Precision GPS Problems Remain as NTIA Requests Additional LightSquared Testing

The NTIA asked that the Defense Department and Transportation Department work together to develop a joint testing plan on LightSquared’s latest proposals aimed at mitigating interference with GPS signals (CD Sept 12 p5). NTIA’s Friday request focuses on information from cellular and personal/general navigation GPS receivers under LightSquared’s modified proposal. NTIA Administrator Larry Strickling sent the request in a letter to Deputy Secretary of Defense William Lynn and Deputy DOT Secretary John Porcari. The request also said further high-precision GPS receiver testing isn’t necessary until a specific solution is presented. Observers said that mean possible further delay to the company’s rollout.

NTIA asks that the Executive Steering Group of the interagency National Executive Committee for Space-Based Positioning, Navigation and Timing (PNT) work with LightSquared to validate testing data submitted by the technical working group (TWG) by Nov. 30. The PNT, which coordinates and advises federal agencies and departments on GPS matters, is co-chaired by the DOD and DOT deputy secretaries. The data validation is necessary because some federal agencies believe the TWG testing in the cellular and personal/general navigation group were “limited in time and scope,” the letter said. The NTIA requests a retest of the minimum number of devices from the original test “necessary to prove statistically that the earlier test results were valid,” the letter said.

LightSquared told the NTIA it won’t begin operations until federal agencies test filters that can stop interference with precision receivers, the letter said. “Given this commitment, we see no reason for any further testing of high-precision receivers until LightSquared presents its filtering solution to the Federal agencies for testing and evaluation,” said Strickling. “At that time, the federal agencies will need to develop and execute a plan to test and analyze LightSquared’s proposed mitigation.”

The NTIA precision filter issue will likely lead to significant delays to the rollout of LightSquared’s network, said satellite industry consultant Tim Farrar. While NTIA appears confident in seeking data confirmation that LightSquared’s revised plan wouldn’t interfere with the vast majority of general use GPS devices, several steps remain before a solution to interference with precision GPS devices can even be tested, he said. No high-precision filter exists, and it will likely be “a year or more before testing on the high-precision issue can be completed and a decision reached,” he said. That possible delay, during which there will be a presidential election and a new FCC chairman could be installed, hurts the fund-raising ability for LightSquared, said Farrar.

The NTIA’s letter “has established a path forward that will finally allow LightSquared to put concerns about the impact of its network on GPS to rest,” said a LightSquared spokesman. “LightSquared has already undergone one of the most extensive batteries of interference testing ever conducted and remains confident that this new round of testing will confirm those earlier results,” he said. “LightSquared is committed to working with the precision GPS users both within the federal government and in the private sector. LightSquared is already working on a technical solution that will resolve those remaining interference issues and that will keep the company on track to beat the FCC’s 2015 build-out deadline. We have always said that we believe this to be a resolvable engineering issue, and we are completely confident in our ability -— working in cooperation with the GPS industry -— to find a solution to the interference problem.”

The Coalition to Save Our GPS said it “supports additional testing of the LightSquared network and is gratified that so many government officials have called for it. The coalition aims to prevent GPS interference from LightSquared. “Because the configuration the company now proposes to use was only tested minimally, shortly before the conclusion of testing, further testing is needed before LightSquared can proceed,” the coalition said. “We remain concerned that LightSquared’s third and most recent proposal this year does not claim to solve interference to high-precision GPS receivers, so it makes sense that testing of those receivers would be delayed until filters actually exist.”