How GPS Phones Work

Cell Phone Basics

A cell phone is basically a sophisticated two-way radio. Towers and base stations, arranged into a network of cells, send and receive radio signals. Cell phones contain low-power transmitters that let them communicate with the nearest tower.
GPS Phones Work
As you travel, you move from one cell to another, and the base stations monitor the strength of your phone’s signal. As you move toward the edge of one cell, your signal strength diminishes. At the same time, the base station in the cell you are approaching notices the strength of your signal increasing. As you move from cell to cell, the towers transfer your signal from one to the next.
In remote locations, towers may be so far apart that they can’t provide a consistent signal. Even when towers are plentiful, mountains and tall buildings can interrupt their signals. Sometimes people have a hard time getting clear signals inside buildings, especially in elevators.
­ Even without a GPS receiver, your cell phone can provide information about your location. A computer can determine your location based on measurements of your signal, such as:

  • Its angle of approach to the cell towers
  • How long it takes the signal to travel to multiple towers
  • The strength of your signal when it reaches the towers

Since obstacles like trees and buildings can affect how long it takes your signal to travel to a tower, this method is often less accurate than a GPS measurement.­­

GPS Receiver Basics

Like a cell phone, a GPS receiver relies on radio waves. But instead of using towers on the ground, it communicates with satellites that orbit the Earth. There are currently 27 GPS satellites in orbit — 24 are in active use and 3 act as a backup in case another satellite fails.
In order to determine your location, a GPS receiver has to determine:

  • The locations of at least three satellites above you
  • Where you are in relation to those satellites

The receiver then uses trilateration to determine your exact location. Basically, it draws a sphere around each of three satellites it can locate. These three spheres intersect in two points — one is in space, and one is on the ground. The point on the ground at which the three spheres intersect is your location.
A GPS receiver has to have a clear line of sight to the satellite to operate, so dense tree cover and buildings can keep it from getting a fix on your location.
GPS receivers and cell phones have a lot in common, and both are very popular. In the next section, we’ll look at some of the features of GPS-enabled cell phones.
For more Detail: How GPS Phones Work


About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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