In September, Gen. William L. Shelton, commander of the U.S. Air Force Space Command, along with Anthony J. Russo, director of the National Coordination Office, Space-Based Positioning, Navigation and Timing (PNT) at NOAA, and others testified before the House Armed Services Subcommittee on Strategic Forces regarding the potential impact of the proposed LightSquared broadband network on GPS related to national security.

In his testimony, Shelton noted that “possible mitigation measures were evaluated, but all were deemed impractical as they would require significant modification, redesign and/or replacement of existing GPS equipment, of which there are literally billions worldwide. For the military alone, there are significant costs involved in re-designing, manufacturing, testing, fielding and integrating new or modified GPS receivers in our military equipment and weapons systems.”

Russo summed up the challenges by pointing out that “the extensive and comprehensive testing done by LightSquared, the NPEF [PNT Systems Engineering Forum] and the GPS Industry conclusively demonstrates harmful interference from LightSquared’s intended deployment of their high-power terrestrial broadband system and should not be allowed to commence commercial operations until the identified problems are resolved to the satisfaction of the FCC.” LightSquared appeared to be fighting a losing battle.

Then, on Sept. 21, LightSquared announced that it had partnered with Javad GNSS Inc. to develop a technology fix-a protective filter designed to make GNSS equipment “compatible” with the LightSquared network. The news was met with broad criticism from the GPS industry. A statement issued by the Coalition to Save Our GPS said, “LightSquared has, as usual, oversimplified and greatly overstated the significance of the claims of a single vendor to have ‘solved’ the interference issue. There have been many vendor claims that have not proven out in rigorous tests and the demanding tests of marketplace acceptance.”

In an interview with POB, Javad GNSS founder Javad Ashjaee downplayed the criticism. “Sometimes technical development gets caught up in the middle of a political controversy,” he said. “We started looking at the issue of in-band interference eight years ago and developed a solution. Two years ago, we began putting into our receivers a spectral analyzer that shows interference. This band of spectrum is getting congested. We cannot claim we own this band and have one mile to the left and one mile to the right because we don’t want to do a little bit of research to stay within our band. We’ve shown we can do that.”

Ashjaee said his company is offering to retrofit existing GPS receivers at cost to make them LightSquared compatible. However, he also said he believes that many of the GPS receivers currently in use will soon be obsolete. “New GPS satellites will transmit new signals that none of those receivers can track currently,” he said, speaking of the L2C, L5 and L1C signals. He said he believes many users will be faced with upgrading their receivers anyway, even apart from the LightSquared debate.

The Coalition to Save Our GPS continued to emphasize that additional testing is necessary to evaluate the impact of interference with the most recent technical proposals. Results from the latest round of tests are due on Nov. 30. LightSquared has threatened legal action if the FCC does not allow the company’s network to move forward after these tests are complete.

Click here to listen to POB Editor Christine Grahl’s interview with Javad Ashjaee.

The website for the Coalition to Save Our GPS is www.saveourgps.org.