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August 6, 2002

A public radio commentary

I have located my Diary Queen, it's at exactly 40 degrees 6.986 minutes North and 88 degrees and 13.178 minutes West. I know this because I've bought a GPS, or Global Positioning unit. Although extremely high tech, it works exactly like old fashioned navigation: Locate three fixed points and triangulate your postion. Of course for the GPS, the fixed points are twenty-eight satellites orbiting the earth.

A GPS unit measures its distance from these satellites using time. Each satellite sends out a signal containing its positon and the time the signal was sent. When it arrives, the handheld receiver measures how long it took to travel, then uses this to calculate its distance from the satellite. And then it reports its position on the globe with an accuracy of about ten feet.

It amazes me that this degree of accuracy can be purchased for about one hundred dollars, the cost of my unit, although for the GPS system to arise it did take Sputnik, twelve billion dollars, and a war.

In 1957, the Soviet Union launched Sputnik, the world's first satellite. One American engineer, Frank McClure of Johns Hopkins, noticed that he could locate Sputnik by measuring the radio signal the satellite emitted. This gave him the idea for a navigation system based on satellites. Over the next twenty years, the U.S. Military developed McClure's idea into the global positioning system we have today, but it took twenty more years before civilians could use it.

GPS caught the attention of the world during the Gulf War of 1991. The military found it was the only way to move across hundreds of miles of trackless Iraqi desert. This use made huge headlines, and interested the public in the few commerically available GPS devices. But oddly, the devices lacked the main element needed to become really useful: Accuracy.

You see, the military fuzzed out the signal on purpose. They added a billionth of second to the clocks, making the GPS no more accurate than about 300 feet. GPS sales soared, though, when, with little fanfare in May 2000 the government shut off this jamming.

Like all powerful technological innovations, serious uses are being found for GPS almost daily, although the best measure of the acceptance of a technology is its use for pure folly.

The latest fad with GPS is called "geocaching." It's a kind of high-tech easter egg hunt. All over the world, players hid caches - usually a log book and new batteries for the finder's GPS - and then post the lognitude and latitude to a web site. Players then hike for hours and endure physical hardship to find the treasures now hidden in at least thirteen countries.

Rest assured that GPS is being put to better uses. So far, a self-guiding plow has been developed, and in the works are talking GPS units that would guide a blind person.

Copyright 2002 William S. Hammack Enterprises