Drone Spectrum Supporters Raise Questions in FCC Reply Comments
The FCC received additional backing for proposals to change commission rules for the 24.45-24.65 GHz band that would provide more spectrum for drones. Support was evident in reply comments on a January NPRM (see 2504160017). The NPRM also sought comment on opening the 450 MHz band “to aeronautical command and control operations” and modernizing “legacy power rules” for aviation air-ground systems in the 849-851 and 894-896 MHz bands.
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Comments were due Friday in docket 24-629. NTIA, on behalf of the administration, and others supported the 24 GHz changes in the initial comment round (see 2504170022).
The record “reflects overwhelming support for the Commission’s proposal to codify use of the 24.45-24.65 GHz band to include Federal and non-Federal radiolocation operations under Part 90 of its rules,” radar company Echodyne said. “While fully supportive of the Commission’s intent, commenters urge the FCC to provide regulatory flexibility to enable users to respond swiftly to threats to public safety.”
MatrixSpace also described broad support for the 24 GHz changes in the initial comments. “Commenters agree that existing rules -- which permit radiodetermination for navigation purposes, but not radiolocation for other applications -- are artificially hampering critical public safety efforts.”
Dale Hatfield, formerly the FCC’s top engineer and now senior fellow at Silicon Flatirons, urged the agency to focus on potential interference risks from the 450 MHz changes. “There appears to be broad agreement in the record that the 450-470 MHz band is well suited to support aviation-related Command and Control and Control and Non-Payload Communications,” Hatfield said.
But he warned about the potential effect of increasing RF noise in the band. “Both engineering observations and anecdotal reports suggest that the environmental noise floor in this and adjacent bands is trending upward,” he said. Relatively little attention has been paid to the fact that the links being considered for drones “are narrowband, low-power, and often operate with tight link budgets, which may leave them uniquely vulnerable to even modest disruptions,” he added: “The cascading effects of interference on these systems, particularly where redundancy and recovery options are limited, warrant closer technical scrutiny.”
On the 800 MHz changes, Gogo Business Aviation noted that only Motorola Solutions offers “specific concerns regarding potential interference to adjacent public safety operations and proposes specific conditions on Gogo’s operations.” Gogo “accepts the need” for the commission to adopt “an appropriate” out-of-band emission limit for commercial air-ground services that “will adequately protect public safety operations,” but the company opposed other changes to the proposed rules.
The Association of Public-Safety Communications Officials said it supports the 800 MHz changes, provided there are “sufficient protections for public safety spectrum operations in adjacent bands.” Because “Gogo’s ground-based transmitters can be sources of interference to public safety handsets listening to 851-854 MHz frequencies, APCO urges the Commission to adopt provisions that require Gogo to ensure public safety operations can continue, interference-free, in adjacent bands.”
The National Regional Planning Council, which represents public safety agencies, noted that the 849-851 MHz band “is immediately adjacent” to the spectrum used by National Public Safety Planning Advisory Committee licensees. “Any rule changes must protect public safety users in the adjacent spectrum from interference, and provide methods for public safety to identify and report any interference should it occur.”