As I headed out to lunch last week in downtown Lawrence, a couple who looked to be in their 60s motioned me over to their car.

“Can you tell me where I can find a motel?” the woman asked. She had several maps opened up on her lap. I pointed her to the SpringHill Suites by Marriott and the Eldridge Hotel.

Her husband then asked for directions to Kansas Highway 10 and seemed confused as I told him the quickest route.

His wife continued looking at the maps in their car. I gave them some other options for hotels. But her husband seemed to be in a hurry to get moving.

“These maps don’t tell you anything,” she said, thanking me as her husband pulled away.

As they left, I wondered if the two travelers might benefit from one of the new Global Positioning System units that not only shows you where you are, but helps you find restaurants, hotels, gas stations and ATMs.

Satellite navigation

GPS units use the U.S. Defense Department’s NAVSTAR Global Positioning System. There are 24 satellites in the system with three spares, which are arrayed about 12,000 miles above the earth. Those satellites send relatively weak radio signals down to earth.

A GPS unit tries to pick up three or more of the satellite signals to calculate the user’s location and altitude within a few feet. The signals won’t work if you’re inside a building, underground or underwater.

GPS units equipped with a Wide Area Augmentation System (WAAS) can narrow down your location. The WAAS system combines GPS signals with fixed signals coming from 25 land-based ground reference stations in North America.

Computing power

One of the latest developments in GPS are devices that hook up to your laptop computer, turning it into a street navigator.

Garmin International, based in Olathe, is scheduled to release one soon.

“It’s a slick little thing,” said Ted Gartner, a Garmin spokesman.

Gartner said he expected the Garmin GPS 18 units to be shipped from Taiwan by mid-June. For about $163, it comes packaged with street-level mapping software of North America and an easy-to-use interface.

The GPS unit, which is about three inches in diameter, has suction cups that stick to your windshield. The unit hooks up to your laptop using either a Universal Serial Bus (USB) or a serial plug-in.

“The cool thing about it, is anybody who has any kind of a PC laptop can load this,” Gartner said. You’ll need a Windows 98 operating system or newer.

The GPS 18, which is WAAS enabled, comes with software that will give you a turn-by-turn routing. And, through your laptop, it will give you voice prompts to get to almost any address — just like having a navigator sitting next to you.

If you’re traveling, it will tell you where you are and help you get to the nearest restaurants, hotels, gas stations or ATM machines, Gartner said.

“We think it’s going to do real well for business travelers who lug around a laptop anyway,” Gartner said. “It’s just a little hockey puck-sized thing that plugs in the back and you’re off and running.”

The voice prompts on it are good enough to help you find your way just by listening, he said. But the advantage of using your own laptop is that somebody sitting in the seat next to you can see a full-screen size map to help navigate.

Another advantage is that you can take it with you from car to car — a portability advantage over built-in car GPS units.

Other laptop GPS products

I wondered if there was anything out there similar. I found that Laptops for Less (www.gpsforlaptop.com) is selling a portable GPS device that hooks up to your laptop for $89. You position it on your car’s roof — a magnet holds it in place — and a six-foot cord connects it to your laptop.

Another laptop GPS device is the Navman eSeries GPS, which comes packaged with the Rand McNally StreetFinder Deluxe Travel Navigation Software. It costs between $109 and $139. It has an antenna that can connect up to 12 satellites to give you a more accurate location (www.navman.com).

After a little hunting, I found the Deluo Laptop GPS (USB or Serial) Deluxe, which works on both Apple or Windows operating systems. It goes for $109 and has the Rand McNally Streetfinder navigation software. It also can connect to a Palm OS or Pocket PC hand-held computer. (www .deluo.com)

GPS and DBG

I caught it on the third ring.

“Hey Dad, what’s up?”

“Just getting ready for work.”

“Cool. Cool. . . Hey, I’m heading for Worlds of Fun. What’s the best way to get there?”

I told him the easiest way I knew.

“You can’t miss it,” I said.

“Are you sure that’s the fastest way?”

I had no idea. There might have been a faster route since the last time I was out that way. But I didn’t want to confuse him.

“Yeah, just take K-10 to I-435. Have a good time.”

Until he gets his own GPS system, he’ll have to rely on DBG (Dad’s Best Guess.)