GPS Units: How Do They Work?
Sunday, October 19th, 2008 Subscribe To Our Feed
Whenever we have some understanding of a technology such as GPS systems and how they work, it helps us appreciate that technology and understand its cost. GPS systems are added – and more often, standard – features in the latest cars, PDAs (Personal Data Assistants) and cell phones. This author isn’t an engineer or scientist, so this article is a simplified explanation of how GPS systems function. Full technical details can be retrieved in other articles posted on the Internet.
The ABCs of GPS
Did you know that there are approximately 2500 satellites currently orbiting the earth? Not surprisingly, GPS satellites account for a great percentage of these. Only about 36 actually are operative – the others are retired GPS satellites. They constantly transmit a low-power radio signal to Earthly GPS receivers (not the other way around). By obtaining a signal from three of these satellites, a GPS is capable of measuring the distance from each and determines a position based on that data.
GPS systems satellites are nearly seventeen feet across when their solar power panels are fully spread out. They run on solar power and as extra insurance have backup batteries installed. They are designed to be operational for a minimum of ten years and weigh some 2,000 pounds. The earliest satellite is from 1978. Rumor has it that this one often relates stories from the old days when satellites had it much harder than they do today. Just kidding!
But Seriously
So what devices qualify as GPS receivers? Any electronic device that is able to receive signals transmitted by the GPS satellites is a GPS receiver. There was probably a GPS receiver on that cruise ship you were on last summer, another in the taxicab you had to the airport last week and then there’s that Navigon 7100 GPS that your boss just bought for his auto. Portable GPS systems for public use are averaging out around $300, give or take a little. Considering you didn’t have to pay to design, build and launch the satellite into space, $300 is a very conservative price.
It’s the US government who bears the price for constructing the satellites and launching them into space. So you can sit back and relax in your car, knowing that this network of satellites will quickly and dependably point you to your destination. So now you should have a fairly good understanding of what goes on behind the scenes when you switch on your GPS system.
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