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AD: What is GPS being used for right now?

BP: I don't think the average man on the street has any idea how ubiquitous GPS has become. All new maps are referenced based on GPS coordinates. Using GPS, we can tell the exact shape of the Earth, and even predict earthquakes. Boats and airplanes use it. I have a close friend, a pilot, who won't take off unless his GPS equipment is working. It provides an enormous safety advantage. GPS offers continuous panoramic views of the Earth and shows the path to the airport. Here at Stanford, we've built devices that control tractors. They beat the winners of the John Deere tractor competition. GPS has been used to calculate the height of Mount Everest to the millimeter. Recently, it's started to be used for Internet communication protocols and other network applications. This technology even times the electricity grid, bringing new power plants online. It's also used extensively for tracking. In South America, hijacked trucks are recovered using GPS.

AD: Ten years from now, what appliances or other products will be equipped with GPS?

BP: What you'll see is that the things now being pioneered will become common practice. All high-end automobiles will use GPS. A third to a half of all farming applications will use it. Companies will use a variation on GPS, called GIS (geographic information systems), to tag an attribute with a location. For example, phone companies will tag telephone poles with a bar code that links to a location. A worker will scan it and learn it's cracked, needs to be replaced or that it's OK. In other words, it ups the power of digital record keeping. Adding location to the other records, the company can prioritize the telephone pole maintenance and direct the repairmen efficiently. Another example can be found in the film industry. Let's say a film crew wants to go back and repeat a shot at a previous location. It turns out that setting up the camera in the exact same place is not trivial, even in an urban area. GIS solves that problem.

AD: What about new applications, not just variations on old ones?

BP: We can talk about differential systems [where more than one location is changing at a time]. GPS measures velocity very accurately. Let's hypothesize a situation in which every automobile broadcasts its velocity and location. The reason there are massive pileups is usually low visibility: you can't see the car ahead of you decelerating. GPS could allow you to know the location of every other car on the road [within a given radius]. With this knowledge, one can anticipate these slowdowns. It's a blind collision avoidance system. For another example of the use of differential systems, look at our fully automatic landing of a Boeing 737. You can conceive of using that technology to get around the hijacking problem. Punch a button and land the plane. GPS-like technology is also used indoors, for what's called kinematic guidance. It's a productivity tool, basically, that keeps all your machinery operating in the right physical configuration [relative to one another].

AD: What technology might someday replace GPS?

BP: Right now most of the work is in improving the GPS system. An important goal is gaining approval for more frequencies. By providing redundant signals, delays in the signal can be better calibrated. A lot of people scratch their heads about these sorts of problems. The biggest shortcoming that GPS has is a relatively weak signal. It can't penetrate buildings very well. There are some ways of digging the signal out of the soup, but the power that's being generated is only 40 watts.

Ever since the Soviets launched sputnik in 1957, satellites have been part of our consciousness. An estimated 2,200 satellites currently orbit the Earth, performing functions ranging from the mundane (weather forecasts and TV signals) to the more imaginative and thrilling (espionage and scientific experiments).

Twenty-four satellites make up the Global Positioning System. Known as GPS, the technology pinpoints our position on the Earth's surface by transmitting signals to ground receivers. Using algorithms that interpret signals from multiple satellites (called “triangulation�), a GPS receiver can determine its location and where it's going.

The most common consumer application of GPS is in navigational systems, such as the devices in rental cars that map and squawk driving directions. But GPS does more than call out turnpike exits. The technology has revolutionized surveying, automated many industrial and logistical processes and even landed planes without pilots.

Bradford Parkinson oversaw the launch of the first GPS satellites in the 1970s while serving in the Air Force. Since 1984, he has been a professor of aeronautics and astronautics at Stanford University, except for a yearlong leave of absence in 1998 when he served as president and CEO of Trimble Navigation, a Sunnyvale, Calif.-based company that develops GPS-enabled products. American Demographics ' David Whelan recently discussed where the technology is headed with this GPS trailblazer.

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