Trilateration

Over time immemorial, man has followed the prompts of nature and her course. Navigators used compasses and the stars to navigate the sea. Hitchhikers had found themselves led outside a deep forest thanks to moss that always grew north and should they need to find a village, the river was there as a guide. Although reliable, they are not exactly accurate. The GPS system has given numbers to locations that still remain uncharted.

Receivers use a special mathematical principle called trilateration. It is used to calculate the location of a receiver accurately by the maters in coordinates. Trilateration uses three distinct spheres (ergo the satellites) and by determining the scope of these three spheres, the intersection of these spheres is usually where you are located. This intersection is then measured from the center of the spheres (ergo their radiis).

This operation requires three distinct circles, which explains the need to have at least three satellites to return their coordinates to you. So what happens is, when the receiver sends a request to the nearest satellite, it returns its position and a time stamp. That position becomes the center of the sphere. How far you are from the center of this sphere is determined by the time stamp. The time stamp and the time it takes for it to arrive to your receiver is used to calculate your own distance from the location of the satellite in terms of geographical topography.

An example is, satellite A returns with an estimated 600 miles from the center, while satellite B returns with 400 miles. You’d know that you are between two satellites that are 600 and 400 miles away from you, but at what direction? Perpendicular? Parallel? Adjacent? You need a third sphere to have two dimensions from your distance. Are your towns parallel from each other or adjacent?

As A and B determines the height, C will determine the width. This gives a clearer picture as to where you are located right now. Constant movement reflects upon the streamed data from the satellite and you’d immediately get an update from where you’re going. 3 coordinates make up the x and y coordinates made only possible by an eye in the sky.

To find out exactly how GPS works in your phone, visit my website about gps tracking.

This entry was posted on Tuesday, March 2nd, 2010 at 2:53 pm and is filed under Cellphones. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.