How a GPS unit works on a golf course

Just how does your handheld GPS device transmit information about the next hole?

Throughout man’s recorded history, navigational devices have been used to determine location on the earth’s surface. First it was the compass, then the sextant, chronometer, radio-based navigation and today’s satellite system or GPS, which stands for global positioning system. The GPS is not only used in your car, but in any means of transportation from an airplane to a golf cart. How they operate is really not that difficult.

We have the U.S. Department of Defense to thank. Starting in 1994, the American military established a satellite system called Constellation that would protect the United States.  They launched 24 satellites, plus 8 spares, that orbit the earth. There are at least three satellites within range of every point on the planet. It is these satellites that determines our position, be it the middle of the Mojave Desert or the seventh hole of your local golf course. 

How the GPS works 

The basic principle behind the GPS is the measurement of time between your GPS unit and the satellites. A minimum of three satellites are used to determine your location. Each satellite sends out a circular signal back to the earth, with the signal travelling at 186,000 miles per second. The time it takes for the signal to travel from the satellites to your GPS is measured in hundredths of seconds. Where all three circular signals cross, that is your location, within eight feet. The technical term for where you are standing is called 3-D trilateration. It is really basic geometry learned in high school, using the formula of speed times time equals distance. To be even more exact, if a golf course installed an additional ground antenna, you could locate your position with a couple of feet. This is called differential GPS and is used by airplanes and large ships.

The last step is easy. Purchase a good GPS unit and turn it on. Courses are preloaded, with automatic course and hole recognition. The GPS unit will locate you and the distance to the flag. It will even indicate hazards such as trees, bunkers and other obstacles. With knowledge of the distance and hazards, it is now up to you to hit it straight.