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What's the good of GPS?

The Global Positioning System (online resources) is a shadowy, poorly-understood technology with more futuristic promise than an episode of Star Trek. More than a few urban (and rural) legends have developed about GPS, which relies on a network of satellites to give you a relatively precise readout of where you are anywhere in the world. (See sidebar for an explanation of how GPS works.) With handheld GPS units now costing little more than a CD player, are there real-world applications of GPS for average people, or is GPS a technology in search of a market?

We're accustomed to dramatic price drops in electronics, but even by those standards GPS costs are plummeting faster than a cannonball dropped off the balcony of the Tower of Pisa. Four years ago, the basic chip set for a hand-held GPS receiver cost US$3,000 to US$4,000, says Ren Clark of Delta Data Systems, a GPS system integrator in Mississippi. Now a chip set-- the underlying brains of the receiver-- with twice the sensitivity costs less than $140. Consumer-level GPS receivers, usually about the size of a large cellular phone, are available for as little as US$150. Even the L.L. Bean mail-order catalogue was selling a GPS receiver for $254 in 1995 [though apparently not in 1999], with a $210 model scheduled for 1996. Professions like surveying, mapping, resource exploration, agriculture, and aviation and maritime sectors were and are the main markets for GPS outside the realm of the military.

However, for the general public, GPS's mythology seems to have grown larger than its actual usefulness. Alwin Simms, a professor in the department of geography at Memorial University in St. John's, notes that "some people buy these things thinking they can locate themselves under a sofa in the living room," when in fact you need a clear line-of-sight to receive the satellite signals. GPS rarely works indoors and often works poorly in the urban canyons of city skyscrapers.

Even Elliott Kaplan, a systems engineer at Mitre Corp. in Boston and author of the book Understanding GPS: Principles and Applications, is hard-pressed to think of a real-world use for GPS for average people. "The largest market will be in automobiles," he predicts, referring to "intelligent transportation systems" that track your progress and show you the correct route to a destination. But even in that application, urban canyons can disrupt the signal, the inertial and wheel-turning sensors needed to integrate the GPS data with what the driver is actually doing are expensive, and the practical problem of driving while watching an animated map on the dashboard has not been solved.

Says Ren Clark, "The housewife that buys a GPS to watch herself drive to the grocery store-- it's like people buying PCs to balance their chequebook. It's good for the PC industry, but damn, you don't need a PC to balance a chequebook."

Hiking, mountaineering, mountain biking, and boating are plausible GPS uses, but even for those applications GPS isn't a panacea. By taking a GPS receiver along with you on a hike, you can do the equivalent of leaving a bread-crumb trail-- stopping for a moment at "waypoints" (landmarks) to program your ongoing location into the GPS receiver. "The unit would then give you directions back to the waypoint trail so you could follow it," says Marshall Aucoin, owner of Aucoin-Page Assoc., an OEM manufacturer in Texas. "[GPS] would not only tell you which way you're heading but which way you're drifting and so on." But, Sims maintains, "a critical word here is 'Do they know how to read a map?' You have to be map-literate, and you also have to be aware of the machine that you're using.

"You've got two kinds of buyers in this recreation [market]. You've got the guy who has more money than sense, and the guy who asks, 'How do I then go and figure out where the heck am I?'... If I tell you that you're at 56° north and 35° west, that has no more meaning if you're not holding a map or if you're standing in the middle of nowhere. That's the long and short of it."