Ligado OK Rejects 1 dB Interference Standard

Leaders of the House and Senate Armed Services committees amplified their opposition to the Ligado order. House and Senate Armed Services are eyeing ways to address such opposition, including via language in their respective versions of the FY 2021 National Defense Authorization Act, Capitol Hill aides and lobbyists told us. Filings detailing lobbying at the commission last week against the company's application were posted.

Dennis Roberson of Roberson and Associates, a Ligado consultant, emailed that the FCC, NTIA and ITU all use a harmful interference standard, while 1 dB "is not a standard and has never been used as such and per this Order, never will be." GPS Innovation Alliance, which pushed the agency to use a 1 dB standard with Ligado (see 2004140005), didn't comment.

Even without a signal from Ligado, receivers can see a 1 dB degradation as a natural occurrence due to GPS satellite signals in view, the FCC said. It said technical studies haven't established how a 1 dB decrease in noise floor relates to performance-based metrics like performance accuracy and thus how a radionavigation satellite service receiver is disrupted.

The order rejects NTIA and DOD concerns. NTIA's December letter to the FCC saying it can't recommend approval (see 1912090011) doesn't say anything new and makes no recommendation, the order said. DOD letters similarly don't have new data or analysis except to point to reports and recommendations that rely on the unpersuasive 1 dB metric, the order said. Subsequent NTIA and DOD submissions earlier this month repeating concerns (see 2004130030) have the same problems, it said. "The potential for harmful interference to U.S. Government GPS receivers is limited and manageable" due to Ligado's power level reductions, coexistence agreements with major GPS device manufacturers and the conditions adopted in the order, it said.

The order "is a reflection of the immense amount of effort and deep technical work that was done by the FCC to ensure that the final decision was based on sound engineering and scientific evidence," Ligado said. "It is evident that the FCC feels strongly that GPS must and will be protected. We look forward to working with all stakeholders to ensure the stringent conditions imposed on us by the FCC are met and this spectrum is ready to support our 5G future.”

The FCC should “withdraw its approval” of the application and work with federal agencies that opposed it to “find a solution that will both support commercial broadband expansion and protect national security assets,” Senate Armed Services Committee Chairman Jim Inhofe, R-Okla., and other leaders said in an opinion piece on C4ISRNET. “If they do not, and unless President [Donald] Trump intervenes to stop this from moving forward, it will be up to Congress to clean up this mess.” Also signing were Senate Armed Services ranking member Jack Reed, D-R.I.; House Armed Services Committee Chairman Adam Smith, D-Wash.; and ranking member Mac Thornberry, R-Texas. Inhofe, Reed and Thornberry previously urged Trump to intervene against Ligado’s application (see 2004160030). Smith also warned against the order.

Senate Armed Services is exploring “all options available, including legislation and hearings,” a committee spokesperson said. Any legislative action would likely need buy-in from the Senate Commerce Committee, lobbyists said. Two Republican committee members -- Sens. Ron Johnson of Wisconsin and Mike Lee of Utah -- publicly backed the Ligado application. Senate Commerce didn’t comment.

House Infrastructure Committee Chairman Peter DeFazio, D-Ore., is opposing the Ligado order. “There is far too much at stake to consider this case closed, and I will continue to press for answers as to how the FCC arrived at its final decision and how it will affect safety and security as we know it,” he said in a statement.

After Thursday’s FCC meeting, Chairman Ajit Pai said the agency approval in the Ligado proceeding has been based on engineering over politics. He also singled out support from such people as Johnson, Lee, Attorney General William Barr, Secretary of State Mike Pompeo, Sen. Mark Warner, D-Va., and Reps. Billy Long, R-Mo., and Doris Matsui, D-Calif.

Commissioners Geoffrey Starks and Jessica Rosenworcel called the vote "an extremely close call" and opted to defer to the technical analysis done by FCC engineering staff. They concurred in their approvals to send a signal about the need for "an improved inter-agency system and a stronger whole-of-government approach to our 5G effort," said their statement.

Commissioner Brendan Carr said the Ligado decision, like FCC action on 5.9 GHz and 28 GHz, was a thorny policy issue that had been passed on by multiple past FCC administrations. It represents "the tough calls" the federal government is expected to make especially in spectrum areas, he responded to our question during a Thursday news briefing. He issued a statement with the order.

There could be limited cases of high-precision GPS receivers where repair or replacement might be needed due to harmful signal interference, the agency said. That would require Ligado to provide base station information and operating parameters to federal agencies before it launches operations in the 1526-1536 MHz band, and craft a program to repair or replace such devices.

The FCC conditioned approval on the company continuing to comply with its GPS maker coexistence agreements. The firm would need to be operating under specific power levels, limiting out-of-band emissions, coordinating with GPS makers, maintaining a base station database for the aviation community, continuing to dedicate at least 6 MHz of L-band spectrum nationwide exclusively to satellite service, and filing biannual reports with the FCC detailing any interference complaints. The satellite company would also need to keep maintaining "stop buzzer" capability to shut down base station transmitters in an area in the event of a large-scale GPS disruption.