Global Positioning System (GPS)

“Rocket science” is a term we often use to describe something complex. Sending a rocket into space is (was?) considered to be exceedingly difficult. So, this is used as the ultimate yardstick when measuring the complexity of a discipline. Is launching a rocket still the hardest problem solved by man?

Unlike space science, GPS however, is a technology that can change the lives of normal people like you and me. It has tremendous potential with a wide variety of avenues for the application of the technology as it offers mind-boggling precision. And to the marvel of the layman, the device is unbelievably small. This can be thought of as the macrocosmic equivalent of the Integrated Circuits (ICs) that perform an amazingly complex set of functions.

Be it aeroplanes, boats, ships or cars, GPS is the ultimate device that not only tells you where you are, but also guides you to your destination. Some of you who have seen it in cars will realise how useful a tool it can be. The size betrays the sequence of behind the scene activities that quietly determine the position to the accuracy of a meter or so. Navigation was the main idea behind developing GPS. But due to the low cost and size of the GPS devices, sky is the limit for possible applications of the device.

How does it work?
When I tell you that I am in Bangalore, you know where the place is located. If I have to drive down to a nearby city, I take the familiar road and use the landmarks on the road to confirm whether I am on the right track. Do ships and planes have this luxury? How do they keep to their courses? Simple. The earth is divided into imaginary horizontal and vertical lines along the earth's surface (latitudes and longitudes), which uniquely identify every point on earth. Using the compass, we can determine our location and navigate towards the destination.

But the compass is a crude tool and hence in the past, sailors used a device called “sextant” which could tell them the latitude and the longitude. It relied on the position of the North Star and the angle of the star to determine the position. This has been the sine qua non for navigation for a long time. Aircrafts used the altimeter (a pressure-based device) along with electronic circuitry for location determination. The technology not only was far from accurate, but also cumbersome.

Then man thought, “let's not rely on nature any longer.” Why use stars for reference when satellites launched by man can be used as beacons instead? Only that instead of sight, we will have to use radio receivers to "see" the satellite. Why not go one step further and use multiple satellites to determine the position? This is precisely what GPS does. In fact, using GPS, we can determine the accurate location of any place on earth, be it on land, water or miles above in the air. Sounds too good to be true?