TEXT OF STORY

Bill Radke: GPS is everywhere -- stock traders use it, farmers. It's in cell phones and cars. Now the GPS satellite system is getting an $8-billion upgrade. Instead of 20 feet, GPS users will be able to zoom in on locations within an arm's length.

We get more now from reporter Sally Herships.

Sally Herships: Who doesn't like trees? Well, to some people, like surveyors, trees can mean big problems. Say you're measuring a site for construction, on a residential street lined with trees.

GAVIN SHROCK: Which is quite scenic and beautiful, except it blocks a lot of satellite signals. Sort of a curse to surveyors.

Gavin Shrock is a GPS expert in Washington. The current GPS signal can't go through trees, or rocks, or even a city bus. And when surveyors can't make GPS work they fall back on more expensive methods -- taking physical measurements at ground level. Shrock says the new satellites will have a stronger signal. So he says surveyors in his state will save a million dollars a year when the new technology is available. And other industries stand to save, too.

SHROCK: Oh, the aviation folks for sure.

More specific location information means more direct flight paths, which means less fuel and more money saved for airlines. Then there's mining, search and rescue...

Shrock: You know, you start to add those up, we're talking billions per year.

But most of us are probably more likely to notice the new GPS technology when we're shopping.

Larry Harris is CEO of Ansible Mobile -- a mobile marketing company.

LARRY HARRIS: For retail, it's going to be pretty much hugest thing since cash registers. I mean you're going to actually be able to do in-aisle stuff.

Right now, if you use a GPS app on your smartphone, marketers can tell when you're within a city block. But when the new, more accurate GPS becomes available, marketers will know when you're inside a particular store. If you want, advertisers will be able to send you coupons while you shop.

HARRIS: They'll be like, "Dude you're back, I see you rock the floss and you really like toothpaste, have we got a deal for you."

Harris says the new GPS system could mean billions for the advertising industry. Boeing is building the new satellites. The first was launched last month. Boeing says the rest will be sent into orbit at a rate of two to three per year.

I'm Sally Herships for Marketplace.