How does GPS Work!

How Does GPS Work?

Today's Automotive GPS systems take the guesswork out of traveling. No more missed turns or hunting for elusive street signs. But just how does a GPS navigation system work?

All GPS navigation systems access a network of 24 NAVSTAR GPS Satellites circling above at an amazing 11,000 miles above the earths surface. Out of these 24 GPS Satellites, there will always be 6-7 over head in the sky at a given time.

When your GPS acquires directions what it is doing is referencing it location between at least 3 of these GPS satellites. A process called Trilateration is used to take the distance between the satellites and calculate the longitude and latitude location of your GPS unit. Essentially, a circle is drawn around each satellite, where all three circles cross is the latitude and longitude location of the GPS navigation system being used.

An easier way to picture how this works is…. You are stuck in a small redneck town in central Illinois, but you do not know exactly where. You wander into the local gas station to ask where you are. The man behind the counter with the seven chickens tells you that you are exactly 124.12 miles from Chicago. Now draw a circle with Chicago in the center, your location will be at a small point on the outside of the circle.

Next, you ask another person at the same gas station who happens to be airing up the hooves on his pet pig where you are at, he responds with " You're a whopping 426.85 miles from Memphis, TN son." You now draw another circle to represent the distance from Memphis.

You inquire with one more person, the man trying to trade food stamps for lottery tickets to the sales clerk. They respond by telling you that happen to be 149.99 miles from Indianapolis, In. You can draw another circle to represent the distance between you and Indianapolis.

At the only point that all three circles intersect will be your location. This will tell you where you are at, which happens to be Pibson City, IL (yes, the people that live there really do give directions this way). GPS work on this same principle.

Written by Ken Walker, Sr. Product Manager at PcPowerZone