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ARRL Encourages Comprehensive Noise Floor Study


In anticipation of an FCC Technological Advisory Council (TAC) investigation into changes and trends to the radio spectrum noise floor to determine if there is an increasing noise problem, ARRL asserted that such a study is long overdue. The FCC Office of Engineering and Technology (OET) announced plans for the TAC study in mid-June and invited comments and answers to questions that the TAC posed concerning the methodologies for such a study. The League’s comments also praised the TAC — an advisory group to the FCC — for tackling the issue and expressed the hope that the noise study might, for the first time, provide a useful, objective basis for spectrum overlays and other future allocation decisions. ARRL allowed that while a noise floor problem exists, “The magnitude of this problem and the extent of it in the 21st century is virtually unknown.”

“The TAC and the leadership in this study initiative are to be congratulated for finally undertaking what has been universally determined to be necessary for well more than 2 decades,” the ARRL said. “The Commission should not have made spectrum management decisions without this noise information, and it is unfortunate that the initiative has been delayed this long.”

The ARRL said that its members can be of use in gathering data for the TAC noise study, but advised that any urgency in initiating the study “be tempered by the prerequisite need to develop a standardized and valid methodology for conducting the study,” in order to “obtain quantitative data regarding the noise floor in various environments and trends over time,” ARRL said.

ARRL said the focus of the TAC noise “study should be an accurate determination of what noise levels exist in as wide a range of indoor and outdoor environments as possible. It should, to the extent possible, determine what types of noise are being found: Broadband, non-specific noise; broad noise spectral peaks; broadband digital noise; and noise occurring on discrete frequencies.”

“We also hope that these comments will serve as a stimulus for the Commission to re-evaluate its ‘hands-off’ policy with respect to the most recalcitrant and unhelpful operators of incidental and unintentional radiators which are causing long-term interference problems, such as electric utilities,” ARRL concluded. “The unwillingness of the Commission to issue meaningful sanctions has led to the virtual absence of any incentive to comply with the Commission’s Part 15 non-interference obligations.”

ARRL pointed out that the FCC had requested that the TAC study the noise floor in 1999 and propose new approaches to spectrum management based on emerging and future technologies. “The TAC concluded that it would be impossible for the Commission to engage in effective spectrum management until it ‘develop[s] a more complete understanding of the current state of the radio noise environment,’” ARRL recounted, noting that TAC urged the Commission to immediately undertake a multi-part noise floor study and cautioned it against implementing new spectrum management techniques or initiatives without first concluding extensive studies.

“Yet, 16 years later, no such study has been conducted,” ARRL said. “Now, and for the past several decades, new noise sources are being developed and have been developed and the proliferation of electronic devices continues as fast as the technology and the regulatory processes will allow.” While many individual sources of RF noise may be consistent with FCC rules, in some cases they may negatively impact the overall electromagnetic noise environment, ARRL said.

“Because the Commission’s resources are woefully inadequate to address RF noise through widespread enforcement of Part 15 and Part 18 rules governing RF emitters after the devices are deployed, the only reasonable means of dealing with them is to enact and enforce, ex ante, appropriate rules for RF emitters that are based on actual knowledge of the noise floor and trends over time,” ARRL said. “The growing number of interference complaints indicates that any increase in noise levels will result in harmful interference, so these rules may need to require a decrease in the permitted limits for emission to balance the aggregate noise potential of a growing number of noise emitting devices.”

The League’s comments include a bibliography, “Articles Relating to the Description, Impact and Study of Man-Made Noise,” compiled by ARRL Lab Manager Ed Hare, W1RFI.



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