by then United States President, Ronald Reagan, and allowed Global Positioning System to be used by civilians.

In 1986, the Challenger Space Shuttle Tragedy delayed further development in GPS, as the shuttles which were to transport Block II satellites were temporarily suspended. Eventually, in 1988, the number of satellites were increased to 24, for better functionality.

In 1990, the GPS facility for public use was temporarily suspended, as the military needed more receivers to enhance its use for military purposes, in the ongoing Gulf War. It was made available for public use in 1993. Simultaneously, it was decided to provide this facility free of cost, all over the world. By 1995, Global Positioning System had become a considerably advanced navigation system. It had achieved 'Full Operational Capacity', and the number of satellites had also increased, thereby increasing the availability and accuracy of the technology.

Previously having a capacity to track a subject within 100m, this system has become so advanced today, that its tracking range has come down to one meter, (and even a few centimeters, in some cases). Used exclusively by military establishments at one point of time, Real Time GPS Tracking has become an important component in fields like aviation, navigation and land surveying today. GPS tracking devices have become the most sought-after gadgets among civilians. GPS integrated car navigation systems, assist drivers to keep a track of routes; while, cell phones and watches with integrated GPS help parents to keep an eye on their children.