The in-car GPS device and satellite navigation unit is one of the World’s most popular gadgets. Millions of GPS devices have been sold over the last 10 years or so, with the main market share being taken by companies such as Garmin and TomTom. It has truly become one of life’s essential gadgets, with drivers either using a standalone product, or some having the product actually built-in to their car’s dashboard – with Smartphones now also taking a share of the spoils. But do you know how GPS actually works in getting you from A to B? Read our simple guide to satellite navigation so you have all the answers at hand the next time someone asks “how does that work?”
The Global Positioning System (GPS) Transmits Signals to Earth
Above the Earth there are currently 24 different satellites orbiting at any single point in time. The GPS system was originally invented and launched by the US Department of Defense as a military tool, but in the early 80s the network was widened so that commercial usage could be made of it. Each satellite in the GPS network orbits the planet twice daily as has done so since the early days of 1983.
Each of the satellites in the GPS grid is set up to send and transmit signals to Earth. Each signal sent contains information on the satellite’s position and number – and each of the 24 in orbit do this at the same time. This means that if you in-car GPS in the car’s window has a clear sight of the sky, it can receive these signal transmissions.
Calculating Speed and Distance Using Trilateration
When you car’s GPS device receive a signal from space there will have been a time delay in the point it was sent from the satellite, to the point your device receives it. Because of this time delay, your product is able to calculate the length of distance back to the satellite in orbit. This is where the clever stuff happens, which is called trilateration – which is the method of distance and speed calculation. Using this method your GPS will receive data from at least three different satellites at the same time in order to determine an exact location. Due to the orbiting sequences, your GPS should always have clear sight to at least four satellites, which is where the ability to be highly accurate with the calculations comes in.
GPS Plots Your Position on the Digital Map
Now, the way in which you car’s GPS figures out where to place your car on the map is the next clever step. All GPS products have maps installed physically on the device and hard disk – which is contrary to what a lot of people believe, with a common misconception being that the maps are beamed down from space. Because you have mapping on your GPS, and the network knows your exact location due to trilateration, the product is able to plot your position on the digital map – (If you want to make sure you have the most up to date maps on your device then make sure you visit the Navteq DVD Supplier.)
Your GPS will be able to overlay your position as your drive, and because signals are being transmitted constantly it can cause the appearance that your car is moving along the map as you go, offering accurate directions and location-based data.