Global positioning system (GPS) signal

From Computer Science Wiki

The Global Positioning System (GPS) is a satellite-based navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

Here's a simplified explanation of how it works:

  1. The GPS system consists of a network of around 30 satellites orbiting the Earth, controlled by a series of ground stations. These satellites are always transmitting signals down to the Earth.
  2. The signals that these satellites send out include information about the satellite's location and the precise time the signal was transmitted.
  3. A GPS receiver (like the one in your smartphone or a standalone GPS device) picks up these signals. It needs to pick up signals from at least four different satellites to accurately determine its location.
  4. The receiver calculates the time it took for each of these signals to arrive. Since the signals travel at the speed of light, this time can be converted into a distance, creating a sphere of possible locations.
  5. By intersecting these spheres from at least four different satellites, the receiver can determine its precise location on Earth. This is known as trilateration.

In the context of rescue robots, having a GPS signal can be immensely useful for navigation purposes. However, it's worth noting that GPS signals can be weak or unavailable indoors or in urban areas with tall buildings, known as urban canyons. This is why rescue robots often use a combination of GPS and other navigation methods like computer vision or lidar for effective operation.