Smartphones, handheld navigators, Heart Rate Monitors & Sports Watches, Fitness Trackers, Smartwatches... Today, GPS receivers can be found in a multitude of electronic devices in order to make our lives a little easier, either when moving from point A to point B, or to determine the speed and distance we have traveled.
The Global Positioning System or GPS was developed in the 1960s by the U. S. Department of Defense. The GPS system we use today consists of several satellites and uses triangulation to determine position with a small margin of error of a few meters. Currently, both the European Union and China are developing their own satellite positioning systems, called Galileo and Beidou, respectively.
An increasing numberof runners are going out for a run with a GPS-enabled electronic device, be it a smartphone, a fitness wristband or a heart rate monitor attached to some part of their body - usually their arm or wrist - as an indispensable accessory when training or competing. The amount of information monitored and stored through the use of these gadgets is of vital importance to improve our performance.
GPS works thanks to a network of 24 satellites in orbit (20200 km high) above the Earth with synchronized trajectories to cover the entire surface of our planet. When we want to determine the position with our heart rate monitor or GPS watch, the receiver locates at least four satellites in the aforementioned network, from which it receives signals with the identification and time of the atomic clock of each of them. Based on these signals, the wearable synchronizes the GPS clock and calculates the time it takes for the electronic device to receive them. In this way, it measures the distance to the satellite by means of triangulation, which is based on calculating the distance of each satellite with respect to the measuring point. Once the distances are known, our position or coordinates with respect to the satellites are determined.
GPS Clock Accuracy
Through this system we can know our position via satellite, however, its accuracy is not entirely accurate, due to own and external causes of the technology used. For example, when you practice running you are constantly moving, and this means that your GPS receiver integrated in your watch or heart rate monitor does not always receive signals from the same satellites. Therefore, these changes of satellites affect the determination of your position.
Regarding the calculation of speed and distance and their various fluctuations, it should be noted that the communication between your device and the satellites takes place every half second, which implies a continuous calculation and return of results when you are running.
In the event that you lose connection with any satellite, your GPS receiver will calculate the distance traveled during that disconnection, and subsequently determine the time you spent going from one point to another. In this way it can calculate the speed at which you ran during those seconds when the connection was lost.
Photo credit: Suunto
