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-- by Deborah K. Wong
Have you ever been lost and wished for one of those "You Are Here" markers? DeLorme's Tripmate and Street Atlas USA 4.0 bundle gives you one, electronically. Its high-performance Global Positioning System (GPS) receiver links directly to any laptop, correctly identifying your precise location anywhere in the U.S. on the newest version of DeLorme's street-level mapping software, Street Atlas USA 4.0.
A cluster of 24 orbiting Defense Department satellites, GPS monitors your position anywhere on the globe. It gives you accurate information such as latitude, longitude, elevation, speed and direction of travel, using the atomic clocks aboard the satellites for precision timing. The satellites broadcast low-power radio waves containing the satellite's identity code and down-to-the-nanosecond time that the message was sent. Tripmate's GPS receiver picks up the signal, identifies the satellite and compares the signal time with its own internal clock. Since radio waves travel at the speed of light, the difference between the send and receive times gives an accurate picture of your distance from the satellite.
I tested this receiver right out of the box on a Dell Latitude P133 portable PC with 24MB of RAM, requesting my location through the day and night, in sun, rain and wind. Response time was the same in all conditions: approximately 60 to 75 seconds.
If your laptop doesn't have a CD-ROM drive, you can select the area on the map where you'll be traveling and download just that data to your portable PC. I popped the CD into my notebook, plugged the Tripmate receiver into the serial port in the rear of my laptop, dropped four AA batteries into its bright-yellow, mouse-like case and attached four black rubber feet to prevent it sliding off my dashboard. Then I launched the Street Atlas software and hit the road.
The program's Initialize GPS dialog box first appeared on my screen to verify my location. When it picked up the proper signals, a lime green arrow appeared on the on-screen map, accurately showing my position as I moved. Tripmate needs to receive signals from at least four satellites to ensure accurate positioning; the map's arrow changes to yellow when the receiver picks up less than four satellites, and changes to red if the data is poor or insufficient.
Tripmate works only with Street Atlas USA 4.0 and AAA Map'n'Go 2.0 software, which is a real drawback if you've already invested in another mapping application. But Street Atlas USA 4.0 creates custom maps, covers the entire U.S. and provides the most graphically rich maps I've ever seen. It can measure the distance between two points, search addresses by latitude and longitude, and see zip code boundaries and demographics. Draw a circle or other shape around a region, and Street Atlas will calculate its area or show you the sights available within its radius. Using the Draw Line tool, you can add new roads, hiking trails or your driveway to maps. It automatically updates your maps with the latest weather, construction or event information via the Internet.
With Tripmate, getting lost will no longer be an excuse for arriving late. Batteries are included; laptop and driver aren't.
Copyright (c) 1997 CMP Media Inc.