Broadband Over Power Lines, 71892-71908 [2011-30045]

Agencies

• FEDERAL COMMUNICATIONS COMMISSION

[Federal Register Volume 76, Number 224 (Monday, November 21, 2011)]
[Rules and Regulations]
[Pages 71892-71908]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-30045]


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FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 15

[ET Docket No. 04- 37; ET Docket No. 03-104; FCC 11-160]


Broadband Over Power Lines

AGENCY: Federal Communications Commission.

ACTION: Final rule.

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SUMMARY: This document affirms the Commission's rules for Access 
Broadband over Power Line (Access BPL) systems. The Commission also 
makes certain minor modifications to improve and clarify the rules. 
These rules provide an appropriate balance between the dual objectives 
of providing for Access BPL technology that has potential applications 
for broadband and Smart Grid while protecting incumbent radio services 
against harmful interference.

DATES: Effective December 21, 2011.

ADDRESSES: Federal Communications Commission, 445 12th Street SW., 
Washington, DC 20554.

FOR FURTHER INFORMATION CONTACT: Anh Wride, Office of Engineering and 
Technology, (202) 418-0577, anh.wride@fcc.gov.

SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Second 
Report and Order, ET Docket Nos. 04-37 and 03-104, FCC 11-160, adopted 
October 20, 2011 and released October 24, 2011. The full text of this 
document is available for inspection and copying during normal business 
hours in the FCC Reference Center (Room CY-A257), 445 12th Street SW., 
Washington, DC 20554. The complete text of this document also may be 
purchased from the Commission's copy contractor, Best Copy and 
Printing, Inc., 445 12th Street SW., Room, CY-B402, Washington, DC 
20554. The full text may also be downloaded at: https://www.fcc.gov.
    People with Disabilities: To request materials in accessible 
formats for people with disabilities (braille, large print, electronic 
files, audio format), send an email to fcc504@fcc.gov or call the 
Consumer & Governmental Affairs Bureau at (202) 418-0530 (voice), (202) 
418-0432 (tty).

Summary of the Second Report and Order

    1. In this Second Report and Order (Second Order), the Commission 
fundamentally affirms its rules for Access Broadband over Power Line 
(Access BPL) systems. The Commission also makes certain minor 
modifications to improve and clarify the rules. These rules provide an 
appropriate balance between the dual objectives of providing for Access 
BPL technology that has potential applications for broadband and Smart 
Grid while protecting incumbent radio services against harmful 
interference.
    2. The Commission adopted rules for Access BPL systems in 2004 and 
affirmed those rules in 2006. The BPL rules were challenged by the 
national association for amateur radio, formally known as the American 
Radio Relay League (ARRL) in the United States Court of Appeals for the 
District of Columbia in ARRL v. FCC. In ARRL v. FCC, the court directed 
the Commission to: (1) Make part of the rulemaking record unredacted 
versions of several staff technical studies which the Commission 
considered in promulgating the rules, (2) provide a reasonable 
opportunity for public comment on those studies, and (3) provide a 
reasoned explanation of its choice of the extrapolation factor for use

[[Page 71893]]

in measuring radiated emissions from Access BPL systems. In response, 
the Commission issued a Request for Further Comment and Further Notice 
of Proposed Rulemaking in this proceeding (RFC/FNPRM). In the RFC/
FNPRM, the Commission took its first step in responding to the 
directives of the court in ARRL v. FCC and also took that opportunity 
to review the Access BPL extrapolation factor and propose certain 
changes to the BPL technical rules that appeared appropriate in view of 
new information and further consideration of this matter. In this 
Second Order, the Commission completes its action addressing the 
court's concerns and its proposals in the RFC/FNPRM. It finds that the 
information submitted in response to the RFC/FNPRM does not warrant any 
changes to the emissions standards or the extrapolation factor. 
However, the Commission is making several refinements to its Access BPL 
rules. In particular, it is: (1) Modifying the rules to increase the 
required notch filtering capability for systems operating below 30 MHz 
from 20 dB to 25 dB; (2) establishing a new alternative procedure for 
determining site-specific extrapolation factors generally as described 
in the RFC/FNPRM, and (3) adopting a definition for the ``slant-range 
distance'' used in the BPL measurement guidelines to further clarify 
its application. The Commission finds that the benefits of the changes 
to the rules outweigh their regulatory costs.
    3. Throughout this proceeding and in its appeal to the court, the 
ARRL has argued that more restrictive technical standards are needed to 
protect the amateur radio service from interference caused by leakage 
of radiofrequency (RF) emissions from Access BPL systems. The 
Commission initially crafted rules for BPL systems that were based on 
our existing emission standards for carrier current communications 
systems--narrow-band devices that couple RF energy onto power line 
wiring for communication purposes--with a number of additional 
requirements to promote avoidance and resolution of harmful 
interference to licensed services that might occur in the context of 
BPL operations. The Commission subsequently affirmed those rules in 
response to petitions for reconsideration by various parties, including 
ARRL. In this process, it has specifically rejected as unnecessary 
repeated requests by ARRL for tighter emissions controls on Access BPL 
operations. In response to the court's direction, it provided 
opportunity in the RFC/FNPRM for interested parties to address the BPL 
technical rules and the information developed by our staff that we 
considered in establishing those rules, explained its rationale for the 
extrapolation factor used in measuring BPL emissions, expressed its 
tentative satisfaction with the extrapolation factor adopted, while 
soliciting comment on whether another value would be more appropriate, 
and proposed a procedure for determining site-specific extrapolation 
factors. The Commission has completed its response to issues raised 
under the court's directive.
    4. The Commission has established a regime of rules for Access BPL 
systems that will provide a robust environment for the development and 
deployment of this important new technology option for delivery of 
broadband internet/data services while at the same time minimizing the 
potential for interference to licensed services caused by leakage from 
power lines of the RF energy used by BPL transmissions. As observed in 
the BPL Order, there is some potential for increased harmful 
interference from BPL operations, particularly in locations within a 
short distance of the power lines used by this technology. Consistent 
with our responsibilities for managing the interference potential of 
devices which can interfere with radio under Section 302 of the 
Communications Act, the Commission has developed a set of rules for BPL 
devices and systems that attempts to minimize instances of interference 
while allowing BPL systems to operate in a viable manner to serve the 
needs of the American public. In this regard, the Commission has stated 
and continues to hold that, on balance, the benefits of Access BPL for 
bringing broadband services to the public are sufficiently important 
and significant so as to outweigh the limited increase in potential for 
harmful interference that may arise. The Commission also agrees with 
NTIA that while some cases of harmful interference may be possible from 
Access BPL emissions at levels at or below the part 15 limits, the 
potential benefits of Access BPL service warrant acceptance of a 
negligible risk of harmful interference that can be managed and 
corrected as needed on a case-by-case basis.
    5. To minimize the potential for harmful interference, facilitate 
its resolution where it may occur, and address cases where its possible 
occurrence could impact critical services, the Commission adopted 
additional regulatory measures beyond the emissions limits in the part 
15 rules. These additional measures generally require Access BPL 
operators to reduce emissions or avoid operation on certain frequencies 
or in certain locations in order to protect licensed services, to use 
equipment that can alter its operation by changing frequencies to 
eliminate harmful interference, to provide information that will assist 
the public in identifying locations where Access BPL operations are 
present and provide notice to radio users before commencing local BPL 
operations in a publicly accessible database. In this manner, the 
Access BPL rules provide an effective means for limiting harmful 
interference and ensuring that any instances of harmful interference 
that may occur can be quickly identified and resolved. As emphasized in 
the BPL Order, Access BPL systems will continue to be treated as 
unlicensed part 15 devices and as such will be subject to the 
conditions in Sec.  15.5(b) of the rules that they not cause harmful 
interference and that they cease operation if they do cause such 
interference, as required by our rules. Upon examination of the 
information and comments received in response to the RFC/FNPRM, the 
Commission continues to believe that these measures are adequate and 
appropriate for managing the potential for harmful interference to all 
licensed radio services that operate on the bands used internally by 
BPL systems, including the amateur radio service.
    6. The Commission is not persuaded by ARRL's newest technical 
submissions, including the reports/standards referenced in its November 
2010 and June 2011 ex parte comments, or its assertions regarding the 
information in the unredacted presentations and in the additional 
information it recently introduced into the record in July 2009 that 
our assessment of the interference potential from BPL operations was 
incorrect or inappropriate, or that modifications to the BPL emissions 
limits and other technical rules to provide additional protection for 
the amateur service are warranted. While there is much valuable and 
valid information and analysis in ARRL's technical presentations, there 
are additional considerations that previously led us to draw different 
conclusions and still lead us to maintain those conclusions now.
    7. With regard to the redacted portions of the staff presentations 
and the preliminary information from early staff work that was released 
in July 2009, the Commission was, of course, aware of that content and 
it was also aware of other considerations and facts that bear on the 
various BPL technical issues. Notwithstanding ARRL's apparent belief 
that the full content of the staff presentations should have led

[[Page 71894]]

us to the conclusion it prefers, the Commission found, and continues to 
find, differently with respect to the regulatory measures that are 
needed to protect the amateur service from interference from BPL 
operations. The presentations in those informally conducted experiments 
were part of our initial internal investigation of BPL and, while there 
is value in them, they are not the sole source of our information on 
BPL performance. In this regard, the Commission considered all of the 
available information on BPL systems and their performance, submissions 
in the comments and other publicly available information. It also 
observes that some of the staff presentations on which ARRL focuses 
were of experimental systems that used early implementations of BPL 
equipment, developed before the BPL Order, that do not appear to have 
complied with the new rules; additionally, information on other system 
implementations, particularly our work with the Manassas, VA system, 
showed different performance characteristics than the systems ARRL 
criticized. In some cases, ARRL simply (and incorrectly) draws 
different conclusions from those presentations than we do. Also, the 
assessments and recommendations in the redacted portions of the 
presentations merely reflect the views of the Laboratory engineers who 
performed the testing and analysis; they do not necessarily reflect the 
consensus view of other engineers, the management of the Laboratory or 
of OET. Indeed, individual views are often conflicting, but are 
encouraged in the interest of producing vigorous debate to lead to a 
thoroughly considered recommendation and decision.

The Potential for Harmful Interference

    8. In the BPL Order, the Commission, with concurrence from NTIA, 
concluded that the current emission limits will restrict Access BPL 
systems to low emitted field strength levels in comparison to the 
signals of licensed radio operations. It found that the effect of these 
limits will be to constrain the harmful interference potential of these 
systems to relatively short distances from the power lines that carry 
the BPL signals. The Commission also recognized that some radio 
operations in the bands being used for Access BPL, such as those of 
amateur radio licensees, may occur at distances sufficiently close to 
power lines as to make harmful interference a possibility. The 
Commission stated that it believed those situations can be addressed 
through interference avoidance techniques by the Access BPL provider 
such as frequency band selection, notching, or judicious device 
placement, and it adopted rules to facilitate such solutions.
    9. The Commission agreed with ARRL that Access BPL on overhead 
lines is not a traditional point-source emitter, but not with its 
argument that Access BPL devices would cause power lines to act as 
miles of transmission lines all radiating RF energy along their full 
length. In this regard, the Commission observed that the part 15 
emission limits for carrier current systems have proven very effective 
at controlling interference from such systems. Also, it indicated that 
the design and configuration of Access BPL systems would be 
inconsistent with the development of cumulative emission effects for 
nearby receivers. The Commission further concluded that because the BPL 
emissions level decreases significantly with distance perpendicular 
from the line, the potential for interference also decays rapidly with 
distance from the line.
    10. The Commission recognized that Access BPL systems present 
concerns for licensed users in the high frequency (HF) and lower 
portions of the very high frequency (VHF) bands, given the propagation 
characteristics of RF signals in the range of frequencies being used 
for these systems, the diversity of users of these frequencies, and the 
fact that Access BPL devices could be installed at many locations in an 
area. While it concluded that there is little likelihood that harmful 
interference would occur from Access BPL operations at the signal 
levels allowed under the current part 15 emission limits, it 
acknowledged that such interference could occur in limited situations 
despite the intentions of BPL operators. To address this interference 
potential, the Commission required BPL operators to comply with 
additional interference mitigation techniques. It stated that such 
steps should be taken particularly in those cases where the occurrence 
of interference would affect critical services or where interference 
could be anticipated to occur. The interference mitigation measures for 
critical services include exclusion from operating on certain frequency 
bands and exclusion from operation in certain areas. For all services, 
the interference mitigation provisions require that BPL system 
operators have the ability to remotely cease operation or apply 
frequency avoidance (notching) on bands where licensed services are 
receiving interference. BPL operators were required to be able to notch 
their operations on affected bands to a level 20 dB below the part 15 
emissions limit for frequencies below 30 MHz (i.e., 1/100th of the 
emissions limits for other unlicensed unintentional radiators).
    11. In the BPL Reconsideration Order, the Commission affirmed its 
selection of 20 dB below the part 15 emissions limit as the minimum 
notching capability for frequencies below 30 MHz. It also revised the 
rules to specify that where an Access BPL operator implements such 
notching, the operator need not provide further protection to mobile 
operations, nor will the operator be required to resolve complaints of 
harmful interference to mobile operations by taking steps over and 
above implementing the ``notch.'' The Commission found that, while this 
level may be above the noise floor, reception of signals in mobile 
operating conditions is generally not reliable at levels at or below 
that level and thus does not warrant protection.
    12. The Commission disagrees with ARRL that the recently released 
materials show interference potential from Access BPL systems to be 
significantly greater than that which we anticipated in the BPL Order, 
that such interference will be preclusive of amateur operations over 
large areas, or that the current rules are not adequate to resolve any 
interference that might occur. Rather, ARRL's in-depth focus on that 
material is in some aspects consistent with the Commission's own 
assessments, in other aspects incorrect, and, importantly, in many 
aspects does not account for the real world conditions affecting the 
propagation of RF emissions at HF frequencies. While ARRL provides 
significant information on the standard engineering principles 
concerning the attenuation rate of emissions from line emitters, it is 
mistaken as to how the attenuation rate should be viewed for purposes 
of measuring BPL emissions. In this regard, the Commission again 
concludes that 40 dB/decade is a best estimate of the expected 
attenuation rate/extrapolation factor in the conditions in which 
measurements are made under the Access BPL measurement guidelines. The 
Commission finds no information in the comments or the newly submitted 
information in ARRL's November 2010 and June 2011 ex parte submissions 
that would warrant modification of the Access BPL rules to require 
notching of all amateur bands at notch depths of at least 35 dB, or 
otherwise provide additional protection for the amateur service. 
However, in reviewing the requirement that Access BPL systems be 
capable of reducing their emissions by 20 dB in a given frequency band 
and current developments in BPL equipment, the

[[Page 71895]]

Commission now finds that it would be appropriate to increase this 
required ``notching'' capability by 5 dB, to 25 dB for BPL systems 
operating below 30 MHz. It responds to the comments with respect to 
each of these sets of materials sequentially listed here.

Unredacted Staff Presentations and Newly Submitted Materials

    13. In its comments, ARRL argues that the unredacted staff 
presentations show that:
    i. Access BPL is not a point-source emitter; it is a distributive 
system that has significant interference potential over a wide area at 
significant distances from (and along) the power line carrying BPL 
signals. It contends that the Commission's measurements show that there 
is virtually no signal decay along the power line 230 meters from the 
coupler.
    ii. The proper distance extrapolation factor for assumed signal 
decay with distance from the power line is much closer to 20 dB/decade 
of distance (20 log R) than to the 40 dB/decade of distance (40 log R) 
adopted by the Commission for frequencies below 30 MHz.
    iii. Access BPL has a considerably higher interference potential to 
licensed radio services than the Commission concluded in the BPL Order 
if operated at the maximum radiated emission levels permitted by the 
Commission's part 15 rules (and the BPL rules adopted in the BPL 
Order). Specifically, interference to licensed mobile radio receivers 
is very likely for very long distances along a power line. The 
presentations also show that systems operating at the part 15 emission 
limits will be at least 25-35 dB stronger than the median values of 
man-made noise at 30-meters distance. Extrapolating this to a mobile 
antenna closer to the lines results in an even higher noise level.
    iv. The Commission erred in concluding that mobile Amateur stations 
would be protected from interference if, in response to an interference 
complaint, the BPL operator reduced the BPL radiated emission level 
from the offending portion(s) of the BPL system by 20 dB below the 
maximum radiated emission level permitted for part 15 devices 
generally. That remedy falls far short of reducing BPL noise to the 
level of ambient noise in residential environments found by 
Commission's technical staff, and falls far short of reducing BPL 
wideband noise levels to the point that mobile communications can be 
conducted in areas substantial distances from the power line.
    v. Measurement of BPL radiated emissions should be done at heights 
not lower than in the same horizontal plane as the overhead power line.
    14. First, the Commission agrees with ARRL that a BPL system does 
not behave as a point-source emitter. Neither, however, can it be 
analyzed as a line emitter. Analysis and prediction of RF propagation 
in the HF frequency region is extremely complex and difficult, and 
particularly at locations close to the ground, as the Commission, ARRL 
and many other commenters have acknowledged throughout this proceeding. 
The Commission's intent in the BPL Order was not to say that power 
lines are point-source radiators, but rather simply that the 
interference potential lessens with distance down the line from the 
coupler--though this occurs at rates that can vary significantly with 
power line topology.
    15. ARRL points out that one of the video files in the staff 
materials released by the Commission in July 2009 shows interference to 
mobile reception of signals in the amateur 20-meter band (14.0-14.35 
MHz). Specifically, it states that the video of the Briarcliff Manor 
system recorded on August 17, 2004 (Briarcliff Video 5) shows 
in a graphic, compelling manner the severe and constant interference 
caused by the BPL system to amateur reception over huge geographic 
areas which obviously precluded essentially all Amateur HF 
communications in the area. It submits that no objective observer of 
this video could possibly conclude that the level of BPL radiated 
emissions permitted by the Commission's Part 15 rules is acceptable. 
ARRL is correct that the interference that is apparent on Briarcliff 
Video 5 is not acceptable and would not be permissible under 
either our part 15 rules or the system operator's experimental license. 
However, while interference can occur from BPL operations along a 
stretch of power lines as shown in that and other videos in the 
preliminary materials released in July 2009, the Commission did not and 
do not find this example to substantiate a need for more restrictive 
rules on BPL systems. First, it does not appear that any of the 
mitigating features that are required in the rules had been applied to 
this system. In addition, our staff did contact the licensee about 
interference from that system several times over the course of its 
operation and the operator took steps first to cease operation on the 
amateur frequencies and then to install new equipment that had notching 
capability. Subsequent examination of that system by field agents of 
the Commission's Enforcement Bureau found no interference, which 
substantiates the effectiveness of our rules when properly observed. 
Also, as indicated by the primary and secondary title screens of 
Briarcliff Video 5, the system was notched only in the 20-
meter amateur band, and not in the 15-meter amateur band, for which 
that video was recorded. Thus, the Commission did not and do not 
consider the interference that appears in Briarcliff Video 5 
to be representative of the performance of a system operating in 
accordance with the set of rules it set forth for Access BPL systems.
    16. The Commission also sees no merit in ARRL's argument that 
statements on the same presentation slide concerning an interference 
problem from the Phonex carrier current system to ARINC aeronautical 
communications and opining that compliant Access BPL ``may be worse'' 
should have served as a factor in its decision on protection for the 
amateur service. In the BPL Order, the Commission recognized the 
critical nature of aeronautical communications and, given the free 
space propagation path from a power line to an aircraft, excluded 
Access BPL systems from operating on frequencies used by that service. 
With respect to the Phonex case, the Commission also observes that the 
Phonex system at issue might not have been the source of the 
interference with ARINC's communications and its performance therefore 
cannot be used as an empirical basis for establishing any benchmarks 
with respect to the interference potential of BPL systems.
    17. ARRL next observes that another presentation slide in the 
Briarcliff Manor presentation recommends that the Commission ``impose 
[a] 5 dB height correction [factor]'' on measurements and a ``20 log R 
extrapolation factor'' if it is going to allow BPL on medium voltage 
(MV) overhead power lines and should use a 20 dB/decade extrapolation 
factor for signal decay with distance from the power line. It observes 
that the presentation states that this ``reduces interference [from 
BPL] to fixed stations.'' Basing the BPL emissions limits and 
measurement procedures on an attenuation rate of 1/R, i.e., 20 dB/
decade would, of course, reduce signal levels and thereby provide 
additional protection to licensed services against interference. The 
Commission notes that the slide in question does not provide a 
``recommendation'' as claimed by ARRL, rather, it only presented 
several options for other staff and management to consider in its 
deliberations. Further, as the Commission concluded previously, it does 
not believe that such

[[Page 71896]]

additional protection is needed or warranted, but rather hold that the 
part 15 ``no interference requirement,'' the part 15 emissions limit 
for carrier current systems, and the interference mitigation measures 
it adopted in the BPL Order collectively provide sufficient protection 
to licensed services from the potential for harmful interference from 
Access BPL operations. The Commission also continues to find that the 
attenuation rate of emissions from power lines is typically higher than 
20 dB/decade and varies with location. At distances within 30 meters of 
the power line and when using the slant-range measurement procedure 
prescribed in our measurement guidelines, 1/R\2\, i.e., 40 dB/decade, 
properly describes the expected attenuation rate at frequencies below 
30 MHz, and variability around that rate is also expected.
    18. It is also important to understand, as the Commission discussed 
in the RFC/FNPRM and ARRL largely ignores, that RF propagation in the 
lower frequencies ranges, and particularly at frequencies below 30 MHz, 
is greatly affected by environmental factors, so that there is 
significant variability in propagation from place to place. These 
include ground absorption and conductivity, terrain, vegetation, and 
the presence of structures and other man-made objects, including 
additional power lines arrayed on pole/towers in the near-field of 
emissions from a power line carrying Access BPL transmissions. In some 
cases, emissions from BPL systems that are expected to be compliant 
with the rules will attenuate with distance at relatively high rates 
and be well below the part 15 limits while emissions from other 
systems, or even from the same system but at a different location, will 
attenuate at a relatively lower rate and exceed the part 15 limits. The 
Commission is aware of these variabilities in this complex operating 
environment and to account for it, has adopted additional provisions 
for mitigating harmful interference that are set forth in the rules. In 
addition, recognizing this variability, it did not base our assessment 
of interference potential on any standard performance factor, such as 
an attenuation rate by itself, but rather on the successful past 
performance of our existing standards and the availability of suitable 
approaches for managing the potential for harmful interference and 
correcting any harmful interference that may occur.
    19. The Commission has also fully considered the issue of how to 
measure Access BPL emissions, including whether a 5 dB correction 
factor was needed for Access BPL measurements below 30 MHz. In the BPL 
Order, it concluded that the existing measurement procedure that 
provides for measurement of the magnetic field at 1-meter height with 
no correction factor was appropriate for measurements in that frequency 
region. There is no additional information in the presentation 
summaries that leads us to find that this decision should be changed.
    20. ARRL points out that slide 20 of the Briarcliff Manor 
presentation listed options of notching or mandatory advance 
coordination for protection of low-VHF public safety channels and that 
the Commission did not adopt either of those options but instead put in 
place a notification requirement. It also observes that the same slide 
listed the 50-54 MHz amateur band that is typically used for both 
mobile and fixed operations and the Commission did not acknowledge the 
interference potential to amateur operations in that band and offered 
no remedy for it. In the BPL Order, the Commission determined that 
public safety systems, because of the often critical and/or safety-of-
life nature of the communications they provide, merit the additional 
protection of advanced notice of BPL operations. The Commission stated 
that an advance notification would provide a public safety operator 
with an opportunity to assess whether there are portions of its 
geographic area of responsibility about which it should make special 
arrangements with the Access BPL operator in order to avoid 
interference. The Commission did not address the frequencies used by 
the amateur service on an individual basis, but rather concluded that 
amateur radio frequencies generally do not warrant the special 
protection of frequency exclusion that was afforded frequencies 
reserved for international aeronautical and maritime safety operations.
    21. ARRL observes that slide 21 of the Briarcliff Manor 
presentation predicts the potential for BPL to cause interference to 
mobile operations to be ``high'' to ``very high.'' It further observes 
that the same slide has a table indicating that the interference 
distance to fixed stations would be 62 meters at 2-8 MHz and 400 meters 
at 8-30 MHz in areas where the noise levels were at the International 
Telecommunication Union (ITU) ``residential'' level. It contrasts these 
statements with our findings in the BPL Order that the potential of 
Access BPL systems was ``low'' and observes that in the case of mobile 
communications where a vehicle is close to the power lines, the 
potential for interference will indeed be higher. While the Commission 
again recognize that at some locations (including where nearby antennas 
are located above the height of the power line) the attenuation rate of 
Access BPL emissions will be lower and at other locations it will be 
higher, these levels are consistent with our interpretations that the 
interference potential is low such that it can be managed adequately 
with the additional interference mitigation measures and the ``no 
harmful interference provisions'' of part 15 that are also in our 
rules. In this regard, the distances from a power line to an amateur 
fixed receiver will be sufficiently short that if harmful interference 
were to occur, the recipient could readily identify its source and 
request that it be resolved. The Commission observes that International 
Broadband Electric Communications, Inc. (IBEC), a major operator of 
Access BPL systems, reports (with confirmation by ARRL in its comments) 
that it has been communicating with the local amateurs and emergency 
services in the areas it covers to implement a successful interference 
resolution process. It states that it has been able to resolve 
interference complaints, as they arise, under the framework of the 
existing Access BPL rules. This information provides confirmation of 
the processes and requirements the Commission established, when used in 
practice, are adequate to prevent most cases of harmful interference to 
licensed services, and to resolve quickly any instances of harmful 
interference that do occur.
    22. Spectrum Notching. The rules provide for mitigation of BPL 
interference where it may occur by notching. In the BPL Order and the 
BPL Reconsideration Order, the Commission found that, for frequencies 
below 30 MHz, a 20-dB notch would appropriately address any harmful 
interference that might occur to mobile operations, given both the low 
signal levels allowed under the part 15 emission limits and the fact 
that a mobile transceiver is generally only in one place for a limited 
period and can readily be re-positioned to provide some separation from 
the Access BPL operation.
    23. In its comments, ARRL argues that slide 13 of the Briarcliff 
Manor presentation summary references predictions from the NTIA Phase 1 
Study that show that the noise floor would rise by more than 20 dB at 
nearly all points, and by 30 dB at most points, along a 340-meter 
modeled power line. It also notes that the slide states that in NTIA's 
measurement activities, NTIA took occasional samples of noise power

[[Page 71897]]

along the line with the Access BPL system turned off and found noise 
levels lower than predicted by the ITU for residential areas. ARRL 
therefore contends that the 20-dB standard for the notching requirement 
is insufficient. The Commission initially noted that NTIA's sampling of 
noise power was only at a very limited number of locations and not 
sufficient to serve as the basis for a conclusion that the noise floor 
is lower than the levels recognized by the ITU. Further, there is not 
sufficient information in any of the submissions regarding changes in 
the noise floor to justify a change from our use of the well-
established ITU-recommended levels for the noise floor in different 
environments.
    24. In its November 2010 ex parte submission, ARRL provides 
additional comments that reference several recent domestic and 
international industry and governmental reports/standards to support 
its request for a 35-dB notch of all the amateur frequency bands. These 
documents include: (1) ITU-R Report SM.2158; (2) ITU-T G.9960; (3) IEEE 
P1901-2010; and (4) OFCOM Report on In-Home PLT devices. All of these 
documents mandate or recommend notching of the amateur frequencies. 
ITU-R Report SM.2158 states that the maximum allowable increase in the 
noise floor due to BPL emissions should not exceed 0.5 dB, based on the 
assumption that the fade margin of the amateur service in long distance 
communications is less than 1 dB. Based on this assumption, ARRL argues 
that a notch depth of 34 dB would be required if a 20-dB/decade 
extrapolation of the FCC emission limits is used and a notch depth of 
43 dB would be needed if the existing extrapolation factor of 40-dB/
decade is used.
    25. In re-examining all of the information pertaining to the depth 
of the notching requirement, the Commission now finds that it would be 
appropriate to increase the required notching capability to be 5 dB 
greater than the 20 dB specification it initially adopted. Previously, 
the Commission observed that when operating with a 20-dB notch below 30 
MHz, the maximum allowed emissions from an Access BPL system is 10 
dB[mu]V/m at the part 15 measurement distance of 30 meters, a level 
which is at or only modestly above the noise floor in the HF bands at 
most locations. The Commission's intention was that Access BPL 
emissions in a notched bandwidth would not be significantly greater 
than the background noise at the distances normally used for protection 
against harmful interference from part 15 unlicensed devices. The 
Commission also evaluated the potential for interference at closer 
distances that can occur when conducting mobile communications while 
traveling adjacent to roadside power lines. It observed that when 
extrapolated to values for the typical closest distance of a mobile 
antenna in motion from roadside power lines (approximately 6 meters 
horizontal distance and 8.5 meters vertical distance, for a slant range 
of 10.4 meters) and adjusted for the typical quasi-peak to average 
ratio of 4 dB for BPL devices operating at high duty factor, the part 
15 limit corresponds to a root-mean-squared (RMS) field strength of 44 
dB[mu]V/m for frequencies at or below 30 MHz. A 20 dB reduction would 
limit emissions to 24 dB[mu]V/m. The Commission concluded that given 
the high variability of the noise floor at HF frequencies, where 
increases of as much as 20 dB or more are common, mobile reception of 
relatively weak signals under 24 dB[mu]V/m is generally intermittent 
and not reliable because both the received signal and the ambient noise 
levels vary up and down (the received signal and noise energy levels 
generally do not rise and fall together) as the vehicle moves.
    26. In carefully reviewing the record on this issue, the Commission 
acknowledged ARRL's point that the modeling in the NTIA Phase 1 Study 
predicts that Access BPL emissions on frequencies below 30 MHz that are 
at the part 15 limit would raise the mobile radio noise floor at 15 MHz 
and 25 MHz by 30 dB in 59% of residential locations. After a 20-dB 
notch, the BPL remaining emissions would still produce a noise floor 
increase of about 10 dB for mobile operations in residential locations 
at those frequencies. As the Commission observed in the BPL 
Reconsideration Order, there is considerable variability around the 
median noise level, such that increases of as much as 20 dB are common 
and reduce the reliability of signals at the margin of expected 
reception. While, the Commission continues to believe that the 
significant variability in background noise levels limits the 
reliability of HF signals below 30 MHz such that BPL emissions at a 
level of 24 dB[mu]V/m should not generally be considered harmful 
interference, it also understand that the 20 dB value for noise 
increases due to diurnal and seasonal factors is the maximum expected 
effect and that in many cases the daily variability in the noise floor 
levels will be somewhat less. The Commission have no specific 
information on the distribution of the diurnal and seasonal variability 
of noise floor levels; however, it believes that an increase of 5 dB in 
the required notching capability, or half the 10-dB current margin of 
BPL emissions affecting mobile reception above the residential noise 
floor, according to NTIA's estimates as supported by ARRL, would take a 
more conservative approach and provide protection for amateur mobile 
operations in more instances, while continuing to recognize the 
variability in emissions that limit the service to mobile amateur 
receivers. Given our understanding supported by the assertions in the 
record that most BPL operators are already using notches of at least 25 
dB, the Commission would expect the cost imposed by this requirement to 
be minimal or nil. It finds that the benefits of providing additional 
protection for licensed services outweigh any potential additional 
costs to BPL providers. Such benefits include a more integrated 
environment where BPL devices may share spectrum with licensed users, 
with lesser concerns for potential harmful interference. BPL devices 
bring expanded benefits to electric utility companies by allowing them 
to monitor, and thereby more effectively manage their electric power 
distribution operations. BPL also brings ``last-mile'' delivery of 
broadband services to some rural and underserved areas.
    27. With respect to the new information in ARRL's November 2010 ex 
parte submission, first the Commission is not persuaded that a 0.5 dB 
increase in the noise floor as used in the ITU-R Report SM.2158 is a 
reasonable assumption for the numerous reasons it stated with respect 
to the significant variability in background noise levels at HF 
frequencies. Further, it appears that the 0.5 dB number was used in the 
ITU Report without any discussion, analysis or other explicit 
rationale. The Commission further noted that in its June 2011 ex parte 
submission, ARRL mentions that ITU-R Recommendation SM.1879, which 
refers to the above report, does recommend that stations operating in 
the Amateur Service be protected t*** level such that noise at the 
protected station is not increased by more than 0.5 dB. Although ARRL 
provided calculations to relate the 0.5 dB increase in the noise floor 
with the part 15 limits to arrive at its requested 35-dB notch number, 
it again did not provide a rationale for using a 0.5 dB increase in the 
noise floor as the protection criterion at HF frequencies. With the 
exception of ITU-R Report SM.2158, the reports/standards submitted by 
ARRL in its November 2010 ex parte comments do not include

[[Page 71898]]

any analysis that shows that 35 dB or some other figure is the proper 
level of notching needed to protect amateur operations, but rather 
simply state as their recommendations and requirements a notching depth 
that existing BPL equipment can meet. The Commission also recognizes 
the ARRL's observation in its June 2011 ex parte submission that in the 
IEEE P1901-2010 standard there is a normative requirement for a 30-dB 
notch depth for the FFT OFDM (HomePlug) technology. While this 
voluntary industry standard is apparently being used by manufacturers 
of HomePlug In-House BPL equipment, it is more stringent than is 
necessary for our regulatory purposes and in any case does not apply to 
the Access BPL applications at issue herein. The Commission also does 
not find persuasive ARRL's argument that deeper notching can be 
implemented without adverse impact on the data rates of BPL technology. 
In this regard, the testing on which ARRL bases this claim was on In-
House rather than Access BPL equipment and in any case our principal 
concern is with imposing regulation that is more restrictive than 
necessary rather than simply minimizing the impact that such regulation 
might have on some aspect of BPL equipment or its operation. While the 
Commission duly note the Republic of Korea's decision to require 
permanent notching of the amateur bands, the relevance of that 
determination by that country's regulatory body at that time to our 
present consideration is not readily apparent, and ARRL provides no 
information regarding either the radio environment or the regulatory 
objectives and standards that informed that decision by which the 
Commission might consider how those considerations might affect our own 
decision making.
    28. The Commission recognizes that one of the documents referenced 
by ARRL, IEEE P1901-2010, is an industry standard for both Access and 
In-House BPL equipment authored by nearly a hundred entities that 
include BPL service and equipment providers and that this standard 
describes a 35-dB spectrum notching for compatibility with amateur 
radio services that can be supported by a type of BPL technology known 
as wavelet OFDM, as elucidated by UTC. Further, as ARRL submits, its 
scrutiny of systems listed in the BPL database indicates that existing 
BPL systems in the U.S. are generally notching the entirety of the HF 
amateur allocations, using equipment capable of notch depths of at 
least 35 dB. Thus, it appears that many BPL systems now in operation 
may be voluntarily observing the notch depth and band avoidances that 
ARRL is requesting. While those industry practices are consistent with 
the ARRL's goals in this matter, the Commission nonetheless finds they 
are more stringent than are justified from a regulatory standpoint. In 
this regard, the Commission does not find that an increase in the 
required notching capability to a level above 25 dB is needed to 
protect against interference to amateur or any other licensed services. 
To require that all systems adhere to a de facto industry 35-dB 
notching standard would unnecessarily constrain BPL operators, as 
stated by UTC, and equipment manufacturers who might choose to design 
for a different level of operation that would comply with the notching 
level the Commission has determined will provide adequate protection. 
Further, to require that all of the amateur bands be notched would 
unnecessarily restrict BPL operations in areas/locations where no 
amateur operations are present that could receive interference.
    29. The Commission sees no statistically-valid support for ARRL's 
position that the ambient noise levels have become so low as to 
contradict our conclusion here that a 25-dB notch is generally 
sufficient to protect licensed services. Further, for fixed stations, 
if a 25-dB notch is not sufficient to resolve observed harmful 
interference or other steps to resolve the interference are not 
successful, under Sec.  15.5(c) of the rules, the operator is then, 
upon notification by a representative of the Commission, required to 
cease operation until the interference is corrected. In such cases, the 
interference might perhaps be resolved by using new equipment that 
includes a filter with a notch capability greater than 25 dB. The 
Commission believes, however, that the new 25-dB notching requirement 
will be sufficient to resolve the great majority of cases of harmful 
interference that might occur and therefore do not see a need to 
require that Access BPL systems routinely use equipment with greater 
notching capability.
    30. In changing the notching level to 25 dB, the Commission is 
aware that Access BPL operators have already installed equipment with 
20-dB notching capability in compliance with the rules and that there 
is some inventory of equipment built to that standard which has not yet 
been installed. While it believes that the greater level of protection 
provided by our rule change is prudent in the long term, it has not 
observed any cases to date where the notching afforded by existing 
equipment has not been adequate to resolve interference. Accordingly, 
given the limited number of devices already deployed and manufactured, 
the Commission will not require their replacement or prohibit their 
installation for replacement or in new constructions. In order to 
afford manufacturers time to redesign their equipment to comply with 
the new, more conservative 25-dB notching requirement, the Commission 
will allow an 18-month period from the date this action is published in 
the Federal Register before the requirement becomes effective.
    31. In its reply comments, ARRL submits that IBEC did not resolve 
interference complaints to amateur fixed stations by doing what the 
existing BPL rules require, other than compliance with the general part 
15 requirement to correct any harmful interference. It states that 
instead, IBEC has avoided or resolved the interference by doing two of 
the things that ARRL has requested as modifications to the existing BPL 
rules: (1) IBEC avoided the use of Amateur bands in its installations, 
and (2) it has used state-of-the-art notch depths of 35 dB. The 
Commission observes that avoiding a frequency band where interference 
could occur is certainly an option that is contemplated under the 
rules. Using a notching capability with attenuation of greater than 
that required in the rules where needed is also consistent with the 
general requirement in part 15 rules that a device not cause harmful 
interference. The Commission does not, however, find the fact that 
equipment which can provide 35-dB notching capability is now available 
and IBEC's choice to use such equipment to be indicative that it should 
require that level of notching capability in all instances. Rather, 
while the rules will now require a notching capability of at least 25 
dB, that level of attenuation will only be deemed sufficient for 
resolving harmful interference in the case of mobile operations; the 
system operator is still responsible for resolving harmful interference 
to fixed operations if the 25-dB notch capability is used and the 
interference remains. Under the notching rules the Commission adopted, 
a BPL system operator has the flexibility to install a notching 
capability greater than 25 dB or to implement other measures for 
resolving harmful interference in cases where the 25-dB notch is not 
sufficient. In this regard, IBEC did, in fact, take the steps required 
under Sec.  15.611(c) of the rules--it configured its systems to be 
capable of remotely reducing power by 35 dB and adjusting operating 
frequencies to avoid site-specific, local use of the same

[[Page 71899]]

frequencies by licensed radio operations. A different operator might 
have chosen an alternative approach for complying with this rule.

Preliminary Documents Released in July 2009

    32. Notwithstanding ARRL's contentions, the Commission did consider 
the information in the presentations in the BPL Order and in the 
formulation of our rules for regulating interference from Access BPL 
emissions. There are no new facts, information, or interpretations in 
those presentations or in ARRL's comments that are inconsistent with 
the Commission's previously stated understandings and findings. These 
presentations, as well as other information in this proceeding, show 
that Access BPL operations can raise the RF noise level to levels above 
the noise floor such that they can cause interference to amateur 
operations in the close vicinity of power lines on which the BPL 
signals are carried. As the presentations show, the area of 
interference is essentially limited to distances close to and along the 
power lines. While some interference is possible at locations close to 
the power line, the Commission believes that in the great majority of 
locations, interference will not occur to radio services because either 
propagation conditions limit the range of the Access BPL emissions or 
there is no licensed amateur station present and operating on the 
frequencies on which such emissions appear. The Commission sees no need 
to require an Access BPL operator to reduce emissions below the part 15 
limits where there is no potential for interference. In addition, it 
requires that a database of Access BPL systems be established to allow 
amateur operators to identify BPL operations in their area before the 
systems commence operation so that they have an opportunity to alert 
the BPL operator of their presence before the system is activated. The 
Commission addressed specific points in ARRL's arguments in paragraphs 
52 through 56 of this Second Report and Order.
    33. The Commission also noted that throughout this proceeding and 
as new equipment that allows BPL operators to better manage their 
frequency use at specific locations has become available, it observed 
BPL operators taking active steps to locate and avoid interference to 
amateur operators. Given that identification and resolution of harmful 
interference can involve expenditures of staff time and resources for 
Access BPL providers and possibly the temporary disruption of service 
to their subscribers, these providers have a strong incentive to take a 
priori steps to ensure that they avoid causing interference to the 
local radio services, including amateurs. Notwithstanding the 
occasional interference that was found by amateurs from the trial 
systems that were operated during the early phases of BPL development 
such as those examined in the staff presentations (and which, in some 
cases, were operating with emissions levels that were found to exceed 
the part 15 limits by amounts ranging from 1 to 4 dB), the Commission 
observed, as described by IBEC and CURRENT in their comments, that 
Access BPL operators are taking effective steps as contemplated in the 
BPL Order to avoid interference to amateur and other licensed services, 
including working with local amateur operators. Moreover, our own 
internal records on enforcement matters show only one complaint of 
interference from Access BPL to fixed licensed operations; that 
complaint was submitted recently and is under investigation at this 
time. In summary, the Commission sees no new information or reasoning 
in ARRL's submissions or other information regarding the three 
additional staff presentations in the preliminary materials released in 
July 2009 that would warrant changing the current rules and, 
specifically, it sees no need to further restrict the operations of BPL 
systems to protect licensed services.

Measurement Distance Extrapolation Issues

The Extrapolation Factor

    34. Overview. In the BPL Order, the Commission set forth guidelines 
for measurement of the emissions from Access BPL systems. These 
guidelines, inter alia, specify that emissions from Access BPL devices 
operating below 30 MHz are to be measured for compliance with the 
radiated emissions limits in Sec.  15.209 of the rules. Those limits 
are based on measurements made at 30-meters horizontal (lateral) 
distance from the device under test. However, for practical reasons 
associated with measurement in the field, the Access BPL measurement 
guidelines recommend that measurements should normally be performed at 
a horizontal separation distance of 10 meters from the overhead power 
line, and they also indicate that measurements can be performed at 3 
meters if necessary because of ambient emissions, safety or practical 
considerations. The field strength of radiated emissions does, however, 
decrease with increasing distance from the emitter due to propagation 
loss. Because of this attenuation with distance, the field strength of 
emissions from a device measured at the 3-meter or 10-meter distances 
specified in the guidelines will generally be higher than those 
measured at the 30-meter distance on which the emission standard is 
based. In order to apply the emissions standard consistently, the 
measurement results must be adjusted to account for distance 
attenuation when measurements are made at a distance other than 30 
meters.
    35. The Commission specified distance extrapolation factors to 
convert the BPL emissions measurements for frequencies below and above 
30 MHz to appropriate values for tests made at the 3-meter and 10-meter 
distances recommended in the BPL measurement guidelines. For BPL 
operations on frequencies below 30 MHz, the frequency range at issue 
here, some commenters in the initial phase of this proceeding, 
including ARRL, recommended the use of an extrapolation factor of 20 
dB/decade, while others recommended an extrapolation factor of 40 dB/
decade. The Commission concluded in the BPL Order that ``[g]iven the 
lack of conclusive experimental data pending large scale Access BPL 
deployments,'' it would ``continue the use of the existing part 15 
distance extrapolation factors'' specified in the rules, i.e., 40 dB/
decade for frequencies below 30 MHz and 20 dB/decade for frequencies at 
or above 30 MHz, but with the distance measured as the slant-range 
distance from the overhead power line to the center of the measurement 
antenna rather than horizontal (lateral) distance from the nearest 
point of the overhead power line carrying the BPL signals to the center 
of the measurement antenna, as illustrated in Figure 1 of Appendix C, 
of this Second Report and Order. This is the horizontal (lateral) 
distance between the center of the measurement antenna and the vertical 
projection of the overhead power line carrying the BPL signals down to 
the height of the measurement antenna when measurements are taken at a 
point that is perpendicular to the power lines. It further stated that 
``if new information became available that alternative emission limit/
distance standards or extrapolation factors would be more 
appropriate,'' it would revisit this issue at another time.
    36. ARRL filed a petition for reconsideration of the Commission's 
decision in the BPL Order to use 40 dB/decade as the extrapolation 
factor for frequencies below 30 MHz. In support of its argument that an 
extrapolation factor of 20 dB/decade should be used, ARRL also 
submitted, through ex parte

[[Page 71900]]

comments, reports on three studies conducted by the United Kingdom's 
Office of Communications (OFCOM) and a standard by the Special 
International Committee on Radio Interference (CISPR) regarding 
emission measurements for BPL systems and a proposal for a sliding 
scale extrapolation factor based on a 1996 CISPR standard. The first 
OFCOM study, ``OFCOM, Ascom PLT Measurements in Winchester (May 11, 
2005)'' (Winchester Study) reported measurements of an underground 
Access BPL trial system in Winchester, United Kingdom. In that study, 
OFCOM concluded that the electromagnetic field attenuates at a rate 
between 20 dB and 25 dB/decade at this BPL installation. The second 
OFCOM study, ``OFCOM, DS2 PLT Measurements in Crieff (May 11, 2005)'' 
(Crieff DS2 Study) reported measurements of an Access BPL trial system 
in Crieff, United Kingdom. That study concentrated only on the benefits 
of programmable notches in the equipment and did not provide any data 
on distance extrapolation. The third OFCOM study, ``OFCOM, Amperion PLT 
Measurements in Crieff (May 11, 2005)'' (Crieff Amperion Study) 
reported measurements of an overhead, pole-mounted Access BPL trial 
system, also in Crieff, United Kingdom. In the Crieff Amperion Study, 
OFCOM concluded that the emitted field attenuates at a rate of 28 dB/
decade.
    37. On reconsideration, the Commission found the OFCOM studies and 
the CISPR standard unpersuasive in that there was no ``new'' or 
convincing information not already known, and affirmed its decision to 
use the existing part 15 distance extrapolation factor of 40 dB/decade 
attenuation rate in the measurements of BPL emissions on frequencies 
below 30 MHz.
    38. In ARRL v. FCC, supra, the court found that the Commission did 
not offer a reasoned explanation for its dismissal of empirical data 
that was submitted ex parte by ARRL, i.e., the three OFCOM studies and 
additional ARRL analysis intended to suggest that an extrapolation 
factor of 20 dB/decade may be more appropriate for Access BPL. The 
court ordered the Commission either to ``provide a reasoned 
justification for retaining an extrapolation factor of 40 dB/decade for 
Access BPL systems sufficient to indicate that it has grappled with the 
2005 studies, or adopt another factor and provide a reasoned 
explanation for it.''
    39. The Commission acted to respond to the court's directive in the 
RFC/FNPRM. Therein, it provided a more detailed explanation of its 
reasons for selecting 40 dB/decade as the extrapolation factor for 
frequencies below 30 MHz and in particular why it does not believe that 
the studies and technical proposal submitted earlier by ARRL provide 
convincing information that it should use an extrapolation factor that 
is different from (and, specifically, less than) 40 dB/decade as 
required in the second element of the court's directive in ARRL v. FCC. 
In summary of that explanation, the Commission stated that:
    i. There were no significant studies that examined the very large 
number of measurements that would be needed to address the different 
site characteristics that affect the attenuation of emissions below 30 
MHz;
    ii. The studies submitted by ARRL in its 2005 ex parte provided 
only anecdotal information on two different types of installations 
(overhead and underground) from two single sites and also had certain 
methodological shortcomings; and
    iii. With respect to its proposal for a sliding scale extrapolation 
factor, ARRL did not provide an explanation as to how its formula was 
derived or how to use it to determine the extrapolation factor, nor did 
it provide a rationale for selecting such a formula or information as 
to the relationship between the performance of emissions from BPL 
technology and the specifications for reduction of power line noise 
adopted in the standard.
    40. In the RFC/FNPRM, the Commission also observed that since its 
adoption of the BPL Reconsideration Order, reports had become available 
on two new technical studies addressing attenuation of BPL emissions 
with distance, one by NTIA in October 2007 that described a second 
phase of its simulation study on the potential for interference from 
Access BPL systems (NTIA Phase 2 Study) and the other by the Federal 
Republic of Brazil (Brazil Study) in June 2008 that presented the 
results of a measurement study of BPL emissions. In addition, it noted 
that the IEEE working group on power line communications technology 
electromagnetic compatibility was working on a standard for EMC testing 
and measurements methodology for BPL equipment and installations (IEEE 
P1775/D2) that included a provision for determining extrapolation 
(distance correction) factors on a site-by-site basis using in situ 
measurements as part of its work on that standard.
    41. In view of these new studies and consistent with its stated 
intention in the BPL Order to revisit the extrapolation factor if new 
information became available and the opportunity provided by the 
Court's remand of the extrapolation factor, the Commission decided to 
conduct further rulemaking to review its decision on the extrapolation 
factor. It requested that interested parties submit additional comment 
and information on the BPL extrapolation factor and specifically asked 
that such comment and information address (1) The three studies and 
proposal for a sliding scale extrapolation factor submitted previously 
by ARRL as part of its ex parte filing of July 8, 2005 in this 
proceeding, (2) the NTIA Phase 2 and Brazil studies with respect to 
their findings on the extrapolation factor for BPL systems, and (3) the 
existing slant-range method as it pertains to the effective field 
attenuation rate in a horizontal distance context. The Commission 
further requested submission of any other new empirical studies or 
information that may provide information regarding the BPL distance 
attenuation extrapolation factor. The Commission stated that its goal 
in this review is to provide BPL measurement procedures that will 
adequately ensure compliance with the Section 15.209 emissions standard 
for emissions at or below 30 MHz without placing unfair or undue 
compliance burdens on equipment manufacturers and users. In conducting 
this review, the Commission indicated that initially it continued to 
believe the existing 40 dB/decade extrapolation factor, in conjunction 
with the slant-range distance method, was reasonable and appropriate 
for adjusting measurements of BPL emissions on frequencies below 30 
MHz.
    42. The Commission also recognized that there is considerable 
variability around the 40 dB/decade value at different sites. The 
result of this variability is that the actual attenuation at some sites 
could be less than 40 dB/decade and using the current extrapolation 
factor at such sites could produce an adjusted measurement that would 
be less than the level that would be measured at the standard 30-meter 
measurement distance specified in Sec.  15.209 of the Commission's 
rules. The Commission therefore requested comment on whether it would 
be desirable to modify the value of the BPL extrapolation factor to be 
30 dB/decade or some other value. It observed that extrapolated 
emission levels based on a 30 dB/decade extrapolation factor when 
applied to slant distance would be comparable to the extrapolated 
emission levels based on a 20 dB/decade extrapolation factor applied to 
horizontal (lateral) distance. Recognizing that reliance on a 30 dB/

[[Page 71901]]

decade extrapolation factor could increase the compliance burden for 
BPL equipment and systems that are tested at locations where the 
attenuation rate is in fact in the range of 40 dB/decade or greater, 
the Commission clarified that in all cases, measurements of Access BPL 
equipment and systems will be allowed to be made at the 30-meters 
distance specified in Sec.  15.209 of the Commission's rules and that 
where possible, the