Discover How GPS Works

Since GPS applications have been opened for public use you may want to know how GPS works.

During the 1970s, the US Department of Defense conceived the idea of the Global Positioning System or GPS. It arose from the need for a system that will accurately determine the position of ballistic missiles, submarines and other military units prior to launching missiles.

GPS technology addressed the flaws of the old methods which are affected by atmospheric conditions, have limited range and suffered from degradation by interference.

Part of how GPS works is that satellites transmit signals to the passive receiving devices on the ground. For it to work effectively, the receiver needs to have an unobstructed view of the sky, which explains why GPS systems are mostly used outdoors. Its operations greatly depend on a very accurate time reference as provided by the atomic clocks of the US Naval Observatory.

Each satellite transmission is actually a transmission of data that indicates the location and current time. All GPS devices have synchronized operations so that the signals are transmitted at the same instant. The signals, which by the way move at the speed of light, arrive at the receiving device at slightly different times.

The distance between the GPS satellites is determined by estimating the amount of time that the radio wave signals reach the receiver. Once the receiver estimates the distance of at least four satellites in each distinct orbit, then it starts calculating and deducing its position in three dimensions.

To lock on four signals, the GPS unit or receiver needs to have at least four channels. Most GPS units have 12 channels. This way, how GPS works is the calculations it performs for the orbits will be done using up to 12 satellites to determine any one point at one time.

GPS satellites are solar powered. They are also given backup batteries to ensure continuous operation in the event of solar eclipse. Small rocket boosters are integrated to keep them flying in the right orbit. On the other hand, GPS systems and devices are designed to work in any type of weather, making it possible to use while in the air, on the land or at the sea, though some conditions limit its usefulness.

For instance, locations with heavy tree covers, cliffs, steep hills and tall buildings may interfere with its operations. But the good thing about GPS systems is that they can be used day or night at any point around the globe. It does not require a subscription fee to use GPS signals for navigation purposes. But the accuracy of the position it determines greatly depend on the type of GPS device that you use.

When discussing how GPS works you have to know something about their accuracy. Most handheld units have about 10 to 20 meter accuracy, though some have already achieved greater than 1 meter GPS accuracy. In addition to pinpointing locations, they are even loaded with features like speedometer, altimeter, barometer, BlueTooth, route data storage, topographic information and many others.

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