The Armed Services Committee Further Weighs in on the FCC’s Grant of Ligado’s Application

Joel Lauren Thayer
12 min readMay 15, 2020


By Joel L. Thayer, Esq.

Recently, a group of senators led by Senator Jim Inhofe, Chairman of the Senate Armed Services Committee, sent a letter[1] to Federal Communications Commission (FCC or “Commission”) Chairman, Ajit Pai, that expressed their discontent with the FCC’s decision to grant Ligado’s long-standing application to modify its license.[2] The letter makes a series of claims that warrant a deeper discussion. Thus, I have developed the analysis below in an attempt to break down the various claims within the letter to assess the FCC’s action, and provide responses from the Ligado Order and the FCC’s record in this proceeding that I feel address the claims asserted.

Claim: We are concerned that the Order does not adequately protect adjacent band operations — including those related to the Global Positioning System (GPS) and satellite communications — from harmful interference that would impact countless commercial and military activities.

Response: The Commission and its expert engineers were very sensitive to this concern, and that is reflected in its order. The Ligado Order goes into painstaking detail as to how GPS is protected. Some of the restrictions include:

  • Creation of Guard Band for GPS: Ligado must not conduct terrestrial operations in the spectrum directly adjacent to the RNSS band and must create a 23 MHz guard band to protect GPS.
  • Repair and Replace: Ligado must cooperate directly with any U.S. government agency that anticipates that its GPS devices may be affected by Ligado’s ATC operations by
    (1) providing base station location information and technical operating parameters to federal agencies prior to commencing operations in the 1526–1536 MHz band; (2) working with the affected agency to identify the devices that could be affected; (3) working with the affected agency to evaluate whether there would be harmful interference from Ligado’s operations; and (4) developing a program to repair or replace any such devices that is consistent with that agency’s programmatic needs, as well as applicable statutes and regulations relating to the ability of those agencies to accept this type of support. (¶ 101).
  • Military Installations: In the event that it is determined that Ligado’s operations will cause harmful interference to a specific, identified GPS receiver operating on a military installation, the FCC expects Ligado and the affected government agency to negotiate an acceptable received power level over the military installation, or to establish limited exclusion zones. (¶ 103).
  • Stop Buzzer Capability: Ligado’s approval is conditioned on Ligado maintaining a 24/7 operations center to continuously monitor transmit power for each base station and have the capability to “cease transmission” of base station transmitters within 15 minutes if needed. (¶¶ 105, 146).

Claim: “Furthermore, the hurried nature of the circulation and consideration of the Order itself — during a national crisis, no less — seemingly ignored the many technical concerns raised by affected stakeholders…… we are concerned with the pace by the Commission to push through an Order first announced on April 16… We believe this accelerated timeline was not adequate to address the significant stakeholder concerns for an Order of this magnitude.”

Response: This proceeding stretches out at least a decade (Ligado first filed this application in 2010, but this proceeding commenced closer to 2003), and is the culmination of an extensive record that articulates every stakeholder’s concern (including the DoD). Ligado also modified its application several times to address these concerns. The Order the FCC recently promulgated builds off these decade-long negotiations and clearly incorporates all of these concerns. This is evident from the fact that the NTIA, DoD, DoT and FAA submitted no complaints to the FCC’s inquiry regarding Ligado’s application circa 2017.

The FCC stated clearly that the DoD has not provided any information to support its assertions that a “vast” number of GPS systems will be impacted. (¶ 100). The FCC also pointed out that the devices the DoD is referring to are operating outside their allocated spectrum.

  • The FCC found that the three April 2020 letters from the DoD do “not include any new technical data on interference” for the FCC to evaluate (¶ 46), and were based on an “inappropriate” metric and an outdated proposal, including much higher power levels than Ligado proposed and the FCC approved. (¶ 100).
  • The FCC explained how the data shows that devices which seem like they may be impacted are operating outside the spectrum allocated to them by the FCC. (¶¶ 50, 56, 57).
  • The FCC acknowledged that “the NTIA and the Air Force long ago agreed that GPS receivers were not entitled to protection outside of their designated band, a contention that the NTIA has not refuted.” (¶ 52)]

Claim: “Many of these concerns center around the significant risks the Ligado proposal poses to GPS functions and satellite communications. You understand how important reliable GPS and satellite communications are to our economic and national security. American families rely on its free precise timing and navigation for thousands of functions every day, including banking, logistics, agriculture, weather and travel.”

Response: Ligado already has coexistence agreements with GPS manufacturers (i.e., Garmin, John Deere, Trimble, NovAtel, Hexagon, Leica and Topcon) that represent the lion’s share of the GPS market and supply devices that provide every GPS function mentioned in this letter. This provides these companies with more legal protection on top of the FCC’s restrictions on Ligado. Additionally, the FCC’s Ligado Order notes that government (including DoD) contracts with some of these suppliers. Thus, these concerns are sufficiently addressed by the FCC’s Ligado Order and other legal mechanisms.

Claim: “The aviation community uses GPS and satellite communications for navigation, terrain and obstacle avoidance, and aircraft tracking necessary to safely operate commercial, business, military, and emergency response aviation activities, including medevac and aerial firefighting.”

Response: The Ligado Order requires Ligado to coordinate with the GPS Industry and aviation community (¶ 145). Moreover, the FCC noted the comment of Metro Aviation, “a leading provider of air medical services that operates more than 130 rotary and fixed-wing aircraft in 20 states, represents that it is confident that Ligado’s proposed operations will not interfere with the safe operation of helicopters. It concludes that Ligado’s proposed standoff cylinder will protect safe helicopter operations, especially given that under the FAA’s visual flight rules, operations within 500 feet of an object require flight by visual reference rather than relying on instruments, including GPS. Metro also states that Ligado’s proposed operations will assist the aviation industry by providing much-needed services that facilitate aviation operations, such as facilitating the delivery of key patient data to the hospital while the aircraft is en route transporting a patient to the hospital.”

Claim: “The agriculture industry uses GPS to facilitate precision-based practices that have facilitated dramatic improvements in productivity. The trucking and logistics industries rely on GPS for route planning and tracking of shipments and equipment to safely and efficiently move freight throughout the country.”

Response: On this issue, the FCC found “that receivers should be able to coexist with Ligado’s modified ATC network operations in the adjacent spectrum.” (¶ 89). The FCC also notes that John Deere, which “manufactures high-precision GPS receivers and GPS-derived technology and incorporates them into its agricultural, construction, surveying, and other equipment, which is used by industry throughout the world,” indicated that its equipment would coexist with the much higher-powered spectrum use parameters stated in Ligado’s initial proposal of 32 dBW (1585 Watts); for comparison, the FCC order finalizes the power level in the downlink spectrum at 10 Watts. Notably, the Agriculture Department did not sign the DoD letter. With respect to trucking and logistics, note that the category of general location and navigation GPS devices used by the trucking and logistics industry have been tested repeatedly and shown not to be impacted by Ligado’s proposed network.

Claim: “FCC’s actions also threaten weather satellites, crucial to saving lives and property when tornadoes, hurricanes and floods strike.”

Response: The FCC Order applies to spectrum bands that are not close to any of the frequencies used by weather satellites and other environmental data services. The weather interests stated here seem to conflate the Ligado Order with a different, ongoing FCC proceeding seeking to auction spectrum for shared commercial use with NOAA (1675–1680 MHz) that dates back to 2014.

Claim: “GPS also forms the backbone of countless military operations and applications.”

Response: The FCC concluded that the power levels it sanctioned Ligado to use protect military aviation applications ( ¶ 105). Also, DoD suppliers of GPS equipment have made spectrum-use agreements with Ligado, and have been on record that GPS devices providing the services described here can coexist with Ligado’s operations and potentially enhance various GPS-enabled operations protections from harmful disruptions (e.g., spoofing or jamming).

Claim: “We are concerned that the FCC has discounted testing and assessments conducted by nine federal agencies in the Interdepartment Radio Advisory Committee process — all expressing concerns that the Ligado plan would interfere with millions of GPS receivers and satellite services across the nation. Further, the FCC did not provide a technical forum to resolve the significant disconnects between this testing and Ligado’s privately funded testing. Given the enormous impact this Order will have on our national GPS network and satellite communications services, we have significant reservations with the decision to move forward with this Order without a thorough and inclusive public discussion of technical risk.”

Response: The FCC went to great lengths to explain its assessment of harmful interference and the testing data in the public record. The Order reviews three tests that examined potential interference concerns relating to Ligado’s proposed terrestrial operations and GPS:

  • The Roberson and Associates Reports (RAA Reports)
  • The National Advanced Spectrum and Communications Test Network Report (NASCTN Report)
  • The DOT Adjacent Band Compatibility Assessment Final Report (DOT ABC Report)

Note that the DoD had requested Ligado to coordinate testing with NASCTN, a federal lab administered by the Pentagon, the NIST and the NTIA to provide “accurate, reliable, rigorously scientific, and unbiased measurements and analyses” in technical spectrum matters. The NASCTN then conducted thousands of hours of comprehensive testing which showed GPS devices can coexist with the parameters of the network Ligado proposed in 2015 without posing a risk to national security.

The FCC explained that the tests employ two different approaches — only one of which is consistent with the FCC’s harmful interference standard: (¶48)

  • One approach — used by the RAA Reports and the NASCTN Report — uses performance-based metrics and evaluated whether Ligado’s proposal would impact GPS operations. (¶48)
  • The other approach — used by DOT ABC Report and the only data relied on by DOD — used an interference protection criterion known as 1 dB C/N0. (¶48). The DOT Report concludes that military GPS systems would be harmed by a power level that is “less than 1/1000 of a Watt.”
  • The FCC stated that 1 dB C/N0 does not assess whether the actual performance of the GPS devices is affected, and accordingly does not directly address whether there would be any “harmful interference” to GPS. (¶48)
  • The FCC stated that there are technical and policy reasons not to adopt 1 dB C/N0: (¶48)
  • It is unreliable: the C/N0 estimators are not capable of accurately and reliably discerning a 1 dB change in the C/N0 (¶59)
  • For example, the GPS Interface Specification, published by the GPS Directorate, indicates to users of the GPS Space Segment that they could expect a variation in the C/N0 of approximately 2 dB due to the movement of the polar-orbiting GPS satellites across the field-of-view of a GPS receiver. (¶52).
  • It leads to bad policy: relying on interference protections based on the worst performing receivers (as the DOT ABC Report’s application of the 1 dB C/N0 metric does) would undermine the FCC’s ability to promote efficient use of its spectrum resources and achieve spectrum management goals. (¶57).

The Order relies on the RAA Reports and the NASCTN Reports, and not the DOT ABC Report.

  • The FCC concludes that its evaluation of the receiver test data presented in the record will rely on performance-based metrics, and not on testing based on application of a 1 dB C/N0 degradation as a measure, which does not assess and is not directly correlated with harmful interference. (¶47)
  • The FCC found “that there are important deficiencies in the DOT ABC report.” It involved a technically flawed methodology which made its data unreliable and the results were based solely on the worst performing GPS receivers. (¶¶ 54, 55, 57)
  • The FCC also noted that if DOT’s proposed metric were used, “incumbent aeronautical mobile telemetry (flight testing) operations in the 1435–1525 MHz band below the MSS band, which operate at a transmitter power of up to 25 Watts, would not be permitted.”

Claim: “Additionally, the Order’s processes for remediation and mitigation of interference to GPS users remain unclear and wholly inadequate to a technology of this importance to the American way of life. Furthermore, creating an unclear and ill-defined standard based on a limited set of tests would impact GPS and satellite communications users dependent on them for safety of life operations. Setting a standard of not causing interference does not guarantee the performance and safety of their use with statistical certainty. A data-driven performance based standard for what constitutes harmful interference guarantees the need for case-by-case reviews — which will require detailed technical consideration of geographic, temporal, atmospheric and other unique factors that could change on a daily, if not hourly, basis. With the FCC setting itself up as the adjudicator of these case-by-case harmful interference disputes, we question whether such a process can realistically be expected to impartially review and take action on each dispute that arises across a nationwide network within a meaningful time period.”

Response: The FCC does not allot spectrum arbitrarily or haphazardly. Congress designated the FCC as the expert agency to determine spectrum allocation. The FCC has been protecting incumbents from interference since 1934. No matter the FCC action, its army of engineers painstakingly evaluate the effect the grant may have on incumbents (public or private), and its impact on the spectrum market at large. This fact, along with a lengthy notice-and-comment procedure, provides stakeholders with enough resources to express their concerns to the FCC, so as to ensure their interests are protected.

Specifically, the Order requires the following Coordination conditions:

Coordination with Federal Agency GPS Users (¶ 144)

  • Replace or repair expeditiously U.S. Government GPS devices, as needed, in case of harmful interference.
  • Launch an information exchange program with USG by October 21, 2020.
  • Determine an acceptable received power level from Ligado’s operations over the military installation or limited exclusion zones.

Coordination with GPS Industry and Aviation Community (¶ 145)

  • At least six months advance notice regarding the activation of base station and network coverage map to:
  • Garmin, Trimble, John Deere, NovAtel, Topcon, Hexagon Positioning Intelligence, Septentrio, Leica; or
  • Any other GPS manufacturing company that Ligado knows could potentially be affected by Ligado’s ATC network operations.
  • Create a database of base station location information and technical parameters for the FCC, FAA and aviation community.

Responsiveness to and Notification of Interference Complaints (¶ 146)

  • Ligado toll free number for reporting incidences of interference to GPS operations from Ligado’s operations.
  • 24/7 network operations center to investigate, validate and resolve any GPS disruption within one hour.
  • 24/7 “stop buzzer” to cease all base station transmissions in the event of a “large-scale” disruption to GPS capability within 15 minutes of an FCC operations request.”

Claim: “We are committed to ensuring that the United States continues its efforts to lead 5G development and deployment. However, we fear that the Ligado decision will actually slow ongoing work between the U.S. Department of Defense and leading 5G developers, in addition to interfering with the operation of GPS.”

Response: The FCC has been met with widespread support from government officials, industry and stakeholder groups. See As I stated in a blog published by Lincoln Network, “Access to spectrum is an essential feature in any working 5G plan. Frankly, one key barrier in opening up this vital resource is government’s stronghold on ‘beachfront’ spectrum whether they own it or not. … This proceeding has been in regulatory limbo for several years due in large part to government stakeholders’ speculative interference claims regarding GPS applications. … The FCC’s draft order in this proceeding provides enough protection for incumbents in adjacent bands, adds more competition into the 5G-IoT space, and allows consumers to have more access to broadband. Everybody wins.”

Joel L. Thayer is an attorney with Phillips Lytle LLP and a member of the firm’s Telecommunications and Data Security & Privacy Practice Teams. Prior to joining Phillips Lytle, he served as Policy Counsel for ACT | The App Association, where he advised the Association and its members on legal and regulatory issues concerning spectrum, broadband deployment, data privacy, and antitrust matters. Prior to ACT, he also held positions on Capitol Hill, as well as at the FCC and FTC. The views expressed here are his own and do not reflect those of Phillips Lytle LLP, or the firm’s clients.


[2] LightSquared Technical Working Group Report; LightSquared License Modification
Application, IBFS Files Nos. SAT-MOD-20120928–00160–00161, SES-MOD-20121001–00872; New LightSquared License Modification Application, IBFS File Nos. SES-MOD-20151231–00981, SAT-MOD-20151231–00090, and SAT-MOD-20131231–0091; Ligado Amendment to License Modification Application IBFS File Nos. SES-MOD-20151231–00981, SAT-MOD-20151231–0090, and SAT-Mod-20151231–00091
, IB Docket Nos. 11–109; 12–340–11–109; 12–340; 11–109, Order & Authorization, FCC 20–48 (2020). Available at (Ligado Order).



Joel Lauren Thayer

Telecom & Tech Attorney for Phillips Lytle, LLP. Views expressed here are my own.