How mobile computers can help you find yourself.

Notebooks, sub-notebooks and personal digital assistants are joining that growing list of electronic armor -- including cellular phones, pagers and pocket calculators -- which define and empower mobile workers. Driving around without your IBM ThinkPad is becoming unthinkable. Leaving behind your NEC UltraLite makes you feel ultra lost. Mobile workers, sensing that they are becoming so accessorized that they soon won't be able to move, may well ask, "What next?" What is next is something you probably haven't yet heard of. Having cut yourself loose from the office by buying a computer that goes wherever you go, you and your colleagues are likely to become increasingly concerned about knowing where you are. The notion of position, meaningless in a desktop environment, becomes significant as soon as you have mobility. Just how significant is the determination of position for mobile workers? This is only beginning to be understood, but to give you an inkling, imagine the impact the sextant had in freeing Western merchants from being timid coast huggers. Basically, no sextant, no Disneyworld.

The next accessory mobile workers will add to their electronic armor is called a Global Positioning System (GPS). Those who don't use it will pay for it anyway, so it is worth learning about. The US Department of Defense has spent over $12 billion on a network of 24 GPS satellites, each with two atomic clocks on board -- just in case one of them breaks. The satellites are continually beaming down the exact time. If you have a GPS receiver that can read the signal of one satellite, you will know precisely what time it is.

But where GPS really gets interesting is when you can pick up the signals of three satellites simultaneously. Since the Defense Department programs the satellites to beam down their scheduled orbits -- a so-called Almanac -- the right software can use triangulation to calculate the position of a satellite receiver. If the satellite receiver is attached to your mobile computer, you can figure out your longitude, latitude and velocity. If you can grab a fourth satellite, you can add altitude. You have, in other words, mastered the age-old puzzle of position.

How easy is it to lock on to four GPS satellites? Since 1993, when the 24th functional satellite was shot into orbit, if you have a GPS receiver and an unobstructed view of the sky, you should be able to do it anytime, anywhere, and in any weather. If you have a mobile computer such an IBM ThinkPad, an NEC Versa or an HP OmniBook, you can add a GPS receiver via the PCMCIA card slot. A credit-card-sized GPS receiver plus software costs less than $800. If you ignore the small matter of $12 billion which US taxpayers have already contributed for launching and maintaining the GPS satellites, use of the GPS data is free. It costs nothing to find out where you stand -- or drive, or sail, or fly, or hike, or patrol.

Standalone, handheld GPS devices have been available for years to give mariners and aviators their latitude/longitudes -- navigational numbers which are meaningless to most business people. A new class of software is now available that takes full advantage of both a GPS receiver and of the gorgeous screen displays available on the latest mobile computers. So-called moving road maps turn your computer into a James Bond-style street navigation system. By placing a magnetized GPS antenna on the roof of your car or on your dashboard, you can funnel satellite time signals into your GPS receiver, which converts them into positioning data. Programs such as AutoMap Road Atlas, Road Scholar, and Personal Travel Guide will use this data to superimpose a blinking icon, representing your current position, on a detailed computerized road map. The cost of a high quality digital map of a city the size of Los Angeles starts at around $50.

Using moving maps is a breeze. As you drive, the icon travels across the map. You can zoom in to get detailed street information, or zoom out to see the big picture, such as how far you are from the airport. You can specify your destination by simply typing in an address, resulting in a destination icon appearing on the moving map to tell you whether your heading in the right direction. Some programs will even suggest a route or show you where you can find the nearest ATM or Denny's. Meanwhile, you can store your actual meanderings on disk and play it back later to help with your expense report or to give directions to a fellow mobile worker.

GPS applications are growing fast, including vehicle tracking, disaster response, resource management, environmental testing, geographic information systems (GIS), synchronization of geographically dispersed events, and, of course, navigation. Whichever application you pick, you will quickly realize that getting there is all the fun.

Gerald Houston is vice president of marketing for Socket Communications, Inc., of Hayward, CA, a leading supplier of connectivity products for mobile computers. Socket developed the Mobile GPS Global Positioning System in partnership with Trimble Navigation of Sunnyvale, CA, the world's largest supplier of GPS receivers.