Driving to work one recent morning, I found it hard to keep my eyes off the laptop on the seat next to me. But Washington traffic was more clogged than usual, so I had lots of chances to glance over and watch a green arrow on a map pinpoint my location as I crawled down Connecticut Avenue.
I was using my commute for a rudimentary test of what could be a handy marriage of cars, computers, map software, and the satellite-based Global Positioning System (GPS). It's no fancy trick for a mapping program to take the data generated by a GPS receiver to mark and track your location on an onscreen map. And one big barrier to wider use of GPS has fallen: You can get the Tripmate from DeLorme for under $150 (800 452-5931). Tripmate includes DeLorme's Street Atlas 4.0 CD-ROM mapping software for Windows and a battery-powered GPS receiver that plugs into a serial port on your laptop.
PRECISION? Unfortunately, while GPS today is nifty for folks who like to play with gadgets and has some limited uses, it has significant drawbacks. To become a mass-market product, GPS must become easier to use, more accurate, and--especially--an integral part of cars.
I tried two different GPS setups, the DeLorme Tripmate and the Compass 3800 from Chicago Map (800 257-9444), a $339 package that includes Precision Mapping 2.0 Windows software and a Garmin GPS 38 receiver. Unlike the Tripmate receiver, the handheld Garmin unit (about the size of a TV remote control) has a data display that makes it usable for hiking and other outdoor activities. In addition, the new editions of Microsoft Automap Street Atlas and Trip Planner are GPS-ready.
The navigation system was designed by the U.S. military for ships and aircraft. (To get a detailed explanation of exactly how GPS works, check out Trimble Navigation's Web site, www. trimble.com/gps/.) For best accuracy, a GPS receiver needs a clear line of sight to at least four of the 24 satellites in orbit. That's easy for ships and planes, but cars have to deal with buildings, terrain, even trees that block off much of the sky.
As a result, GPS often works worst where it's needed most. It's O.K. in open country, where you can pinpoint your location within 100 meters or so. But in built-up areas, accuracy plummets. A 500-meter error in the country is no problem; in a congested city, you may be lost if you're off by two blocks. Several times, for example, the display put me in the middle of the Potomac River as I drove along its banks.
LAPTOP. In Japan, where the lack of a street numbering system makes navigating Tokyo a nightmare, GPS sales have been slow. Japanese receivers use gyroscopes to calculate position between good satellite fixes. But mechanical components make these receivers very expensive, more than $1,500. A possible solution is being designed by U.S. chipmaker SiRF Technology. SiRF has designed a low-cost system that it says can maintain good accuracy for periods when it can see only two satellites--and sometimes just one.
Lower prices and higher accuracy are necessary, but not sufficient, conditions for giving GPS mass-market appeal. Struggling to read a laptop screen in bright daylight while trying to find your way through strange streets is something only the truly gadget-hungry will want to do. But a cheap, accurate, and simple system with a dashboard map display would be attractive in cars. Pilot systems are being offered by Hertz and Avis in some locations, and I expect a major auto maker will offer a GPS option, though perhaps not before the 1999 model year. For most people, this is a technology that's not quite ready today, but the future is tantalizing.