Tests have shown that a proposed commercial broadband wireless service, known as LightSquared, effectively jams the GPS receivers that many military, aircraft and agricultural technologies depend upon.
The results of a test, submitted to the Federal Communications Commission on July 6, show “LightSquared signals, operating according to their originally filed deployment plan interfere with every type of receiver in the test,” said Air Force Gen. William Shelton, commander of space command.
The frequency band GPS operates in has always been intended to be “a quiet neighbourhood,” said Shelton. “GPS could coexist with other signals of the same magnitude…However, if you put a rock band in the middle of that very quiet neighbourhood, it’s a very different sort of circumstance.”
Since the test, LightSquared has offered an alternative plan that would only use lower power broadcasts and only the lower 10 megahertz of their frequencies. “We conducted only limited testing on broadcasts in the lower 10 alone, but precision receivers and even some cell phones were still affected,” said Shelton, adding that additional testing on the revised business model would be necessary.
The Defense Department has not yet received a sufficiently clear description of a LightSquared’s lower 10 MHz deployment plan, so at this point it has been unable to analyse its new aggregate interference environment, said Teri Takai, DoD chief information officer.
It’s possible a technical solution exists, where the LightSquared network would not jam GPS receivers, said Shelton. However, it would likely require testing and changes to DoD software. “We have not estimated cost,” said Shelton, but he did estimate receiver updates could cost billions of dollars and take more than a decade to complete — due to the fact that “there are probably a million receivers out there in the military, maybe even more than that.”
“The commission will not authorize LightSquared to begin commercial service if its operation would cause harmful interference to GPS,” said Julius Knapp, chief of the FCC’s office of engineering technology.
While several lawmakers said they appreciated Knapp’s assurance, the FCC has faced questions regarding its involvement in the LightSquared approval process.
Source: Fierce Government