U.S. preps GPS defense

The United States is gearing up to protect its turf at the upcoming World

Radiocommunication Conference next month. At the last conference in 1997,

it nearly lost hold of the radio spectrum used for satellite navigation

systems.

A proposal was submitted three years ago to allow mobile satellite services

to transmit signals using the same bands reserved for radionavigation systems

such as the Global Positioning System. In response, U.S. government officials

launched a full-fledged effort to study interference issues and prepare

its defense of exclusive use of that portion of the spectrum for radionavigation

systems when the issue is reconsidered next month.

"I think we've won this one," said James Vorhies, an electronics engineer

in the Office of Spectrum Management at the National Telecommunications

and Information Administration, speaking at a GPS conference late last month.

Already, Inmarsat, a provider of satellite services to users of mobile

communications devices, has scrapped plans to transmit in a portion of the

spectrum used by GPS. However, "some countries want to keep this alive,"

Vorhies said.

Other industry and government officials stressed that the issue is not

closed and that European countries may cling to the proposal at the WRC

2000 meeting — to be held May 1 to June 2 in Istanbul, Turkey — for future

negotiations that could have nothing to do with GPS.

"Anything can happen during WRC," said F. Michael Swiek, executive director

of the U.S. GPS Industry Council. "As long as the proposal is out there,

the proposal is still on the table."

Despite support from Latin American and Asia-Pacific organizations to

help the United States suppress the resolution, European representatives

are unlikely to give up easily on their request for territory that could

have future uses, he said.

GPS, a satellite system that provides accurate positioning and timing

signals to receivers on the ground, in the air or in space, is widely used

for military and civilian aircraft navigation and defense command and control

systems.

Because of the critical nature of these applications, the Defense Department

and aviation industry are determined that nothing interfere with the accuracy

or availability of GPS signals. Therefore, the United States intends to

block any proposal that involves using the spectrum presently dedicated

to radio-navigation services.

While spectrum protection is an area of mutual interest for the United

States and Europe, both of which have existing and proposed radionavigation

satellite systems, the European delegation to the WRC needs to take into

account the views of its member states, said Lt. Col. Julie Karner, assistant

director for space and multilateral cooperation at the State Department.

Karner has been working with European officials to negotiate agreements

on GPS and the Galileo satellite navigation system being developed by Europe.

The meeting also will consider a space-to-space allocation for GPS.

Currently, the GPS spectrum is protected only for transmission from GPS

satellites to receivers on earth or in the air. However, growing use of

GPS by NASA and DOD to navigate the orbit of satellites has prompted a request

to extend that protection to include transmissions to receivers on orbiting

spacecraft.

Decisions about the modernization of GPS signals for civilian users

and a new navigation system being developed by the European Union have brought

new issues that will require attention at WRC.

The United States is requesting a radio spectrum for GPS that can be

used by the aviation industry to navigate and land aircraft in low visibility.

However, European countries already use that same spectrum for aviation-related

distance measuring equipment, which could interfere with the GPS signal

at high altitudes, Vorhies said. The United States would like that equipment

moved elsewhere, but Europe plans to increase its use in the next few years.

Vorhies said he does not foresee a problem, though.