---

• Archives Search

---

Home >> Archives >> Stories

Controversy swirls around potential GPS interference

By Larry Dreiling

A company planning to provide a new kind of national wireless communication service has set off a firestorm within the agricultural, aircraft, and national security arenas.

These industries fear potential interference to GPS receivers from the recently launched LightSquared communications network.

LightSquared is a company that plans to provide a wholesale, nationwide 4G-LTE wireless broadband network integrated with satellite coverage. The plan is to cover all parts of the U.S. with wireless service, with the intent that even remote rural areas would have 4G services via satellite when its standard terrestrial service would not reach customers.

LightSquared would combine existing mobile satellite communications services with a ground-based wireless communications network that uses the same radio spectrum as the satellites. Last January, the Federal Communications Commission gave LightSquared conditional approval to build out its ground-based wireless network.

The controversy amid the GPS community arose when it became aware that base stations of the LightSquared network would transmit signals in a radio band immediately adjacent to the GPS frequencies. The GPS community is concerned because testing has shown that LightSquared's ground-based transmissions overpower the relatively weak GPS signal from space.

Although LightSquared will operate in its own radio band, that band is so close to the GPS signals that most GPS devices pick up the stronger LightSquared signal and become overloaded or jammed. That would keep farmers, in particular, from using finely tuned Real Time Kinematic systems for precision planting.

The worst-case scenario, the coalition posits, as described in a statement: "LightSquared's plans to build up to 40,000 ground stations transmitting radio signals one billion times more powerful than GPS signals as received on earth could mean 40,000 'dead spots'—each miles in diameter—disrupting the vitally important services GPS provides."

There is also concern that the FCC may approve a technical solution to the problem that requires millions of existing GPS users to upgrade or replace their devices.

This is according to a report from the National Executive Committee for Space-Based Positioning, Navigation, and Timing, a U.S. government organization established by presidential directive to advise and coordinate federal departments and agencies on matters concerning the GPS and related systems.

The U.S. Departments of Agriculture, Defense, State, Commerce, Interior, Transportation, and Homeland Security, as well as the Joint Chiefs of Staff and NASA are members of PNT, one of a bevy of federal agencies trying to sort out the controversy.

The problem is so worrisome that a number of members of the GPS community have formed Save Our GPS, a coalition of manufacturers, retailers, and users of GPS equipment.

The coalition includes familiar corporate names like Garmin, Ag Leader Technology, and John Deere. Trade associations such as the Association of Equipment Manufacturers, National Cotton Council, and the Aircraft Owners and Pilots Association also are members.

Meanwhile, the FCC ordered LightSquared to create a working group with the GPS community "to address interference concerns regarding GPS and, further, that this [working group] process must be completed to the Commission's satisfaction before LightSquared commences offering commercial service."

LightSquared committed $20 million to the working group and worked closely with the U.S. GPS Industry Council and other participants to complete interference testing.

LightSquared submitted a report in late June, along with a separate document providing their recommendation, to the FCC. LightSquared, PNT said, cannot commence commercial operations of its terrestrial network until the FCC, "after consultation with NTIA [National Telecommunications and Information Administration], concludes that harmful interference concerns have been resolved and sends a letter to LightSquared stating that the process is complete."

Independent of the FCC-ordered study, the government's National Space-Based PNT Systems Engineering Forum conducted its own testing of the potential interference to military and civilian GPS users from LightSquared's terrestrial network. The unclassified NPEF report was released July 6.

Federal agencies have conducted extensive technical studies to understand the interference effects and seek potential mitigations. Their initial analysis is complete and was provided to the FCC through the NTIA. The results demonstrate that implementing LightSquared's planned deployment for terrestrial operations poses a significant potential for harmful interference to GPS services.

Prior to the FCC order and authorization of January 2011, multiple federal agencies expressed concern about potential GPS interference from LightSquared. On behalf of the Executive Branch, NTIA sent a letter to the FCC stating that the LightSquared proposal raised "significant interference concerns that warrant full evaluation" to ensure that federal agencies' use of GPS is not adversely impacted.

Members of Congress also got involved, including Senate Agriculture Committee Ranking Member Pat Roberts of Kansas.

"I introduced legislation to require that no funds be used by the FCC to approve Lightsquared's proposal until we're confident that its wireless network does not interfere with precision agriculture and other critical uses of GPS," Roberts said. "Due to congressional outcry, the FCC is carrying out extensive testing of the proposed network. I think we put those involved on notice that interference will not be tolerated."

The same day the NPEF report was released, the NTIA Administrator sent another letter to the FCC stating that based on the government testing and analysis, his earlier concerns about GPS interference remain unresolved. He recommended that the FCC continue to withhold authorization for LightSquared to commence commercial operations.

In December, a government technical group reviewed the findings from testing of LightSquared's proposal to provide new broadband service.

Preliminary analysis of the test findings found no significant interference with cellular phones. However, the testing did show that LightSquared signals caused harmful interference to the majority of other tested general-purpose GPS receivers. Separate analysis by the Federal Aviation Administration also found interference with a flight safety system designed to warn pilots of approaching terrain.

The findings were presented to PNT, which led both sides to offer statements to the media.

"As far back as June, LightSquared has been downplaying GPS interference concerns, insisting that LightSquared and the GPS devices consumers use every day in their cars, trucks and boats, and used to make air travel safer to prevent loss of life in aviation accidents could coexist. The results are in—there are substantial risks to all of these everyday activities," Jim Kirkland, vice president and general counsel of Trimble, a representative of one of the founding members of Save Our GPS, said in a statement.

Included in the risks, Kirkland said, is "proven, undisputed interference" to high-precision GPS devices used in critical economic activities, including agriculture and construction, and used in critical government activities, including storm warning systems, mapping, and disaster monitoring and management.

"LightSquared insists that new equipment can reduce interference to high-precision GPS devices," Kirkland said, "but completely ignores the massive retrofit and replacement effort that would be required, which would cost billions of dollars across government and private industry and require years-long certification processes in industries like aviation.

"As we stated in response to LightSquared's most recent filing with the FCC, LightSquared continues to recycle the litany of inaccurate and self-serving claims it has made in its ongoing effort to deny its obligation to avoid harmful interference to millions of government and private GPS users."

In their statement, LightSquared claimed a right to the spectrum, and asked the FCC to confirm LightSquared's right to use the spectrum licensed to them. In addition, the company asked the FCC to confirm that commercial GPS manufacturers have no right to interference protection from LightSquared's network since they are not licensed users of that spectrum.

"The one inescapable conclusion from two rounds of independent testing is that the incompatibility problem is not caused by LightSquared's network," Jeff Carlisle, LightSquared's executive vice president for regulatory affairs and public policy, said in a statement.

"It is clear that GPS devices are purposefully designed to look into LightSquared's licensed spectrum, and given this evidence, we believe decision-makers should consider LightSquared's legal rights as the licensee."

The company asserts that commercial GPS manufacturers are responsible for having designed and sold unlicensed devices that use spectrum licensed to LightSquared and its predecessor companies.

"Commercial GPS receivers are not licensed, do not operate under any service rules, and thus are not entitled to any interference protection whatsoever," LightSquared wrote in its petition to the agency.

The petition also notes that the FCC itself has stated that the GPS industry has been on notice for almost a decade that LightSquared was planning to use its spectrum to launch a nationwide broadband network.

"LightSquared has had FCC authorization to build its network for over eight years and that authorization was endorsed by the GPS industry, and fully reviewed and allowed to proceed by several other government agencies," said Carlisle. "Commercial GPS device-makers have had nearly a decade to design and sell devices that do not infringe on LightSquared's licensed spectrum. They have no right to complain in the eleventh-hour about incompatibility when they had ample opportunity to avoid this problem."

"While we ask the FCC today to confirm our legal rights, LightSquared remains fully committed to cooperate with all parties—the GPS industry, GPS users, and the federal government—to ensure that LightSquared's network is deployed in a way that is compatible with GPS users," said Carlisle.

In that vein of cooperation, LightSquared submitted proposed mitigation techniques to remedy the interference to GPS simultaneously with the technical working group final report.

On Jan. 13, just as this story was being completed, a memo to Assistant Secretary of Commerce for Communication and Information Lawrence Strickling from the co-chairs of PNT Executive Committee (PNT EXCOM), was posted on gps.gov, indicating further government testing "It is the unanimous conclusion of the test findings by the National Space-Based PNT EXCOM Agencies that both LightSquared original and modified plans for its proposed mobile network would cause interference to many GPS receivers. Additionally, an analysis by the Federal Aviation Administration has concluded that the LightSquared proposals are not compatible with several GPS-dependent aircraft safety-of-flight systems.

"Based upon this testing and analysis, there appear to be no practical solutions or mitigations that would permit the LightSquared broadband service, as proposed, to operated in the next few months or years without significantly interfering with GPS. As a result, no additional testing is warranted at this time."

The letter went on to say the EXCOM Agencies continue to strongly support the president's June 28, 2010, Memorandum to make available a total of 500 MHz of spectrum over the next 10 years, suitable for broadband use.

"We proposed to draft new GPS Spectruminterference standards that will help inform future proposals for non-space, commercial uses in the bands adjacent to the GPS signals and ensure that any such proposals are implemented with affecting existing and evolving uses of space-based PNT services vital to economic, public safety, scientific, and national security needs," the letter concluded.

The letter was signed by Deputy Secretary of Defense Ashton Carter and Deputy Secretary of Transportation John Porcari, co-chairs of the PNT executive committee.

In response, LightSquared said Jan. 18 that the process used to test GPS devices by Air Force Space Command on behalf of the PNT EXCOM was rigged by manufacturers of GPS receivers and government end users to produce bogus results, and revealed details of the testing to document its accusations.

LightSquared also asked NASA's Inspector General to investigate an apparent conflict of interest of one of the members of PNT advisory board, saying Dr. Bradford Parkinson has professional connections to companies that are members of the Coalition to Save Our GPS. LightSquared then called on the NTIA to objectively re-evaluate this initial round of testing and also to evaluate mitigation proposals the company has proposed and on the FCC and the NTIA to conduct the second round of tests on high-precision devices at an independent third-party laboratory to ensure objectivity and transparency.

Meanwhile, the controversy continues.

Larry Dreiling can be reached by phone at 785-628-1117, or by email at ldreiling@aol.com.

---