Eyes in the Sky: How GPS Tracking Works

Almost everybody benefits from GPS tracking these days. It’s in our phones, our cars, and our computers. We wear devices on our wrists, around our necks, in our pockets, and in our shoes. We use them to keep track of exercise distances and routes, monitor our elderly family members, keep tabs on our children, protect our pets, and track down stolen possessions.  Hundreds if not thousands of uses for GPS tracking exist, and more are being designed every day. But with all that information flying around, how often do we think about how it actually works? Where do those coordinates come from and how accurate are they?

A Little History

The GPS satellite system was designed by the United States military in 1973 to assist with military operations. The first satellites were in orbit by 1989 and the system was functional by 1995. Although originally conceived as a military project, the satellites emit signals on two separate channels. The unencrypted channel can be used by anyone and is available for civilian and commercial applications. The second channel, which is also slightly more precise, is encrypted for military use only.

So How Does It Work?

The GPS system currently consists of 31 satellites orbiting the Earth. At least 24 of these satellites must remain functional in order for GPS to be accessible from anywhere in the world. At regular intervals, the satellites emit signals which contain both the current location and time of transmission. In order to determine an accurate location on Earth, a receiving device uses data obtained from three satellites to pinpoint its position using trilateration. The current location of the device is where the three signals intersect.

How Can GPS Tracking Be Used?

The potential uses for GPS tracking are nearly endless. Here are just a few of the currently available options:

• Vehicle tracking devices that enable emergency alert systems in case of an accident


• Life alert necklaces for the elderly


• GPS tracking shoes used for Alzheimer patients


• GPS-enabled pet collars to track lost pets


• Wrist watches to help parents keep tabs on their kids


• Runners’ watches to map routes and calculate distances


• Trackers used in boat races to accurately determine a winner and to follow the course of the race


• Wildlife conservation trackers to observe animal movements


• Fleet vehicle tracking to monitor bus routes, delivery vehicles, police cars, construction equipment, and more


• Mobile marketing to deliver location-based advertisements to your smartphone


• Law enforcement tracking of suspected criminals and parolees


• Protection for victims of domestic violence

These applications are just a drop in the bucket. There are hundreds more potential uses for GPS tracking. The only limit is the creativity of developers for creating new devices and capabilities.

Who is Responsible for Maintaining the System?

The United States owns and operates the GPS system that is currently in use around the world. Theoretically, the satellites that serve any particular region can be turned off, denying access to that region during a time of war, for instance. This capability has never been put to use, however, despite the U.S. participation in several wars since the GPS system was first launched. The theoretical possibility has nevertheless prompted other national governments to begin developing their own systems. The earliest of these, the Galileo network being developed in Europe, is not projected to be completed until 2019.

How Accurate is the System?

The encrypted signals used by the military can determine the location of an object to within 30 centimeters. Civilian devices using the unencrypted signals are not that precise, but can still pinpoint a location within about three meters. That’s a whole lot better than the 25 meter accuracy originally possible for civilian devices. Still, despite the better capabilities of modern GPS tracking devices, they can be thrown off by objects deflecting or blocking the satellite signal. If you’ve ever discovered that your GPS tracking device thought you were somewhere else, it’s probably because the signal was deflected by a building or geological formation.

Are There Any Limitations on How GPS Tracking Can Be Used?

Privacy concerns have prompted some groups to advocate for stricter laws governing the use of GPS tracking data. Two examples include law enforcement and mobile marketing. The Supreme Court weighed in on the use of GPS tracking by law enforcement to track suspected criminals, ruling that a warrant must be obtained before a tracking device may be attached to a person’s vehicle or belongings. Privacy concerns have also been expressed regarding the use of cell phone trackers by marketers. One bill proposed that citizens must give consent before marketers can obtain location information for marketing purposes. However, that bill has not yet gained enough traction to come to a vote.

GPS tracking is part of our daily lives. It has revolutionized the way we interact, shop, conduct business, exercise, travel, and care for loved ones. Thanks to twenty-four eyes in the sky, originally developed as a U.S. military operation, you never need to be lost again.

Eyes in the Sky: How GPS Tracking Works