[Federal Register Volume 89, Number 203 (Monday, October 21, 2024)]
[Rules and Regulations]
[Pages 84096-84105]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-24105]


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FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 73

[MB Docket No. 22-405; FCC 24-105; FR ID 250466]


Rules for FM Terrestrial Digital Audio Broadcasting Systems

AGENCY: Federal Communications Commission.

ACTION: Final rule.

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SUMMARY: In this document, the Federal Communications Commission 
(Commission) adopts rules to allow digital FM broadcast radio stations 
to operate with different power levels on the upper and lower digital 
sidebands, by notification to the Commission. The rule changes will 
facilitate greater digital FM radio coverage without interfering with 
adjacent-channel FM broadcast stations. The intended effect is to 
advance the broader adoption of digital FM broadcasting by authorizing 
digital FM broadcasters to implement such asymmetric sideband operation 
by simple notification to the Commission, rather than by requesting 
experimental authorization as is the current practice.

DATES: This final rule is effective November 20, 2024, except for the 
amendments in instruction 4 (47 CFR 74.404) and instruction 5 (47 CFR 
74.406), which are delayed indefinitely. The Commission will announce 
the effective date of the rule changes to 47 CFR 73.404 and 73.406 in 
the Federal Register.

FOR FURTHER INFORMATION CONTACT: Albert Shuldiner, Chief, Media Bureau, 
Audio Division, (202) 418-2721, <a href="/cdn-cgi/l/email-protection#de9fb2bcbbacaaf08db6abb2bab7b0bbac9eb8bdbdf0b9b1a8"><span class="__cf_email__" data-cfemail="beffd2dcdbccca90edd6cbd2dad7d0dbccfed8dddd90d9d1c8">[email protected]</span></a>; Thomas 
Nessinger, Senior Counsel, Media Bureau, Audio Division, (202) 418-
2709, <a href="/cdn-cgi/l/email-protection#a4f0cccbc9c5d78aeac1d7d7cdcac3c1d6e4c2c7c78ac3cbd2"><span class="__cf_email__" data-cfemail="eabe8285878b99c4a48f999983848d8f98aa8c8989c48d859c">[email protected]</span></a>. For additional information concerning 
the Paperwork Reduction Act (PRA) information collection requirements 
contained in this document, contact Cathy Williams at (202) 418-2918, 
<a href="/cdn-cgi/l/email-protection#d596b4a1bdacfb82bcb9b9bcb4b8a695b3b6b6fbb2baa3"><span class="__cf_email__" data-cfemail="2162405549580f76484d4d48404c52614742420f464e57">[email protected]</span></a>.

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 <a href="/cdn-cgi/l/email-protection#395f5a5a0c090d795f5a5a175e564f"><span class="__cf_email__" data-cfemail="593f3a3a6c696d193f3a3a773e362f">[email protected]</span></a> 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.

[[Page 84097]]

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

[[Page 84098]]

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 Sec.  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-

[[Page 84099]]

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 Sec.  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 dB[micro] 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 
dB[micro] 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 Sec.  73.404, paragraphs (e) and (f). In 
their comments, they submitted corrected tables as well as corrections 
to the proposed rule change to Sec.  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:

------------------------------------------------------------------------
 IBOC Station's F(50,10) field strength at     Maximum permissible FM
     the upper or lower first-adjacent           digital ERP for the
  station's analog 60 dB[micro] F(50,50)     respective (upper or lower)
                  contour                             sideband
------------------------------------------------------------------------
51.2 dB[micro] and above..................  -17 dBc.
50.7 dB[micro] to 51.1 dB[micro]..........  -16 dBc.
50.3 dB[micro] to 50.6 dB[micro]..........  -15 dBc.
49.6 dB[micro] to 50.2 dB[micro]..........  -14 dBc.
49.5 dB[micro] or less....................  -13 dBc.
------------------------------------------------------------------------


[[Page 84100]]

    If, in a subsequent Order, the Commission modifies the formula used 
to determine the maximum permissible digital power level, it will 
adjust this table at that time.
    15. Interference Mitigation and Remediation. The Commission found 
that the interference mitigation and remediation procedures set forth 
in the 2010 MB DAB Order are sufficient to remedy any reports of inter-
station interference as a result of asymmetric sideband operation, 
given that reduction of power on one sideband necessarily reduces the 
potential for interference and therefore makes such interference less 
likely. The Commission reserved further consideration of modified 
interference mitigation and remediation procedures in the FM digital 
power increase context, and anticipates addressing such concerns in a 
future Report and Order in this proceeding.
    16. Pending Proceedings. The Commission adopted the proposal that 
any licensees with asymmetric sideband operation under experimental 
authorizations that are compliant with the rules adopted in this First 
R&O may file Schedule 335-FM notification at any time after the 
effective date of the rules adopted in this First R&O and before the 
existing experimental authority expires. NPRM, 38 FCC Rcd at 7171, 
para. 30. No commenter opposed this proposal. Therefore, after the 
rules adopted in this First R&O take effect and the changes to Schedule 
335-FM are approved by the Office of Management and Budget and there is 
an announcement of such approval published in the Federal Register, any 
station currently employing asymmetric sideband operation under 
experimental authorization that is compliant with the rules adopted in 
this First R&O may transition to non-experimental asymmetric sideband 
operation by notifying the Commission through Schedule 335-FM at any 
time prior to expiration of the experimental authorization. Although 
the Commission does not require that stations currently operating with 
power greater than -14 dBc under existing special temporary 
authorization file Schedule 335-FM, it encourages such stations to 
update their records in LMS using Schedule 335-FM in order that their 
sideband power levels are properly reflected in LMS. Any station 
seeking a power increase above -14 dBc in the future must request 
authority to do so using Schedule 335-FM.

Procedural Matters

Final Regulatory Flexibility Analysis

    17. As required by the Regulatory Flexibility Act of 1980, as 
amended (RFA) an Initial Regulatory Flexibility Analysis (IRFA) was 
incorporated in the Modifying Rules for FM Terrestrial Digital Audio 
Broadcasting Systems, (NPRM), released on August 1, 2023. Modifying 
Rules for FM Terrestrial Digital Audio Broadcasting Systems, Notice of 
Proposed Rulemaking, 38 FCC Rcd 7158 (2023). The Federal Communications 
Commission (Commission) sought written public comment on the proposals 
in the NPRM, including comment on the IRFA. No comments were filed 
addressing the IRFA. This Final Regulatory Flexibility Analysis (FRFA) 
conforms to the RFA. 5 U.S.C. 604.

A. Need For, and Objectives of, the Report and Order

    18. In the First Report and Order, the Commission found that it is 
in the public interest to allow FM broadcast stations transmitting a 
hybrid analog-digital signal to operate with different digital 
effective radiated power (ERP) on the upper and lower digital 
sidebands, upon notification to the Commission on FCC Form 2100, 
Schedule 335-FM. This replaces the current procedure whereby a digital 
FM station must apply for an experimental authorization to operate with 
different digital ERP on the upper and lower digital sidebands 
(asymmetric sideband operation); this experimental authority must be 
renewed annually.
    19. 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. The advantage to 
asymmetric sideband operation is that it allows a digital FM station to 
operate with lower power on the digital sideband closer to a first-
adjacent-channel analog FM station, thus reducing the potential for 
interference to that station, while enabling the digital FM station to 
increase power to the digital sideband where there is no or only a very 
distant analog FM station to protect from interference. For example, a 
Class A digital FM station on Channel 251 might have a Class A analog 
FM station on Channel 250 within 75 kilometers of the digital station, 
while being several hundred kilometers from the nearest analog FM 
station on Channel 252. In such a situation, the digital FM station 
would reduce digital ERP on the lower digital sideband, protecting the 
analog station on Channel 250, while increasing power and, therefore, 
signal coverage on the upper digital sideband where there is no 
adjacent channel station to protect. The total digital ERP transmitted 
over the two digital sidebands would be the same as it would be if both 
sidebands were transmitting at the same digital ERP (symmetric sideband 
operation), thus there would be no increase in the total digital energy 
emitted by the digital FM station.
    20. The Commission in the First Report and Order adopted its 
proposal to allow digital FM stations wishing to use asymmetric 
sideband operation to do so by notifying the Commission using FCC Form 
2100, Schedule 335-FM, and modified that schedule by including fields 
to report the digital ERP being transmitted on each digital sideband, 
as well as the total digital ERP. It made an exception, however, for 
digital FM stations operating on Channels 296-300 (107.1-107.9 MHz), at 
the top of the FM broadcast band, which must continue to seek 
experimental authorization for asymmetric sideband operation. This was 
deemed necessary to protect users in the lower frequencies of the 
Aeronautical Radio Navigation Spectrum (ARNS) from possible 
interference resulting from higher power on an upper digital sideband. 
The Commission further concludes that a station permanently 
discontinuing asymmetric operation need not disclose its reasons for 
doing so. It also implemented the proposal that any FM licensees 
operating facilities under experimental or special temporary 
authorizations that are compliant with the rules adopted in this 
proceeding may transition to asymmetric sideband operation by filing 
Schedule 335-FM notifications after the effective date of the rules 
adopted in the First Report and Order. Commenters generally supported 
the Commission's proposal to allow asymmetric sideband operation upon 
simple notice to the Commission, though some raised concerns regarding 
notifications, interference remediation, and the transition to 
asymmetric sideband operation. The Commission observed that adopting 
rules simplifying the process of initiating asymmetric sideband 
operation is likely to reduce inter-station interference rather than 
exacerbate it, and thus concluded that existing interference mitigation 
and remediation procedures are sufficient at the present time, but also 
concluded that Form 2100, Schedule 335-FM should be amended to provide 
fields for the notifying station to indicate the

[[Page 84101]]

digital ERP transmitted on each digital sideband, as well as the total 
digital ERP.
    21. 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).

B. Summary of Significant Issues Raised by Public Comments in Response 
to the IRFA

    22. There were no comments filed that specifically addressed the 
proposed rules and policies presented in the IRFA.

C. Response to Comments by the Chief Counsel for Advocacy of the Small 
Business Administration

    23. Pursuant to the Small Business Jobs Act of 2010, which amended 
the RFA, the Commission is required to respond to any comments filed by 
the Chief Counsel for Advocacy of the Small Business Administration 
(SBA), and to provide a detailed statement of any change made to the 
proposed rules as a result of those comments. 5 U.S.C. 604(a)(3). The 
Chief Counsel did not file any comments in response to the proposed 
rules in this proceeding.

D. Description and Estimate of the Number of Small Entities to Which 
the Rules Apply

    24. The RFA directs the agencies to provide a description of and, 
where feasible, an estimate of the number of small entities that may be 
affected by the rules adopted herein. 5 U.S.C. 604(a)(4). The RFA 
generally defines the term ``small entity'' as having the same meaning 
as the terms ``small business,'' ``small organization,'' and ``small 
government jurisdiction.'' 5 U.S.C. 601(6). In addition, the term 
``small business'' has the same meaning as the term ``small business 
concern'' under the Small Business Act. 5 U.S.C. 601(3). A small 
business concern is one which: (1) is independently owned and operated; 
(2) is not dominant in its field of operation; and (3) satisfies any 
additional criteria established by the SBA. 15 U.S.C. 632.
    25. Radio Stations. This industry is comprised of ``establishments 
primarily engaged in broadcasting aural programs by radio to the 
public.'' U.S. Census Bureau, 2017 NAICS Definition, ``515112 Radio 
Stations.'' Programming may originate in their own studio, from an 
affiliated network, or from external sources. The SBA small business 
size standard for this industry classifies firms having $47 million or 
less in annual receipts as small. U.S. Census Bureau data for 2017 show 
that 2,963 firms operated in this industry during that year. Of this 
number, 1,879 firms operated with revenue of less than $25 million per 
year. Based on this data and the SBA's small business size standard, we 
estimate a majority of such entities are small entities.
    26. The Commission estimates that as of June 30, 2024, there were 
4,413 licensed commercial AM radio stations and 6,620 licensed 
commercial FM radio stations, for a combined total of 11,033 commercial 
radio stations. Broadcast Station Totals as of June 30, 2024, Public 
Notice, DA 24-644 (rel. July 3, 2024) (July 2024 Broadcast Station 
Totals PN), https://docs.fcc.gov/public/attachments/DA-24-644A1.pdf. Of 
this total, 11,032 stations (or 99.99%) had revenues of $47 million or 
less in 2023, according to Commission staff review of the BIA Kelsey 
Inc. Media Access Pro Database (BIA) on July 3, 2024, and therefore 
these licensees qualify as small entities under the SBA definition. In 
addition, the Commission estimates that as of June 30, 2024, there were 
4,356 licensed noncommercial (NCE) FM radio stations, 1,965 low power 
FM (LPFM) stations, and 8,906 FM translators and boosters. The 
Commission however does not compile, and otherwise does not have access 
to financial information for these radio stations that would permit it 
to determine how many of these stations qualify as small entities under 
the SBA small business size standard. Nevertheless, given the SBA's 
large annual receipts threshold for this industry and the nature of 
radio station licensees, the Commission presumes that all of these 
entities qualify as small entities under the above SBA small business 
size standard.
    27. We note, however, that in assessing whether a business concern 
qualifies as ``small'' under the above definition, business (control) 
affiliations must be included. The Commission's estimate, therefore, 
likely overstates the number of small entities that might be affected 
by its action, because the revenue figure on which it is based does not 
include or aggregate revenues from affiliated companies. In addition, 
another element of the definition of ``small business'' requires that 
an entity not be dominant in its field of operation. The Commission is 
unable at this time to define or quantify the criteria that would 
establish whether a specific radio or television broadcast station is 
dominant in its field of operation. Accordingly, the estimate of small 
businesses to which the rules may apply does not exclude any radio or 
television station from the definition of a small business on this 
basis and is therefore possibly over-inclusive. An additional element 
of the definition of ``small business'' is that the entity must be 
independently owned and operated. Because it is difficult to assess 
these criteria in the context of media entities, the estimate of small 
businesses to which the rules may apply does not exclude any radio or 
television station from the definition of a small business on this 
basis and similarly may be over-inclusive.

E. Description of Projected Reporting, Recordkeeping, and Other 
Compliance Requirements for Small Entities

    28. The First Report and Order adopts procedures that will create 
new reporting, recordkeeping, and compliance obligations for small 
digital FM stations that operate with asymmetric power on the digital 
sidebands. Specifically, it replaces the current requirement that 
digital FM stations request experimental or special temporary 
authorization for asymmetric sideband operation with a new, simplified 
notification procedure on existing FCC Form 2100, Schedule 335-FM. This 
form will be modified to collect the total digital ERP and the digital 
ERP on each of the upper and lower digital sidebands used by a digital 
FM station. Form 2100, Schedule 335-FM, will now be the means by which 
a small, digital FM station will report (or request authority in the 
case of an increase of total digital ERP above -14 dBc) the following 
actions: the initiation of hybrid digital operation; the initiation of 
asymmetric sideband operation at any power level, as well as the 
permanent 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 below -14 dBc. Form 2100, 
Schedule 335-FM will also be amended to provide a digital FM station 
proposing to increase total digital ERP above -14 dBc to certify that 
it complies with the power levels set forth in table 1 to amended Sec.  
73.404(f) (regulating In Band On Channel Digital Audio Broadcast 
Operations), which is based on the current formula used to calculate 
acceptable power levels, but adapted to calculate those levels on a 
per-sideband basis. As is currently required, a station choosing to 
increase total digital ERP to a level 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 newly adopted table 1 to 73.404(f). However, the

[[Page 84102]]

Commission will continue to require that small and other entities 
request experimental authorization for a digital FM station on Channels 
296-300 seeking to engage in asymmetric sideband operation to avoid any 
potential issues regarding interference with the ARNS.
    29. Requiring small and other entities to use FCC Form 2100, 
Schedule 335-FM for the provision of the digital ERP is minimally 
burdensome, as this form will collect the same or similar information 
the notifying FM station would use to request asymmetric sideband 
operation and is less burdensome than preparing an application for 
experimental authorization and renewing such authorization annually. 
Small entities will likely use the same processes and professional 
staff to comply with the FCC Form 2100, Schedule 335-FM requirements. 
Accordingly, although there is not sufficient evidence quantifying the 
compliance cost of the adopted rule changes, the Commission anticipates 
the approaches it has taken to implement the requirements will have 
minimal cost implications and should significantly reduce compliance 
requirements for small entities that may have smaller staff and fewer 
resources.

F. Steps Taken To Minimize Significant Economic Impact on Small 
Entities and Significant Alternatives Considered

    30. The RFA requires an agency to provide, ``a description of the 
steps the agency has taken to minimize the significant economic impact 
on small entities . . . including a statement of the factual, policy, 
and legal reasons for selecting the alternative adopted in the final 
rule and why each one of the other significant alternatives to the rule 
considered by the agency which affect the impact on small entities was 
rejected.'' 5 U.S.C. 604(a)(6).
    31. In the First Report and Order, the Commission considered a 
number of alternatives that will minimize the impact of the revised 
rules. Specifically, the Commission adopted measures to simplify the 
implementation of asymmetric sideband operation for digital FM 
stations, by notification through Form 2100, Schedule 335-FM rather 
than application for experimental authorization and annual renewal. The 
Commission sought to weigh the impact of these measures on small and 
other entities against the public interest benefits gained from them 
and has determined that the benefits outweigh the costs. As some 
commenters have observed, the burden of filing an experimental 
application and annual renewals has likely discouraged many digital FM 
stations from implementing asymmetric sideband operation, and has 
therefore impeded the implementation of such operation and its 
corresponding benefits, including expanded signal coverage and 
interference protection. The Commission concludes that these benefits 
outweigh the burdens imposed by the current procedures, and justify the 
simplified process adopted in the First Report and Order.
    32. The Commission also observes that adopting rules simplifying 
the process of initiating asymmetric sideband operation is likely to 
reduce inter-station interference rather than exacerbate it, and thus 
concludes that existing interference notification and remediation 
procedures are sufficient at the present time, but also concludes that 
Form 2100, Schedule 335-FM should be amended to provide space for the 
notifying station to indicate the digital ERP transmitted on each 
digital sideband, as well as the total digital ERP. While the provision 
of these items of information are a minimal additional burden, they 
consist of information that is readily available to the broadcaster and 
will assist other FM stations in evaluating interference complaints.
    33. The use of Form 2100, Schedule 335-FM will simplify required 
station submissions, and harmonizes such submissions with the recent 
transition of the Media Bureau's application filing system to LMS. The 
Commission also considered whether a station permanently discontinuing 
asymmetric sideband operation should be required to include a short 
statement disclosing its reasons for doing so when notifying the 
Commission, and determined such information was not necessary based on 
commenter input. This decision will eliminate an added burden to 
certain stations, as well as allow them to preserve the confidentiality 
of their business decision making. The Commission further concludes 
that digital FM stations currently using asymmetric sideband operation 
under experimental or special temporary authorizations shall be able to 
continue operation upon notification using Form 2100, Schedule 335-FM, 
provided such notification is submitted before the experimental 
authorization or STA expires. This option has been determined to be the 
least burdensome alternative, as compared to other options such as 
filing a one-time application with annual renewal. Finally, to avoid 
any potential issues regarding interference with the ARNS, the 
Commission will continue to require experimental authorization for a 
digital FM station on Channels 296-300 seeking to engage in asymmetric 
sideband operation. This will impact relatively few digital FM 
stations, and has been deemed necessary to protect ARNS users pending 
the results of testing by aviation industry stakeholders and the 
broadcast industry proponents of the new procedures.

G. Report to Congress

    34. The Commission will send a copy of the First Report and Order, 
including this FRFA, in a report to Congress pursuant to the 
Congressional Review Act, 5 U.S.C. 801(a)(1)(A). In addition, the 
Commission will send a copy of the First Report and Order, including 
this FRFA, to the Chief Counsel for Advocacy of the SBA. A copy of the 
First Report and Order and FRFA (or summaries thereof) will also be 
published in the Federal Register.
    35. Paperwork Reduction Act Analysis. This First Report and Order 
may contain new or modified information collection requirements subject 
to the Paperwork Reduction Act of 1995 (PRA). Public Law 104-13, 109 
Stat 163 (1995) (codified at 44 U.S.C. 3501-3520). 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, 
Public Law 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. We have assessed the 
effects of the required collection of information on these small 
entities.
    36. 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 this rule is non-major 
under the Congressional Review Act, 5 U.S.C. 804(2). The Commission 
will send a copy of this First Report and Order to Congress and the 
Government Accountability Office pursuant to the Congressional Review 
Act, 5 U.S.C. 801(a)(1)(A).

Ordering Clauses

    37. Accordingly, it is ordered that, pursuant to the authority 
contained in sections 1, 4(i), 4(j), 301, 302a, 303, 307, 308, 309, 
316, 319, and 324 of the

[[Page 84103]]

Communications Act of 1934, as amended, 47 U.S.C. 151, 154(i), 154(j), 
301, 302a, 303, 307, 308, 309, 316, 319, and 324 the foregoing First 
Report and Order is adopted, and the Commission's rules are hereby 
amended as set forth herein.
    38. It is further ordered that the First Report and Order and the 
amendments to the Commission's rules shall be effective 30 days after 
publication of a summary in the Federal Register, except that the 
amendments to Sec. Sec.  73.404 and 73.406, which may contain new or 
modified information collection requirements, will not become effective 
until OMB completes review of any information collection requirements 
that the Media Bureau determines is required under the Paperwork 
Reduction Act. The Commission directs the Media Bureau to announce the 
effective date of the rule changes to Sec. Sec.  73.404 and 73.406 by 
subsequent Public Notice.
    39. It is further ordered that the Office of the Managing Director, 
Performance and Program Management, shall send a copy of the First 
Report and Order in a report to Congress and the Government 
Accountability Office pursuant to the Congressional Review Act, 5 
U.S.C. 801(a)(1)(A).
    40. It is further ordered that the Commission's Office of the 
Secretary shall send a copy of this First Report and Order, including 
the Final Regulatory Flexibility Analysis, to the Chief Counsel for 
Advocacy of the Small Business Administration.

List of Subjects in 47 CFR Part 73

    Communications equipment, Radio, Reporting and recordkeeping 
requirements.

Federal Communications Commission.
Marlene Dortch,
Secretary.

Final Rules

    For the reasons discussed in this preamble, the Federal 
Communications Commission amends 47 CFR part 73 to read as follows:

PART 73--RADIO BROADCAST SERVICES

0
1. The authority citation for part 73 continues to read as follows:

    Authority:  47 U.S.C. 154, 155, 301, 303, 307, 309, 310, 334, 
336, 339.


0
2. In Sec.  73.310, revise paragraphs (a) and (b) to read as follows:


Sec.  73.310  FM technical definitions.

    (a) Frequency modulation. The following definitions pertain to 
frequency modulation, as defined in Sec.  73.310(a)(17).
    (1) Antenna height above average terrain (HAAT). HAAT is calculated 
by: determining the average of the antenna heights above the terrain 
from 3 to 16 kilometers (2 to 10 miles) from the antenna for the eight 
directions evenly spaced for each 45[deg] of azimuth starting with True 
North (a different antenna height will be determined in each direction 
from the antenna): and computing the average of these separate heights. 
In some cases less than eight directions may be used. (See Sec.  
73.313(d).) Where circular or elliptical polarization is used, the 
antenna height above average terrain must be based upon the height of 
the radiation of the antenna that transmits the horizontal component of 
radiation.
    (2) Antenna power gain. The square of the ratio of the root-mean-
square (RMS) free space field strength produced at 1 kilometer in the 
horizontal plane in millivolts per meter for 1 kW antenna input power 
to 221.4 mV/m. This ratio is expressed in decibels (dB). If specified 
for a particular direction, antenna power gain is based on that field 
strength in the direction only.
    (3) Auxiliary facility. An auxiliary facility is an antenna 
separate from the main facility's antenna, permanently installed on the 
same tower or at a different location, from which a station may 
broadcast for short periods without prior Commission authorization or 
notice to the Commission while the main facility is not in operation 
(e.g., where tower work necessitates turning off the main antenna or 
where lightning has caused damage to the main antenna or transmission 
system) (See Sec.  73.1675).
    (4) Center frequency. The term ``center frequency'' means:
    (i) The average frequency of the emitted wave when modulated by a 
sinusoidal signal.
    (ii) The frequency of the emitted wave without modulation.
    (5) Composite antenna pattern. The composite antenna pattern is a 
relative field horizontal plane pattern for 360 degrees of azimuth, for 
which the value at a particular azimuth is the greater of the 
horizontally polarized or vertically polarized component relative field 
values. The composite antenna pattern is normalized to a maximum of 
unity (1.000) relative field.
    (6) Composite baseband signal. A signal which is composed of all 
program and other communications signals that frequency modulates the 
FM carrier.
    (7) Effective radiated power. The term ``effective radiated power'' 
means the product of the antenna power (transmitter output power less 
transmission line loss) times:
    (i) The antenna power gain, or
    (ii) the antenna field gain squared. Where circular or elliptical 
polarization is employed, the term effective radiated power is applied 
separately to the horizontal and vertical components of radiation. For 
allocation purposes, the effective radiated power authorized is the 
horizontally polarized component of radiation only.
    (8) Equivalent isotropically radiated power (EIRP). The term 
``equivalent isotropically radiated power (also known as ``effective 
radiated power above isotropic) means the product of the antenna input 
power and the antenna gain in a given direction relative to an 
isotropic antenna.
    (9) FM Blanketing. Blanketing is that form of interference to the 
reception of other broadcast stations which is caused by the presence 
of an FM broadcast signal of 115 dB[micro] (562 mV/m) or greater signal 
strength in the area adjacent to the antenna of the transmitting 
station. The 115 dB[micro] contour is referred to as the blanketing 
contour and the area within this contour is referred to as the 
blanketing area.
    (10) FM broadcast band. The band of frequencies extending from 88 
to 108 MHz, which includes those assigned to noncommercial educational 
broadcasting.
    (11) FM broadcast channel. A band of frequencies 200 kHz wide and 
designated by its center frequency. Channels for FM broadcast stations 
begin at 88.1 MHz and continue in successive steps of 200 kHz to and 
including 107.9 MHz.
    (12) FM broadcast station. A station employing frequency modulation 
in the FM broadcast band and licensed primarily for the transmission of 
radiotelephone emissions intended to be received by the general public.
    (13) Field strength. The electric field strength in the horizontal 
plane.
    (14) Free space field strength. The field strength that would exist 
at a point in the absence of waves reflected from the earth or other 
reflecting objects.
    (15) Frequency departure. The amount of variation of a carrier 
frequency or center frequency from its assigned value.
    (16) Frequency deviation. The peak difference between modulated 
wave and the carrier frequency.
    (17) Frequency modulation. A system of modulation where the 
instantaneous radio frequency varies in proportion to the instantaneous 
amplitude of the modulating signal (amplitude of modulating signal to 
be measured after pre-emphasis, if used) and the

[[Page 84104]]

instantaneous radio frequency is independent of the frequency of the 
modulating signal.
    (18) Frequency swing. The peak difference between the maximum and 
the minimum values of the instantaneous frequency of the carrier wave 
during modulation.
    (19) Multiplex transmission. The term ``multiplex transmission'' 
means the simultaneous transmission of two or more signals within a 
single channel. Multiplex transmission as applied to FM broadcast 
stations means the transmission of facsimile or other signals in 
addition to the regular broadcast signals.
    (20) Percentage modulation. The ratio of the actual frequency 
deviation to the frequency deviation defined as 100% modulation, 
expressed in percentage. For FM broadcast stations, a frequency 
deviation of <plus-minus>75kHz is defined as 100% modulation.
    (b) Stereophonic sound broadcasting. The following definitions 
pertain to stereophonic sound broadcasting, as defined in Sec.  
73.310(b)(8).
    (1) Cross-talk. An undesired signal occurring in one channel caused 
by an electrical signal in another channel.
    (2) FM stereophonic broadcast. The transmission of a stereophonic 
program by a single FM broadcast station utilizing the main channel and 
a stereophonic subchannel.
    (3) Left (or right) signal. The electrical output of a microphone 
or combination of microphones placed so as to convey the intensity, 
time, and location of sounds originating predominately to the 
listener's left (or right) of the center of the performing area.
    (4) Left (or right) stereophonic channel. The left (or right) 
signal as electrically reproduced in reception of FM stereophonic 
broadcasts.
    (5) Main channel. The band of frequencies from 50 to 15,000 Hz 
which frequency-modulate the main carrier.
    (6) Pilot subcarrier. A subcarrier that serves as a control signal 
for use in the reception of FM stereophonic sound broadcasts.
    (7) Stereophonic separation. The ratio of the electrical signal 
caused in sound channel A to the signal caused in sound channel B by 
the transmission of only a channel B signal. Channels A and B may be 
any two channels of a stereophonic sound broadcast transmission system.
    (8) Stereophonic sound. The audio information carried by plurality 
of channels arranged to afford the listener a sense of the spatial 
distribution of sound sources. Stereophonic sound broadcasting 
includes, but is not limited to, biphonic (two channel), triphonic 
(three channel) and quadrophonic (four channel) program services.
    (9) Stereophonic sound subcarrier. A subcarrier within the FM 
broadcast baseband used for transmitting signals for stereophonic sound 
reception of the main broadcast program service.
    (10) Stereophonic sound subchannel. The band of frequencies from 23 
kHz to 99 kHz containing sound subcarriers and their associated 
sidebands.

0
3. In Sec.  73.402, add paragraph (i) to read as follows:


Sec.  73.402   Definitions.

* * * * *
    (i) Asymmetric sideband operation. For digital FM stations, the use 
of different power levels on the upper and lower digital sidebands in a 
hybrid or extended hybrid DAB system.

0
4. Delayed indefinitely, in Sec.  73.404, add paragraphs (e) and (f) to 
read as follows:


Sec.  73.404   IBOC DAB operation.

* * * * *
    (e) Except stations operating on Channels 296-300 (107.1-107.9 
MHz), FM stations may transmit hybrid IBOC signals with asymmetric 
power on the digital sidebands, as defined in Sec.  73.402(i). Stations 
operating on Channels 296-300 (107.1-107.9 MHz) may seek an 
experimental authorization to transmit hybrid IBOC signals with 
asymmetric power on the digital sidebands.
    (f) All FM stations transmitting hybrid IBOC signals may operate 
with total digital effective radiated power of up to -14 dBc. No 
station may operate its digital carriers with a total effective 
radiated power in excess of -10 dBc. A station planning to operate with 
a total digital effective radiated power in excess of -14 dBc must 
certify compliance with table 1 to this paragraph (f) by calculating 
the F(50,10) signal strength of its analog signal at the first adjacent 
station's F(50,50) 60 dB[micro] contour. Compliance with this table 
must be established for the upper and lower IBOC digital sidebands 
separately. All calculations must be made using the standard FCC 
contour prediction methodology.

    Table 1 to Paragraph (f)--Maximum Permissible FM Digital ERP per
                                Sideband
------------------------------------------------------------------------
 IBOC station's F(50,10) field strength at     Maximum permissible FM
     the upper or lower first-adjacent           digital ERP for the
  station's analog 60 dB[micro] F(50,50)     respective (upper or lower)
                  contour                             sideband
------------------------------------------------------------------------
51.2 dB[micro] and above..................  -17 dBc.
50.7 dB[micro] to 51.1 dB[micro]..........  -16 dBc.
50.3 dB[micro] to 50.6 dB[micro]..........  -15 dBc.
49.6 dB[micro] to 50.2 dB[micro]..........  -14 dBc.
49.5 dB[micro] or less....................  -13 dBc.
------------------------------------------------------------------------


0
5. Delayed indefinitely, in Sec.  73.406, add paragraphs (d)(5) and (6) 
to read as follows:


Sec.  73.406  Notification.

* * * * *
    (d) * * *
    (5) Any digital FM station taking any of the following actions must 
notify the Commission of such action on Form 2100, Schedule 335-FM:
    (i) Upon initiation of hybrid digital operation;
    (ii) Upon initiation of asymmetric sideband operation at any power 
level. For FM stations employing asymmetric sideband operation as 
defined in Sec.  73.402(i), the notification must include a 
certification that the proposed digital sideband power on each sideband 
conforms to the Maximum Permissible FM Digital ERP set forth in table 1 
to Sec.  73.404(f), and that the total digital sideband power will not 
exceed the total power if the digital sideband operation were 
symmetric. The notifying station may commence asymmetric sideband 
operation upon filing Form 2100, Schedule 335-FM, and may continue such 
operation unless notified by the Commission that such operation is not 
rule-compliant;
    (iii) Discontinuing asymmetric sideband operation and reverting to 
symmetric sideband operation. The digital FM station must file Form 
2100, Schedule 335-FM within 30 days of discontinuing asymmetric 
sideband operation; or
    (iv) Decreasing total digital Effective Radiated Power from a level 
above -14

[[Page 84105]]

dBc to a level at or below -14 dBc. The digital FM station must file 
Form 2100, Schedule 335-FM within 30 days of decreasing power.
    (6) Any digital FM station seeking authority to increase total 
digital Effective Radiated Power above -14 dBc must submit Form 2100, 
Schedule 335-FM. The submission must include a certification that the 
proposed FM digital Effective Radiated Power is permitted, using the 
table set forth in table 1 to Sec.  73.404(f). Certifications must be 
based on the most restrictive analog field strength of the proponent at 
any nearby first-adjacent channel station's 60 dB[micro] contour. The 
station choosing to operate with total digital ERP above -14 dBc may 
initiate such operation upon approval from the Commission.

[FR Doc. 2024-24105 Filed 10-18-24; 8:45 am]
BILLING CODE 6712-01-P


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