What is GPS?

GPS (Global positioning system) is a system of positioning, navigation, and timing (PNT) services made up of three segments: space navigation, a control segment, and a user segment.  A GPS receiver, which can be in a smartphone, navigation device, etc., needs signals from at least four satellites (although three are considered acceptable if a fourth is unavailable), and from these signals the receiver determines the times sent, and the satellite positions corresponding to these times sent. This information is used to pinpoint the receiver’s exact location on the globe in relation to the location of the satellites. The system is currently owned and operated by the U.S. Air Force.

The History of GPS Technology

The technology used in GPS was initially created for the United States Air Force by the Raytheon Company, and was born out of the Air Force’s need of an accurate guidance system. In 1960 a scientist by the name of Dr. Ivan Getting left his position at Raytheon Company, and armed with the knowledge of what was at the time the most advanced navigational technology in the world, he began developing the Global Positioning System. Together with a team of aerospace engineers and scientists, Getting developed the three-dimension global positioning system concept.

In 1957, at the height of the Cold War and the Space Race, the former U.S.S.R. launched Sputnik, the first ever Soviet satellite. While observing Sputnik, U.S. scientists realized they could track the satellite’s orbit by listening to the changes in its radio frequency using the Doppler effect, a technique that had previously been used to describe why the pitch of a car’s horn seems to change as it speeds away. In 1960, using the knowledge gained from tracking Sputnik, the U.S Navy was able to launch TRANSIT, the first satellite navigational system, which was used to help guide the Navy’s fleet of ballistic missile submarines.

In 1967, the U.S. Navy developed the Timation technique, a system that “uses a highly stable, synchronized clock in the satellite,” a technology on which GPS is dependent; by 1974, the first atomic clocks were put into orbit.  By 1978, the U.S. military had launched the first four GPS satellites. Until 1983, GPS technology was available for U.S. military use only, until a tragedy of such a magnitude occurred that the benefits of GPS technology could no longer in good conscience be restricted from civilian use.  In 1983, Korean Air Lines Flight 007, a civilian Korean Air airplane carrying 269 passengers, was shot down after mistakenly entering Soviet airspace — killing all passengers on board. In response to this tragedy, President Ronald Reagan issued a directive that when GPS technology was operational, it would be free and available to the world.

On Feb. 14, 1989, the first modern satellite was launched. By July 17, 1995, the global positioning system was complete.  This system consists of a constellation of 24 2,000-pound satellites that each circle the world once every 12 hours, from 12,000 miles above the earth. The satellites broadcast their location and the exact time the signal was transmitted to earth via radio signals, and by collecting this information from four or more satellite’s signals, GPS receivers can determine their “own location, speed and elevation with great accuracy – usually within a few meters or even less.”

In 1996, President Bill Clinton made further advances in the use of GPS as a civilian tool when he issued a policy directive declaring that GPS was a dual-use system technology, meaning it was to be used for both peaceful and military aims. In 2000, the U.S. military stopped its practice of intentionally blurring the signals for security purposes, and as a result, there soon became a civilian demand for GPS technology. As with many early incarnations of technology, the US Government had a monopoly of knowledge on the GPS.  Due to the public’s desire for these products and technologies, GPS devices immediately became 10-times more accurate, and over time have become cheaper and cheaper to buy and produce.

Finally, in 2004, President Bush further ensured the availability and accessibility of personal GPS units when he issued a policy that would ensure that civilian GPS would be free of direct user fees.  Soon after, in 2005, the first modernized GPS satellite was launched. This modern satellite began transmitting a second civil signal that “provide[d] civil users with an open access signal on a different frequency.”

The Expansion of Personal GPS Use

The Expansion of Personal GPS Use

Despite the civilian demand for personal GPS units, at first most cell phone companies were hesitant to put GPS technology into their phones. But in 1999, the Federal Communications Commission required that they include a way to track their customers for 911 calls and rescue workers.

In 2006, Sprint became the first carrier to begin using signal triangulation from cell-phone towers, creating an augmented global positioning system. Called “family locator services,” this system allows family members to track one anther’s whereabouts, as long as each person has their cell phone on them. Several other carriers have since followed suit.

Presently, the global positioning system technology is owned and operated by the United States military. But several other nations have plans in place to implement their own nationally owned positioning systems. This year, China launched five GPS satellites for their regional system, Beidou, and plans to be able to expand their coverage to the entire Asia-Pacific region by 2012. By 2020, they hope to go global, with a total of 35 satellites. The Russian global navigation system, GLONASS, is presently in the process of being restored (currently 23 of the 24 satellites are active). The European Union is also in the process of launching a global navigation system (Galileo), with plans to be fully operational by 2013.

>>Applications of GPS Technology


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