More about GPS
What’s inside a Sat Nav device?
From the outside a Sat Nav looks like nothing more than a sleek digital device, with a touch screen, However, within the shell is a host of modern electronics that allows it to pick up signals from satellites orbiting thousands of miles above the earth and to calculate your precise position and speed on the planet.
Each component inside a Sat Nav has a specific purpose and each is essential to the functioning of the device. The rechargeable lithium-ion battery provides the power for the screen and the internal electronics. There are also circuits to control the display and to respond to user interaction via the touch-sensitive display and buttons. There are also circuits to control the information, map and route displayed as well as to produce audio – Text-to-Speech – directions in some models. Some Sat Navs, such as the Mio Moov 580 even have Bluetooth capability.
In order to carry out its main job of locking on to the global positioning system (GPS), a Sat Nav has an aerial inside. This receives the microwave signals from the satellites in the GPS constellation. These signals are then amplified and fed to the integrated circuits that analyse the signals and calculate your position. The circuitry uses a system known as trilateration, which is the 3D equivalent of triangulation on a map. The trilateration process depends on the GPS device being able to determine the distance to the satellites by timing the signals using its inbuilt clock. The clock itself is an electronic circuit known as an oscillator.
