Federal Communications Commission FCC 23-61
Before the
Federal Communications Commission
Washington, D.C. 20554
In the Matter of
Modifying Rules for FM Terrestrial Digital Audio 
Broadcasting Systems)
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)MB Docket No. 22-405
ORDER AND NOTICE OF PROPOSED RULEMAKING
Adopted:  July 31, 2023 Released:  August 1, 2023
Comment Date: [30 days after date of publication in the Federal Register]
Reply Comment Date: [45 days after date of publication in the Federal Register]
By the Commission:
I. INTRODUCTION
1. In this Order and Notice of Proposed Rulemaking (NPRM), we grant two Petitions for 
Rulemaking and propose changes to our digital audio broadcasting (DAB) technical rules that would 
permit additional FM stations to increase FM hybrid digital effective radiated power (FM Digital ERP) 
beyond the existing levels without the need for individual Commission authorization.  In addition, we 
propose to allow a digital FM station to operate with asymmetric power on the digital sidebands.  This 
would allow stations to operate with different power levels on the upper and lower digital sidebands, as a 
way to facilitate greater digital FM radio coverage without interfering with adjacent channel FM stations.1 
2. The two Petitions for Rulemaking were consolidated by the Media Bureau (Bureau) 
because the proposed rule changes both relate to improving digital FM signal quality and minimizing the 
effect of the digital FM station signal on adjacent channel FM transmissions.2  The petitioners point out 
the increasing penetration of digital FM receivers, especially in automobiles, and note that station 
conversions to digital have not experienced an equivalent growth.  Petitioners submit that a significant 
contributor to the slower digital conversion rate is the difficulty of replicating an FM station’s analog 
signal using currently allowable digital FM power levels.  In the earlier of the two petitions, filed 
December 9, 2019, petitioners National Association of Broadcasters (NAB), Xperi Corporation (Xperi), 
and National Public Radio (NPR) request 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 
1 We note that the Low Power FM service, the FM translator service, and the FM booster service are all eligible to 
operate in hybrid mode, in the same manner as the full-power FM service.  See Digital Audio Broadcasting Systems 
and Their Impact on the Terrestrial Radio Broadcast Service, Second Report and Order, First Order on 
Reconsideration and Second Further Notice of Proposed Rule Making, 22 FCC Rcd 10344, 10366-67, 10381-81, 
paras. 56-58, 92-93 (2007) (DAB Second R&O).  In this NPRM any references to the “FM service” or “FM” include 
all of these discrete FM services, unless noted otherwise.
2 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).Federal Communications Commission FCC 23-61
2there is no adjacent analog FM station or a more distant adjacent station.3  In the second petition, filed 
October 26, 2022, NAB and Xperi request that the FCC update the methodology stations use to determine 
maximum FM digital power levels.4  We grant these petitions and seek comment on whether the rule 
changes proposed below, based on the Asymmetric Sideband Petition and Power Increase Petition, 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.  We 
additionally seek comment on:  whether such rule changes would cause or increase interference to analog 
FM stations adjacent to 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.  We 
tentatively conclude that adoption of the proposed rule changes would advance the Commission’s 
ongoing commitment to developing terrestrial digital broadcasting with minimal to no adverse effects, 
including any harmful interference, on existing service.  We therefore seek comment from broadcasters, 
engineers, and other interested parties to help us clarify some of the issues raised by the proposed rule 
changes and to assess their relative costs and benefits.
II. BACKGROUND
3.Power Increase Petition; History of Digital FM Power Limits.  In 2002, the Commission 
selected in-band, on-channel (IBOC) technology to enable radio broadcast stations to commence digital 
broadcasting.5  In the DAB R&O, the Commission adopted notification procedures allowing existing FM 
radio stations to begin digital transmissions immediately on an interim basis using the IBOC system.6  
The iBiquity FM IBOC digital system includes several hybrid modes and separate all-digital modes.  In 
the hybrid and extended hybrid modes, a station simultaneously transmits both the analog and digital 
signals.7  In the all-digital modes, the station drops the analog signal and is able to increase the capacity of 
the digital signal.  The Commission initially limited digital operations to the hybrid digital mode,8 which 
permits the simultaneous transmission of both the analog and digital signals within the current spectral 
emissions mask of a single FM channel, placing redundant blocks of digital information in the sidebands 
on both sides of and immediately adjacent to the analog signal.9    
4. iBiquity and several independent parties conducted extensive field and laboratory tests of 
the IBOC system prior to Commission adoption.  Based on the National Radio Systems Committee’s 
3 Petition for Rulemaking of Nat’l Ass’n of Broad., Xperi Corp., and Nat’l Public Radio, MB Docket No. 22-405 
(filed Dec. 9, 2019), https://www.fcc.gov/ecfs/document/1125972022299/1 (Asymmetric Sideband Petition).
4 Petition for Rulemaking of Nat’l Ass’n of Broad. and Xperi Inc., MB Docket No. 22-405 (filed Oct. 26, 2022), 
https://www.fcc.gov/ecfs/document/10261669202264/1 (Power Increase Petition).
5 Digital Audio Broadcasting Systems And Their Impact On The Terrestrial Radio Broadcast Service, First Report 
and Order, 17 FCC Rcd 19990 (2002) (DAB R&O).  DAB generally refers to the digital service broadcast by radio 
stations whereas IBOC generally refers to the technical system supporting DAB service.  While early DAB orders 
addressed both AM and FM digital broadcasting, this NPRM deals exclusively with digital FM operations and 
regulations.
6 iBiquity subsequently was sold, and the acquiring company renamed itself Xperi.
7  The extended hybrid mode adds an additional 50 kbps (kilobits per second) to the 96 kbps digital capacity of the 
hybrid mode.  See DAB Second R&O, 22 FCC Rcd at 10344, para. 2.  See also 47 CFR § 73.402 Definitions.
8  The Commission subsequently authorized use of the FM IBOC extended hybrid digital mode in the DAB Second 
R&O.  See DAB Second R&O, 22 FCC Rcd at 10352, paras. 18-19.
9 The sideband frequency higher than the FM channel’s center frequency is known as the upper sideband, while that 
which is lower than the FM channel’s center frequency is known as the lower sideband.Federal Communications Commission FCC 23-61
3(NRSC)10 evaluation of those test results, in December 2001 the NRSC approved the NRSC-5 standard,11 
which specifies a digital FM ERP equal to one percent of authorized analog FM power (20 decibels below 
carrier or -20 dBc).  Subsequently, the Commission adopted this as the maximum digital power level for 
the hybrid digital mode of the FM IBOC system the Commission authorized in the 2002 DAB R&O.12  In 
2010, the Bureau released an Order increasing the allowable power level of the FM station’s digital 
sidebands from -20 dBc to -14 dBc, upon electronic notification to the Commission.13  In the 2010 MB 
DAB Order, the Bureau further allowed certain FM stations to increase digital power above -14 dBc, to 
up to -10 dBc, upon a showing that such power increase would comply with the formula in the 2010 MB 
DAB Order, and therefore would not cause harmful interference to adjacent analog FM stations.14  
5. Petitioners state that digital FM receiver penetration continues to grow:  according to the 
October 2022 Power Increase Petition, there are over 90 million autos in the U.S. with digital receivers; 
receiver penetration has exceeded 40% in some markets; and almost 60% of new automobiles sold in the 
U.S. are equipped with digital IBOC receivers.15  Petitioners NAB and Xperi contend, however, that 
many stations have resisted adopting IBOC technology due to the inability to replicate their analog signal 
coverage with digital coverage, owing to the limits placed on digital sideband power.16  They maintain 
that the Commission, by its own admission,17 overprotected adjacent-channel FM analog stations when 
implementing the allowable FM digital power table set forth in the 2010 MB DAB Order, and further state 
that 12 years of experience with the current FM digital power levels has yielded few if any complaints of 
interference from hybrid digital FM transmissions.18  As evidence for its contentions, petitioners NAB 
and Xperi attach an analysis of existing digital FM stations transmitting at the current allowable limit of    
-14 dBc, but whose digital signal substantially overlaps that of adjacent analog FM stations.  They assert 
that in none of these real-world situations have there been any instances of digital-to-analog 
interference.19  NAB and Xperi further attach the results of their own field test, conducted under 
experimental authority, using three stations in the New York market, two adjacent “interfering” stations 
and one “interfered with” station.  In this study the adjacent-channel digital stations operated first with 
FM digital signals at -14 dBc, and then at -10 dBc, while recordings were made of the adjacent channel 
analog station under each condition.  According to a panel of listeners—consisting of NAB and Xperi 
employees—who evaluated the recordings, there was “no significant change or degradation of the desired 
[FM analog] signal when the 1st-adjacent channel interferer went from -14 dBc to -10 dBc” even though 
10  The NRSC is an industry group jointly sponsored by the National Association of Broadcasters and the Consumer 
Technology Association.
11 Press Release, NRSC, NRSC Approves Digital Radio Broadcasting Standard (Apr. 16, 2005).
12  See DAB R&O, 17 FCC Rcd at 20004 n.67 and Appendix B, 17 FCC Rcd at 20041-43. See also 47 CFR § 
73.404(a). 
13 Digital Audio Broadcasting Systems And Their Impact on the Terrestrial Radio Broadcast Service, Order, 25 FCC 
Rcd 1182, 1189, para. 16 (MB 2010) (2010 MB DAB Order).
14 Id. at 1182, 1189-90, paras 16-20.  See also 47 CFR §73.404(a).  The showing required to obtain FM digital 
power of between -14 dBc and -10 dBc included the calculation results using the following formula:  Allowable FM 
digital power = [2.27 * (60 - FM digital station F(50,10) dBµ)) - 33.6].  Thus, a licensee desiring FM digital ERP in 
excess of -14 dBc total power is required to calculate the digital station’s analog F(50,10) field strength at all points 
on the protected 60 dBµ F(50,50) contour of a potentially affected first-adjacent channel analog FM station.  This 
calculation must be performed using each station’s  licensed analog facilities and the standard FCC contour 
prediction methodology.  2010 MB DAB Order, 25 FCC Rcd at 1187, 1190, paras. 12, 20.
15 Power Increase Petition at 3-4.
16 Id. at 4-5.  See 47 CFR § 73.404(a).
17 2010 MB DAB Order, 25 FCC Rcd at 1189, para. 19.
18 Power Increase Petition at 6, 9-10.
19 Id. at 10-17 and Appendix 1.Federal Communications Commission FCC 23-61
4these stations were operating at levels far in excess of the levels permitted under the current 
methodology.20
6.Asymmetric Sideband Petition.  The Commission’s existing rules assumed that digital 
power would be the same on both digital sidebands.21  NAB, Xperi, and NPR, in the Asymmetric 
Sideband Petition, assert that with asymmetric sidebands a digital FM station could protect one adjacent 
analog FM station while concurrently increasing power on the other sideband frequency in order to 
expand its digital coverage and building penetration.22  These petitioners conducted a study that they state 
demonstrates that many more digital FM stations could increase power above -14 dBc on at least one 
sideband.  Out of 10,875 digital FM stations studied, petitioners contend that 6,120 could increase power 
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.23  These petitioners also note that, under the current rules, stations 
may only request asymmetric sidebands under an experimental authorization.24  They argue that the need 
to request experimental authorization, and the temporary nature of such authorizations, discourages use of 
asymmetric sidebands,25 which in turn limits digital FM stations to the power level needed to protect the 
closer or higher-powered adjacent-channel analog FM station.26  Petitioners thus request that we amend 
our 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.27  The Bureau sought comment on the 
consolidated Power Increase Petition and Asymmetric Sideband Petition in the FM Digital Comment PN, 
released November 28, 2022.28
III. DISCUSSION
7. After review of the Power Increase Petition and the Asymmetric Sideband Petition, and 
the comments filed in response, we conclude that the record discloses sufficient reasons to justify the 
institution of a rulemaking proceeding seeking further comment on these proposals.29  We tentatively 
conclude that the proposals in both the Power Increase Petition and the Asymmetric Sideband Petition 
represent steps toward improving the terrestrial digital FM broadcast radio service.  We seek comment on 
our proposal to allow additional stations to increase FM digital power levels, to authorize asymmetric 
sideband power levels without the need for experimental authorization, and to rely on our existing 
interference mitigation and remediation processes, and notification procedures.  
20 Id. at 17-20 and Appendices 2-3.
21 See 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20 (setting forth methodology for calculating maximum 
permissible FM Digital ERP that assumes operation with symmetric sidebands).  A station wishing to operate with 
asymmetric sideband power must request experimental operation, including a showing that the digital sideband 
signal contours will not overlap adjacent stations’ protected contours.  The staff generally grants requests that do not 
propose prohibited overlap.
22 Id.
23 Id. at 9-11.  Petitioners’ study was conducted in 2017.
24 Asymmetric Sideband Petition at 11.
25 Id.
26 Id. at 8-10.
27 Id. at 8-11.
28 FM Digital Comment PN, supra note 4, at 1.
29 See 47 CFR § 1.407.Federal Communications Commission FCC 23-61
5A. Power Increase Petition
8. We propose to amend our rules to change the power increase methodology and 
notification procedures, consistent with the Petition.  Specifically, we propose to change the methodology 
used by digital FM stations to determine whether they are eligible to increase digital FM power up to -10 
dBc, or 10% of analog power.  We also propose that such increases be allowed without the need for 
additional individual special authorization, but upon basic notification to the Commission.  We further 
propose that stations notify the Commission of a power increase up to -10 dBc in the Bureau’s Licensing 
and Management System (LMS), using the same notification procedures as currently used to notify the 
Commission of digital operation up to -14 dBc.
9.Maximum Permissible FM Digital ERP Table.  We propose to amend our rules to modify 
the methodology a digital FM station must use to determine whether it is eligible to increase its power 
above -14 dBc.  This modification, if adopted, would allow more stations to increase power up to -10 dBc 
without the requirement of submitting a contour analysis.  As stated in note 1, supra, secondary services 
such as LPFM and FM translators are eligible to operate in hybrid mode.  To the extent that such a 
secondary service station seeks to increase its digital power, it would use the same methodology set forth 
herein.  As summarized above, currently a digital FM station may operate with digital power up to -14 
dBc.  Additionally, a digital FM station could apply to operate with power of up to -10 dBc (10% of 
analog power), pursuant to the table adopted in the 2010 MB DAB Order.30  Petitioners now assert that the 
intervening dozen years of experience with the established 2010 power limits, as well as follow-up field 
tests and other studies, demonstrate that most digital FM stations should be able to operate at power levels 
of up to -10 dBc without special Commission authorization, and without causing interference to adjacent 
channel FM facilities.31  They propose an updated table for determining maximum permissible FM Digital 
ERP as follows:32  
Proponent Analog F(50,10) Field Strength at First 
Adjacent Station’s33 Analog 60 dBµ F(50,50) 
Contour (Symmetric Sideband Operation)Maximum 
Permissible FM 
Digital ERP
57.9 dBµ and above -14 dBc
56.5 dBµ to 57.8 dBµ -13 dBc
55.6 dBµ to 56.4 dBµ -12 dBc
54.1 dBµ to 55.5 dBµ -11 dBc
54.0 dBµ or less -10 dBc
As detailed in the 2010 MB DAB Order,34 a licensee desiring FM Digital ERP in excess of -14 dBc  must 
calculate the station’s analog F(50,10) field strength at all points on the 60 dBµ F(50,50) contour of a 
potentially affected first-adjacent channel analog FM station.  This calculation must be done using each 
30 See supra note 14.  See also 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20.
31 Power Increase Petition at 9-15, 17-20, and Appendices 1 and 2.
32 Id. at 7-8.  The table is derived from an updated formula proposed by petitioners, as follows:  Allowable IBOC 
power (dBc, total power) = 44 – [IBOC Station F(50,10) dBµ at the desired station 60 dBµ F(50,50) contour] (if 
using symmetric sidebands), or Allowable IBOC power (dBc, per sideband) =  41 – [IBOC Station F(50,10) dBµ at 
the desired station 60 dBµ F(50,50) contour] (if using asymmetric sidebands).  Petitioners note that total power is 3 
dB greater than that of each individual sideband, explaining the 3 dB difference between the two formulas.
33 As petitioners note, “the word ‘protected’ has been struck from the first column heading in the table to emphasize 
that the 60 dBµ contour is the contour of interest regardless of station class.”  Power Increase Petition at 6 n.12.  We 
also note that, as stated in note 1, supra, digital LPFM stations and FM translators and boosters may avail 
themselves of the increased maximum permissible digital ERP.  However, this does not provide secondary stations 
with additional protection from interference by full-service stations.
34 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20.Federal Communications Commission FCC 23-61
6station’s licensed analog facilities and the standard FCC contour prediction methodology.35  Once the 
most restrictive analog F(50,10) field strength of the proponent station has been determined, the licensee 
will use the updated table to determine the proponent station’s maximum permissible FM Digital ERP.
10. As discussed above, petitioners studied pairs of stations in which the digital FM station 
operated at -14 dBc, yet the station’s signal strength at the protected contour of the adjacent analog FM 
station is greater than that allowed by the current methodology.36  Despite this, petitioners state that none 
of the studied analog FM stations reported any significant interference from the digital FM stations, in 
spite of signal strengths higher than permitted by the current methodology.  We note that we have not 
received any interference complaints from any of the adjacent channel stations most likely to experience 
interference from the stations that petitioners studied, with greater-than-normal power ratios.  We request 
comment on the methodology or interpretation of petitioners’ studies, and whether they support 
petitioners’ claim that use of the proposed revised table will not result in harmful interference.  
11. The majority of commenters support the proposals set forth in the Power Increase 
Petition.37  Most agreed with petitioners that allowing more stations to increase digital power would assist 
FM digital stations to expand their digital service areas, as well as improve building signal penetration.38  
As discussed below, two commenters express concern about the effect of increased digital FM power on 
Low-Power FM (LPFM) and smaller Class A FM stations, contending that such stations serve listeners 
outside the protected 60 dBµ contour.39 
12. We tentatively conclude that the record collected to date supports our proposed 
methodology change.  We reiterate that the Commission initiated the process of authorizing digital 
broadcast operations in 1999 with the eventual goal of moving terrestrial broadcasting from an all-analog 
to an all-digital world.40  Although we have stated repeatedly that there is no timetable for this eventual 
change to all-digital broadcast radio41—and do not alter that stance in any way today—our objective 
remains to advance the progress of digital radio without causing harmful interference or disruption to 
35 See 47 CFR § 73.313.  As explained in the 2010 MB DAB Order, 25 FCC Rcd at 1190 n.43, since the 
Commission’s rules permit only a limited differential in the location of separate FM analog and digital transmitting 
facilities and there will be very little difference in the predicted maximum permissible FM Digital ERP for an 
eligible FM station if calculated from either of the two locations, we require use of the licensed analog facilities for 
this calculation.
36 Power Increase Petition at 10-15 and Appendix 1 at 7-34.  Because each digital station studied was operating at 
the current maximum allowable power level of -14 dBc, none were required to make a special authorization showing 
using the current methodology.
37 See, e.g., Comments of Beasley Media Group Licenses, LLC (Beasley Comments) at 4 (contending that there can 
be “no downside to adjusting the formula for power levels.”; Comments of CMG Media Corp. (CMG Comments) at 
2 (supporting “swift grant of the [Power Increase] Petition and the Asymmetric Sideband Petition as the next step in 
the technological advancement of the radio industry.”); Comments of Communications Technologies, Inc. (CTI 
Comments) at 3; Comments of New York Public Radio (NYPR Comments) at 2 (stating that adoption of the 
updated digital power methodology and asymmetric sideband operation “will do much to spur improvements and 
increased adoption of HD Radio technology nationwide.”); Comments of E. Glynn Walden (Walden Comments) at 
3; Comments of Kevin J. Haider (Haider Comments) at 1; Comments of David Maxson (Maxson Comments) at 1 
(“The NAB/Xperi technical assessment demonstrates their proposed protection equation will be more than sufficient 
to maintain interference-free use of the FM spectrum.”).
38 See, e.g., CMG Comments at 2; Comments of Nautel Maine, Inc. (Nautel Comments) at 2; Walden Comments at 
2.
39 See infra paras. 14-17, for a discussion of the effect of increased FM digital power on secondary service stations.
40 See DAB R&O, 17 FCC Rcd at 19992-93, para. 7.  See also Digital Audio Broadcasting Systems and Their Impact 
on the Terrestrial Radio Broadcast Service, Notice of Proposed Rulemaking, MM Docket No. 99-325, 15 FCC Rcd 
1722, 1730, para. 16 (1999).
41 See, e.g., DAB Second R&O, 22 FCC Rcd at 10350-51, para. 13.Federal Communications Commission FCC 23-61
7existing analog operations.  This is especially true given the record evidence of increased digital FM 
receiver penetration,42 even though we recognize that such receivers are far from ubiquitous, and that the 
record is less complete with regard to non-automotive digital FM receiver penetration.  It is this desire to 
encourage continued adoption of digital FM broadcast technology that informs our tentative conclusions 
and proposals in this NPRM.
13. We tentatively conclude that the proposals set forth in the Power Increase Petition 
support the goal of furthering the progress of digital FM broadcast radio.  We therefore propose to amend 
our rules to change the methodology used by digital FM stations to determine whether they are eligible to 
operate with allowable IBOC power up to and including -10 dBc, and to permit any existing FM digital 
station currently operating with power below -10 dBc that satisfies the table we propose to adopt herein, 
to increase allowable IBOC power without seeking prior Commission authorization and without the 
requirement of submitting a contour overlap analysis.  We further propose to adopt the petitioners’ table 
for calculating maximum allowable FM IBOC power set forth in paragraph 9, above.  We seek comment 
on this proposal.  Are the contours and power levels set forth in the Maximum Permissible FM Digital 
ERP Table reasonable from an engineering standpoint?  If not, how would commenters modify the table?  
To the extent that any such modifications are proposed, we request that commenters detail the engineering 
rationale underlying any such modifications.  If commenters generally support providing greater 
flexibility for stations to increase their FM digital power but disagree with the use of the Maximum 
Permissible FM Digital ERP Table, what other methods would they suggest for calculating maximum FM 
digital power?
14.  Interference and Proposed Interference Remediation Procedures.  We seek comment on 
whether changing the power increase methodology will create an unacceptable risk of interference to 
adjacent-channel stations.  Most commenters agree with petitioners that interference has not been and 
would not be an issue with the proposal to broaden the number of stations eligible to increase digital 
power levels.43  Petitioners, and those who concur with them, base their contentions on the technical 
analyses and field studies they cite.44  Some commenters, however, express caution surrounding digital 
interference to FM analog stations, especially smaller stations.  These commenters argue that the 
proposed change to the methodology could harm smaller stations such as Class A FM stations, LPFM 
stations, and FM translators and AM stations rebroadcasting over FM translators,45 as well as other 
entities beside FM stations, such as broadband providers.46
42 See Power Increase Petition at 2-4; Asymmetric Sideband Petition at 2-5.
43 See, e.g., Beasley Comments at 3 (asserting that the Power Increase Petition proposals are “supported by thorough 
engineering studies” and that there is “no downside” to adjusting the digital power methodology); Maxson 
Comments at 1 (“The NAB/Xperi technical assessment demonstrates their proposed protection equation will be 
more than sufficient to maintain interference-free use of the FM spectrum.”); Reply Comments of 
iHeartCommunications, Inc. (IHC Reply) at 3-4 (stating that “the comprehensive technical analysis, long-term real-
life experiences and field studies presented to the Commission in the NAB/Xperi Petition justify adjusting the IBOC 
formula to permit certain stations to operate above -14 dBc,” and further that real-world experience and field studies 
demonstrate that the current methodology is too conservative).
44 Power Increase Petition at 9-15, 17-20, and Appendices 1 and 2.
45 See Comments of Santiam Community Radio Corp. (Santiam Comments) at 1; Letter from Robert McAllan, CEO, 
Press Communications, LLC, to Marlene H. Dortch, Secretary, FCC, MB Docket No. 22-405, at 1-2 (filed Mar. 2, 
2023) (Press First Ex Parte).  See also Comments of NPR (NPR Comments) at 3 (requesting that any new rules 
protect FM stations that are not increasing digital power levels).  See also infra para. 17, for a discussion of the 
effect of increased FM digital power on secondary service stations.
46 See Letter from Maureen O’Connell, Vice President, Regulatory Affairs, Charter Communications, to Marlene H. 
Dortch, Secretary, FCC, MB Docket No. 22-405, at 1 (filed July 28, 2023) (Charter Ex Parte).Federal Communications Commission FCC 23-61
815. In the 2010 MB DAB Order, the Bureau set forth detailed procedures to identify and 
remedy complaints of digital-to-analog FM interference among full-service FM broadcast stations.47  
Those procedures require, first, that an analog FM station receiving verifiable listener complaints of 
digital interference within its protected contour contact the digital FM station, and that the stations 
cooperate to confirm the interference and attempt to eliminate it using voluntary tiered FM digital power 
reductions.48  If the stations are unable to agree on appropriate interference remediation measures, the 
affected analog FM licensee may file a complaint with the Media Bureau.49  Media Bureau staff will 
review each complaint and order appropriate action within 90 days of filing the complaint.  If the Bureau 
has not acted within 90 days, the interfering station must reduce its digital power, and ongoing complaints 
of interference may require subsequent stepped reductions of digital power.50
16. Like the petitioners and commenters,51 we have noted few interference complaints from 
full-service analog FM stations resulting from adjacent-channel digital transmissions.  Given the paucity 
of interference complaints, we tentatively conclude that the interference remediation procedures outlined 
above and set forth in the 2010 MB DAB Order will continue to suffice to handle such digital-to-analog 
interference complaints as may arise between full-service FM stations.  These interference mitigation and 
remediation procedures would therefore remain in place to guard against any instances of actual 
interference to other facilities.  We seek comment on this tentative conclusion.  To the extent that 
commenters believe that these current procedures would be inadequate to deal with the increased power 
levels proposed in this NPRM, we ask that they state specifically where the current system is deficient, 
and describe in detail the interference identification and remediation measures they feel are needed.
17. As discussed in the 2010 MB DAB Order, as secondary services LPFM and FM 
translators stations are not eligible for the interference remediation procedures adopted therein.52  Because 
secondary services are not protected from interference from full-service stations, we do not propose to 
modify this approach such that secondary services can use these interference remediation procedures to 
claim interference from full-service stations.  However, although the number of secondary service stations 
employing hybrid digital operation to date is small, we invite comment as to whether we should adopt any 
digital interference remediation procedures for secondary service analog stations claiming interference 
from secondary service digital stations.  All full-service stations, including Class A stations, may take 
advantage of the interference remediation procedures set forth in the 2010 MB DAB Order and as 
proposed herein.
47 2010 MB DAB Order, 25 FCC Rcd at 1191-93, paras. 24-30.
48 Id. at 1193, para. 27.  If the stations resolve the interference by voluntarily reducing FM digital power, the digital 
FM station must notify the Commission of the reduced digital power level, and maintain its digital ERP at the jointly 
agreed-upon level.  Id.
49 This complaint must contain the following:  (a) at least six reports of ongoing (not transitory) objectionable 
interference; (b) a map showing the location of the reported interference; (c) a detailed description of the nature and 
extent of the interference experienced at each mapped location; and (d) a complete description of the tests and 
equipment used to identify the alleged interference and the scope of the unsuccessful efforts to resolve the 
interference.  Id. at 1193, para. 28.
50 Id. at 1193, para. 29.  After 90 days, if the Media Bureau has not acted on the complaint, stations operating with 
FM digital ERP in excess of -14 dBc must immediately reduce FM Digital ERP to -14 dBc.  If ongoing complaints 
of objectionable interference from the FM digital facilities persist, the Bureau may require subsequent 3 dB 
reductions in FM Digital ERP to -17 dBc and -20 dBc, respectively, until it acts on the pending interference 
complaint.  Stations operating with FM digital ERP of -14 dBc or less must immediately reduce FM Digital ERP to -
17 dBc.  If interference complaints persist after this initial reduction, the Bureau will order the station to reduce FM 
digital ERP to the currently permitted maximum of -20 dBc and require it to remain at that level until the Bureau 
acts on the pending FM digital interference complaint.  Id.
51 See Power Increase Petition at 10-17 and Appendix 1.  See also, e.g., Beasley Comments at 3.
52 2010 MB DAB Order, 25 FCC Rcd at 1192-93, para. 26.Federal Communications Commission FCC 23-61
918. Commenter Aaron Read labels as “disingenuous” a system of determining interference 
based on listener complaints; rather, he argues for a “a clear, objective, mathematical/contour-based 
system” for resolving interference issues before the problem becomes acute.53  Commenters may wish to 
address whether the station complaints described above should be based on objective criteria such as 
“agreed-upon [mathematical] formulas,” rather than listener reports.54  Should the number of reports of 
ongoing interference required (currently six) be increased or decreased?  Should a complaining station be 
allowed instead to submit studies and/or measurements demonstrating that the digital FM signal within 
the complaining station’s protected contour exceeds allowable limits?  Additionally, how should a digital 
FM station that has increased its digital power be treated if and when an adjacent-channel analog FM 
station subsequently increases its analog power, and/or moves its facilities closer to the digital FM 
station?  Should we give precedence to the analog FM signal?  Alternatively, should the digital FM 
facility that now seeks a power increase be protected over a subsequent facility modification by an 
adjacent-channel analog FM station?
19. Two commenters raise the issue of how a digital FM station power increase would affect 
protection to incumbent stations.  One commenter recounts its experience as an LPFM operator, having 
its signal blanketed by a local digital signal operating at only four percent of its analog ERP.55  It asks that 
any increase to FM digital sideband power be “carefully considered” due to its impact on LPFM and other 
smaller stations, suggesting that LPFM and FM translator signals should be protected from digital signal 
encroachment to at least the 50 dBµ contour.56  Another commenter asserts that the proposed power 
increase would largely benefit large station group owners at the expense of small broadcasters, and would 
“destroy well-established listening patterns to analog FM stations,” especially in areas like New Jersey 
where the FM band is saturated with services.57  It believes that small Class A stations should be protected 
beyond their 60 dBµ contours,58 and further argues that the proposed rule changes would give large Class 
B stations in metropolitan areas such as New York and Philadelphia an unfair competitive advantage over 
smaller, local analog FM stations.59  Both commenters argue that protection to the 60 dBµ contour is 
insufficient for analog FM stations on adjacent channels that, they contend, have listenership well beyond 
that contour.60  We tentatively conclude that there is no need to provide protection from actual 
interference outside the protected contour of an analog FM station from the digital signal of a full-service 
FM station, and seek comment on this conclusion.  Should protection of incumbent analog FM stations on 
adjacent channels be increased beyond the 60 dBµ contour and, if so, to what contour?  Commenters are 
asked to give detailed evidence for or against increasing the level of protection to analog FM stations on 
adjacent channels from increased FM digital sideband power proposals.  Press offers a number of 
proposals to remedy what it sees as the problems the Power Increase Petition would cause to smaller, 
coastal FM stations, including:  (i) allowing such stations to move up to three miles inland under certain 
53 Comments of Aaron Read (Read Comments) at 1-2.  See also Comments of CDE (CDE Comments) at 2; Reply 
Comments of CDE (CDE Reply) at 2 (requesting that we adopt procedures to establish the presence or absence of 
interference as a result of the increase in digital sideband power before increasing power levels; also opposing a 
“global” increase in FM digital power absent “appropriate interference studies” to determine the potential of actual 
interference).
54 Read Comments at 1.
55 Santiam Comments at 1.
56 Id.
57 Press First Ex Parte at 1-2.
58 Letter from Robert McAllan, CEO, Press Communications, LLC, to Marlene H. Dortch, Secretary, FCC, MB 
Docket No. 22-405, at 6-8 (filed Mar. 23, 2023) (Press Second Ex Parte).
59 Id. at 1-2, 13-15.  Press also asserts that expanding FM digital service at the expense of smaller Class A stations 
would effectively cancel the latter’s proven analog service “for a digital service that has to date shown little, if any, 
public interest benefit.”  Id. at 1.
60 See Santiam Comments at 1; Press Second Ex Parte at 5-8.Federal Communications Commission FCC 23-61
10conditions; (ii) adopting a universal analog 60 dBµ protection in Zone I61 for all co-, first-, and second-
adjacent analog Class A to Class B station-to-station separations; and (iii) extending protection beyond 
the 60 dBµ contour for Class A stations to the 45 dBµ contour or even a 50 dBµ Longley-Rice contour.62  
While noting that Press’s proposed solutions appear to be geographically targeted and class-specific, we 
invite comment on Press’s proposals.  Finally, Charter Communications (Charter) expresses concern that 
changing our methodology for determining digital FM stations’ eligibility to increase their power, and 
allowing such power increases without prior Commission authorization, could cause harmful interference 
to Charter’s broadband systems, which use the same frequencies as FM broadcast radio for both upstream 
and downstream transmissions.63  Charter urges that seeking comment about the potential effects of this 
proposal on other users of the 88-108 MHz band will yield the benefit of a complete record on the subject 
before we take any action.64  We therefore invite comment as to the potential effect of our proposed 
change in the methodology for calculating digital FM power levels on all stakeholders utilizing the 88-
108 MHz frequency band, whether they are broadcasters or providers of other services.
20.Superpowered FM Stations.  We propose to continue to limit the power level for 
previously authorized superpowered FM stations to the station’s class maximum.65  REC Networks 
(REC), while generally supportive of the proposals in the Power Increase Petition, notes that the proposed 
power increases should not be permitted for previously authorized superpowered stations, which 
historically have been limited in digital power to the class maximum power under section 73.211 of the 
rules.66  REC notes that the Power Increase Petition proposes to let a digital FM station meeting the 
proposed new table to increase its digital ERP up to -10 dBc, or 10% of the analog ERP.  It states that 
allowing legacy superpowered FM stations to increase digital power to this level could allow certain 
stations to increase digital power to above the class maximum, resulting in harmful interference.67  We 
tentatively conclude that a superpowered station’s digital ERP should continue to be limited to the class 
maximum provided in sections 73.211 and 73.511.68  Thus, we propose that a superpowered FM station 
seeking to increase its digital power above -14 dBc may request experimental authorization or special 
temporary authorization (STA) to do so, and the staff will review such requests on a case-by-case basis.  
We solicit comment on this conclusion and proposal, and request that commenters opposing this view 
detail the reasons why they believe that a digital FM station whose power greatly exceeds its class 
maximum will not cause excessive interference to adjacent channel analog facilities.69
61 47 CFR § 73.205(a).  Zone I consists of all of the states of Illinois, Indiana, Ohio, West Virginia, Pennsylvania, 
Maryland, Delaware, New Jersey, Connecticut, Rhode Island, and Massachusetts, and portions of Wisconsin, 
Michigan, Virginia, New York, Vermont, New Hampshire, and Maine.
62 Press Second Ex Parte at 17-18.
63 Charter Ex Parte at 1.
64 Id. at 1-2.
65 As noted in Appendix A, to conform to the publishing conventions of the National Archives and Records 
Administration’s Office of the Federal Register, we propose to add paragraph numbers to the list of definitions in 47 
CFR §§ 73.310(a) and (b).  See Appendix A.  The definitions restated in Appendix A are identical to the current 
definitions, except for the definition of “Previously authorized superpowered FM station,” which is a new definition 
we propose to add.
66 Comments of REC Networks (REC Comments) at 1-3.  See also 47 CFR § 73.211.  Superpowered FM stations 
have been previously authorized to operate with facilities that exceed the ERP/Height Above Average Terrain 
(HAAT) limitations of 47 CFR §§ 73.211 or 73.511 for their specific class of station.
67 REC Comments at 2-3.
68 47 CFR §§ 73.211, 73.511.
69 A station may determine whether it is, by definition, a superpowered FM station using the Media Bureau’s Digital 
Maximum ERP Calculator for Superpowered FM Stations (https://www.fcc.gov/media/radio/digital-radio-
superpowered-fm-stations).Federal Communications Commission FCC 23-61
1121.Notification of FM Digital Power Increase.  We seek comment on the type of 
notification, if any, we should require of a digital FM station increasing digital power, and whom should 
be notified.  NPR states that it does not oppose the proposals in the Power Increase Petition as long as any 
adopted notification procedures also include a provision that the FM digital station increasing power 
notify the licensees of first-adjacent channel FM stations at least 30 days prior to implementation of the 
power increase, but in no event after the power increase has already taken place.70  The International 
Association of Audio Information Services (IAAIS), representing radio reading services that use analog 
FM station sub-carriers to provide audio versions of publications for print-disabled individuals, likewise 
requests that a host station increasing digital power to -10 dBc provide written notification to any radio 
reading services on that host station’s sub-carriers, as well as to all radio reading services broadcasting 
over any adjacent channel stations’ sub-carriers.71
22. Under the current system, stations increasing symmetric digital sideband power to levels 
up to -14 dBc need submit LMS Form 2100, Schedule 335-FM, FM Digital Notification (Schedule 335-
FM), without any further showings or analysis to be submitted to the staff for approval.  The digital FM 
station must electronically notify the Media Bureau of increased power FM digital operation within 10 
days of commencement of operations at increased power.72  Although these notifications are available to 
the public from the FCC’s database, the staff takes no action on the notifications, and they do not appear 
in the Commission’s public notices of broadcast applications or broadcast actions.  Symmetric digital 
operation at power levels between -14 dBc and -10 dBc currently require both notification on Schedule 
335-FM and a showing that the contours generated do not overlap with the protected contours of adjacent-
channel FM stations.  Such showings are confirmed by the staff.  Under our proposal herein, such 
showings would no longer be required for power increases up to -10 dBc—the station seeking a power 
increase would only have to provide notification by filing Schedule 335-FM, and the staff would neither 
grant nor deny such notification.  We tentatively conclude that this notification-only procedure should be 
sufficient for digital FM stations increasing digital sideband power the additional 4 dB we propose to 
allow in this NPRM, and seek comment on this conclusion.  We likewise tentatively conclude that 
Schedule 335-FM notification should be required for any digital FM station permanently reducing digital 
power, and further tentatively conclude that any such notification of digital FM power reduction be 
accompanied by a short statement of the reason(s) for the power reduction (e.g., interference complaints, 
inadequate signal coverage, etc.), and seek comment on this tentative conclusion.  
23. Although the filing of Schedule 335-FM does not generate a separate LMS Public Notice, 
all filed LMS forms are searchable, and are thus available to the public using the LMS “Search” 
function.73  We thus seek comment on whether this accessibility should provide adequate notice to other 
stations and interested parties that a first-adjacent channel FM digital station is increasing its digital 
power.  We seek comment on whether Schedule 335-FM filings in LMS will provide adequate notice or if 
we should adopt any other notification procedure.  Commenters holding differing views should explain 
why we should require additional specific notice, i.e., to first-adjacent stations or entities other than the 
Commission, than is currently required.  Should we require direct notice to all potentially affected first-
adjacent channel FM stations in addition to that provided by the notification filed in LMS?  Should 
potential direct notice to first-adjacent channel FM stations be given a certain period of time before the 
digital station is allowed to implement the digital power increase, such as the 30 days suggested by 
NPR?74  In the alternative, should the station increasing digital power be required not only to file 
Schedule 335-FM, but further be obliged to wait a certain period of time before implementing the power 
increase, so as to give interested parties an opportunity to comment and/or object?  We ask that 
70 NPR Comments at 1, 3-4.
71 Comments of IAAIS (IAAIS Comments) at 2-3.
72 2010 MB DAB Order, 25 FCC Rcd at 1189, para. 16.
73 https://enterpriseefiling.fcc.gov/dataentry/public/tv/publicSearchLanding.html.
74 NPR Comments at 3.Federal Communications Commission FCC 23-61
12commenters provide reasons for their positions regarding notice, and further to provide specifics as to 
both the type of notice that should be given and the key recipients of that notice.
24. IAAIS expresses concerns about digital FM sideband power and its effects on radio 
reading services.  Radio reading services, using primarily volunteer staff, provide valuable services by 
reading daily and weekly newspapers, magazines, current books, and other programs of interest to blind, 
visually impaired, physically disabled, and other print-disabled persons, who cannot easily access or 
consume written media.75  While these important services employ a variety of methods to deliver their 
content, the majority of IAAIS members broadcast over analog FM radio subcarriers.76  With regard to 
IAAIS’s concerns about the effect of increased digital FM sideband power on such subcarriers, even 
absent a general requirement of direct notice of digital power increase to potentially affected stations, 
should such radio reading services receive special notification from the station proposing to increase 
digital power, whether that is the station hosting the radio reading service or a nearby adjacent channel 
station?  If so, what form should that direct notice take?  If, after reviewing comments, we determine that 
a station increasing digital power must notify all first-adjacent channel stations of the increase, should we 
further require that any first-adjacent channel station receiving such notice notify any radio reading 
service(s) that it hosts?  
B. Asymmetric Sideband Petition
25. We propose to grant blanket authorization to digital FM stations to originate digital 
transmissions at different power levels on the upper and lower digital sidebands without having to request 
experimental authorization.  As with any digital FM power increase resulting from the proposed revised 
power table, discussed above, we propose that a digital FM station need only notify us of asymmetric 
sideband operation by filing notification (Schedule 335-FM) in the Bureau’s LMS database.
26.Asymmetric Sideband Operation / Interference Issues.  Currently, as discussed above, 
digital FM stations must use the same ERP on both the upper and lower digital sidebands.77  Thus, as 
pointed out by petitioners NAB, Xperi, and NPR, any digital FM station’s digital power was limited to 
that needed to protect the nearer of the adjacent channel analog FM stations, regardless of whether there 
was a need to limit power on the other sideband.78  Petitioners contend that allowing calculation of the 
maximum allowable digital FM ERP on a per-sideband basis allows such stations to optimize their digital 
signal coverage while still protecting analog FM stations on adjacent channels.79  For example, a digital 
FM station with an analog station only on the first adjacent channel above its frequency could selectively 
reduce power on the upper sideband to avoid causing interference, while maintaining or even increasing 
digital ERP on the lower sideband to enhance signal coverage without interfering with a nearby station.  
Alternatively, a digital FM station in the same situation could maintain its digital ERP on the upper 
sideband while increasing power on the lower sideband. The 2019 Asymmetric Sideband Petition 
proposed an adjustment to the current methodology for calculating maximum FM Digital ERP, that would 
75 IAAIS Comments at 1.
76 Id.  A subcarrier, known also as Subsidiary Communications Authority or SCA, is a separate audio or data 
channel that is transmitted along with the main audio signal over a broadcast station.  These subcarrier channels are 
not receivable with a regular radio; special receivers are required. 
77 See 2010 MB DAB Order, 25 FCC Rcd at 1190, para. 20 (setting forth methodology for calculating maximum 
permissible FM Digital ERP that assumes operation with symmetric sidebands).  A station wishing to operate with 
asymmetric sideband power must request experimental operation, including a showing that the digital sideband 
signal contours will not overlap adjacent stations’ protected contours.  The staff will grant requests that do not 
propose prohibited overlap.  
78 Asymmetric Sideband Petition at 9.
79 Id. at 8-9.Federal Communications Commission FCC 23-61
13subtract 3 dB, owing to the 3 dB difference between total digital power and per-sideband power.80  The 
2022 Power Increase Petition proposes a new formula to calculate maximum digital power per sideband, 
updated to comport with the Power Increase Petition proposal.81  The proposed new method for 
calculating per-sideband FM Digital ERP yields the following table:  
Proponent Analog F(50,10) Field Strength at First 
Adjacent Station’s Analog 60 dBµ F(50,50) 
Contour (Asymmetric Sideband Operation)Maximum Permissible FM 
Digital ERP
54.9 dBµ and above -14 dBc
53.5 dBµ to 54.8 dBµ -13 dBc
52.6 dBµ to 53.4 dBµ -12 dBc
51.1 dBµ to 52.5 dBµ -11 dBc
51.0 dBµ or less -10 dBc
When operating in symmetric mode, each digital sideband contributes exactly half of the total authorized 
digital power for that station.  For example, a station that is authorized to operate in symmetric mode with 
a total digital power of -10 dBc operates with half that power (-13 dBc) in each digital sideband.  When a 
station operates in asymmetric mode with one digital sideband having more power than the other, it is 
necessary to ensure that each sideband is limited to the appropriate contour-limited value from the table, 
and that the total digital power in both sidebands together does not exceed the total amount of digital 
power that would be authorized if the station were operating in symmetric mode.  Accordingly, the 
Effective Radiated Power at each sideband must be adjusted so that the total sideband powers do not 
exceed the total power that would be authorized for that station operating in symmetric sideband mode.
27. Those commenters that addressed the Asymmetric Sideband Petition uniformly supported 
it.82  Many of the supporters noted that eliminating the need to seek experimental authorization for 
asymmetric sideband operation would encourage more stations to adopt this operational mode.83  
28. Given the general lack of commenter objection and the record as presented by the 
petitioners and certain commenters, we propose to authorize asymmetric sideband operation for FM 
digital broadcasters operating at any power level, without the need first to seek experimental 
authorization.  As with any potential FM digital power increase, as discussed at paragraph 22, above, we 
propose that a digital FM station seeking to operate with asymmetric sidebands must notify the Bureau 
using Schedule 335-FM.  We reiterate that the filing of Schedule 335-FM with the Commission does not 
trigger the release of a separate Public Notice in LMS, but that, like all LMS forms, the filing is 
80 Id. at 6 (proposing the formula:  Allowable IBOC Power = [2.27 * (60 – IBOC station F(50,10) dBµ) – 36.6]).  
See also Power Increase Petition at 7 n.13.
81 The updated formula is:  Allowable IBOC power (dBc, per sideband) = 41 – [IBOC Station F(50,10) dBµ at the 
desired station 60 dBµ F(50,50) contour].  Power Increase Petition at 7.
82 See IHC Reply at 2-3; Walden Comments at 3; REC Comments at 4; Read Comments at 1; NYPR Comments at 
5; Nautel Comments at 1; Haider Comments at 1; CTI Comments at 3; CMG Comments at 2-4; Beasley Comments 
at 2-3.  See also NPR Comments at 2; Xperi Reply at 3.  It must be noted that Press, which filed its ex parte 
presentations after the commenting period expired, questions whether the proposals in the Asymmetric Sideband 
Petition, if adopted, would actually protect adjacent FM analog stations to the extent it believes is required.  See 
Press Second Ex Parte at 4.
83 See Beasley Comments at 3 (reporting experimental operation of its station WCSX(FM), Birmingham, Michigan, 
with asymmetric sidebands as having “uniformly positive” results, improving the stability and robustness of the 
digital signal while generating no interference reports); REC Comments at 4; Walden Comments at 3; IHC Reply at 
1-2; NYPR Comments at 5 (stating that its classical music station WQXR-FM, Newark, New Jersey, is limited on 
one sideband from increasing digital power, but is not so limited on the other sideband, thus the use of asymmetric 
sidebands would enable it greatly to improve its digital service).Federal Communications Commission FCC 23-61
14searchable and thus available to members of the public using the LMS “Search” function.84  We therefore 
seek comment on whether notification to the Commission should suffice to provide notice to other 
interested parties, including adjacent channel stations.  To the extent that commenters believe that more or 
different notice should be required, we ask that they specify the type of notice and the reasons why form 
availability in LMS is not sufficient.  We further tentatively conclude that Schedule 335-FM notification 
should be required for any digital FM station that permanently reverts to symmetric sideband operation 
from asymmetric sideband operation, and further tentatively conclude that any such notification of return 
to symmetric sideband operation be accompanied by a short statement of the reason(s) for this action.  We 
seek comment on this tentative conclusion.
29. Likewise, we believe that the interference mitigation and remediation procedures set forth 
in the 2010 MB DAB Order should be sufficient to remedy any reports of inter-station interference as a 
result of asymmetric sideband operation.  We observe that asymmetric sideband operation per se should 
not cause an increase in interference or complaints thereof, as stations employing such operation are 
already protecting the closer of the adjacent stations to their sideband frequencies, and the only power 
increases should be toward adjacent channel stations that are more distant, either physically or by 
frequency.  Again, to the extent that commenters believe that more stringent interference mitigation and 
remediation procedures are required, we ask that such commenters detail the measures they deem 
necessary as well as the precise reasons why the current procedures are inadequate.
C. Other Issues
30.Pending Proceedings.  If we authorize the proposals set forth in the Power Increase 
Petition and the Asymmetric Sideband Petition, we propose that experimental requests and applications 
for special temporary authorizations that have not been the subject of any staff decision as of the effective 
date of any rules adopted in any subsequent Report and Order in this proceeding will be decided based on 
the new rules.85  We further propose that experimental requests and applications for special temporary 
authorizations that have been the subject of a staff decision, even if the subject of a pending petition for 
reconsideration or application for review, will be decided based on the rules in effect at the time staff 
issued its decision.  We further propose that any licensees operating facilities under experimental or 
special temporary authorizations, that are compliant with any rules adopted in this proceeding, need only 
file notification on Schedule 335-FM within 30 days of the effective date of any rules adopted in a 
subsequent Report and Order in this proceeding. We seek comment generally on these issues.
31.Digital Equity and Inclusion.  Finally, the Commission, as part of its continuing effort to 
advance digital equity for all,86 including people of color, persons with disabilities, persons who live in 
rural or Tribal areas, and others who are or have been historically underserved, marginalized, or adversely 
affected by persistent poverty or inequality, invites comment on any equity-related considerations87 and 
84 https://enterpriseefiling.fcc.gov/dataentry/public/tv/publicSearchLanding.html.
85 See Amendment of Part 74 of the Commission’s Rules Regarding FM Translator Interference, Report and Order, 
34 FCC Rcd 3457, 3482, para. 49 (2019), citing Melcher v. FCC, 134 F.3d 1143, 1165 (D.C. Cir. 1998); Chadmoore 
Commc'ns, Inc. v. FCC, 113 F.3d 235, 241 (D.C. Cir.1997); Hispanic Inf. & Telecomm. Network, Inc. v. FCC, 865 
F.2d 1289, 1294-95 (D.C.Cir.1989) (“The filing of an application creates no vested right to a hearing; if the 
substantive standards change so that the applicant is no longer qualified, the application may be dismissed.”).
86 Section 1 of the Communications Act of 1934 as amended provides that the FCC “regulat[es] interstate and 
foreign commerce in communication by wire and radio so as to make [such service] available, so far as possible, to 
all the people of the United States, without discrimination on the basis of race, color, religion, national origin, or 
sex.”  47 U.S.C. § 151.
87 The term “equity” is used here consistent with Executive Order 13985 as the consistent and systematic fair, just, 
and impartial treatment of all individuals, including individuals who belong to underserved communities that have 
been denied such treatment, such as Black, Latino, and Indigenous and Native American persons, Asian Americans 
and Pacific Islanders and other persons of color; members of religious minorities; lesbian, gay, bisexual, 
transgender, and queer (LGBTQ+) persons; persons with disabilities; persons who live in rural areas; and persons 
(continued….)Federal Communications Commission FCC 23-61
15benefits (if any) that may be associated with the proposals and issues discussed herein.  Specifically, we 
seek comment on how our proposals may promote or inhibit advances in diversity, equity, inclusion, and 
accessibility, as well the scope of the Commission’s relevant legal authority.
IV. PROCEDURAL MATTERS
32.Regulatory Flexibility Act.  The Regulatory Flexibility Act of 1980, as amended (RFA),88 
requires that an agency prepare a regulatory flexibility analysis for notice and comment rulemakings, 
unless the agency certifies that “the rule will not, if promulgated, have a significant economic impact on a 
substantial number of small entities.”89  Accordingly, we have prepared an Initial Regulatory Flexibility 
Analysis (IRFA) concerning the possible impact of potential rule and/or policy changes contained in this 
NPRM on small entities.  The IRFA is set forth in Appendix B.  Written public comments are requested 
on the IRFA.  Comments must be filed by the deadlines for comments on the NPRM indicated on the first 
page of this document and must have a separate and distinct heading designating them as responses to the 
IRFA.
33.Paperwork Reduction Act.  This document contains new or modified information 
collection requirements.  The Commission, as part of its continuing effort to reduce paperwork burdens 
and pursuant to the Paperwork Reduction Act of 1995, Public Law 104-13, invites the general public and 
the Office of Management and Budget (OMB) to comment on the information collection requirements 
contained in this document, as required by the Paperwork Reduction Act of 1995, Public Law 104-13.  In 
addition, pursuant to the Small Business Paperwork Relief Act of 2002, Public Law 107-198, see 44 
U.S.C. § 3506(c)(4), we seek specific comment on how we might further reduce the information 
collection burden for small business concerns with fewer than 25 employees.
34.Ex Parte Rules - Permit-But-Disclose.  This proceeding shall be treated as a “permit-but-
disclose” proceeding in accordance with the Commission’s ex parte rules.90  Persons making ex parte 
presentations must file a copy of any written presentation or a memorandum summarizing any oral 
presentation within two business days after the presentation (unless a different deadline applicable to the 
Sunshine period applies).  Persons making oral ex parte presentations are reminded that memoranda 
summarizing the presentation must (1) list all persons attending or otherwise participating in the meeting 
at which the ex parte presentation was made, and (2) summarize all data presented and arguments made 
during the presentation.  If the presentation consisted in whole or in part of the presentation of data or 
arguments already reflected in the presenter’s written comments, memoranda, or other filings in the 
proceeding, the presenter may provide citations to such data or arguments in his or her prior comments, 
memoranda, or other filings (specifying the relevant page and/or paragraph numbers where such data or 
arguments can be found) in lieu of summarizing them in the memorandum.  Documents shown or given 
to Commission staff during ex parte meetings are deemed to be written ex parte presentations and must 
be filed consistent with rule 1.1206(b).  In proceedings governed by rule 1.49(f) or for which the 
Commission has made available a method of electronic filing, written ex parte presentations and 
memoranda summarizing oral ex parte presentations, and all attachments thereto, must be filed through 
the electronic comment filing system available for that proceeding, and must be filed in their native 
format (e.g., .doc, .xml, .ppt, searchable .pdf).  Participants in this proceeding should familiarize 
themselves with the Commission’s ex parte rules.
otherwise adversely affected by persistent poverty or inequality.  See Exec. Order No. 13985, 86 Fed. Reg. 7009, 
Executive Order on Advancing Racial Equity and Support for Underserved Communities Through the Federal 
Government (January 20, 2021).
88 5 U.S.C. §§ 601-612.  The RFA has been amended by the Small Business Regulatory Enforcement Fairness Act 
of 1996 (SBREFA), Publ. L. No. 104-121, Title II, 110 Stat. 857 (1996).
89 5 U.S.C. § 605(b).
90 47 CFR §§ 1.1200 et seq.Federal Communications Commission FCC 23-61
1635.Filing Requirements—Comments and Replies.  Pursuant to sections 1.415 and 1.419 of 
the Commission’s rules, 47 CFR §§ 1.415, 1.419, interested parties may file comments and reply 
comments on or before the dates indicated on the first page of this document.  Comments may be filed 
using the Commission’s Electronic Comment Filing System (ECFS).  See Electronic Filing of Documents 
in Rulemaking Proceedings, 63 FR 24121 (1998).
•Electronic Filers:  Comments may be filed electronically using the Internet by accessing the 
ECFS:  http://apps.fcc.gov/ecfs/.  
•Paper Filers:  Parties who choose to file by paper must file an original and one copy of each 
filing. 
•Filings can be sent by commercial overnight courier, or by first-class or overnight U.S. Postal 
Service mail.  All filings must be addressed to the Commission’s Secretary, Office of the 
Secretary, Federal Communications Commission.
oCommercial overnight mail (other than U.S. Postal Service Express Mail and Priority 
Mail) must be sent to 9050 Junction Drive, Annapolis Junction, MD  20701. 
oU.S. Postal Service first-class, Express, and Priority mail must be addressed to 45 L 
Street, NE, Washington DC  20554
•Effective March 19, 2020, and until further notice, the Commission no longer accepts any 
hand or messenger delivered filings.  This is a temporary measure taken to help protect the 
health and safety of individuals, and to mitigate the transmission of COVID-19.91  
•During the time the Commission’s building is closed to the general public and until further 
notice, if more than one docket or rulemaking number appears in the caption of a proceeding, 
paper filers need not submit two additional copies for each additional docket or rulemaking 
number; an original and one copy are sufficient.
36.People with Disabilities.  To request materials in accessible formats for people with 
disabilities (braille, large print, electronic files, audio format), send an e-mail to fcc504@fcc.gov or call 
the Consumer & Governmental Affairs Bureau at 202-418-0530 (voice), 202-418-0432 (tty).
37.Availability of Documents.  Comments, reply comments, and ex parte submissions will 
be available for public inspection during regular business hours in the FCC Reference Center, Federal 
Communications Commission, 45 L Street, NE, Washington, DC 20554.  These documents will also be 
available via ECFS.  Documents will be available electronically in ASCII, Microsoft Word, and/or Adobe 
Acrobat. 
38.Additional Information.  For additional information on this proceeding, contact Thomas 
Nessinger, Thomas.Nessinger@fcc.gov, of the Media Bureau, Audio Division, at (202) 418-2709, or 
James Bradshaw, James.Bradshaw@fcc.gov of the Media Bureau, Audio Division, at (202) 418-2739.
V. ORDERING CLAUSES
39. Accordingly, IT IS ORDERED, pursuant to section 1.407 of the Commission’s rules, 47 
CFR § 1.407, that the Petition for Rulemaking of the National Association of Broadcasters, Xperi 
Corporation, and National Public Radio filed on Dec. 9, 2019 and the Petition for Rulemaking of the 
National Association of Broadcasters and Xperi Corporation filed on Oct. 26, 2022 ARE GRANTED.
40.IT IS FURTHER 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 Communications Act of 1934, as 
91 See FCC Announces Closure of FCC Headquarters Open Window and Change in Hand-Delivery Policy, Public 
Notice, 35 FCC Rcd 2788 (2020).Federal Communications Commission FCC 23-61
17amended, 47 U.S.C. §§ 151, 154(i), 154(j), 301, 302a, 303, 307, 308, 309, 316, 319, and 324 this Notice 
of Proposed Rulemaking IS ADOPTED. 
41.IT IS FURTHER ORDERED that the Commission’s Office of the Secretary, Reference 
Information Center, SHALL SEND a copy of this Notice of Proposed Rulemaking, including the Initial 
Regulatory Flexibility Analysis, to the Chief Counsel for Advocacy of the Small Business 
Administration.
FEDERAL COMMUNICATIONS COMMISSION
Marlene H. Dortch
SecretaryFederal Communications Commission FCC 23-61
APPENDIX A
Proposed Rule Changes
For the reasons discussed in this preamble, the Federal Communications Commission proposes to 
amend 47 CFR part 73 to read as follows:
PART 73 – RADIO BROADCAST SERVICES
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.
2. In § 73.310 revise paragraphs (a) and (b) to read as follows:
§ 73.310 FM technical definitions.
(a) Frequency modulation.  The following definitions pertain to frequency modulation, as defined 
in § 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° 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 § 
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 § 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. Federal Communications Commission FCC 23-61
19(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 dBµ (562 mV/m) or 
greater signal strength in the area adjacent to the antenna of the transmitting station. The 115 dBµ 
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 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. Federal Communications Commission FCC 23-61
20(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 ±75kHz is defined as 100% modulation. 
(21) Previously authorized superpowered FM station.  An FM station authorized to operate with 
facilities that exceed the Effective Radiated Power/Height Above Average Terrain limitations of 
§§ 73.211 or 73.511 for their specific class.
(b) Stereophonic sound broadcasting. The following definitions pertain to stereophonic sound 
broadcasting, as defined in § 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.
* * * * *Federal Communications Commission FCC 23-61
213. In § 73.402 add paragraph (i) to read as follows:
§ 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.
4. In § 73.404 add paragraphs (e), (f), and (g) to read as follows:
§73.404 IBOC DAB operation.
* * * * *
(e) All FM stations transmitting hybrid IBOC signals may operate with total 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 using symmetric sidebands planning to operate with a total 
radiated power in excess of -14 dBc must confirm compliance with Table 1 below by calculating 
the signal strength of its analog signal at the first adjacent station’s 60 dBµ contour.  All 
calculations must be made using the standard FCC contour prediction methodology.
Table 1 to Paragraph (e) – Maximum Permissible FM Digital ERP for Symmetric Sideband 
Operation
Proponent Analog F(50,10) Field Strength at First 
Adjacent Station’s Analog 60 dBµ F(50,50) 
Contour (Symmetric Sideband Operation)Maximum Permissible FM 
Digital ERP
57.9 dBµ and above -14 dBc
56.5 dBµ to 57.8 dBµ -13 dBc
55.6 dBµ to 56.4 dBµ -12 dBc
54.1 dBµ to 55.5 dBµ -11 dBc
54.0 dBµ or less -10 dBc
(f) FM stations may transmit hybrid IBOC signals with asymmetric power on the digital 
sidebands, as defined in § 73.402(i).  Where asymmetric operation is used, the Effective Radiated 
Power at each sideband must be adjusted so that the total sideband powers do not exceed the total 
power that would be authorized for the station operating in symmetric sideband mode.  A station 
using asymmetric sidebands planning to operate with a radiated power in excess of -17 dBc on 
either sideband (upper or lower) must confirm compliance with Table 1 below by calculating the 
signal strength of its analog signal at the respective (upper or lower) first adjacent station’s 60 
dBµ contour.  All calculations must be made using the standard FCC contour prediction 
methodology.
Table 1 to Paragraph (f) – Maximum Permissible FM Digital ERP for Asymmetric 
Sideband OperationFederal Communications Commission FCC 23-61
22Proponent Analog F(50,10) Field Strength at the 
Upper or Lower First Adjacent Station’s Analog 
60 dBµ F(50,50) Contour (Asymmetric Sideband 
Operation)Maximum Permissible FM 
Digital ERP for the 
Respective (Upper or 
Lower) Sideband
54.9 dBµ and above -17 dBc
53.5 dBµ to 54.8 dBµ -16 dBc
52.6 dBµ to 53.4 dBµ -15 dBc
51.1 dBµ to 52.5 dBµ -14 dBc
51.0 dBµ or less -13 dBc
(g) The digital effective radiated power of a previously authorized superpowered FM station, as 
defined in § 73.310(a)(7) and (21), must be limited to the class maximum set forth in §§ 73.211 
and 73.511.
5. In § 73.406 add paragraphs (d)(5), (d)(6), (d)(7), and (d)(8), to read as follows:
§73.406 Notification.
* * * * *
(d) * * *
(5) If applicable, for FM stations planning to operate with symmetric sidebands in excess of -14 
dBc, a certification that the proposed FM digital Effective Radiated Power is permitted, using the 
table set forth in Table 1 to § 73.404(e).  Certifications must be based on the most restrictive 
analog field strength of the proponent at any nearby first-adjacent channel station’s 60 dBµ 
contour.  
(6) If applicable, for FM stations employing asymmetric sideband operation as defined in § 
73.402(i), 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 § 73.404(f), and that the total 
digital sideband power will not exceed the total power if the digital sideband operation were 
symmetric.
(7) Any digital FM station permanently reducing digital power must notify the Commission of 
such digital power reduction on Form 2100, Schedule 335-FM.  Any such notification of digital 
FM power reduction must include a short statement of the reason(s) for the power reduction.
(8) Any digital FM station permanently discontinuing asymmetric sideband operation and 
returning to symmetric sideband operation must notify the Commission of such return to 
symmetric sideband operation on Form 2100, Schedule 335-FM.  Any such notification of 
discontinuing asymmetric sideband operation must include a short statement of the reason(s) for 
such action.Federal Communications Commission FCC 23-61
APPENDIX B
Initial Regulatory Flexibility Analysis
1. As required by the Regulatory Flexibility Act of 1980, as amended (RFA),1 the Federal 
Communications Commission (Commission) has prepared this Initial Regulatory Flexibility Analysis 
(IRFA) concerning the possible significant economic impact on a substantial number of small entities by 
the policies and rules proposed in the Notice of Proposed Rulemaking (NPRM).  Written public comments 
are requested on this IRFA.  Comments must be identified as responses to this IRFA and must be filed by 
the deadlines for comments provided on the first page of the NPRM.  The Commission will send a copy 
of the NPRM, including this IRFA, to the Chief Counsel for Advocacy of the Small Business 
Administration (SBA).2  In addition, the NPRM and IRFA (or summaries thereof) will be published in the 
Federal Register.3
A. Need for, and Objectives of, the Proposed Rules
2. In the NPRM, the Commission proposes to revise its methodology for determining 
whether a digital FM station may increase the effective radiated power (ERP) on its digital sidebands; to 
allow a digital FM station to implement or increase digital ERP from 14 dB below the analog carrier ERP 
(expressed as -14 dBc) to -10 dBc, without the need to do more than notify the Commission of such 
operation by FCC form; and to allow a digital FM station to operate with different power levels on its 
upper and lower digital sidebands, without first having to seek experimental authorization for such 
operation.  The Commission initiated the NPRM in response to two Petitions for Rulemaking that were 
consolidated by the Media Bureau (Bureau) because the proposed rule changes both relate to improving 
digital FM signal quality and minimizing the effect of the digital FM station signal on adjacent channel 
FM transmissions.  In the earlier of the two petitions, filed December 9, 2019, petitioners National 
Association of Broadcasters (NAB), Xperi Corporation (Xperi), and National Public Radio (NPR) request 
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.4  In the second petition, filed October 26, 2022, NAB and Xperi request 
that the FCC adopt an updated methodology to determine digital FM power levels for stations seeking to 
exceed the currently authorized FM digital effective radiated power (ERP) of -14 dBc.5  The Commission 
seeks comment on whether the rule changes proposed, based on the Asymmetric Sideband Petition and 
Power Increase Petition, would serve the public interest by providing digital FM stations with the ability 
to increase power and, concomitantly, increase coverage area, building penetration, and provide a more 
robust digital signal.  Petitioners, and most commenters on the petitions, maintain that the current method 
for determining digital FM power overprotects analog FM stations on adjacent frequencies from digital 
interference, and that higher digital FM power levels would enable digital FM stations to more closely 
replicate their analog FM coverage with digital coverage.  With regard to the Asymmetric Sideband 
Petition, petitioners contend 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 
1 See 5 U.S.C. § 603.  The RFA, see 5 U.S.C. §§ 601-612, has been amended by the Small Business Regulatory 
Enforcement Fairness Act of 1996 (SBREFA), Pub. L. No. 104-121, Title II, 110 Stat. 857 (1996).
2 5 U.S.C. § 603(a).
3 Id.
4 Petition for Rulemaking of Nat’l Ass’n of Broad., Xperi Corp., and Nat’l Public Radio, MB Docket No. 22-405 
(filed Dec. 9, 2019), https://www.fcc.gov/ecfs/document/1125972022299/1 (Asymmetric Sideband Petition).
5 Petition for Rulemaking of Nat’l Ass’n of Broad. and Xperi Corp., MB Docket No. 22-405 (filed Oct. 26, 2022), 
https://www.fcc.gov/ecfs/document/10261669202264/1 (Power Increase Petition).Federal Communications Commission FCC 23-61
24analog FM stations on adjacent channels.6  For example, a digital FM station with an analog station only 
on the first adjacent channel above its frequency could selectively reduce power on the upper sideband to 
avoid causing interference, while maintaining or even increasing digital power on the lower sideband to 
enhance signal coverage without interfering with a nearby station.  Alternatively, a digital FM station in 
the same situation could maintain its digital power on the upper sideband while increasing power on the 
lower sideband.
3. The Commission seeks comment on the following issues relating to digital FM station 
operations: (1) to change the methodology used by digital FM stations to determine whether they are 
eligible to increase digital FM ERP up to -10 dBc, or 10% of analog power, upon basic notification to the 
Commission and without the need for additional individual special authorization; (2) to allow a power 
increase up to -10 dBc by notifying the Commission in the Bureau’s Licensing and Management System 
(LMS), utilizing the same notification procedures as currently used; (3) whether changing the method for 
calculating whether a digital FM station can increase its digital power will create an unacceptable risk of 
interference to adjacent-channel stations; (4) whether to continue to limit the power level for previously 
authorized superpowered FM stations to their class maximum; (5) the type of notification, if any, we 
should require of a digital FM station increasing digital power, and whom should be notified; (6) whether 
the interference mitigation and remediation procedures currently used for inter-station digital FM 
interference should be sufficient to remedy any reports of interference to FM broadcast stations or other 
spectrum users as a result of a station’s increase in its digital power; (7) whether to grant blanket 
authorization to digital FM stations to originate digital transmissions at different power levels on the 
upper and lower digital sidebands without having to request experimental authorization; and (8) whether 
the interference mitigation and remediation procedures currently used for inter-station digital FM 
interference should be sufficient to remedy any reports of inter-station interference as a result of 
asymmetric sideband operation. 
B. Legal Basis
4. The proposed action is authorized pursuant to sections 1, 4(i), 4(j), 301, 302a, 303, 307, 
308, 309, 316, 319, and 324 of the 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. 
C. Description and Estimate of the Number of Small Entities To Which the Proposed 
Rules Will Apply
5. The RFA directs agencies to provide a description of, and where feasible, an estimate of 
the number of small entities that may be affected by the proposed rules, if adopted.7  The RFA generally 
defines the term “small entity” as having the same meaning as the terms “small business,” “small 
organization,” and “small governmental jurisdiction.”8  In addition, the term “small business” has the 
same meaning as the term “small business concern” under the Small Business Act.9  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.10  
6 Id. at 8-9.
7 5 U.S.C. § 603(b)(3).
8 Id. § 601(6).
9 Id. § 601(3) (incorporating by reference the definition of “small-business concern” in 15 U.S.C. § 632).  Pursuant 
to 5 U.S.C. § 601(3), the statutory definition of a small business applies “unless an agency, after consultation with 
the Office of Advocacy of the Small Business Administration and after opportunity for public comment, establishes 
one or more definitions of such term which are appropriate to the activities of the agency and publishes such 
definition(s) in the Federal Register.”  Id. § 601(3).
10 15 U.S.C. § 632.Federal Communications Commission FCC 23-61
256.Radio Stations.  This industry is comprised of “establishments primarily engaged in 
broadcasting aural programs by radio to the public.”11  Programming may originate in their own studio, 
from an affiliated network, or from external sources.12  The SBA small business size standard for this 
industry classifies firms having $41.5 million or less in annual receipts as small.13  U.S. Census Bureau 
data for 2017 show that 2,963 firms operated in this industry during that year.14  Of this number, 1,879 
firms operated with revenue of less than $25 million per year.15  Based on this data and the SBA’s small 
business size standard, we estimate a majority of such entities are small entities.  
7. The Commission estimates that as of March 31, 2023, there were 4,472 licensed 
commercial AM radio stations and 6,681 licensed commercial FM radio stations, for a combined total of 
11,153 commercial radio stations.16  Of this total, 11,151 stations (or 99.98 %) had revenues of $41.5 
million or less in 2022, according to Commission staff review of the BIA Kelsey Inc. Media Access Pro 
Database (BIA) on April 7, 2023, and therefore these licensees qualify as small entities under the SBA 
definition.  In addition, the Commission estimates that as of March 31, 2023, there were 4,219 licensed 
noncommercial (NCE) FM radio stations, 1,999 low power FM (LPFM) stations, and 8,939 FM 
translators and boosters.17  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, we 
presume that all of these entities qualify as small entities under the above SBA small business size 
standard. 
8. We note, however, that in assessing whether a business concern qualifies as “small” 
under the above definition, business (control) affiliations18 must be included.  Our estimate, therefore, 
likely overstates the number of small entities that might be affected by our 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.  We are 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 
11 See U.S. Census Bureau, 2017 NAICS Definition, “515112 Radio Stations,” 
https://www.census.gov/naics/?input=515112&year=2017&details=515112.  
12 Id.
13 13 CFR § 121.201, NAICS Code 515112 (as of 10/1/22 NAICS Code 516110).
14 U.S. Census Bureau, 2017 Economic Census of the United States, Selected Sectors: Sales, Value of Shipments, or 
Revenue Size of Firms for the U.S.: 2017, Table ID: EC1700SIZEREVFIRM, NAICS Code 515112,
https://data.census.gov/cedsci/table?y=2017&n=515112&tid=ECNSIZE2017.EC1700SIZEREVFIRM&hidePrevie
w=false.  We note that the US Census Bureau withheld publication of the number of firms that operated for the 
entire year. 
15 Id.  The available U.S. Census Bureau data does not provide a more precise estimate of the number of firms that 
meet the SBA size standard.  We note that the U.S. Census Bureau withheld publication of the number of firms that 
operated with sales/value of shipments/revenue in the individual categories for less than $100,000, and $100,000 to 
$249,999 to avoid disclosing data for individual companies (see Cell Notes for the sales/value of shipments/revenue 
in these categories).  Therefore, the number of firms with revenue that meet the SBA size standard would be higher 
than noted herein.  We also note that according to the U.S. Census Bureau glossary, the terms receipts and revenues 
are used interchangeably, see https://www.census.gov/glossary/#term_ReceiptsRevenueServices.
16 See Broadcast Station Totals as of March 31, 2023, Public Notice, DA 23-300 (MB rel. Apr. 6, 2023) (March 
2023 Broadcast Station Totals PN).
17 See March 2023 Broadcast Station Totals PN.
18 “[Business concerns] are affiliates of each other when one concern controls or has the power to control the other 
or a third party or parties controls or has the power to control both.” 13 CFR § 21.103(a)(1).Federal Communications Commission FCC 23-61
26estimate 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.
9.Low Power FM Stations.  The SBA small business size standard for Radio Stations19 
applies to low power FM stations.  The Radio Stations industry comprises establishments primarily 
engaged in broadcasting aural programs by radio to the public.20  Programming may originate in their own 
studio, from an affiliated network, or from external sources.21  The SBA small business size standard for 
this industry classifies firms having $41.5 million or less in annual receipts as small.22  U.S. Census 
Bureau data for 2017 show that 2,963 firms in this industry operated during that year.23  Of this number, 
1,879 firms operated with revenue of less than $25 million per year.24  Therefore, based on the SBA’s size 
standard we conclude that the majority of low power FM stations are small.  
10. Additionally, according to Commission data as of March 31, 2023, there were 1,999 Low 
Power FM licensed broadcast stations and 8,939 FM Translator Stations.25  The Commission does not 
compile and otherwise does not have access to financial information for these stations that would permit it 
to determine how many of the stations would qualify as small entities under the SBA size standard.  
However, given that low power FM stations and FM translators and boosters are very small and limited in 
their operations and unlikely to have annual receipts anywhere near the SBA small size standard, we will 
presume that these licensees qualify as small entities under the SBA size standard.
D. Description of Projected Reporting, Recordkeeping, and Other Compliance 
Requirements for Small Entities
11. In this section, we identify the reporting, recordkeeping, and other compliance 
requirements proposed in the NPRM and consider whether small entities are affected disproportionately 
by any such requirements.  As discussed above, the NPRM seeks comment on changes to the 
Commission’s rules governing digital FM broadcast stations.  Allowing some broadcasters that are small 
entities to increase digital FM power, or to operate with asymmetric sideband power, as proposed in the 
NPRM would be a voluntary process.  Each FM station that meets the proposed requirements can make an 
19 See U.S. Census Bureau, 2017 NAICS Definition, “515112 Radio Stations,” 
https://www.census.gov/naics/?input=515112&year=2017&details=515112. 
20 Id.
21 Id.
22 13 CFR § 121.201, NAICS Code 515112 (as of 10/1/22 NAICS Code 516110).  
23 U.S. Census Bureau, 2017 Economic Census of the United States, Selected Sectors: Sales, Value of Shipments, or 
Revenue Size of Firms for the U.S.: 2017, Table ID: EC1700SIZEREVFIRM, NAICS Code 515112, 
https://data.census.gov/cedsci/table?y=2017&n=515112&tid=ECNSIZE2017.EC1700SIZEREVFIRM&hidePrevie
w=false.  We note that the US Census Bureau withheld publication of the number of firms that operated for the 
entire year. 
24 Id.  The available U.S. Census Bureau data does not provide a more precise estimate of the number of firms that 
meet the SBA size standard.  We note that the U.S. Census Bureau withheld publication of the number of firms that 
operated with sales/value of shipments/revenue in the individual categories for less than $100,000, and $100,000 to 
$249,999 to avoid disclosing data for individual companies (see Cell Notes for the sales/value of shipments/revenue 
in these categories).  Therefore, the number of firms with revenue that meet the SBA size standard would be higher 
that noted herein.  We also note that according to the U.S. Census Bureau glossary, the terms receipts and revenues 
are used interchangeably, see https://www.census.gov/glossary/#term_ReceiptsRevenueServices.
25 See March 2023 Broadcast Station Totals PN.    Federal Communications Commission FCC 23-61
27individual decision about whether operating with higher digital power and/or asymmetric sideband power 
is a feasible technical and economic upgrade option.  The Commission does not propose to compel, but 
rather merely to authorize, the proposed digital power increases and operations.  The NPRM proposes 
new mandatory reporting, recordkeeping, and compliance requirements for small entities that are FM 
licensees and choose to increase their power and/or adopt asymmetric sideband operation.  We note that 
the adoption of the proposed rules may require modification of current requirements and processes for 
small entities that choose to implement these operational changes, and may require modification of FCC 
forms, including but not limited to, FCC Form 2100, Schedule 335-FM, which is the form currently used 
to notify the Commission of the initiation of digital operations.  The NPRM thus may impose additional 
obligations or expenditure of resources on small businesses that elect to modify their digital service, and 
may require small entities to hire professionals to comply with the proposed rules.
12. The NPRM seeks comment on the notification and interference mitigation and 
remediation obligations of digital FM stations, including small entities.  For example, our proposal to 
amend our rules to modify the methodology a digital FM station must use to determine whether it is 
eligible to increase its power above -14 dBc, if adopted, would reduce compliance obligations for small 
entities by allowing them to increase power up to -10 dBc without submitting a contour analysis.  Small 
entity stations that seek to increase digital sideband power by the addition of 4 dB would need to notify 
the Commission by filing Schedule 335-FM.  At this time the Commission cannot quantify the cost of 
compliance for small entities that choose to modify their operations pursuant to the NPRM proposals.  
However, we expect the information we receive in comments to help the Commission identify and 
evaluate relevant compliance matters for small entities, including compliance costs and other burdens that 
may result from potential changes discussed in the NPRM.
E. Steps Taken to Minimize Significant Economic Impact on Small Entities and 
Significant Alternatives Considered
13. The RFA requires an agency to describe any significant, specifically small business, 
alternatives that it has considered in reaching its proposed approach, which may include the following 
four alternatives (among others):  “(1) the establishment of differing compliance or reporting 
requirements or timetables that take into account the resources available to small entities; (2) the 
clarification, consolidation, or simplification of compliance and reporting requirements under the rule for 
such small entities; (3) the use of performance, rather than design standards; and (4) an exemption from 
coverage of the rule, or any part thereof, for such small entities.”26
14. The NPRM considers a voluntary process by which some FM stations may operate at 
increased digital power and/or with differing power levels on each digital sideband.  According to 
commenters, the proposal would benefit digital FM broadcasters and listeners alike by promoting greater 
adoption of FM digital transmission systems.  Commenters also assert that adoption of the NPRM 
proposals would increase the robustness of the digital FM broadcast service by improving stations’ signal 
quality, including building penetration and allowing a digital FM licensee to expand its digital service 
area to approximate more closely its analog service area.  Other commenters caution that the proposed 
change may harm small entities by causing surrounding interference for smaller stations such as Class A 
FM stations, LPFM stations, and stations broadcasting over FM translators.
15. In the NPRM, the Commission considers specific steps it could take and alternatives to 
the proposed rules that could minimize potential economic impact on small entities that might be affected 
by the proposed rule change, as well as any other rule changes that may be required.  For example, to 
avoid increasing burdens on digital FM broadcasters, the Commission proposes that any notification of 
increases in digital FM ERP and/or initiation of asymmetric sideband operation be made by filing FCC 
Form 2100, Schedule 335-FM, in the searchable LMS database.  This is the same form currently used to 
notify the Commission of the initiation of digital operations.  Under the proposed rule changes fewer 
26 5 U.S.C. § 603(c)(1)-(c)(4).Federal Communications Commission FCC 23-61
28stations would be required to submit a contour study with Schedule 335-FM, as is currently the case for 
digital FM stations proposing digital power levels above -14 dBc.  Therefore, the administrative impact of 
the proposed rule changes will be similar to that of existing digital FM service, will be less burdensome 
for most digital FM broadcasters, and thus is not likely to have an additional adverse economic impact on 
small entities.
16. The Commission also considers alternatives to its current interference remediation 
procedures, including whether station complaints should be assessed based on listener complaints or 
based on studies and/or measurements demonstrating that a digital FM signal within the complaining 
station’s protected contour exceeds allowable limits.  Another alternative considered in relation to 
interference that may impact small entities is whether protection of incumbent analog FM stations on 
adjacent channels should be increased beyond the 60 dBµ contour.  We tentatively conclude that this 
protection is not necessary, however, we also consider whether this protection should be increased and, if 
so, to what contour.  The Commission expects to more fully consider the economic impact and 
alternatives for small entities following the review of comments filed in response to the NPRM.
F. Federal Rules that May Duplicate, Overlap, or Conflict With the Proposed Rules
17. None.