How Does Nav System Work

All modern sat-nav systems rely on the Global Positioning System (GPS) known as Navstar. … A GPS receiver works by comparing the location and time data to its own and working out its distance from the satellite.

How does GPS work in aviation?

​The aircraft GPS receiver measures distance from a satellite using the travel time of a radio signal. Each satellite transmits a specific code, called a course/acquisition (CA) code, which contains information on the satellite’s position, the GPS system time, and the health and accuracy of the transmitted data.

Why do you need 4 satellites for GPS?

You need four satellites because each data from one satellite put you in a sphere around the satellite. By computing the intersections you can narrow the possibilities to a single point. Three satellites intersection places you on two possible points. The last satellite give you the exact location.