GPS knows no bounds

While the aviation community awaits delivery of a certified system to help guide pilots during landings, other applications of the much-anticipated technology are emerging.

Raytheon Co. is slated to turn over the Wide Area Augmentation System (WAAS), a network of ground stations that correct satellite signals and broadcast them to receivers on aircraft, to the Federal Aviation Administration in 2003.

In the meantime, groups outside the aviation industry, many in agriculture and the maritime industries, already are picking up — and benefiting from — the signal.

"There's a ton of people out there now using WAAS for just about everything," said Harold Bell, FAA's WAAS product team leader.

WAAS enhances information provided by the Global Positioning System (GPS), a 24-satellite constellation built by the Defense Department that allows users to determine their positions anywhere in the world.

Anyone with a WAAS-enabled receiver can use the system as long as it's not for flight safety, said John Britigan, Raytheon's director of satellite navigation. "It's such a public utility now that in the end, everybody in the country is going to be impacted by this."

Vendors have taken note.

"We saw benefits to GPS across many other markets than the one others were focusing on," said Pete Brumbaugh, a spokesman for Garmin International Inc., which began testing WAAS after it went operational in August 2000.

The company released its first fully WAAS-enabled receiver in January 2001, Brumbaugh said. It delivers similar capabilities to the Differential Global Positioning System (DGPS) at less cost, he added.

Like FAA's WAAS, the Coast Guard's DGPS network, launched in 1996, improves the accuracy of GPS by broadcasting corrections. Unlike WAAS, however, DGPS users must have a beacon transmitter to pick up the signal.

The WAAS gear costs about $150 to $250, according to Brumbaugh. By contrast, no extra equipment or fees are needed to take advantage of WAAS. Further, manufacturers can incorporate the capability by making an algorithmic change in the receiver's software.

"We saw it not just as an aviation technology, but as a differential technology," he said.

Since its arrival on the GPS scene, WAAS has gained a significant following with more than 200,000 users at last count, according to FAA's Bell.

"We didn't expect it to [reach] the level we are realizing," he said. "We're real enthusiastic about it."

Some of the predominant nonaviation uses for WAAS include surveying, precision agriculture and maritime navigation (see box).

"I would have never thought that WAAS would show up in the World Trade Center," he said. After the Sept. 11 terrorist attacks, rescue workers searching the rubble at ground zero used the signal to record locations, Bell said. WAAS offered greater availability and accuracy than raw GPS signals, Raytheon's Britigan said.

The technology also has assisted crop dusters, or aerial applicators, enabling them to apply pesticides as needed and decrease runoff. "It's all automatic now," he said.

In addition, mariners use it to maneuver through waterways. Other applications include 911 emergency locating and time synchronization.

"It's mainly because it's out there," Bell said of the nonaviation uses.

Still, not everybody with access to WAAS is encouraged to tap in. "The Coast Guard has put out warnings that [you] can't use it for certain applications," primarily those with a safety component, he said.

"It comes down to a usage issue," Brumbaugh said. "There are some limitations to WAAS."

For instance, the Coast Guard has installed DGPS in foreign ports, but WAAS stops working 80 miles to 100 miles from shore, Bell said.

"Differential [GPS] is still going to have a purpose. It's an established system," Brumbaugh said.

The FAA expects to commission WAAS for aviation use in July 2003, Bell said. "Raytheon is several months ahead of schedule," he said.

At that point, pilots flying airplanes with the necessary equipment will join the ranks of WAAS users.

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A bumper crop

A sample of nonaviation uses for the Federal Aviation Administration's Wide Area Augmentation System:

* Surveying — To collect up-to-date geographical data.

* Precision agriculture — To improve crop management tasks, including pesticide application and recordkeeping.

* Maritime navigation — To aid in the navigation of vessels.

* E-911 services — To locate wireless phone users making emergency calls.