STEPHEN TRIMBLE / WASHINGTON DC
Structure will avoid overlaying US military m-code
The European Commission has selected a signal architecture for the Galileo global navigation satellite system that avoids overlaying the US military m-code, yet may introduce a new signal interference problem with the US global positioning system, according to US officials.
The Galileo signal structure, unveiled last week in bilateral US-European Union talks in The Hague, shifts the planned frequency assigned to the public regulated service (PRS) for police and security users away from the m-code, which will remain the domain of the US Department of Defense.
The m-code concession, described as a "breakthrough" by US officials, comes shortly before the PRS frequency is required to be approved by the International Telecommunication Union. The EU describes the deal as a "very important step for Galileo".
A new threat to the negotiations has emerged over the EC's selection of a new open service (OS) frequency for commercial users that US officials say conflicts with US military needs. The new Galileo open service signal would have a "significant impact on military operations", a US government official says. Another official says the problem involves the spacing between GPS jammers and receivers on the battlefield, with the new OS frequency requiring a distance of tens of kilometres.
A compromise proposed by the USA last week would shift the Galileo OS signal to a frequency that partially overlays the m-code, which US officials consider a significant gesture. "We're trying to decide how much pain we can stand," says a US official. If the EC accepts the proposal, the USA would shift the planned GPS III frequency to the same signal, allowing Galileo and GPS commercial users access to both satellite systems.
ADDITIONAL REPORTING BY JULIAN MOXON IN LONDON
Source: Flight International