GPS Users Fear Getting Lost In Wireless Expansion

GPS devices have become ubiquitous: Millions of drivers rely on them for directions.

The government hopes to construct a new air traffic control system based on GPS navigation rather than use radar.

They've also become an important tool in agriculture.

But a multibillion-dollar proposal to provide broadband Internet access using satellites and a network of 40,000 antennas could interfere with their devices. This could potentially make it harder for first responders to find emergencies, aviators to fly and drivers to navigate.

A Powerful Signal

Rick Richter, owner of Richter Aviation in Maxwell, Calif., flies what used to be known as crop dusters. He uses GPS every day.

"It provides swath guidance to within one meter accuracy of where we would like to put the chemicals, or the crop protection products, or the seeds or fertilizers," he says. "So it allows for a precise application of our products and reduces the environmental impacts."

Richter is president of the National Agricultural Aviation Association, one of several groups that want to put the brakes on the construction of a new broadband service by a company called LightSquared.

In a video on its website, LightSquared offers an enticing vision:

"Wireless devices will work in every single part of the country," the video explains. "People will be able to send e-mail from the Grand Canyon. Download a full-length movie in mere minutes while on the move. Make a phone call far away from Anywheresville."

Richter says the problem is that the radio signals the broadband carrier wants to use for its wireless network would interfere with signals GPS uses.

"There's no doubt there's going to be interference," he says. "You can almost guarantee that because the signal is so much more powerful than a GPS signal."

In fact, the government's own tests have shown the LightSquared signals cause some GPS receivers to lose signal strength and others were knocked out entirely.

'A Zoning Dispute'

That's because the part of the radio spectrum which the FCC granted to LightSquared is right next door to the part of the spectrum GPS services use.

Communications consultant Scott Cleland of the Precursor Group says it's a bit like a zoning dispute, "where people already have houses or they already have buildings and somebody comes along next to them and wants to build a skyscraper or wants to build something that has a very different use than what they had before. And so, what this is, is like a giant spectrum zoning spat."

LightSquared, the new guy in the neighborhood, has already invested billions of dollars in its network. Based on the FCC's go-ahead, LightSquared launched a satellite that's seven stories tall last November, and it plans to build about 40,000 ground transmitters.

Company Vice President Jeff Carlisle is confident the two sides can work something out.

"We want to make sure we're deploying our network responsibly and that requires us to sit down cooperatively and talk with the GPS folks and figure out the most efficient way to do it," he says. "If that requires some filtering on their side and some transmission modifications on ours, we're open to talking about that, absolutely."

One possible solution would be for LightSquared to use the part of the spectrum it has been allocated that's farthest from the part GPS receivers use.

The company had hoped to roll out its network later this year, but it's clear it has some obstacles to navigate around first.

Copyright 2011 National Public Radio. To see more, visit