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HIAWATHA BRAY | TECH LAB

Next-gen GPS puts its best foot forward

Michael Fein/Bloomberg News/File

By Globe Staff 

How accurate does GPS navigation need to be? It depends on who’s driving — you or your car.

Today’s GPS is accurate enough to steer a human driver to the shopping mall. Just get us close enough and we can figure out the rest on our own.

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But the coming generation of self-driving cars will have to be told exactly where to go, and they’ll have to be accurate to within a few inches. Commonplace GPS devices aren’t nearly this good. But that’s about to change.

Next year, a California company called Broadcom will introduce a new generation of GPS navigation chips that will use less battery power and work well even in urban canyons, where skyscrapers often block GPS signals. But coolest of all for location geeks, the new chips promise a major bump in accuracy. Today’s models are accurate to 15 or 20 feet, at best. Broadcom promises to nail down the user’s location to within 30 centimeters, or about one foot.

Broadcom says the chips will first appear in smartphones in 2018. The company says it’s talking to manufacturers that plan to use it, but won’t say which ones.

Phones with super-accurate GPS chips will change our lives in small but significant ways. Ever stand on the corner waiting for an Uber or Lyft driver who’s half a block away, but who thinks he’s exactly where you’re supposed to be? That will happen a lot less often with high-accuracy GPS.

Or try using your phone navigation system when traveling on foot. It almost never gives me an accurate fix on where I’m walking — more like a half-hearted approximation. A GPS with one-foot accuracy would keep me on the right side of the street, and its better signal strength would help when I’m strolling through downtown areas or tree-lined streets. Even augmented reality games like Pokemon Go, which overlay digital images over real-world objects, will look a lot more realistic when the player’s device knows exactly where it’s located.

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There’s nothing new about hyper-accurate GPS. For years, soldiers and sailors have had systems that can measure latitude and longitude down to the inch. But they cost thousands of dollars and require large antennas that won’t fit in a shirt pocket. These units are more accurate because they receive two separate radio signals from each satellite, then combine them for a more precise fix.

The Broadcom system works in much the same way. It picks up the standard GPS signal, plus a new signal that’s stronger and less prone to interference. The Air Force has launched a dozen GPS satellites since 2010 that broadcast the new signal. Others have been added to the navigation satellite networks of the European Union and India. Between them, about 30 of the next-gen satellites will be in orbit by next year, in time to let the Broadcom chip work its magic.

But while better GPS will come in handy in our smartphones, it will be a lifesaver when installed in self-driving vehicles.

Todd E. Humphreys, associate professor of engineering at the University of Texas, said that one of the key advantages of autonomous vehicles is the ability to send them down the road in tight formations called “platoons.” Cars would be separated by just a few yards, reducing wind resistance by drafting like NASCAR drivers do, slashing fuel consumption and dramatically increasing the number of cars that could fit on a highway.

But platooning will work only if each car knows its exact location, down to the foot. “You can’t be two meters off, you can’t be one meter off,” Humphreys said. “Maybe you can be 30 centimeters off.”

Companies like Google are creating high-definition digital road maps for this purpose, but they’ll need to be checked against the car’s onboard sensors, and these will be calibrated against a centimeter-grade GPS receiver.

High-end GPS becomes even more important when it snows and road markings are obscured. Even a car’s on-board radar won’t know if it’s about to roll off the pavement and onto the shoulder. With a centimeter-grade GPS and a high-definition digital map of the highway, the car won’t need to see whether it’s centered in the correct lane. It’ll just know.

For self-driving vehicles to work, GPS needs to be just this good. And it’s just about there.


Hiawatha Bray can be reached at hiawatha.bray@globe.com
Follow him on Twitter @GlobeTechLab.