[Federal Register Volume 83, Number 224 (Tuesday, November 20, 2018)]
[Proposed Rules]
[Pages 58513-58522]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-25101]


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FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 73

[MB Docket No. 13-249; FCC 18-139]


Revitalization of the AM Radio Service

AGENCY: Federal Communications Commission.

ACTION: Proposed rule.

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SUMMARY: In this document, the Commission adopted a Second Further 
Notice of Proposed Rulemaking (Second FNPRM), in which it sought 
comment on alternative revised proposals to change the interference 
protection given to Class A AM radio broadcast stations. These 
proposals were revised based on responses to the Further Notice of 
Proposed Rule Making in this proceeding.

DATES: Comments may be filed on or before January 22, 2019 and reply 
comments may be filed on or before February 19, 2019.

ADDRESSES: You may submit comments, identified by MB Docket No. 13-249, 
by any of the following methods:
     Federal Communications Commission's Website: http://apps.fcc.gov/ecfs//. Follow the instructions for submitting comments.
     People with Disabilities: Contact the FCC to request 
reasonable accommodations (accessible format documents, sign language 
interpreters, CART, etc.) by email: [email protected] or phone: 202-418-
0530 or TTY: 888-835-5322.
    For detailed instructions for submitting comments and additional 
information on the rulemaking process, see the SUPPLEMENTARY 
INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Albert Shuldiner, Chief, Media Bureau, 
Audio Division, (202) 418-2700; Thomas Nessinger, Senior Counsel, Media 
Bureau, Audio Division, (202) 418-2700. For additional information 
concerning the Paperwork Reduction Act (PRA) information collection 
requirements contained in this document, contact Cathy Williams at 202-
418-2918, or via the internet at [email protected].

SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Second 
Further Notice of Proposed Rulemaking (Second FNPRM), MB Docket No. 13-
249; FCC 18-139, adopted and released on October 5, 2018. The full text 
of this document will be available for public inspection and copying 
via ECFS, and during regular business hours at the FCC Reference 
Information Center, Portals II, 445 12th Street SW, Room CY-A257, 
Washington, DC 20554. The full text of this document can also be 
downloaded in Word or Portable Document Format (PDF) at http://www.fcc.gov/ndbedp.

Synopsis

    1. The 73 Class A AM stations in the United States are authorized 
to broadcast at up to 50 kW both day and night and, by current rule, 
are designed to render primary and secondary service over extended 
areas and are afforded extensive daytime and nighttime protection from 
interference by co- and adjacent-channel AM stations. Currently, Class 
A AM stations in the continental United States are protected during the 
day to their 0.1 mV/m groundwave contour from co-channel stations, and 
to their 0.5 mV/m groundwave contour from adjacent-channel stations. At 
night, such Class A stations are protected to their 0.5 mV/m-50 percent 
skywave contour from co-channel stations and to their 0.5 mV/m 
groundwave contour from adjacent-channel stations.
    2. In the Further Notice of Proposed Rulemaking (AMR FNPRM), FCC 
15-142, 30 FCC Rcd 12145, 81 FR 2818, Jan. 19, 2016, in this AM 
Revitalization proceeding, the Commission recognized that many of the 
areas previously receiving only Class A secondary service are now 
served by FM stations and smaller, more local AM stations. 30 FCC Rcd 
at 12168, 12170, paras. 51, 55. In the latter case, local AM service is 
often curtailed by the need for a local AM station to protect a 
(sometimes distant) Class A station's service. The Commission therefore 
tentatively concluded in the AMR FNPRM (1) that all Class A stations 
should be protected, both day and night, to their 0.1 mV/m groundwave 
contour, from co-channel stations, thus maintaining daytime protection 
but reducing protection to secondary coverage service areas at night; 
(2) that all Class A stations should continue to be protected to the 
0.5 mV/m groundwave contour, both day and night, from first adjacent 
channel stations; and (3) that the critical hours protection of Class A 
stations should be eliminated completely. The Commission sought comment 
on these proposals.
    3. The AMR FNPRM proposals attracted voluminous and diverse 
comments. The licensees of Class A stations, represented primarily by 
the AM Radio Preservation Alliance (AMRPA), argue against the proposals 
and in favor of retaining the current protection rules. AMRPA argues 
that the Commission's proposal would do ``significant harm'' to the AM 
band by creating new interference, and point out the vital role that 
Class A stations have played in prior emergencies, such as Hurricane 
Katrina, noting further that 25 such stations are Primary Entry Points 
(PEPs) for the Integrated Public Alert and Warning System (IPAWS), 22 
of which have been outfitted by the Federal Emergency Management Agency 
(FEMA) to improve operating capability in national emergencies. A 
number of other commenters joining AMRPA in opposing the AMR FNPRM 
proposal agree that the proposal would reduce those stations' utility 
during national emergencies. Others contend that the proposal will 
increase nighttime interference in exchange for little in the way of 
increased nighttime coverage for less-powerful stations, while still 
others object to losing the ability to listen to distant signals for 
extended time periods.
    4. On the other hand, a number of commenters supported the

[[Page 58514]]

Commission's proposal. Many believe that Class A AM stations' current 
protected status may be an anachronism with little relevance to a world 
with more FM stations, the internet, and other forms of communications. 
Some licensees of AM stations that must reduce nighttime power to 
protect Class A stations wish to improve their local nighttime service. 
Some point out that the extended skywave service that Class A licensees 
seek to protect has become increasingly unreliable and prone to 
interference, particularly given high environmental noise floors caused 
by various sources of radiofrequency noise. Many also criticize some of 
the opponents' calculations of potential signal losses due to the 
proposed rule changes, questioning opponents' technical showings. As 
for emergency communications, some commenters note that Class A 
stations seldom broadcast weather or other alerts for distant areas 
beyond their immediate communities of license, and thus contend that it 
is more valuable for local stations to have the ability to broadcast 
emergency alerts and other locally relevant emergency information at 
night.
    5. A third category of commenters believe that changes to Class A 
protections are necessary, but do not believe the Commission's 
proposals to be the correct approach. Most share certain premises: That 
a 0.1 mV/m signal is not listenable under most circumstances; that 
nighttime skywave service is sporadic and unreliable; and that the 
wide-area coverage of Class A stations written into the rules should be 
preserved to at least some extent. At the same time, these commenters 
propose solutions that they believe will offer some relief to AM 
broadcasters currently protecting Class A stations that are sometimes 
many hundreds of miles away.
    6. The majority of these commenters propose instead that Class A 
stations be protected to their 0.5 mV/m groundwave contour, both day 
and night, from co-channel stations and, in some cases, first-adjacent 
channel stations as well. They differ in how they believe Class A 
stations should be protected from nighttime skywave interference from 
other stations. Some propose nighttime protection of a Class A 
station's 0.5 mV/m groundwave contour based on the RSS values 
calculated for Class A stations in the continental United States, and 
further propose that the interfering contour should be the 0.025 mV/m-
10 percent skywave contour based on single signal calculations. Others 
propose that Class A stations be protected to their nighttime 0.5 mV/m 
groundwave contours in a similar fashion to the way that Class B 
stations are currently protected to their 2.0 mV/m nighttime groundwave 
contours; they state that other stations making facility changes would 
have to show that they do not increase interference above the 0.5 mV/m 
groundwave contour, or the 50 percent exclusion RSS nighttime 
interference-free (NIF) level, if higher, of any Class A station; 
believing that this more fairly protects the actual interference-free 
service enjoyed by Class A AM stations, rather than the theoretical 
service being protected by the current rules or the Commission's 
proposed rules. These commenters, however, do not all agree with the 
Commission's proposal to eliminate critical hours protection to Class A 
AM stations, favoring instead protection to the Class A stations' 0.5 
mV/m groundwave contours during those hours.
    7. In the Second FNPRM, the Commission now seeks further comment on 
revised proposals for amending protections to Class A AM stations. Some 
commenters purport to demonstrate that protection of the 0.1 mV/m 
contour as proposed in the AMR FNPRM would be excessive because a 0.1 
mV/m signal cannot be heard under current noise conditions and suggest 
that it is only necessary to protect Class A stations to their 0.5 mV/m 
groundwave contour. However, other commenters disagree. The Commission 
seeks further comment on this determination.
    8. Moreover, commenters argue that some skywave protection of Class 
A stations is desirable. The Commission therefore seeks comment on 
revised proposals for amending protections to Class A AM stations, 
which include alternative protection standards for critical hours and 
nighttime hours. These alternative protection standards are proposed as 
revisions to the proposed rules set forth at 81 FR 2818, Jan. 19, 2016. 
The following proposals all provide Class A stations with less 
protection than they currently enjoy; in the case of the critical hours 
proposals, Alternative 1 provides Class A stations with less protection 
than does Alternative 2, and in the case of the nighttime protection 
proposals, Alternative 2 in some cases provides Class A stations with 
less protection than does Alternative 1:

Daytime Hours Proposal

     During daytime hours, Class A AM stations are protected to 
their 0.5 mV/m daytime groundwave contour, from both co-channel and 
first-adjacent channel stations;

Critical Hours Proposals

     Alternative 1: During critical hours, Class A AM stations 
are afforded no protection from other AM stations, as proposed in the 
AMR NPRM (no change to current 47 CFR 73.99), or
     Alternative 2: During critical hours, Class A AM stations 
are protected to their 0.5 mV/m groundwave contour (revise 47 CFR 
73.99);

Nighttime Hours Proposals

     Alternative 1: During nighttime hours, there may be no 
overlap between a Class A AM station's 0.5 mV/m nighttime groundwave 
contour and any interfering AM station's 0.025 mV/m 10 percent skywave 
contour (calculated using the single station method); or
     Alternative 2: During nighttime hours, Class A AM stations 
are protected from other AM stations in the same manner as Class B AM 
stations are protected, that is, interference may not be increased 
above the greater of the 0.5 mV/m nighttime groundwave contour or the 
50 percent exclusion RSS NIF level (calculated using the multiple 
station method).
    9. The Commission seeks comment on these alternative proposals and 
asks once again for the comments to address those issues set forth in 
the AMR FNPRM concerning the effects on licensees and listeners of each 
type of station that could result from the combination of reduced 
protection to Class A stations and power increases by co- and adjacent-
channel stations that this proposal would allow. The Commission also 
asks that commenters be mindful of the engineering comments already 
submitted concerning the calculation of listener interference, and, 
with this in mind, requests realistic estimates of the numbers of 
listeners that may lose primary service, as opposed to secondary or 
sporadic service, under each of the alternatives. Is there common 
agreement that protection of the 0.1 mV/m contour is excessive because 
a 0.1 mV/m signal cannot be heard under current noise conditions or are 
there studies to the contrary? Is the appropriate level of protection 
to the 0.5 mV/m groundwave contour? Likewise, the Commission seeks 
realistic estimates of the populations that could receive new primary 
local service, especially nighttime service, under each of these 
alternatives. It also seeks comment on whether its statutory authority 
imposes any limitations on implementation of these proposals, and 
whether such implementation is consistent with the

[[Page 58515]]

public interest. Finally, the Commission asks for comment on the effect 
of these proposals on AM broadcasters that are small entities and seek 
comment as to alternatives that would minimize burdens on such small 
entities.
    10. The Commission also asked for specific comments addressing the 
effect of these proposals, if any, on the functioning of the Emergency 
Alert System (EAS) and IPAWS. FEMA's IPAWS Office noted in comments 
that twenty-five Class A stations are Primary Entry Point (PEP) 
stations, and stated that under certain circumstances, the Commission's 
original proposal would diminish the reach of EAS alerts from these 
stations. The Commission sought comment as to the effect of its 
alternative proposals on emergency communications. In particular, it 
requested that any such evaluation include specifics as to what effect, 
if any, our proposals would have on the ability of other radio stations 
to receive EAS alerts from Class A stations that function as PEPs. It 
asked commenters to identify the affected stations and the populations 
covered by such stations to the extent possible. Such comments should 
also include an evaluation of the current reliability of Class A 
nighttime skywave service in providing emergency communications to 
distant listeners and to other radio stations that are not PEPs, 
compared to the expected reliability and reach of such communications 
if any of the alternative proposals are adopted. Commenters were also 
asked to address the potential benefits during emergencies of having 
more local service on the AM band available to listeners.
    11. The AMR FNPRM also included a tentative conclusion to roll back 
1991 rule changes pertaining to calculation of nighttime RSS values of 
interfering field strengths and nighttime interference-free service. 30 
FCC Rcd at 12170-73. It also proposed a return to predicting the 
nighttime interference-free coverage area using only the interference 
contributions from co-channel stations and the 50 percent exclusion 
method. Id. at 12172. The AMR FNPRM also included a proposed revision 
to daytime protection to Class B, C, and D AM stations, to return to 
the pre-1991 0 dB daytime 1:1 protection ratio for first adjacent 
channels; change second adjacent channel groundwave protection to match 
the current levels for third adjacent channel protection; and eliminate 
third adjacent channel groundwave protection. Additionally, the AMR 
FNPRM included a proposal to change the daytime protected contour for 
Class B, C, and D stations to the 2.0 mV/m contour. These proposals 
were intended to allow AM broadcasters greater flexibility to make 
station modifications designed to increase signal strength to their 
primary service areas.
    12. While not revising these proposals at this time, the Commission 
requested that in light of the alternative Class A protection proposals 
set forth above, commenters state whether they would revise their 
previously submitted comments regarding calculation of RSS values and 
changes to Class B, C, and D daytime protection and, if so, in what way 
and for what reasons. Commenters should consider the proposed revisions 
to AM station protection in terms of a new system designed to maximize 
local radio service without unduly jeopardizing wide-area service.
    13. The Commission thus sought comment on the rule changes proposed 
above, including the costs and benefits associated with the various 
proposals. It also sought comment on the costs and benefits of any 
other alternative approaches to addressing the issues raised in the 
record. To the extent possible, commenters should quantify the claimed 
costs and benefits and provide supporting information.

Comments and Reply Comments

    14. Pursuant to Sec. Sec.  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).
     All hand-delivered or messenger-delivered paper filings 
for the Commission's Secretary must be delivered to FCC Headquarters at 
445 12th Street SW, Room TW-A325, Washington, DC 20554. All hand 
deliveries must be held together with rubber bands or fasteners. Any 
envelopes must be disposed of before entering the building.
     Commercial Mail sent by overnight mail (other than U.S. 
Postal Service Express Mail and Priority Mail) must be sent to 9050 
Junction Drive, Annapolis Junction, MD 20701.
     U.S. Postal Service first-class, Express, and Priority 
mail should be addressed to 445 12th Street SW, Washington, DC 20554.

Procedural Matters

Ex Parte Rules

    15. This proceeding shall be treated as a ``permit-but-disclose'' 
proceeding in accordance with the Commission's ex parte rules. 47 CFR 
1.1200 et seq. 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 47 CFR 1.1206(b). In proceedings governed by 
47 CFR 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.

Initial Regulatory Flexibility Analysis

    16. The Regulatory Flexibility Act of 1980, as amended (RFA), 
requires that a regulatory flexibility analysis be prepared for notice 
and comment rule making proceedings, unless the agency certifies that 
``the rule will not, if promulgated, have a significant economic impact 
on a substantial number of small entities.'' The RFA generally defines 
the term ``small entity'' as having the same meaning as the terms 
``small business,'' ``small organization,'' and ``small governmental 
jurisdiction.'' In addition, the term ``small business'' has the same 
meaning as the term ``small business concern'' under the Small Business 
Act. A ``small

[[Page 58516]]

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 Small Business 
Administration (SBA).
    17. As required by the Regulatory Flexibility Act of 1980, as 
amended (RFA),\1\ the Commission has prepared this Initial Regulatory 
Flexibility Analysis (IRFA) of the possible significant economic impact 
on a substantial number of small entities by the policies proposed in 
the Second FNPRM. Written public comments are requested on this IRFA. 
Comments must be identified as responses to the IRFA and must be filed 
by the deadlines for comments on the Second FNPRM provided in paragraph 
18. The Commission will send a copy of this entire Second FNPRM, 
including this IRFA, to the Chief Counsel for Advocacy of the Small 
Business Administration (SBA). 5 U.S.C. 603(a). In addition, the Second 
FNPRM and the IRFA (or summaries thereof) will be published in the 
Federal Register. Id.
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    \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), Public Law 104-121, Title II, 110 Stat. 857 (1996).
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Need For, and Objectives of, the Proposed Rules

    18. This rulemaking proceeding is initiated to obtain further 
comments concerning certain proposals designed to revitalize the AM 
broadcast radio service. It is based in substantial part on proposals 
raised by commenters in this rulemaking proceeding, in response to the 
Commission's call in the original NPRM in this proceeding for further 
ideas and proposals.
    19. Specifically, the Commission seeks comment on the following: 
(1) Whether to change the nighttime and critical hours signal 
protection to Class A AM stations, based on new alternative proposals; 
(2) whether to change the methodology for calculating nighttime root 
sum square (RSS) values, based on the new alternative proposals for 
protection to Class A AM stations; and (3) whether to change daytime 
signal protection to Class B, C, and D stations, based on the new 
alternative proposals for protection to Class A AM stations.

Legal Basis

    20. The authority for this proposed rulemaking is contained in 
sections 1, 2, 4(i), 301, 303(r), 307, 316, and 403 of the 
Communications Act of 1934, 47 U.S.C. 151, 152, 154(i), 301, 303(r), 
307, 316, and 403.

Description and Estimate of the Number of Small Entities to Which the 
Proposed Rules Will Apply

    21. The RFA directs the Commission to provide a description of and, 
where feasible, an estimate of the number of small entities that will 
be affected by the proposed rules. 5 U.S.C. 603(b)(3). The RFA 
generally defines the term ``small entity'' as encompassing the terms 
``small business,'' ``small organization,'' and ``small governmental 
entity.'' Id. section 601(6). In addition, the term ``small business'' 
has the same meaning as the term ``small business concern'' under the 
Small Business Act. Id. section 601(3). A small business concern is one 
which: (1) Is independently owned and operated; (2) is not dominant in 
its field of operation; and (3) satisfies any additional criteria 
established by the Small Business Administration (SBA). 15 U.S.C. 632.

Radio Stations

    22. The proposed rules and policies could apply to AM radio 
broadcast licensees, and potential licensees of the AM radio service. A 
radio broadcasting station is an establishment primarily engaged in 
broadcasting aural programs by radio to the public. Id. Included in 
this industry are commercial, religious, educational, and other radio 
stations. Id. Radio broadcasting stations which primarily are engaged 
in radio broadcasting and which produce radio program materials are 
similarly included. Id. However, radio stations that are separate 
establishments and are primarily engaged in producing radio program 
material are classified under another NAICS number. Id. The SBA has 
established a small business size standard for this category, which is: 
Firms having $38.5 million or less in annual receipts. 13 CFR 121.201, 
NAICS Code 515112 (updated for inflation in 2008). According to the 
BIA/Kelsey, MEDIA Access Pro Database on May 14, 2018, 4,630 (99.94%) 
of 4,633 AM radio stations have revenues of $38.5 million or less. 
Therefore, the majority of such entities are small entities. We note, 
however, that, in assessing whether a business concern qualifies as 
small under the above definition, business (control) affiliations 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.
    23. In addition, an element of the definition of ``small business'' 
is that the 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 station is dominant in its field of 
operation. Accordingly, the estimate of small businesses to which rules 
may apply do not exclude any radio station from the definition of a 
small business on this basis and therefore may be over-inclusive to 
that extent. Also as noted, an additional element of the definition of 
``small business'' is that the entity must be independently owned and 
operated. We note that it is difficult at times to assess these 
criteria in the context of media entities and our estimates of small 
businesses to which they apply may be over-inclusive to this extent.

Description of Projected Reporting, Recordkeeping and Other Compliance 
Requirements

    24. The proposed rule and procedural changes may, in some cases, 
impose different reporting, recordkeeping, or other requirements on 
existing and potential AM radio licensees and permittees. In the case 
of proposed changes to the technical rules regarding calculation of 
daytime and nighttime interfering contours, and changes to daytime, 
nighttime, and critical hours protection to some stations, there would 
be changes in the calculation of inter-station interference and 
reporting of same. However, the information to be filed is already 
familiar to broadcasters, and the nature of the interference 
calculations would not change, only the values that are acceptable, so 
any additional burdens would be minimal.

Steps Taken To Minimize Significant Impact on Small Entities, and 
Significant Alternatives Considered

    25. The RFA requires an agency to describe any significant 
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 or reporting requirements under the rule for 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 small 
entities.\2\ In the Second FNPRM, the Commission seeks to assist AM 
broadcasters by changing certain daytime, nighttime, and critical hours 
interference protection standards as they apply to certain classes of 
AM

[[Page 58517]]

stations. The Commission seeks comment as to whether its goal of 
revitalizing the AM service could be effectively accomplished through 
these means. The Commission is open to consideration of alternatives to 
the proposals under consideration, as set forth herein, including but 
not limited to alternatives that will minimize the burden on AM 
broadcasters, most of which are small businesses. There may be unique 
circumstances these entities may face, and we will consider appropriate 
action for small broadcasters when preparing a Fourth Report and Order 
in this matter.
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    \2\ 5 U.S.C. 603(b).
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Federal Rules Which Duplicate, Overlap, or Conflict With, the 
Commission's Proposals

    26. None.
    27. To request materials in accessible formats for people with 
disabilities (Braille, large print, electronic files, audio format), 
send an email to [email protected] or call the Consumer and Governmental 
Affairs Bureau at 202-418-0530 (voice), 202-418-0432 (TTY).

Ordering Clause

    28. Accordingly, it is ordered that, pursuant to the authority 
contained in sections 1, 2, 4(i), 301, 303(r), 307, 316, and 403 of the 
Communications Act of 1934, as amended, 47 U.S.C. 151, 152, 154(i), 
301, 303(r), 307, 316, and 403, this Second Further Notice of Proposed 
Rule Making is adopted.

List of Subjects

47 CFR Part 73

    Communications equipment, Radio, Reporting and recordkeeping 
requirements.

47 CFR Part 74

    Communications equipment, Radio.

Federal Communications Commission.
Cecilia Sigmund,
Federal Register Liaison, Office of the Secretary.

Proposed Rules

    For the reasons discussed in the preamble, the Federal 
Communications Commission proposes to amend 47 CFR part 73 as follows:

PART 73--RADIO BROADCAST SERVICES

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

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

0
2. Amend Sec.  73.21 by revising the last two sentences of paragraph 
(a) introductory text and paragraph (a)(1) to read as follows:


Sec.  73.21  Classes of AM broadcast channels and stations.

    (a) * * * These stations are protected from objectionable 
interference within their primary service areas. Stations operating on 
these channels are classified as follows:
    (1) Class A Station. A Class A station is an unlimited time station 
that operates on a clear channel and is designed to render primary 
service over an extended area at relatively long distances from its 
transmitter. Its primary service area is protected from objectionable 
interference from other stations on the same and adjacent channels. 
(See Sec.  73.182). The operating power shall not be less than 10 kW 
nor more than 50 kW. (Also see Sec.  73.25(a)).
* * * * *


Sec.  73.24  [Amended]

0
3. Amend Sec.  73.24 as follows:
0
Option 1: Amend Sec.  73.24 by removing paragraph (h) and redesignating 
paragraphs (i) and (j) as paragraphs (h) and (i).
0
Option 2: Amend Sec.  73.24 by revising paragraph (h) to read as 
follows:


Sec.  73.24  Broadcast facilities; showing required.

* * * * *
    (h) That, in the case of an application for a Class B or Class D 
station on a clear channel, the proposed station would radiate, during 
two hours following local sunrise and two hours preceding local sunset, 
in any direction toward the 0.5 mV/m groundwave contour of a co-channel 
United States Class A station, no more than the maximum value permitted 
under the provisions of Sec.  73.187.
* * * * *
0
4. Amend Sec.  73.37 by revising the table in paragraph (a) to read as 
follows:


Sec.  73.37  Applications for broadcast facilities, showing required.

    (a) * * *

----------------------------------------------------------------------------------------------------------------
                                                       Contour of
                                                    proposed station
            Frequency separation (kHz)              (classes B, C and     Contour of any other station (mV/m)
                                                        D) (mV/m)
----------------------------------------------------------------------------------------------------------------
0................................................               0.025  0.500 (Class A).
                                                                  0.5  0.025 (Class A).
                                                                0.100  2.0 (Other classes).
                                                                  2.0  0.100 (Other classes).
10...............................................               0.500  0.500 (Class A).
                                                                  2.0  2.0 (Other classes).
20...............................................                25.0  25.0 (All classes).
----------------------------------------------------------------------------------------------------------------

* * * * *
0
5. Amend Sec.  73.99 by revising paragraphs (b)(2) and (3), (c)(1)(ii) 
and (iii), (d)(2) and (3), (f)(1) and (3) to read as follows:


Sec.  73.99  Presunrise service authorization (PSRA) and postsunset 
service authorization (PSSA).

* * * * *
    (b) * * *
    (2) Class D stations situated outside the 0.5 mV/m nighttime 
groundwave contours of co-channel U.S. Class A stations to commence 
PSRA operation at 6 a.m. local time and to continue such operation 
until sunrise times specified in their basic instruments of 
authorization.
    (3) Class D stations located within the co-channel 0.5 mV/m 
groundwave contours of U.S. Class A stations, to commence PSRA 
operation either at 6 a.m. local time, or at sunrise at the nearest 
Class A station located east of the Class D station (whichever is 
later), and to continue such operation until the sunrise times 
specified in their basic instruments of authorization.
* * * * *
    (c) * * *
    (1) * * *
    (ii) Protection is to be provided to the 0.5 mV/m groundwave 
contours of co-channel U.S. Class A stations or the NIF groundwave 
contour based on the 50

[[Page 58518]]

percent RSS exclusion method, whichever is greater.
    (iii) In determining the protection to be provided, the effect of 
each interfering signal will be evaluated such that interference may 
not be increased above the 0.5 mV/m nighttime groundwave contour or the 
NIF groundwave contour based on the 50 percent RSS exclusion method, 
whichever is greater.
* * * * *
    (d) * * *
    (2) Class D stations situated outside the 0.5 mV/m groundwave 
contours of co-channel U.S. Class A stations to commence PSSA 
operations at sunset times specified in their basic instruments of 
authorization and to continue for two hours after such specified times.
    (3) Class D stations located within the co-channel 0.5 mV/m 
groundwave contours of U.S. Class A stations to commence PSSA operation 
at sunset times specified in their basic instruments of authorization 
and to continue such operation until two hours past such specified 
times, or until sunset at the nearest Class A station located west of 
the Class D station, whichever is earlier. Class D stations located 
west of the Class A station do not qualify for PSSA operation.
* * * * *
    (f) * * *
    (1) Class D stations operating in accordance with paragraphs (b)(1) 
and (2), (d)(1) and (2) of this section are required to protect the 0.5 
mV/m groundwave contours or the NIF groundwave contour of co-channel 
Class A stations based on the 50 percent RSS exclusion method, 
whichever is greater.
* * * * *
    (3) Class D stations operating in accordance with paragraphs (d)(2) 
and (3) of this section are required to limit the extent of the 0.025 
mV/m skywave 10% contour to the co-channel Class A 0.5 mV/m ground wave 
or the NIF groundwave contour based on the 50%-RSS exclusion method, 
whichever is greater. The location of the 0.5 mV/m contour or the NIF 
contour of a Class A station will be determined by use of Figure M3, 
Estimated Ground Conductivity in the United States. When the 0.5 mV/m 
contour extends beyond the national boundary, the international 
boundary shall be considered the 0.5 mV/m contour.
* * * * *


Sec.  73.182  [Amended]

0
6. Amend Sec.  73.182 as follows:
0
Option 1: Amend Sec.  73.182 by:
0
a. Revising paragraphs (a)(1) through (3), (c) and (d);
0
b. Removing paragraphs (g) and (h);
0
c. Redesignating paragraphs (i) through (t) as paragraphs (g) though 
(r); and
0
d. Revising newly redesignated paragraphs (i) and (j), (m)(1), and the 
tables in paragraphs (o) and (p).
    The revisions read as follows:


Sec.  73.182  Engineering standards of allocation.

    (a) * * *
    (1) Class A stations operate on clear channels with powers between 
10 kW and 50 kW. These stations are designed to render primary service 
over a large area protected from objectionable interference from other 
stations on the same and adjacent channels. Class A stations may be 
divided into two groups: those located in any of the conterminous 
United States and those located in Alaska.
    (i) Class A stations in the conterminous United States operate on 
the channels assigned by Sec.  73.25 with minimum power of 10 kW, 
maximum power of 50 kW, and minimum antenna efficiency of 275 mV/m/kW 
at 1 kilometer. The Class A stations in this group are afforded 
protection as follows:
    (A) Daytime. To the 0.5 mV/m groundwave contour from stations on 
the same or adjacent channels.
    (B) Nighttime. There shall be no overlap between the Class A 
station's 0.5 mV/m nighttime groundwave contour and any interfering AM 
station's 0.025 mV/m-10% skywave contour, calculated based on a single 
station method.
    (ii) Class A stations in Alaska operate on the channels assigned by 
Sec.  73.25 with minimum power of 10 kW, maximum power of 50 kW, and 
minimum antenna efficiency of 215 mV/m/kW at 1 kilometer. The Class A 
stations in this group are afforded protection, both daytime and 
nighttime, to the 0.1 mV/m groundwave contour from other co-channel 
stations and to the 0.5 mV/m groundwave contour from other stations on 
first adjacent channels.
    (2) Class B stations are stations which operate on clear and 
regional channels with powers not less than 0.25 kW or greater than 50 
kW. These stations render primary service, the area of which depends on 
their geographic location, power, and frequency. It is recommended that 
Class B stations be located so that the interference received from 
other stations will not limit the service area to a groundwave contour 
value greater than 2.0 mV/m groundwave contour both daytime and 
nighttime, which are the values for the mutual protection between this 
class of stations and other stations of the same class.
    Note: * * *
    (3) Class C stations operate on local channels, normally rendering 
primary service to a community and the suburban or rural areas 
immediately contiguous thereto, with powers not less than 0.25 kW or 
greater than 1 kW, except as provided in Sec.  73.21(c)(1). Such 
stations are normally protected to the daytime 2.0 mV/m contour. On 
local channels the separation required for the daytime protection shall 
also determine the nighttime separation. Where directional antennas are 
employed daytime by Class C stations operating with power equal to or 
greater than 0.25 kW, the separations required shall in no case be less 
than those necessary to afford protection assuming nondirectional 
operation with power of 0.25 kW. In no case will nighttime power of 
0.25 kW or greater be authorized to a station unable to operate 
nondirectionally with power of 0.25 kW during daytime hours. The actual 
nighttime limitation will be calculated. For nighttime protection 
purposes, Class C stations in the 48 conterminous United States may 
assume that stations in Alaska, Hawaii, Puerto Rico, and the U.S. 
Virgin Islands operating on 1230, 1240, 1340, 1400, 1450, and 1490 kHz 
are Class C stations.
* * * * *
    (c) All classes of AM broadcast stations have in general three 
types of service areas, i.e., primary, secondary and intermittent. (See 
Sec.  73.14 for the definitions of primary, secondary and intermittent 
service areas.) All classes of AM stations render service to a primary 
area but the secondary and intermittent service areas may be materially 
limited or destroyed due to interference from other stations, depending 
on the station assignments involved.
    (d) The groundwave signal strength required to render primary 
service is 2 mV/m for communities with populations of 2,500 or more and 
0.5 mV/m for communities with populations of less than 2,500. Because 
only Class A stations have protected primary service extending beyond 
the 2 mV/m contour, the groundwave signal strength constituting primary 
service for Class A stations is that set forth in paragraphs (a)(1)(i) 
and (ii) of this section. See Sec.  73.184 for curves showing distance 
to various groundwave field strength contours for different frequencies 
and ground conductivities, and also see Sec.  73.183, ``Groundwave 
signals.''
* * * * *

[[Page 58519]]

    (i) Objectionable nighttime interference from a broadcast station 
occurs when, at a specified field strength contour with respect to the 
desired station, the field strength of an undesired co-channel station 
exceeds for 10% or more of the time the values set forth in these 
standards. The value derived from the root-sum-square of all 
interference contributions represents the extent of a station's 
interference-free coverage.
    (1) With respect to the root-sum-square (RSS) values of interfering 
field strengths referred to in this section, calculation of nighttime 
interference-free service is accomplished by considering co-channel 
signals in order of decreasing magnitude, adding the squares of the 
values and extracting the square root of the sum, excluding those 
signals which are less than 50% of the RSS values of the higher signals 
already included. This is known as the ``50% Exclusion Method.''
    (2) The RSS value will not be considered to be increased when a new 
interfering signal is added which is less than the appropriate 
exclusion percentage as applied to the RSS value of the interference 
from existing stations, and which at the same time is not greater than 
the smallest signal included in the RSS value of interference from 
existing stations.
    (3) It is recognized that application of the 50% Exclusion Method 
for calculating the RSS interference may result in some cases in 
anomalies wherein the addition of a new interfering signal or the 
increase in value of an existing interfering signal will cause the 
exclusion of a previously included signal and may cause a decrease in 
the calculated RSS value of interference. In order to provide the 
Commission with more realistic information regarding gains and losses 
in service (as a basis for determination of the relative merits of a 
proposed operation) the following alternate method for calculating the 
proposed RSS values of interference will be employed wherever 
applicable.
    (4) In cases where it is proposed to add a new interfering signal 
which is not less than 50% of the RSS value of interference from 
existing stations or which is greater than the smallest signal already 
included to obtain this RSS value, the RSS limitation after addition of 
the new signal shall be calculated without excluding any signal 
previously included. Similarly, in cases where it is proposed to 
increase the value of one of the existing interfering signals which has 
been included in the RSS value, the RSS limitation after the increase 
shall be calculated without excluding the interference from any source 
previously included.
    (5) If the new or increased signal proposed in such cases is 
ultimately authorized, the RSS values of interference to other stations 
affected will thereafter be calculated by the 50% Exclusion Method 
without regard to this alternate method of calculation.
    (6) Examples of RSS interference calculations:
    (i) Existing interferences:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    Station No. 4--0.58 mV/m.
    The RSS value from Nos. 1, 2 and 3 is 1.31 mV/m; therefore 
interference from No. 4 is excluded for it is less than 50% of 1.31 mV/
m.
    (ii) Station A receives interferences from:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    It is proposed to add a new limitation, 0.68 mV/m. This is more 
than 50% of 1.31 mV/m, the RSS value from Nos. 1, 2 and 3. The RSS 
value of Station No. 1 and of the proposed station would be 1.21 mV/m 
which is more than twice as large as the limitation from Station No. 2 
or No. 3. However, under the above provision the new signal and the 
three existing interferences are nevertheless calculated for purposes 
of comparative studies, resulting in an RSS value of 1.47 mV/m. 
However, if the proposed station is ultimately authorized, only No. 1 
and the new signal are included in all subsequent calculations for the 
reason that Nos. 2 and 3 are less than 50% of 1.21 mV/m, the RSS value 
of the new signal and No. 1.
    (iii) Station A receives interferences from:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    No. 1 proposes to increase the limitation it imposes on Station A 
to 1.21 mV/m. Although the limitations from stations Nos. 2 and 3 are 
less than 50% of the 1.21 mV/m limitation, under the above provision 
they are nevertheless included for comparative studies, and the RSS 
limitation is calculated to be 1.47 mV/m. However, if the increase 
proposed by Station No. 1 is authorized, the RSS value then calculated 
is 1.21 mV/m because Stations Nos. 2 and 3 are excluded in view of the 
fact that the limitations they impose are less than 50% of 1.21 mV/m.
    (j) Objectionable nighttime interference from a station shall be 
considered to exist to a station when, at the field strength contour 
specified in paragraph (o) of this section with respect to the class to 
which the station belongs, the field strength of an interfering station 
operating on the same channel exceeds for 10% or more of the time the 
value of the permissible interfering signal set forth opposite such 
class in paragraph (o) of this section.
* * * * *
    (m) Computation of skywave field strength values:--(1) Fifty 
percent skywave field strength values. To compute fifty percent skywave 
field strength values, Formula 1 of Sec.  73.190, entitled ``Skywave 
field strength, 50% of the time (at SS+6)'' shall be used.
* * * * *
    (o) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Signal strength contour of area protected     Permissible interfering signal ([micro]V/m)
                                                           from objectionable interference ([micro]V/m) ------------------------------------------------
         Class of station           Class of channel used ----------------------------------------------
                                                                  Day \1\               Night \1\               Day \1\                 Night \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
A.................................  Clear................  SC 500...............  SC 500...............  SC 25................  SC 25
                                                           AC 500...............  AC 500...............  AC 500...............  AC 500
B.................................  Regional.............  SC 2000..............  SC 2000..............  SC 100...............  Not presc.
                                                           AC 2000..............  AC 2000..............  AC 2000..............  Not presc.
C.................................  Local................  2000.................  Not presc \3\........  SC 100...............  Not presc.
D.................................  Regional.............  2000.................  Not presc............  SC 100...............  Not presc.
                                                                                                         AC 2000..............  Not presc.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Groundwave.
\2\ Skywave field strength for 10 percent or more of the time.
\3\ During nighttime hours, Class C stations in the contiguous 48 States may treat all Class B stations assigned to 1230, 1240, 1340, 1400, 1450, and
  1490 kHz in Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands as if they were Class C stations.
Note: SC = Same channel; AC = Adjacent channel; SW = Skywave; GW = Groundwave.


[[Page 58520]]

    (p) * * *

----------------------------------------------------------------------------------------------------------------
                                                                                   Desired groundwave to:
                                                                           -------------------------------------
        Frequency separation of desired to undesired signals (kHz)              Undesired        Undesired 10%
                                                                             groundwave  (dB)    skywave  (dB)
----------------------------------------------------------------------------------------------------------------
0.........................................................................                 26                 26
10........................................................................                  0                  0
----------------------------------------------------------------------------------------------------------------

* * * * *
0
Option 2: Amend Sec.  73.182 by:
0
a. Revising paragraphs (a)(1) through (3), (c) and (d);
0
b. Removing paragraphs (g) and (h);
0
c. Redesignating paragraphs (i) through (t) as paragraphs (g) though 
(r); and
0
d. Revising newly redesignated paragraphs (i) and (j), (m)(1), and the 
tables in paragraphs (o) and (p).
    The revisions read as follows:


Sec.  73.182  Engineering standards of allocation.

    (a) * * *
    (1) Class A stations operate on clear channels with powers between 
10 kW and 50 kW. These stations are designed to render primary service 
over a large area protected from objectionable interference from other 
stations on the same and adjacent channels. Class A stations may be 
divided into two groups: Those located in any of the conterminous 
United States and those located in Alaska.
    (i) Class A stations in the conterminous United States operate on 
the channels assigned by Sec.  73.25 with minimum power of 10 kW, 
maximum power of 50 kW, and minimum antenna efficiency of 275 mV/m/kW 
at 1 kilometer. The Class A stations in this group are afforded 
protection as follows:
    (A) Daytime. To the 0.5 mV/m groundwave contour from stations on 
the same or adjacent channels.
    (B) Nighttime. Interference may not be increased above the 0.5 mV/m 
nighttime groundwave contour or the NIF groundwave contour based on the 
50 percent RSS exclusion method, whichever is greater.
    (ii) Class A stations in Alaska operate on the channels assigned by 
Sec.  73.25 with minimum power of 10 kW, maximum power of 50 kW, and 
minimum antenna efficiency of 215 mV/m/kW at 1 kilometer. The Class A 
stations in this group are afforded protection, both daytime and 
nighttime, to the 0.1 mV/m groundwave contour from other stations on 
the same channel and to the 0.5 mV/m groundwave contour from other 
stations on first adjacent channels.
    (2) Class B stations are stations which operate on clear and 
regional channels with powers not less than 0.25 kW or greater than 50 
kW. These stations render primary service, the area of which depends on 
their geographic location, power, and frequency. It is recommended that 
Class B stations be located so that the interference received from 
other stations will not limit the service area to a groundwave contour 
value greater than 2.0 mV/m groundwave contour both daytime and 
nighttime, which are the values for the mutual protection between this 
class of stations and other stations of the same class.
    Note: * * *
    (3) Class C stations operate on local channels, normally rendering 
primary service to a community and the suburban or rural areas 
immediately contiguous thereto, with powers not less than 0.25 kW or 
greater than 1 kW, except as provided in Sec.  73.21(c)(1). Such 
stations are normally protected to the daytime 2.0 mV/m contour. On 
local channels the separation required for the daytime protection shall 
also determine the nighttime separation. Where directional antennas are 
employed daytime by Class C stations operating with power equal to or 
greater than 0.25 kW, the separations required shall in no case be less 
than those necessary to afford protection assuming nondirectional 
operation with power of 0.25 kW. In no case will nighttime power of 
0.25 kW or greater be authorized to a station unable to operate 
nondirectionally with power of 0.25 kW during daytime hours. The actual 
nighttime limitation will be calculated. For nighttime protection 
purposes, Class C stations in the 48 conterminous United States may 
assume that stations in Alaska, Hawaii, Puerto Rico, and the U.S. 
Virgin Islands operating on 1230, 1240, 1340, 1400, 1450, and 1490 kHz 
are Class C stations.
* * * * *
    (c) All classes of AM broadcast stations have in general three 
types of service areas, i.e., primary, secondary and intermittent. (See 
Sec.  73.14 for the definitions of primary, secondary and intermittent 
service areas.) All classes of AM stations render service to a primary 
area but the secondary and intermittent service areas may be materially 
limited or destroyed due to interference from other stations, depending 
on the station assignments involved.
    (d) The groundwave signal strength required to render primary 
service is 2 mV/m for communities with populations of 2,500 or more and 
0.5 mV/m for communities with populations of less than 2,500. Because 
only Class A stations have protected primary service extending beyond 
the 2 mV/m contour, the groundwave signal strength constituting primary 
service for Class A stations is that set forth in paragraphs (a)(1)(i) 
and (ii) of this section. See Sec.  73.184 for curves showing distance 
to various groundwave field strength contours for different frequencies 
and ground conductivities, and also see Sec.  73.183, ``Groundwave 
signals.''
* * * * *
    (i) Objectionable nighttime interference from a broadcast station 
occurs when, at a specified field strength contour with respect to the 
desired station, the field strength of an undesired co-channel station 
exceeds for 10% or more of the time the values set forth in these 
standards. The value derived from the root-sum-square of all 
interference contributions represents the extent of a station's 
interference-free coverage.
    (1) With respect to the root-sum-square (RSS) values of interfering 
field strengths referred to in this section, calculation of nighttime 
interference-free service is accomplished by considering co-channel 
signals in order of decreasing magnitude, adding the squares of the 
values and extracting the square root of the sum, excluding those 
signals which are less than 50% of the RSS values of the higher signals 
already included. This is known as the ``50% Exclusion Method.''
    (2) The RSS value will not be considered to be increased when a new 
interfering signal is added which is less than the appropriate 
exclusion percentage as applied to the RSS value of the interference 
from existing stations, and which at the same time is

[[Page 58521]]

not greater than the smallest signal included in the RSS value of 
interference from existing stations.
    (3) It is recognized that application of the 50% Exclusion Method 
for calculating the RSS interference may result in some cases in 
anomalies wherein the addition of a new interfering signal or the 
increase in value of an existing interfering signal will cause the 
exclusion of a previously included signal and may cause a decrease in 
the calculated RSS value of interference. In order to provide the 
Commission with more realistic information regarding gains and losses 
in service (as a basis for determination of the relative merits of a 
proposed operation) the following alternate method for calculating the 
proposed RSS values of interference will be employed wherever 
applicable.
    (4) In cases where it is proposed to add a new interfering signal 
which is not less than 50% of the RSS value of interference from 
existing stations or which is greater than the smallest signal already 
included to obtain this RSS value, the RSS limitation after addition of 
the new signal shall be calculated without excluding any signal 
previously included. Similarly, in cases where it is proposed to 
increase the value of one of the existing interfering signals which has 
been included in the RSS value, the RSS limitation after the increase 
shall be calculated without excluding the interference from any source 
previously included.
    (5) If the new or increased signal proposed in such cases is 
ultimately authorized, the RSS values of interference to other stations 
affected will thereafter be calculated by the 50% Exclusion Method 
without regard to this alternate method of calculation.
    (6) Examples of RSS interference calculations:
    (i) Existing interferences:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    Station No. 4--0.58 mV/m.
    The RSS value from Nos. 1, 2 and 3 is 1.31 mV/m; therefore 
interference from No. 4 is excluded for it is less than 50% of 1.31 mV/
m.
    (ii) Station A receives interferences from:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    It is proposed to add a new limitation, 0.68 mV/m. This is more 
than 50% of 1.31 mV/m, the RSS value from Nos. 1, 2 and 3. The RSS 
value of Station No. 1 and of the proposed station would be 1.21 mV/m 
which is more than twice as large as the limitation from Station No. 2 
or No. 3. However, under the above provision the new signal and the 
three existing interferences are nevertheless calculated for purposes 
of comparative studies, resulting in an RSS value of 1.47 mV/m. 
However, if the proposed station is ultimately authorized, only No. 1 
and the new signal are included in all subsequent calculations for the 
reason that Nos. 2 and 3 are less than 50% of 1.21 mV/m, the RSS value 
of the new signal and No. 1.
    (iii) Station A receives interferences from:
    Station No. 1--1.00 mV/m.
    Station No. 2--0.60 mV/m.
    Station No. 3--0.59 mV/m.
    No. 1 proposes to increase the limitation it imposes on Station A 
to 1.21 mV/m. Although the limitations from stations Nos. 2 and 3 are 
less than 50% of the 1.21 mV/m limitation, under the above provision 
they are nevertheless included for comparative studies, and the RSS 
limitation is calculated to be 1.47 mV/m. However, if the increase 
proposed by Station No. 1 is authorized, the RSS value then calculated 
is 1.21 mV/m because Stations Nos. 2 and 3 are excluded in view of the 
fact that the limitations they impose are less than 50% of 1.21 mV/m.
    (j) Objectionable nighttime interference from a station shall be 
considered to exist to a station when, at the field strength contour 
specified in paragraph (o) of this section with respect to the class to 
which the station belongs, the field strength of an interfering station 
operating on the same channel exceeds for 10% or more of the time the 
value of the permissible interfering signal set forth opposite such 
class in paragraph (o) of this section.
* * * * *
    (m) Computation of skywave field strength values:--(1) Fifty 
percent skywave field strength values. To compute fifty percent skywave 
field strength values, Formula 1 of Sec.  73.190, entitled ``Skywave 
field strength, 50% of the time (at SS+6)'' shall be used.
* * * * *
    (o) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Signal strength contour of area protected     Permissible interfering signal  ([micro]V/m)
                                                           from objectionable interference ([micro]V/m) ------------------------------------------------
         Class of station           Class of channel used ----------------------------------------------
                                                                  Day \1\               Night \1\               Day \1\                 Night \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
A.................................  Clear................  SC 500...............  SC 500\3\............  SC 25................  SC 25
                                                           AC 500...............  AC 500...............  AC 500...............  AC 500
B.................................  Regional.............  SC 2000..............  SC 2000..............  SC 100...............  Not presc.
                                                           AC 2000..............  AC 2000..............  AC 2000..............  Not presc.
C.................................  Local................  2000.................  Not presc \3\........  SC 100...............  Not presc.
D.................................  Regional.............  2000.................  Not presc............  SC 100...............  Not presc.
                                                                                                         AC 2000..............  Not presc.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Groundwave.
\2\ Skywave field strength for 10 percent or more of the time.
\3\ Class A AMs are protected such that interference may not be increased above the greater of the 0.5 mV/m nighttime ground wave contour or the 50%
  exclusion RSS NIF level.
\4\ During nighttime hours, Class C stations in the contiguous 48 States may treat all Class B stations assigned to 1230, 1240, 1340, 1400, 1450, and
  1490 kHz in Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands as if they were Class C stations.
Note: SC = Same channel; AC = Adjacent channel; SW = Skywave; GW = Groundwave.

    (p) * * *

[[Page 58522]]



----------------------------------------------------------------------------------------------------------------
                                                                                   Desired groundwave to:
                                                                           -------------------------------------
        Frequency separation of desired to undesired signals (kHz)              Undesired        Undesired 10%
                                                                             groundwave  (dB)    skywave  (dB)
----------------------------------------------------------------------------------------------------------------
0.........................................................................                 26                 26
10........................................................................                  0                  0
----------------------------------------------------------------------------------------------------------------

* * * * *


Sec.  73.187  [Amended]

0
7. In paragraphs (a)(1), (2)(ii), and (3) remove all references to 
``0.1 mV/m'' and add in their place ``0.5 mV/m''.


Sec.  73.190  [Amended]

0
8. In paragraph (e), on right-hand side of Figures 9, 10, and 11, 
remove the axis label ``Distance from 0.1 mV/m Contour in Miles'' and 
add in its place ``Distance from 0.5 mV/m Contour in Miles.''

[FR Doc. 2018-25101 Filed 11-19-18; 8:45 am]
BILLING CODE 6712-01-P