Rules for FM Terrestrial Digital Audio Broadcasting Systems

SUPPLEMENTARY INFORMATION:

This is a summary of the Commission's First Report and Order (First R&O), MB Docket No. 22-405; FCC 24-105, adopted on September 24, 2024, and released on September 25, 2024. The full text of this document will be available via the FCC's Electronic Comment Filing System (ECFS), https://www.fcc.gov/cgb/ecfs/. Documents will be available electronically in ASCII, Microsoft Word, and/or Adobe Acrobat. Alternative formats are available for people with disabilities (braille, large print, electronic files, audio format), by sending an email to fcc504@fcc.gov or calling the Commission's Consumer and Governmental Affairs Bureau at (202) 418-0530 (voice), (202) 418-0432 (TTY).

Paperwork Reduction Act of 1995 Analysis

This document may contain new or modified information collection requirements subject to the Paperwork Reduction Act of 1995 (PRA), Public Law 104-13. All such new or modified information collections will be submitted to the Office of Management and Budget (OMB) for review under section 3507(d) of the PRA, 44 U.S.C. 3507(d). OMB, the general public, and other Federal agencies are invited to comment on any new or modified information collection requirements contained in this proceeding. In addition, we note that pursuant to the Small Business Paperwork Relief Act of 2002 (Pub. L. 107-198, 116 Stat 729 (2002) (codified at 44 U.S.C. 3506(c)(4)). the Commission previously sought specific comment on how it might further reduce the information collection burden for small business concerns with fewer than 25 employees. In the First R&O, the Commission assessed the effects of the required collection of information on these small entities.

Congressional Review Act

The Commission has determined, and the Administrator of the Office of Information and Regulatory Affairs, Office of Management and Budget, concurs, that these rules are non-major under the Congressional Review Act, 5 U.S.C. 804(2). The Commission will send a copy of the First R&O to Congress and the Government Accountability Office (GAO) pursuant to 5 U.S.C. 801(a)(1)(A).

Synopsis

1. Introduction. In a 2022 document, the Commission's Media Bureau (Bureau) consolidated into one rulemaking proceeding two separate Petitions for Rulemaking, both proposing changes to the rules that the petitioners urged would improve digital FM signal quality and minimize the effect of the digital FM station signal on adjacent channel FM transmissions. Media Bureau Seeks Comment on Petitions for Rulemaking Proposing Amendments to FM Broadcast Digital Radio Rules, Public Notice, DA 22-1226 (MB Nov. 28, 2022) (FM Digital Comment PN). In the first petition, filed December 9, 2019, petitioners National Association of Broadcasters (NAB), Xperi Corporation (Xperi), and National Public Radio (NPR) (collectively Asymmetric Petitioners), requested blanket authorization to set digital power at different levels on each digital sideband, thus allowing a digital FM station to protect, for example, an analog FM station on a lower first-adjacent channel, while enabling an increase in digital power on the upper sideband where there is no adjacent analog FM station or a more distant adjacent station. In the second petition, filed October 26, 2022, NAB and Xperi requested that the FCC update the methodology stations use to determine maximum FM digital power levels. In the Order and notice of proposed rulemaking (NPRM), FCC 23-61, 88 FR 57033 (Aug. 22, 2023), the Commission granted these petitions and sought comment on whether the rule changes proposed by the petitioners would serve the public interest, by providing FM digital stations with the ability to increase power and, concomitantly, increase coverage area, building penetration, and provide a more robust digital signal. The Commission additionally sought comment on: whether such rule changes would cause or increase interference to analog FM stations adjacent to a digital FM station; whether the proposed rule changes would have other adverse effects on incumbent FM stations; whether and to whom notice of increased digital FM power should be provided; and whether additional interference remediation procedures should be introduced.

2. Broadcasters, engineers, and listeners filed comments and reply comments in response to the NPRM. Additionally, commenters such as the Aerospace Industries Association; Air Line Pilots Association, International; Garmin International, Inc.; and the General Aviation Manufacturers Association filed comments expressing concern about higher digital power levels at the upper end of the FM broadcast band causing interference to users in the adjacent Aeronautical Radio Navigation Spectrum (ARNS), from 108.0-117.95 MHz. The commenters state that preliminary industry studies suggest that further testing is needed; to that end, aviation industry commenters are working with NAB and Xperi, but state that comprehensive testing will take additional time. See Supplemental Comments of Air Line Pilots Ass'n, Int'l; Airlines for America; Aviation Spectrum Res., Inc.; The Boeing Co.; Garmin; and GAMA, filed Apr. 1, 2024, at 2-4. See also Letter from First Officer Chris Sidor, Air Line Pilots Ass'n, Int'l, et al., to Marlene H. Dortch, Secretary, FCC, MB Docket No. 22-405, at 3 (filed Sept. 19, 2024) (providing testing updates); Letter from Ashruf El-Dinary, Xperi Inc., to Marlene H. Dortch, Secretary, FCC, MB Docket No. 22-405 (filed Sept. 23, 2024). Accordingly, in the interest of a complete record, the Commission deferred action on the proposal relating to maximum FM digital power levels, and in the First R&O acts only on the proposals relating to the Asymmetric Sideband Petition, with appropriate safeguards for stations on Channels 296-300.

3. Background. The FM digital radio system inserts redundant digital sidebands above and below a station's existing analog signal. The Commission's existing rules assume that digital power is the same on both digital sidebands, i.e., symmetric sideband operation. Currently, an FM station that wishes to employ asymmetric sideband operation, using different power on each digital sideband, must apply for an experimental authorization and renew that authorization annually. The request for experimental authorization must include a showing that the digital sideband signal contours will not overlap adjacent stations' protected contours. NAB, Xperi, and NPR (Asymmetric Petitioners), in the Asymmetric Sideband Petition, assert that with asymmetric sidebands a digital FM station can limit the power of one digital sideband to protect the adjacent analog FM station on that side while concurrently increasing the power of the other sideband in order to expand its overall digital coverage and improve its building penetration. Asymmetric Sideband Petition at 8-9. Similarly, a station could reduce power on the sideband causing interference to another station and maintain the desired power level on the other digital sideband. See NPRM, 38 FCC Rcd at 7169, para. 26. The Asymmetric Petitioners conducted a study that they state demonstrates that many more digital FM stations could increase power on at least one sideband above the current limit of −14 dBc. Out of 10,875 digital FM stations studied in 2017, petitioners contend that 6,120 could increase power on both sidebands to −10 dBc under the current rules, whereas if asymmetric sidebands were allowed, an additional 3,496 stations could increase one sideband to −10 dBc, with another 532 being able to increase one sideband's power to between −14 and −10 dBc. Asymmetric Petitioners also argue that the need to request experimental authorization, and the temporary nature of such authorizations, discourages use of asymmetric sidebands, which in turn limits digital FM stations to the power level needed to protect the adjacent-channel analog FM station that is most susceptible to digital interference. The Asymmetric Petitioners thus requested that the Commission amend its rules to allow FM stations to operate with asymmetric digital sidebands, without having to request experimental authorization to do so, in order to remove unnecessary regulatory barriers and promote broader adoption of terrestrial digital FM broadcasting. Asymmetric Sideband Petition at 8-11.

4. Discussion. The Commission concluded that the record contains considerable support for asymmetric sideband operation, and thus adopted the relevant proposals set forth in the NPRM, with some modifications to the rules that were proposed. (In addition, as proposed in the NPRM, 38 FCC Rcd 7158, n.65, to conform to the publishing conventions of the National Archives and Records Administration's Office of the Federal Register, the Commission added paragraph numbers to the list of definitions in 47 CFR 73.310(a) and (b). The definitions numbered and restated in the First R&O are identical to the current definitions.) The Commission therefore authorized digital FM stations, except stations operating on Channels 296-300, to originate digital transmissions at different power levels on the upper and lower digital sidebands without having to request experimental authorization, consistent with the requirements set forth herein. As further discussed below, a digital FM station need only notify the Commission of asymmetric sideband operation by filing notification on Form 2100, Schedule 335-FM—FM Digital Notification (Schedule 335-FM) in the Bureau's Licensing and Management System (LMS) database.

5. Asymmetric Sideband Operation Authorization. The Commission agreed with the commenters and found that asymmetric sidebands will promote the adoption of digital radio without increasing the risk of interference to existing analog broadcasts. Those commenters that addressed this proposal generally supported it. Some expressed approval of the proposal as being an affirmative step toward broader adoption of digital radio, with some specifically stating that eliminating the need for prior experimental authorization will encourage more stations to adopt FM digital operation. Many commenters opine that asymmetric operation will reduce interference to adjacent-channel analog FM stations, with some offering anecdotal or experimental evidence to support these claims. The Commission's current policy requiring the same power on both the upper and lower digital sidebands limits an FM station's digital power to that needed to protect the adjacent-channel analog FM station most susceptible to interference, regardless of whether there is a need to limit power on the other sideband. Asymmetric Petitioners contended, and commenters agreed, that allowing calculation of the maximum allowable digital FM power on a per-sideband basis allows such stations to optimize their digital signal coverage while still protecting analog FM stations on adjacent channels. The Commission agreed and, based on the record presented, found that it is in the public interest to allow asymmetric sideband operation, except on Channels 296-300, without the need for an experimental authorization.

6. Notice. The Commission further found that allowing a digital FM station to report its asymmetric sideband operation through a simple notification removes a regulatory barrier, compared to the current procedure of applying for an experimental license to operate asymmetrically, and having to file for annual renewals of that authorization. At the same time, the Commission believed it is important for it to track asymmetric operation in order to address any potential interference problems that may arise and to allow stations to identify if their adjacent-channel stations are using asymmetric sidebands. The Commission found that a simple notification should provide the correct balance between its desire to streamline the regulatory burden on stations adopting asymmetric operations and the need to be able to identify stations employing this functionality. The need to track stations employing asymmetric sideband operation includes identifying those stations that discontinue such operation. The Commission therefore similarly required that stations permanently terminating asymmetric sideband operation notify the Commission of such termination on Schedule 335-FM. The Commission also noted that this is consistent with the approach it takes for initial authorization of digital broadcasting. FM broadcast licensees have never needed to file a separate application for authorization to initiate hybrid digital operation; all that has been required is notification to the Commission. The Commission found the public interest would be similarly served by declining to require a separate application to initiate asymmetric sideband operation and allow stations to commence asymmetric sideband operation based on a simple notification.

7. To provide notification to the Commission, stations choosing asymmetric sideband operation will be required to file a revised Schedule 335-FM. The filing of Schedule 335-FM with the Commission does not trigger the release of a separate Public Notice in LMS, but like all LMS forms is searchable and thus available to members of the public using the LMS “Search” function. The Commission concluded this approach will provide the public with real time information on which stations have adopted asymmetric operations.

8. Some commenters sought further modification to the proposal regarding notice of asymmetric band operation. One advocated for the Commission to “maintain a readily accessible record of information” on every station increasing power, suggesting that this would include stations employing asymmetric sideband operation, arguing that listeners may find it difficult to identify digital-to-analog FM interference, and that such a public record of stations altering their digital power profile would assist in identifying interfering stations. Another believed that Schedule 335-FM should be modified to allow the notifying station to provide the effective radiated power (ERP) of the digital signal on both the upper and lower digital sidebands, as well as the total digital ERP. This commenter disagreed with the NPRM's proposal to modify § 73.406(d)(7) through (8) of the Commission's rules to require licensees to file Schedule 335-FM with a short statement of the reason(s) for discontinuing digital operation, including a return to symmetric sideband operation from asymmetric operation. It believed that specifying a reason is unnecessary because such operations “are not mandatory, are a voluntary business choice of the individual station, and the decision may be competitively sensitive.”

9. The Commission concurred with the latter commenter that Schedule 335-FM should be modified to require a party giving notification of asymmetric sideband operation to indicate the digital ERP on both upper and lower digital sidebands, as well as the total digital ERP. The Commission believed that requiring these data to be included in Schedule 335-FM should suffice to advise broadcasters and the public, through LMS, about digital operations. It thus found it unnecessary to adopt the suggestion that it implement a separate database of FM stations broadcasting in hybrid digital mode and the per-sideband digital power of such stations. The Commission concurred with the objection to the proposed requirement of providing a reason for discontinuation, agreeing that it is unnecessary given the voluntary nature of asymmetric sideband operation. It thus adopted the tentative conclusion that Schedule 335-FM notification should be required for any digital FM station that reverts to symmetric sideband operation from asymmetric sideband operation, but did not adopt the proposal to require any such notification of return to symmetric sideband operation to be accompanied by a short statement of the reason(s) for this action.

10. Reporting on Schedule 335-FM. After the effective date of the rules adopted in the First R&O, licensees will be required to use Schedule 335-FM to provide notice to the Commission. This will serve as a replacement for many of the current requests for experimental authorization and informal requests. As noted above, licensees will be required to use Schedule 335-FM to notify the Commission of the commencement or discontinuance of asymmetric sideband operation as a replacement for requests for experimental authorization. A station adopting asymmetric sideband operation must notify the Commission upon commencement of such operation by filing Schedule 335-FM. The Commission directed the Bureau to inform the digital FM station within 30 days of filing Schedule 335-FM if its asymmetric sideband operation is non- rule compliant. The station may commence asymmetric sideband operation upon submitting Schedule 335-FM and may continue such operation unless it receives notice of noncompliance during that 30-day period. Similarly, a digital FM station must notify the Bureau on Schedule 335-FM within 30 days of discontinuing asymmetric sideband operation.

11. The Commission also made an administrative change to the procedures used by licensees seeking to increase digital power above −14 dBc. Those requests, previously submitted by informal request, will be submitted using Schedule 335-FM. This minor administrative change will help streamline processing of these requests and will further the Commission's efforts to transition all broadcast filings to the Bureau's Licensing and Management System (LMS).

12. The 2010 MB DAB Order (Digital Audio Broadcasting Systems And Their Impact on the Terrestrial Radio Broadcast Service, Order, 25 FCC Rcd 1182 (MB 2010)), increased the allowable total power level of an FM station's digital sidebands from the previous maximum of −20 dBc to −14 dBc. 2010 MB DAB Order, 25 FCC Rcd at 1189, para. 16. The −14 dBc power level is for both FM digital sidebands combined; when both sidebands are operating at the same power level, each sideband would operate at −17 dBc, or 3 dB lower than the combined symmetrical digital sideband power, representing one-half of the total allowed digital ERP for each sideband. The same order allowed FM stations, except for grandfathered superpowered stations, to seek additional authorization to increase total digital power above −14 dBc, up to −10 dBc, through an informal request including a showing that such power increase would comply with the formula set forth in the 2010 MB DAB Order, and therefore would not cause harmful interference to adjacent analog FM stations. As noted, in this First R&O the Commission did not revise the formula that determines the maximum permissible digital power a station may use. However, for purposes of administrative efficiency, the Commission modified the current informal process used to request an increase in total digital power above −14 dBc. After the effective date of the rules adopted in the First R&O, digital FM stations must use Schedule 335-FM to request an increase in total digital ERP above −14 dBc, using table 1 to § 73.404(f) adopted in the First R&O, and will also report certain digital power decreases on Schedule 335-FM. Table 1 is based on the table set forth in the 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20, adapted for use on a per-sideband basis. Certifications of compliance with table 1 to new 47 CFR 73.404(f) must be based on the most restrictive analog field strength of the proponent at any nearby first-adjacent-channel station's 60 dBµ contour. See 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20. Although the table has been modified, the information submitted by the station is the same as it is currently. After the effective date of the First R&O, a digital FM station will report the following actions (or request authority in the case of an increase of total digital ERP above −14 dBc) by submitting Schedule 335-FM: the initiation of hybrid digital operation; the initiation of asymmetric sideband operation at any power level, as well as the discontinuance of asymmetric sideband operation; an increase of total digital ERP above −14 dBc; or a decrease in total digital ERP from a level above −14 dBc to a level at or below −14 dBc; in other words, an FM digital station not currently operating with total digital ERP above −14 dBc need not report further digital power reductions. A station choosing to operate with total digital ERP between −14 dBc and −10 dBc must still attach to its Schedule 335-FM submission an exhibit demonstrating that the proposed FM digital ERP is permitted for each digital sideband, using table 1 to 73.404(f), adopted in the First R&O. As is the case with the current informal request process, a digital FM station choosing to operate with total digital ERP above −14 dBc may initiate such operation upon approval from the Commission.

13. Changes to “per-sideband” table. Although the Asymmetric Petitioners support the Asymmetric Sideband Petition they co-authored with NPR, they identified shortcomings in the tables presented in the NPRM to determine the maximum allowable ERP of each digital sideband. Asymmetric Petitioners point out that total sideband power is necessarily calculated on a per-sideband basis, computing lower and upper digital sideband power by calculating the field strength of the digital FM station's F(50, 10) contour at its overlap with the 60 dBµ F(50, 50) contour of, respectively, the lower and upper first-adjacent analog stations. The Asymmetric Petitioners contend that the tables in paragraphs 9 and 26 of the NPRM are mis-labeled and thus are incorrect, as are their counterparts in Appendix A to the NPRM, the then-proposed new tables to § 73.404, paragraphs (e) and (f). In their comments, they submitted corrected tables as well as corrections to the proposed rule change to § 73.404.

14. The Commission agreed with Asymmetric Petitioners to the extent that the column headings of the tables in the NPRM were mis-labeled, and further agreed that the maximum permissible FM digital ERP is better displayed on a per-sideband basis, as the combination of the sideband ERPs adds up to the full digital ERP. The Asymmetric Petitioners proposed a per-sideband table, but their proposed table was calculated based upon adoption of the proposals in the NPRM to update the methodology used to determine maximum FM digital power. As no commenters objected to the use of a per-sideband table, and as the Commission did not adopt at this time the proposals to update the methodology for determining FM digital power levels, the Commission modified and adopted Xperi and NAB's corrected “Maximum permissible FM digital ERP per-sideband” table to comport with the current limits on FM digital ERP, as follows: