Finding Your Way GPS: By using the Global Positioning System - a network of 24 military satellites, you can easily find your way.

THE BALTIMORE SUN

It's easy to feel lost in the forest of modern technology. But you can put that technology to work to find yourself - anywhere in the world.

With a GPS receiver, it's easy to figure out where you are - and almost as easy to figure out how to get where you're going - whether you're walking, sailing, flying or driving.

Though they lack the artistic elegance of a good, old-fashioned map, these gadgets offer something more: a floating "You are here" indicator.

GPS receivers get their name (and their information) from the Global Positioning System, a network of 24 navigational satellites placed in orbit by the Department of Defense to help troops, planes and ships find their way. By locking onto three or more satellites, the receiver can determine your latitude, longitude, altitude, the direction you're traveling and even your speed.

Several kinds of GPS navigation tools are on the market: hand-held receivers that will help you find your way back to camp or dock, GPS units built into top-of-the-line automobiles, .. and units that hook up to a laptop computer in your boat, car or plane.

The technology is catching on among consumers. The GPS Industry Council says 2 million hand-held receivers are in use, and about 250,000 GPS receivers - for both hand-held units and computers - are being produced each month.

To get one, you'll pay from $100 to $1,000 (even more if it's built into your car). More money buys more accuracy, built-in mapping capability and other bells and whistles.

Just don't expect absolute precision. Most GPS receivers can report your position within 100 meters, but the system is capable of far greater accuracy.

The problem is that the government deliberately fudges the signals that civilians use, so that foreign armies with GPS receivers can't rely on the same degree of accuracy as our forces. U.S. military GPS receivers get the real signal and are accurate to within a few feet.

Still, boaters in U.S. coastal waters can plot their positions more closely by using the Coast Guard's Differential GPS service, an add-on system of land-based transmitters that can correct your location to within 10 meters, sometimes less.

To get the Coast Guard signals, you'll have to buy an additional differential beacon receiver, available from many GPS manufacturers. But they're not cheap - expect to pay an additional $400 to $500. You' ll also need a regular GPS receiver that's equipped to process the Coast Guard signals.

With these caveats in mind, we tried out a handful of off-the-shelf GPS products to see how they performed. Here's what we found:

Handheld GPS units

We checked out two popular models, the Magellan GPS Pioneer, available for $99.99, and Garmin's GPS II Plus, which sells for $386.

The Pioneer is the low end of Magellan's line, and it isn't loaded with features. But it's easy to use and will take you where you want to go.

To get it working, take it outside with the antenna pointing up, turn it on and watch the screen light up while it acquires the satellite signals it needs.

At this point, you may want to enter your position (which Pioneer calls a "landmark"). The receiver stores this location in memory, so you can find your way back to camp, your truck, your marina or your mom.

I started in my parents' large back yard and took a brisk walk. Then I hit a button labeled "Goto" to see whether the Magellan would lead me back, as advertised.

When I chose the landmark I had already entered, the Pioneer told me which way to go (example: 30 degrees left). When I deliberately ignored the directions and wandered aimlessly, the machine corrected me. Finally, I stopped where I had first programmed the landmark, and the Pioneer told me I was within 0.008 miles of my destination. Close enough!

Although it basically works the same way, the Garmin GPS II has more features. Its antenna swivels, and the rectangular screen can be oriented vertically or horizontally.

This handy feature, combined with the unit's nonskid surface, makes it fun to use on the dashboard of the car, in a boat or even mounted to your bike. There are also two choices for the navigation screen: You can make it look like a compass or a highway.

In the car, the unit not only showed my position and heading, but also my speed and the heading I would need to get back to my landmark.

Speaking of landmarks, the GPS II adds a neat wrinkle: You can designate what kind of landmark each way point represents with symbols that include houses, boats and tents. The mapping screen draws a line that shows your route as you move from landmark to landmark.

While teh Garmin GPS II Plus offered more features, its display wasn't as bright as the Magellan Pioneer's. Both units run for up to 24 hours on four AA batteries.

Road adventures

Some of the most impressive applications of GPS technology involve automobile tracking and routing systems. We tried two of them, one for PCs, one for the Macintosh.

TravRoute's Door-to-Door CoPilot software and receiver ($399.99) track your car on a map displayed on your PC screen. The software lets you plan a trip by entering your point of departure and destination, then guides you through the journey turn by turn.

The wildest thing: It talks to you. So if you're the type who likes to yell at your co-pilot when you're lost, you can be confident that you'll win the argument. CoPilot is unfailingly polite and says, "You're welcome" when you say, "Thank you."

To make CoPilot work, you plug the GPS receiver into the serial port of your laptop PC and put the receiver, a 4-inch white disk, on the dashboard so that it can "see" the satellites. Then you start up the CoPilot software.

Finding a place for the laptop is the real trick. Though a dashboard mount would be ideal, the passenger seat works.

Once you've entered your destination, the program formulates a route and you're on your way. With the voice recognition turned on, you don't have to look at the PC at all. Just say "Next turn"

and the computer will respond with directions. You can demand other information with commands such as "Speed?" and "Where am I?"

In "Passenger" mode, the computer displays the map on the screen; otherwise, after a few minutes, the screen goes blank. If you stray off your route, CoPilot automatically calculates a new one and revises its directions.

This sounds really great, and occasionally it is. But sometimes, as on my relatively straightforward commute home to the southern 'burbs, CoPilot sends you on routes that are almost comically roundabout. The program froze a couple of times in midroute, and I discovered that you'll take your life in your hands if you rely on its designation of one-way streets.

When I tried the software in a semirural Pennsylvania community, CoPilot couldn't direct me beyond the one-store, one-church "downtown" to my destination on a side road. The tracker, however, worked well no matter what road I traveled, and I could always see my destination on the map while a trail of arrows on the screen marked my progress.

Sometimes, however, because of the GPS receiver's margin of error, CoPilot and other tracking software will locate you on the wrong road - generally a nearby parallel street. This is a particular problem in cities, where streets are close together and it's hard to get a fix on enough satellites.

TravRoute is testing a version of CoPilot that links up to government computers collecting real-time traffic information from roadway sensors in major metropolitan areas. When it's ready (you'll need a digital cellular modem), you'll be able to spot traffic problems ahead and estimate delays.

DeLorme's Tripmate ($159) also offers door-to-door routing and voice recognition in its PC version only. But we tried out the Macintosh version, because - as in so many things - it's one of the few software options Mac users have.

fTC TripMate's simplicity was refreshing after the loops and whirls of CoPilot. It shows you your location on its excellent atlas-quality maps, but you have to figure out your next turn yourself.

The Tripmate package includes the receiver and the Street Atlas software. You can also opt to buy Phone Search USA's $29 program and database which allows you to find an address and export it to the mapping software.

! Pub date: 5/18/98

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