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How does a GPS cellphone work

GPS on Smart Phone

Today Cellphones are man’s best friend. With the advent of 3G, the era of faster data communication has arrived. People rely on their phone for every other work, but the most important function is the GPS tracker that we all are getting habituated of. Think about a situation when you are in a new city and you don’t know how to reach the destination. Well, GPS is the solution. Just use the GPS app installed in your phone to know the shortest path. Even the cab driver won’t be able to fool you. Isn’t it a great advantage? Have you ever given thought how GPS system works? If you haven’t, then it is the right place to learn that about.

Cell phone tracking basics

Before starting with GPS, you need to understand the basic principles of cellphone operation. It is kind of a modified radio that relies on signal receiving and transmission passing with the aid of radio towers. Phone can also be tracked without GPS. This system relies on pinpointing which radio tower the cell phone is interacting with since cellphone emits radio signal in all direction. The nearest and farthest, all the towers eventually receive the signal but the strength varies. Using the signal strength Vs distance ratio and with the help of all towers, a cell phone can easily be pinpointed. You might have watched in crime shows that cellphone triangulation needs time.

To pinpoint a phone, at least 6 to 7 tower interactions are needed since phone towers are located far away from each other. It needs time to interact with all towers that’s why phone is required to keep sending signals for a long time before it can be pinpointed. But this system is not full proof as radio signals are often bent and obstructed by buildings.

GPS tracking

Global positioning system (GPS), tracking is based on exactly the same principle but it relies on Satellites in space rather than the signal towers. The GPS device transmits signal with an authentication code to GPS satellites in space which first recognizes the phone and then connects with it. When a phone is connected with 3 or more satellites, the cell phone with GPS can be tracked. Each satellite has a zone of functioning. When the phone interacts with three or more satellites, then the phone can be easily triangulated using the intersection of these three 3-D spherical zones.

The three satellites create two intersection zones, of which the first one is in space and the second one is on ground. The ground intersection zone is the position of the cell phone. More the number of satellites, the phone is able to interact with, the less is the size of intersection zone in the ground and thus more is the accuracy. That is why with each service, the accuracy varies. But 20 to 30 m here and there doesn’t make the picture unclear.

There are 30 GPS satellites of which 27 stay active all over the earth and the rest 3 are for backup in case of malfunctioning of any. Since all GPS satellites work in unison under US government, the pinpointing analysis is done at a single place, which is then transmitted back to the phone. These phones have an app to know the map of the area. Interacting with the map app, the GPS triangulation gives the exact location on the phone.

So in short, the GPS cell phones need to have GPS installed with the GPS interacting authentication that can be bought with the GPS service and a map app integrated with GPS signal decoder to show the correct position on the GPS map of the cell phone.

So, next time when you are lost and found by the GPS, you should know that at least three satellites are watching over you like angels.

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