Broadband Power Line Systems, 1360-1379 [05-246]

Agencies

• FEDERAL COMMUNICATIONS COMMISSION

[Federal Register Volume 70, Number 5 (Friday, January 7, 2005)]
[Rules and Regulations]
[Pages 1360-1379]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-246]


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FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 15

[ET Docket No. 04-37 and ET Docket No. 03-104; FCC 04-245]


Broadband Power Line Systems

AGENCY: Federal Communications Commission.

ACTION: Final rule.

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SUMMARY: This document adopts new requirements and measurement 
guidelines for a new type of carrier current system that provides 
access to broadband services using electric utility companies' power 
lines. This new technology offers the potential for the establishment 
of a significant new medium for extending broadband access to American 
homes and businesses. Given that power lines reach virtually every 
residence and business in every community and geographic area in this 
country, Access BPL service could be made available nearly everywhere. 
This new broadband delivery medium could also serve to introduce 
additional competition to existing cable, DSL, and other broadband 
services. We believe these actions will promote the development of BPL 
systems by removing regulatory uncertainties for BPL operators and 
equipment manufacturers while ensuring that licensed radio services are 
protected from harmful interference.

DATES: Effective February 7, 2005, except for Sec. Sec.  15.615(a) 
through (e) which contain information collection requirements that are 
not effective until approved by the Office of Management and Budget. 
The FCC will publish a document in the Federal Register announcing the 
effective date for those sections.

Final Paperwork Reduction Act of 1995 Analysis

    This document contains modified information collection 
requirements. The Commission, as part of its continuing effort to 
reduce paperwork burdens, invites the general public to comment on the 
information collection requirements contained in this R&O as required 
by the Paperwork Reduction Act of 1995, Public Law 104-13. Public and 
agency comments are due March 8, 2005.

ADDRESSES: Comments on the information collection requirements should 
be addressed to the Office of the Secretary, Federal Communications 
Commission, 445 12th Street, SW., Washington, DC 20554. In addition to 
filing comments with the Secretary, a

[[Page 1361]]

copy should be submitted to Leslie Smith, Federal Communications 
Commission, Room 1-C804, 445 12th Street, SW., Washington, DC 20554, or 
via Internet to Leslie.Smith@fcc.gov, and to Kristy L. LaLonde, OMB 
Desk Officer, 10234 NEOB, 725 17th Street, NW., Washington, DC 20503 or 
via the Internet to Kristy--L.--LaLonde@omb.eop.gov or via fax at (202) 
395-5167.

FOR FURTHER INFORMATION CONTACT: Anh Wride, Office of Engineering and 
Technology, (202) 418-20577, e-mail: Anh.Wride@fcc.gov, TTY (202) 418-
2989.

SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Report 
and Order, ET Docket No. 04-37 and ET Docket No. 03-104, FCC 04-245, 
adopted October 14, 2004, and released October 28, 2004. 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, Qualex 
International, 445 12th Street, SW., Room CY-B402, Washington, DC 
20554. The full text may also be downloaded at: www.fcc.gov. Alternate 
formats are available to persons with disabilities by contacting Brian 
Millin at (202) 418-7426 or TTY (202) 418-7365.

Congressional Review Act

    The Commission will send a copy of this Report & Order, in a report 
to be sent to Congress and the General Accounting Office pursuant to 
the Congressional Review Act, see 5 U.S.C. 801(a)(1)(A).

Summary of Report and Order

    1. In the Report and Order, the Commission adopted new rules for 
Access Broadband over Power Line (Access BPL) systems, a new type of 
carrier current technology that provides access to high speed broadband 
services using electric utility companies' power lines. This new 
technology offers the potential for the establishment of a significant 
new medium for extending broadband access to American homes and 
businesses. Given that power lines reach virtually every residence and 
business in every community and geographic area in this country, Access 
BPL service could be made available nearly everywhere. This new 
broadband delivery medium could also serve to introduce additional 
competition to existing cable, DSL, and other broadband services. In 
addition, the National Telecommunications and Information 
Administration (NTIA) has undertaken a significant effort to both study 
Access BPL technology, including its operating characteristics and 
interference potential, and to make specific recommendations to the 
Commission for policies to encourage its implementation and to manage 
its interference potential. Our staff has worked closely with NTIA on 
this matter and the policy decisions and rules we adopted reflect that 
cooperation and embody many of NTIA's recommendations.
    2. Along with NTIA, we recognize the concerns of authorized radio 
service users in both the private and government sectors for the need 
to ensure that radio frequency (RF) energy from BPL signals on power 
lines does not cause harmful interference to licensed radio services. 
The record and our investigations indicate that BPL network systems can 
generally be configured and managed to minimize and/or eliminate this 
harmful interference potential. Our goals in developing the rules for 
Access BPL are to provide a framework that will both facilitate the 
rapid introduction and development of BPL systems and protect licensed 
radio services from harmful interference. Specifically, we adopted: new 
operational requirements for Access BPL to promote avoidance and 
resolution of harmful interference; new administrative requirements to 
aid in identifying Access BPL installations; and specific measurement 
guidelines and certification requirements to ensure accurate and 
repeatable evaluations of emissions from Access BPL and all other 
carrier current systems. We believe these actions will promote the 
development of BPL systems by removing regulatory uncertainties for BPL 
operators and equipment manufacturers while ensuring that licensed 
radio services are protected from harmful interference.

Part 15--Existing Rules

    3. Carrier current systems use alternating current (AC) electric 
power lines to carry communications by coupling very low power RF 
signals onto the AC electric wiring. Traditionally, these systems have 
included amplitude modulated (AM) radio systems on school campuses and 
devices intended for the home, such as intercom systems and remote 
controls for electrical appliances and lamps. Carrier current systems 
operate on an unlicensed basis under part 15 of the Commission's rules. 
As a general condition of operation, part 15 devices may not cause 
harmful interference to authorized radio services and must accept any 
interference that they receive.
    4. The part 15 rules for carrier current systems currently specify 
radiated and conducted emission limits for devices operating below 30 
MHz and above 30 MHz. Carrier current systems operating from 9 kHz to 
30 MHz are subject to radiated emission limits on emissions from any 
part of the wiring or power network connected to the RF power source. 
For carrier current systems that contain their fundamental emission 
within the standard AM broadcast band of 535 to 1705 kHz and are 
intended to be received using standard AM broadcast receivers, there is 
no limit on conducted emissions. All other carrier current systems 
operating below 30 MHz are subject to a conducted emission limit only 
within the AM broadcast band. Carrier current devices operating above 
30 MHz must meet the radiated emission limits of Sec.  15.109(a), (b) 
or (g) for digital devices, which are further divided into two types. 
Class A equipment includes devices marketed for use in a commercial, 
industrial or business environment, excluding devices which are 
marketed for use by the general public or are intended to be used in 
the home. Class B equipment includes devices marketed for use in a 
residential environment, notwithstanding use in commercial, business 
and industrial environments. The rules require Access BPL systems to 
comply with the limits for Class A or B devices depending on whether 
they are marketed for use in a commercial, industrial or business 
environment on the one hand or for use by the general public or in the 
home on the other. Under this Class A/Class B regime, Access BPL 
systems that operate on medium voltage lines external to residential 
environments are considered Class A devices. Carrier current devices 
that do not operate on frequencies below 30 MHz are subject to the 
general conducted emission limits below 30 MHz. The existing part 15 
rules also address power line carrier systems, which are low-speed 
carrier current systems operating between 10 kHz and 490 kHz, used by 
an electric public utility entity for protective relaying, telemetry, 
etc., for general supervision of the power system. Because of their 
specialized use and operating frequency range, power line carrier 
systems are not subject to specific emission limits as are general 
carrier current systems.
    5. The Commission believes that the widespread introduction of 
Access BPL service would further our goals for broadband service 
consistent with the challenges indicated. This new

[[Page 1362]]

technology offers the potential to give rise to a major new medium for 
broadband service delivery. Services provided on Access BPL could offer 
high speed Internet and data communications that compete with, 
complement, or extend the broadband services provided on existing 
media. Given the ubiquitous nature of the electric power network, 
Access BPL could conceivably also offer these services to virtually 
every element of the broadband market, including residential, 
institutional, and commercial users. In addition, it is possible that 
Access BPL could provide a means to expedite the availability of 
broadband Internet service to consumers and business in rural and other 
underserved areas. We also find that encouraging the deployment of the 
technology in the United States will support globalization of products 
and services, promote continued U.S. leadership in broadband 
technology, and bring important benefits to the American public.
    6. The Commission understand the significant concerns of licensed 
radio service users about the potential for Access BPL services to 
cause harmful interference to their operations. It is our intention to 
ensure that Access BPL operations do not become a source of harmful 
interference to licensed radio services. Based on extensive research, 
analyses, and practical experience, the Commission also continues to 
believe that the interference concerns of licensed radio users can be 
adequately addressed and that Access BPL systems will be able to 
operate successfully on an unlicensed, non-harmful interference basis 
under the part 15 model. In this regard, we find that the harmful 
interference potential from Access BPL systems operating in compliance 
with the existing part 15 emission limits for carrier current systems 
is low in connection with the additional rules we adopted. From the 
information provided by our field tests, the tests conducted by NTIA, 
theoretical predictions by NTIA and ARRL, and experience of the several 
tests of Access BPL systems, we observe that the potential for any 
harmful interference is limited to areas within a short distance of the 
power lines used by this technology. As emphasized by NTIA's Phase 1 
study and comments, interference can be rapidly eliminated through 
various means should it occur. We pointed out to the individual 
amateurs commenting in this proceeding that the definition of ``harmful 
interference'' as used in Sec.  15.5 of the rules is set forth in Sec.  
2.1 of the rules. We disagree with ARRL's position that there is no 
reason to act now in this proceeding and that we should delay our 
decision on rules for Access BPL to provide more time to develop rules 
to prevent this technology from causing harmful interference. As 
indicated, the broadband service capabilities of Access BPL systems 
offer important opportunities for establishing a new medium for 
broadband access and for introducing new competition in the broadband 
market. We believe that it is important to set forth rules that will 
promote this service now, rather than delay. In addition, the record 
provided in response to the Inquiry and the NPRM, including the 
extensive studies conducted by NTIA, is more than sufficient to assure 
us that the rules we adopted will adequately protect licensed services 
from harmful interference. While some cases of harmful interference may 
be possible from Access BPL emissions at levels up to the part 15 
limits, we agree with NTIA that the benefits of Access BPL service 
warrant acceptance of a small and manageable degree of interference 
risk.
    7. As stated in the NPRM, we believe 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 
potential for increased harmful interference that may arise. Moreover, 
the Commission continue to believe that cases where interference may 
occur or where its possible occurrence would impact critical services 
can be addressed through additional regulatory measures. These 
additional measures will generally require Access BPL operators to 
reduce emissions or avoid operation on certain frequencies in order to 
protect licensed services, to use equipment that can alter its 
operation by changing operating frequencies to eliminate interference, 
to make available information that will assist the public in 
identifying locations where Access BPL operations are present, and to 
provide notice to radio users before commencing local BPL operations. 
In this way, the new rules provide effective means for preventing any 
interference and will ensure that any instances of interference that 
may occur can be quickly identified and resolved. We emphasize that 
Access BPL systems will continue be treated as unlicensed part 15 
devices and as such will be subject to the conditions that they not 
cause harmful interference and that they cease operation if they do 
cause such interference, as required by our rules. As discussed in 
paragraph 50, of the Report and Order, except for a few specific 
frequencies that are reserved for international aeronautical safety 
operations, we do not believe that excluding BPL operations from 
frequencies used by any specific service, such as the low VHF TV bands, 
is necessary or appropriate. Rather, we believe requiring BPL equipment 
to have the capability to avoid any locally used frequency is the most 
effective approach to ensuring that harmful interference to licensed 
operations is avoided.
    8. The Commission is amending its part 15 rules with changes 
intended to facilitate the deployment of Access BPL technology while 
protecting licensed users of the spectrum. Specifically, we are: 
defining Access BPL for purposes of our rules; maintaining the existing 
part 15 emission limits for carrier current systems for Access BPL; 
requiring that Access BPL devices employ adaptive interference 
mitigation techniques; requiring that Access BPL system operators 
provide information on the areas where their systems are installed and 
other technical parameters in a central data base that would be 
accessible by the public; and adopting specific measurement guidelines 
for both Access BPL and other carrier current systems to ensure that 
measurements are made in a consistent manner and provide for repeatable 
results in determining compliance with our rules.

Definition of Access BPL

    9. The Commission adopted a modified version of the proposed 
definition of Access BPL that includes changes as suggested by the 
commenting parties. In this regard, we agree that the definition of 
Access BPL should not include the low-speed power line carrier systems 
used by electric utilities as defined in our rules. Transmissions on 
these systems have very short duty cycles that pose very low 
interference potential as opposed to the constant operation that 
characterizes Access BPL. We also agree that the definition for Access 
BPL should limit the low frequency cut-off to above 1.705 MHz, which is 
the upper frequency for the AM broadcast band. We agree that the 
definition for Access BPL should not include power lines located within 
a customer's premises or within a utility's own premises. These lines 
generally carry low voltage power, are not under the ownership or 
integral control of the power service operator, are isolated from the 
medium voltage lines by a distribution transformer such that a bypass 
device must be used to reach them with BPL signals, and pose lower 
potential as sources of interference because their emissions are 
attenuated

[[Page 1363]]

by the structure in which they are located. We also see no need to 
limit ownership or control of BPL operations to electric utility 
operators. We believe that an independent BPL provider can take the 
same steps and precautions as an electric utility operator in working 
with its equipment vendor, the power system, and licensed radio users 
to ensure that an Access BPL system does not cause harmful interference 
and to resolve any interference. We also see no need to specifically 
mention aerial or underground lines in the definition. Furthermore, we 
note that the record in this proceeding only addresses Access BPL 
systems operating over medium voltage and low voltage lines. Because 
the high voltage lines are located physically higher, can carry very 
high voltages, and have different configurations as well as 
characteristics with respect to potential harmful interference, we are 
excluding them from the definition for Access BPL at this time. Access 
BPL systems intended for high voltage lines can however operate under 
the requirements for experimental licensing in part 5 of the Commission 
rules.
    10. We therefore are amending Sec.  15.3 of the rules to include 
the following definition for Access BPL:

    Access Broadband Over Power Line (Access BPL). A carrier current 
system installed and operated on an electric utility service as an 
unintentional radiator that sends radio frequency energy on 
frequencies between 1.705 MHz and 80 MHz over medium voltage lines 
or low voltage lines to provide broadband communications and is 
located on the supply side of the utility service's points of 
interconnection with customer premises. Access BPL does not include 
power line carrier systems as defined in Sec.  15.3(t) of this part 
or In-House BPL systems as defined in Sec.  15.3(gg) of this part.

    11. While we are not generally addressing rules for In-House BPL 
systems, except for measurement procedures, we do find it useful and 
appropriate to set forth a definition of such systems in the rules. As 
NTIA and Southern point out, specifying a definition of In-House BPL 
systems will fully define all forms of BPL and help to clarify the 
differences between Access BPL and In-House systems. We find that the 
definition of In-House BPL suggested by NTIA properly identifies these 
systems. Accordingly, we adopted the following definition for In-House 
BPL:

    In-House Broadband Over Power Line (In-House BPL). A carrier 
current system, operating as an unintentional radiator, that sends 
radio frequency energy to provide broadband communications on 
frequencies between 1.705 MHz and 80 MHz over low-voltage electric 
power lines that are not owned, operated or controlled by an 
electric service provider. The electric power lines may be aerial 
(overhead), underground, or inside walls, floors or ceilings of user 
premises. In-House BPL devices may establish closed networks within 
a user's premises or provide connections to Access BPL (as defined 
in Sec.  15.3(ff) of this part) networks, or both.

    We also encourage industry efforts to develop standards for In-
House BPL systems and devices that are complementary to and compatible 
with Access BPL operations.
    12. Access BPL Systems Above 80 MHz. We agree with Corridor that 
Access BPL systems operating in higher regions of the spectrum, such as 
the Corridor Access BPL system at 5.8 GHz, should not be subject to the 
rules adopted herein for Access BPL systems operating in the HF and low 
VHF spectrum. We find that the record in this proceeding does not 
provide sufficient information regarding Access BPL operating in 
spectrum above 80 MHz, hence a decision regarding this type of Access 
BPL technology cannot be effectively rendered at the present time; 
however, Access BPL systems not covered in the above definition are 
subject to existing applicable part 15 rules for carrier current 
systems. However, we will monitor the development of Access BPL systems 
that operate on frequencies above 80 MHz and may consider additional 
requirements for Access BPL systems operating above 80 MHz in a future 
rulemaking if appropriate.

Emission Limits

    13. General Emission Limits. The Commission continues to believe 
that it is appropriate to apply the existing part 15 radiated emission 
limits to Access BPL systems. We are not persuaded by the arguments of 
ARRL and others representing licensed spectrum users that the current 
emission limits are insufficient to limit the general interference 
potential of these systems. The 0 dB[mu]V/m limit suggested by the ARRL 
is typically below the noise floor in the HF and low VHF bands and 
would be unnecessarily and prohibitively restrictive for Access BPL 
operators. Along with NTIA, we conclude that the current emission 
limits will restrict Access BPL systems to very low emitted power 
levels in comparison to the signals of licensed radio operations. 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 they occupy. In fact, in most cases the level of emissions 
from Access BPL systems will be at or close to the noise floor at 
distances beyond a hundred meters of an installed power line. We 
recognize 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. We believe that those situations can be addressed through 
interference avoidance techniques by the Access BPL provider such as 
frequency band selection, notching, or judicious device placement; the 
rules we are specifying facilitate such solutions. We do not see 
evidence that BPL operation will significantly contribute RF energy to 
generally raise the background noise level. In addition, because power 
lines inherently can radiate significant noise emissions as noted by 
NTIA and ARRL, good engineering practice is to locate sensitive 
receiver antennas as far as practicable from power lines. This practice 
will also help prevent interference from Access BPL emissions. In fact, 
as stated by NTIA, power line noise emissions at frequencies up to 800 
MHz may actually be reduced as Access BPL systems are deployed. 
Furthermore, we see no need to impose a strict band-pass filtering on 
Access BPL, and we deny Echelon's request in this regard.
    14. Although we agree with ARRL that Access BPL on overhead lines 
is not a traditional point-source emitter, we do not believe that 
Access BPL devices will cause the power lines to act as countless miles 
of transmission lines all radiating RF energy along their full length. 
First, the part 15 emission limits for carrier current systems have 
proven very effective at controlling interference from such systems. 
Also, for the reasons indicated by PPL Telcom, we believe that the 
design and configuration of Access BPL systems will be inconsistent 
with the development of cumulative emissions effects for nearby 
receivers. Moreover, the NTIA Phase 1 Study and our own field 
measurements of Access BPL installations indicate that these systems 
are not efficient radiators, nor are their emissions cumulative such 
that they permeate areas in which they are located. Rather, we find 
that emissions from Access BPL systems tend to dissipate after a short 
distance from a coupler along a line, and then remain relatively the 
same for some distance. Along the line there also may be multiple 
points where emissions may be relatively higher but within the part 15 
limits. However, because the signal level decreases significantly with 
distance perpendicular from the line, the potential for interference 
also decays

[[Page 1364]]

rapidly with distance from the line. To ensure that the effects of the 
power line as a radiator are taken into consideration when testing for 
compliance with our part 15 rules, the measurement procedures we 
adopted for Access BPL systems, as discussed in the Report and Order, 
specify that emission measurements are to be made at several specific 
distances from the Access BPL equipment source, and that measurements 
are to be taken parallel to the power line to find the maximum 
emissions from the BPL system.
    15. Notwithstanding our decision on emission limits, we do 
recognize that Access BPL systems present concerns for licensed users 
in the HF and low 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 will be installed at many locations in an area. While we 
conclude, that the likelihood that interference from Access BPL 
operations will occur is low at the signal levels allowed under the 
current part 15 emission limits, such interference could occur in 
limited situations despite the intentions of BPL operators. Moreover, 
even if interference were to occur to amateur operations at the 
distances indicated by the ARRL, as recommended by NTIA, there are 
additional interference mitigation techniques that we are requiring of 
BPL providers to address such interference potential. We believe 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.
    16. We find no need to subject Access BPL equipment to a conducted 
emission limit that would apply for compliance measurement purposes 
before the equipment is shipped and installed. We note that Access BPL 
manufacturers already test their equipment for the proper power levels 
in a laboratory as part of their manufacturing procedures, and in any 
case, the radiated emissions from a representative model of equipment 
would be measured in-situ at three sites as part of the equipment 
authorization process. We therefore find that requiring conducted 
emission tests in the laboratory would be a redundant and unnecessary 
procedure.
    17. The Class A limits are appropriate because Access BPL devices 
are not marketed to the general public and operate on the medium 
voltage power lines as commercial facilities. Those portions of Access 
BPL systems that operate above 30 MHz on the low-voltage power lines 
from the distribution transformer to a residence and all in-house 
wiring connected to a BPL device are subject to Class B radiated 
emission limits. The Class B limits are appropriate for these 
operations because they are located within residential environments and 
are marketed for use by the general public. Although Access BPL systems 
are required to comply with the less stringent Class A limits, 
operators will nonetheless have a strong incentive to exercise the 
utmost caution in installing and operating their systems to avoid 
harmful interference and ensure uninterrupted service to their 
customers, given that there is significant investment in the deployment 
of the service. We do not find that a 10 dB increase in the allowable 
emissions levels is warranted or desirable for systems that can reduce 
emissions by 40 dB in selected bands, as suggested by Satius. We 
believe that it is important that Access BPL systems comply with the 
emission limits across their entire operating range in order to 
minimize the potential for interference in all bands, not just those 
where interference may be more likely at a particular location.
    18. Other Protection Measures. We agree with NTIA and the parties 
representing public safety agencies that critical Federal Government 
and other services specified by NTIA and public safety warrant 
additional protection. These services, including national defense, 
maritime distress and safety, aeronautical navigation and 
communications, emergency response, radioastronomy, and others provide 
important safety and research services whose functions would be 
afforded additional protection against possible interference from 
Access BPL operations. We agree with and adopted NTIA's approach for 
addressing additional protection to critical Federal Government and 
other radio operations. The excluded frequency bands amount only to a 
total of 1731 kHz, or 2% of the spectrum within the 1.7-80 MHz band. 
The exclusion zones are relatively few, on only the 2173.5 to 2190.5 
kHz global maritime distress signaling band with prohibited distances 
of 1 km from coast station facilities, and 73.0-74.6 MHz band used by 
the ten Very Long Baseline Array facilities of radio astronomy 
observatories with prohibited distances of 29 km and 11 km for Access 
BPL systems using overhead medium voltage power lines and other Access 
BPL implementations, respectively. We agree with NTIA that the 
potential for interference from Access BPL to the critical services in 
exclusion zones is somewhat greater for transmissions carried on 
overhead medium voltage lines than other Access BPL implementations, 
i.e., transmissions carried on underground lines or low voltage lines. 
In this regard, emissions from underground power lines are generally 
attenuated by the earth materials in which they are buried, while 
emissions from low voltage lines are generally lower because such lines 
are generally used only for short feeder links from a transformer to a 
customer service location and these lines are more closely spaced with 
an accompanying neutral line--and in fact are often twisted together 
with the neutral line. The close spacing--together with the shorter 
length--reduces radiated RF emissions relative to those from overhead 
medium voltage lines. In addition, the requirement to contact and work 
with the Federal Government in the 53 consultation areas is not 
generally expected to result in major impact on Access BPL operators' 
flexibility to use specific frequency bands. We therefore find that 
avoiding operation on the frequencies excluded under these restrictions 
and requirements will not be burdensome for Access BPL operators and 
manufacturers in order to protect distress and safety communications. 
Indeed, several manufacturers and Access BPL operators have indicated 
that they are capable of, and already do, notch out certain frequency 
bands. We disagree with Ameren, PLCA, and Southern that the mandatory 
consultation provisions imposed on Access BPL operators impose burdens 
on Access BPL operators not borne by other unlicensed broadband 
operators without countervailing benefits. For example, in part 76, we 
require that cable operators conduct measurements annually to ensure 
that signal leakage does not create interference risks. Moreover, the 
distributive nature and other technical characteristics of Access BPL 
pose somewhat higher potential for interference than point-source 
wireless broadband systems that warrant additional protective measures. 
In addition, the consultation actions will benefit Access BPL operators 
by leading them to select frequencies at the beginning of their service 
so as to avoid interference to critical services that might have to be 
corrected later. Accordingly, we adopted NTIA's list of consultation 
areas, excluded bands, and exclusion zones to which Access BPL 
equipment must adhere. For all other radio communication operations not 
addressed in these special provisions, radio operators have the 
opportunity to inform local BPL operators of the

[[Page 1365]]

pertinent details of their operations and BPL operators have the 
opportunity to apply that information as appropriate to prevent 
interference.
    19. With regard to the consultation areas, we will require Access 
BPL operators to provide notification to the parties listed as Federal 
Government contact points, as designated in the rules, for the area in 
which their systems will operate at least 30 days prior to initiation 
of service. The notification shall include: the name of the Access BPL 
provider; the frequencies of the Access BPL operation; the postal zip 
codes served by the Access BPL operation; the manufacturer of and type 
of Access BPL equipment being deployed (i.e., FCC ID); point of contact 
information (both telephone and e-mail address); and the proposed or 
actual date of initiation of Access BPL operation. We will also require 
that systems located in consultation areas that were in operation prior 
to the effective date of these rules provide this notice to the 
appropriate contact point within 45 days of that date. NTIA has 
indicated that it plans to arrange to have information made available 
to BPL operators on Federal Government operations. We expect parties to 
consult in good faith to ensure that no harmful interference is caused 
to licensed operations and that any constraints on BPL deployments are 
minimized to those necessary to avoid harmful interference.
    20. As indicated in the NPRM, we believe that the risk of harmful 
interference to State and local public safety services, i.e., EMS, 
fire, law enforcement, and emergency management agencies from Access 
BPL operations is essentially low. In general, we believe that a 
properly designed and operated Access BPL system will pose little 
interference hazard to services such as aeronautical, maritime and 
public safety that are designed to operate with relatively high signal-
to-noise ratios. In analyzing the potential for harmful interference to 
public safety systems, we took into account the fact that low-level 
part 15 signals from Access BPL devices attenuate rapidly as the 
distance from the power line increases; and that most public safety 
systems are designed so that mobile and portable units receive a signal 
level significantly above the noise floor. From an interference 
analysis standpoint, this latter characteristic distinguishes public 
safety systems from amateur radio stations using high-sensitivity 
receivers to receive signals from transmitters often thousands of miles 
away. However, it is foreseeable that under certain rare circumstances 
a public safety unit could: (a) Operate in close proximity to a power 
line carrying Access BPL transmissions at a location where field 
strength is near the part 15 limit; (b) be tuned to a frequency 
radiated by an Access BPL device; and (c) be receiving a weak signal 
from a distant, or obstructed, public safety base station. In general, 
potential harmful interference under these conditions would be limited 
to public safety units operating on systems using low-band VHF channels 
(25-50 MHz). We therefore conclude that the interference protections 
set forth will be adequate to foreclose harmful interference to public 
safety systems except perhaps under such unusual circumstances.
    21. However, we also conclude that public safety systems merit 
additional protection because of the often critical and/or safety-of-
life nature of the communications they provide. Given the importance 
and nature of public safety communications, we believe it is necessary 
to require Access BPL systems to notify the public safety agencies in 
their local areas, i.e., State and local police, fire, emergency 
medical, any special emergency coordinators, call box operators, and 
other entities that are eligible for public safety licenses under Sec.  
90.20 of the rules. This advance notification will provide public 
safety operators 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. Consistent with our decision on notifications for 
Federal Government consultation areas, we will require that this 
notification be provided to local public safety agencies at least 30 
days prior to a system's initial operation, the activation of any major 
extensions of the system, or any changes in its operating 
characteristics, i.e., transmitting frequencies. The notification shall 
include: (1) The name of the Access BPL provider, (2) the frequencies 
of the Access BPL operation, (3) the postal zip codes served by the 
Access BPL operation, (4) the manufacturer of and type of Access BPL 
equipment being deployed (i.e., FCC ID), (5) point of contact 
information (both telephone and e-mail address), and (6) the proposed 
or actual date of initiation of Access BPL operation. We will also 
require that systems in operation prior to the effective date of these 
rules provide this notice to local public safety agencies within 45 
days of that date.
    22. We do not see a need to establish Access BPL-free zones around 
airports, military bases, hospitals, police stations and fire stations, 
as requested by NAC/Amherst. To the extent that these services warrant 
special protection, they will be afforded protection through the 
excluded bands, exclusion zones and consultation areas specified by 
NTIA. We similarly do not find that amateur radio frequencies warrant 
the special protection afforded frequencies reserved for international 
aeronautical and maritime safety operations. We note that in many 
instances amateur frequencies are used for routine communications and 
hobby activities. While we recognize that amateurs may on occasion 
assist in providing emergency communications, we believe that the 
general part 15 provisions and the specific provisions being adopted 
for Access BPL operations are sufficient to protect these amateur 
operations.

Interference Mitigation

    23. We continue to believe that it is important that Access BPL 
systems include capabilities that allow them to modify their operations 
to mitigate or avoid instances of harmful interference that may arise. 
These capabilities will allow Access BPL system operators to resolve 
interference found to occur at specific locations or in specific areas 
of their plant in an expeditious manner and without disrupting service 
to their broadband service subscribers. We agree with NTIA that Access 
BPL operators would have strong incentives to voluntarily implement 
such equipment and operating practices. We also agree with NTIA that, 
notwithstanding these incentives, it is necessary that we adopt 
requirements for interference mitigation capabilities to ensure that 
any interference can be resolved quickly without the need to address 
the tension that might arise over the possible disruption of service to 
BPL subscribers if mitigation capabilities were not available. The 
concerns of those commenting parties who argue that the mitigation 
requirements would not be sufficient to protect their operations from 
interference by BPL operations are misplaced. That protection will be 
provided by: (1) The emissions limits for Access BPL systems; (2) the 
provisions for consultation areas, excluded bands, and exclusion zones; 
and (3) the requirement that Access BPL systems not cause interference, 
as set forth above. The mitigation requirements are intended to ensure 
that Access BPL systems are designed with features that support 
interference mitigation, both during initial installation, if sensitive 
local communications systems are identified in advance, and after 
installation, when the newly required operational

[[Page 1366]]

capabilities will allow Access BPL system operators to expeditiously 
resolve any instances of interference that may occur, without the need 
to cease operations and thereby disrupt the broadband data services 
they provide to their subscribers.
    24. Accordingly, we have adopted requirements that Access BPL 
systems incorporate capabilities to modify their systems' operations 
and performance to mitigate or avoid potential harmful interference to 
radio services and to deactivate specific units found to actually cause 
harmful interference that cannot be remedied through modification of 
their operations as proposed, but with certain modifications. Our 
approach in specifying these requirements is to provide Access BPL 
equipment manufacturers and operators with flexibility to design and 
implement a broad range of products and system designs to meet 
particular service and operational needs while ensuring that systems 
have the capabilities to make operational changes to avoid any 
interference that may arise. The specific provisions of the mitigation 
requirements and the comments that concern them are addressed below. We 
also see no basis for subjecting Access BPL systems to requirements for 
addressing interference complaints that are different and more 
stringent than our procedures for addressing interference from other 
types of unlicensed devices. In this regard, we will continue to 
subject Access BPL systems to the procedures of Sec.  15.5(c) of the 
rules. Under this rule, parties who believe they are experiencing 
interference from an unlicensed device are first expected to bring the 
matter to the attention of the operator of the unlicensed device. If 
that action does not resolve the interference, the party may then seek 
intervention by the Commission.
    25. To be more specific, in the event a BPL interference complaint 
is filed by a licensee with the Commission, the Commission will contact 
the complainant and/or the BPL provider to determine if they have first 
attempted to resolve the interference complaint among themselves. If 
they have not made such an attempt, the complaint will be forwarded to 
the BPL provider for action and the complainant notified that they will 
be contacted by the BPL provider concerning their interference 
complaint. The Commission may periodically monitor the resolution 
process to ensure that the parties are working in good faith and making 
appropriate progress in resolving the interference complaint. If the 
parties have attempted to address the complaint but the matter remains 
unresolved, the Commission, through its Enforcement Bureau with 
assistance from the Office of Engineering and Technology will review 
the complaint and take appropriate action. In general, the Commission 
will contact the BPL operator and request information on what steps 
they have taken to address the licensee's complaint. If these actions 
are deemed insufficient to resolve the interference complaint, the 
Commission will instruct the BPL operator to take immediate remedial 
actions, such as ``notching'' or avoiding specific frequencies, or 
ceasing operations. In specific instances, the Commission may undertake 
field testing and measurements to address interference complaints and 
determine the most appropriate remedial action.
    26. Frequency Avoidance. We conclude that the most appropriate 
approach regarding mitigation techniques that involve altering system 
operation is to require that Access BPL systems incorporate the 
capability to avoid the use of specific frequency bands. The ability to 
alter a system's operation to notch-out transmissions from specific 
frequencies where interference is occurring is a necessary feature for 
resolving interference without disrupting service to BPL subscribers. 
While other mitigation capabilities, such as adaptive or commanded 
power control, are desirable system features that can serve to reduce 
interference potential, they generally would provide a much lower 
degree of benefit in eliminating interference than frequency avoidance. 
Limiting the requirement for operational modification capabilities to 
frequency avoidance is also consistent with our intent to minimize the 
impact of these requirements on manufacturers and system operators so 
as preserve their flexibility to design products and systems that will 
best meet the needs of Access BPL subscribers.
    27. In considering specifications for the notching requirement, we 
find that the most important consideration is to ensure that the notch 
provides enough filtering to effectively reduce the potential for 
interference. Our experience in examining the field performance of 
various Access BPL operations indicates that at frequencies below 30 
MHz, a notching capability that provides at least a 20 dB reduction of 
Access BPL emissions below the current applicable part 15 emission 
limits is adequate to resolve interference occurrences that might 
result to mobile reception from such operations. In this regard, we 
will generally assume that a 20 dB notch is sufficient to resolve any 
harmful interference that might occur to mobile operations, given the 
low signal levels allowed under the part 15 emission limits and the 
fact that a mobile transceiver can readily be re-positioned to provide 
some separation from the Access BPL operation. The interference 
potential from emissions at this low level would be limited to a very 
short range from an Access BPL device or a power line on which Access 
BPL transmissions are carried. We also believe that notching at this 
level with some distance separation will generally avoid interference 
to fixed operations, including those that use more sensitive receivers. 
Above 30 MHz we believe that a notching capability of at least 10 dB is 
sufficient to provide the same level of protection, given the more 
stringent part 15 emission limits that apply to Access BPL 
transmissions above 30 MHz and the increased attenuation of emissions 
that occurs from propagation losses as the frequency of operation 
increases. With regard to NAS/CORF's requests for protection of 
radioastronomy, we note that special protections are provided for 
radioastronomy in the exclusion zones and consultation requirements for 
Access BPL.
    28. We do not believe it is necessary to specify the bandwidth over 
which the notching capability must function. Rather, we will adopt the 
more general requirement that Access BPL systems must be capable of 
avoiding transmissions in any frequency band or bands in order to 
eliminate any instances of interference with the operations of licensed 
radio services. We therefore are amending our rules to require that 
Access BPL devices have the capability to reduce emissions by at least 
20 dB below the part 15 emission limits in frequency bands below 30 MHz 
and 10 dB below those limits in frequency bands 30 MHz and above. We 
believe that these provisions adequately set forth the structure of the 
required capabilities for modifying the operation of an Access BPL 
system. We are not specifying requirements for use of the frequency 
avoidance capabilities. Rather, we believe that system operators should 
have the discretion to use this capability or any other alternative 
available to them as they might deem appropriate to resolve specific 
situations involving interference that they may encounter in the course 
of their operations.
    29. We do not find any justification for a requirement that Access 
BPL operators notch the frequencies of any or all of those services 
that use frequencies in the HF and low VHF

[[Page 1367]]

bands. We believe that the emission limits, consultation areas, 
excluded bands, exclusion zones, and the requirement that Access BPL 
systems not cause interference, are generally sufficient to control the 
interference potential of these systems. The required notching 
capability will enable a system operator to address any specific 
instances of interference that might otherwise arise. We also decline 
to adopt a rule requiring transmission of identification codes. As NTIA 
states, such codes could increase the potential for interference from 
Access BPL operations. We also do not believe that it would be 
practicable for ARINC or any other operator to identify an Access BPL 
system as the source of interference and contact its operator on a real 
time basis to resolve the interference. As NTIA indicates in its letter 
of September 24, 2004, no practical method has been identified for 
Access BPL systems to transmit an identifying code. We believe that the 
Access BPL notification requirements will provide sufficient 
information to locate and mitigate interference.
    30. Shut Down Requirement. We continue to believe that Access BPL 
equipment and systems should have the capability to deactivate 
individual system components. This feature will allow systems to 
deactivate limited portions of their plant so that localized 
interference problems can be addressed without affecting service to all 
of their subscribers. As a secondary benefit, the shut-down feature 
will allow system operators to rapidly diagnose whether their 
operations are causing reported interference. We are also requiring 
that the shut-down feature in individual devices be remote-controllable 
from the central system operations facility or other appropriate 
location. This will allow rapid response to resolve interference in any 
emergency or other urgent situation that might arise. We also agree 
with Progress Energy the required shut-down capability should be 
manually controlled. Moreover, we have no record on which to base a 
decision on the conditions under which an automated capability would be 
activated. We also recognize that, depending on how it would be 
triggered, an automated shut-down capability could unnecessarily have 
detrimental effects on a power utility service's operations in addition 
to disrupting broadband service to its Access BPL customers.
    31. It is not our intention that a service shut-down be the first 
step in a system operator's response to a valid interference complaint. 
As suggested by several of the commenting parties, we would anticipate 
that shut-down would be a last resort when all other efforts to 
satisfactorily reduce interference have failed. We disagree with Ameren 
that the shut-down requirement will add unnecessary costs and 
complexity to Access BPL equipment. As NTIA and our own field testing 
indicate, most Access BPL systems and equipment already include the 
capability to shut down specific components of their operation. 
Accordingly, we are requiring that Access BPL systems incorporate 
features that will allow the deactivation of individual components on a 
remote-controlled basis, to be implemented. We reiterate, however, that 
the Commission, through a duly authorized representative, is the sole 
authority that may direct an Access BPL operator to cease operating any 
of its devices to eliminate interference.

Access BPL Notification and Database Requirements

    32. We believe that the Access BPL notification and database 
requirements proposed in the NPRM are appropriate and sufficient to 
ensure that any potential interference to licensed services from BPL 
operations can be adequately identified and quickly addressed. The 
primary intent of our notification and database requirements is to 
ensure that licensed users of the spectrum have a publicly accessible 
and centralized source of information on BPL operations to determine 
whether there may be Access BPL operations on particular frequencies 
within their local area so that any incident of harmful interference 
can be resolved should it occur. The information contained in the 
notification database need only be sufficient to determine whether 
there may be a BPL operation in the local area, the nature of the BPL 
operations, whether the BPL system is operating on frequencies that 
could potentially be a source of harmful interference to the licensed 
user and to identify an appropriate contact person who can work 
directly with the complainant to resolve the harmful interference if it 
is determined to be caused by the local BPL operations. Additional or 
more detailed relevant information needed by a radio operator could be 
requested via the contact person indicated in the data base, as 
appropriate.
    33. We therefore are adopting rules that will require the BPL 
industry to establish within July 6, 2005, a centralized publicly 
accessible Access BPL notification database. We note that two 
organizations have indicated their willingness to perform this task and 
that the issue of ``independence'' of the database manager has been 
raised by some of the commenting parties. The responsibilities and 
duties of the database manager are to maintain complete, accurate and 
timely records of FCC-mandated information. We are not requiring, as 
some parties have suggested, that the database manager be involved in, 
monitor, or manage the interference resolution process. The party 
responsible for avoiding interference is clearly the Access BPL 
operator and his responsibilities are clearly set forth in the existing 
procedures under Sec.  15.5(c) of the Commission rules. We therefore do 
not find that the database manager need be an ``independent'' third-
party with no relationship to the BPL or utility industry and are not 
adopting such a requirement.
    34. With regard to the information to be included in the database, 
we adopted rules that will require the Access BPL operator to provide 
the BPL industry designated database manager with the following 
information 30 days prior to initiation of any operation or service: 
(1) The name of the Access BPL provider; (2) the frequencies of the 
Access BPL operation; (3) the postal zip codes served by the specific 
Access BPL operation; (4) the manufacturer and type of Access BPL 
equipment being deployed (i.e., FCC ID); (5) point of contact 
information (both telephone and e-mail address) for interference 
inquiries and resolution; and (6) the proposed/or actual date of Access 
BPL operation. The database manager shall be required to enter this 
information into the publicly accessible database within 3 business 
days of receipt. This will allow some period of time for the database 
manager and BPL provider to address any questions with regard to 
information submitted and to ensure that information entered into the 
database is correct. We believe that the above information provides 
sufficient specificity for identifying potential interference while at 
the same time avoiding valid concerns that sensitive information on 
critical infrastructure not be revealed.
    35. We believe that using zip codes, as suggested by Southern, 
would sufficiently identify the area of Access BPL deployment without 
revealing specific sensitive information and would facilitate a more 
organized approach to identification and resolution of harmful 
interference. We note that zip codes are easily understood and can be 
identified by both licensees and BPL operators. With regard to those 
parties that request more comprehensive information, we do not find 
that benefits of providing such information in the database would

[[Page 1368]]

outweigh the substantial cost of collecting and reporting this 
additional information. We note, for example, that NTIA's proposals to 
require information on modulation types, number of carriers, range of 
transmission duty cycle, minimum and maximum carrier spacing, symbol 
rates per carrier, etc., would provide little additional guidance on 
whether interference were being caused in a particular instance as 
compared to the more simple requirement of identifying BPL operating 
frequencies. In addition, we are requiring that BPL equipment must be 
certified and therefore more detailed technical information will be 
available through our equipment authorization files for those parties 
desiring such information. We also are not requiring Access BPL 
operators to have multi-lingual contact persons. We believe that 
requiring both telephone and e-mail contact information is sufficient 
to address interference inquiries. We are also not requiring that 
telephone contact positions be staffed 24 hours per day and seven days 
a week. We believe that our emission requirements and other mitigation 
rules will ensure that interference is generally avoided. We believe 
that telephone contact staffing during normal business hours is 
sufficient and also note that e-mail would generally allow interference 
reports to be filed at any time.
    36. We expect the Access BPL operators and licensees to cooperate 
in good faith to identify and resolve instances of harmful 
interference. We require the notification database for Access BPL 
operators to notify the operation of its devices and systems to 
facilitate the speedy resolution of interference. Speedy resolution of 
interference will not result if the database information on Access BPL 
deployments is abused and the BPL operators are deluged with frivolous 
interference complaints. We expect the Access BPL operators to take 
every complaint of interference seriously and to diagnose the possible 
cause of interference quickly. At the same time, we expect the 
complainant to have first taken reasonable steps to confirm that 
interference rather than a receiver system malfunction is occurring 
and, to the extent practicable, to determine that the interference 
source is located outside the complainant's premises. We expect both 
parties to cooperate to determine a mutually acceptable schedule to 
diagnose and resolve the interference complaint, recognizing that the 
Access BPL operator may have to prioritize any complaints of 
interference that it receives (e.g., from a public safety agency). With 
regard to public safety operations, however, we will require that the 
BPL operator respond to complaints of harmful interference from public 
safety users within 24 hours; the BPL provider shall be required to 
immediately cease the operations causing the public safety complaint if 
it fails to respond to such complaint within 24 hours. Any complaints 
of interference that are not resolved in accordance with the mutually 
agreed schedule may be filed with the Commission along with the 
particulars of the interference case. Upon receipt of the interference 
complaint, the Commission will investigate the complaint and take 
action against the Access BPL operator if it is found to be causing 
harmful interference. If, on the other hand the Commission uses its 
resources to investigate an interference complaint that is found to be 
frivolous, the Commission will impose appropriate sanctions for abuse 
of its administrative process.

Measurement Guidelines

Access BPL Systems

    37. We find the extensive measurement and modeling efforts 
presented in the NTIA Phase 1 Study and the Technical Appendix to 
NTIA's comments to be highly useful in our efforts to develop 
appropriate measurement procedures for Access BPL. The scientific 
engineering in those submissions clarifies the interference potential 
of Access BPL on radio reception and the recommended techniques for 
measurement of Access BPL emissions provide us with a well thought-out 
plan on which to base our decisions on measurement issues. Our 
decision, takes into account NTIA's research and adopts a modified 
version of its recommendations.
    38. We find that our proposed measurement procedure for testing 
Access BPL systems including the presence and testing of all of their 
electronic components to be reasonable as each component is part of the 
Access system of that installation. We do not agree with Southern that 
the testing should be limited to three representative signal injection 
points. Southern believes that the highest levels of emissions on 
overhead systems are found at the signal injection point, and it states 
that the biggest variable affecting emissions is impedance mismatch 
between the signal injection system and the power system at the point 
of injection, which could be a coupler or a repeater. We agree with 
Southern that each injection point affects the radiated emissions. 
However, Southern's suggestion of selecting only representative signal 
injection points precludes the presence of other components, e.g., 
booster, concentrator, extractor, etc. if they should be together at an 
installation to make up the complete Access BPL system. Our requirement 
for a typical installation takes into account the topology of the power 
lines and of all Access BPL devices at that installation, thus choosing 
only representative injection points, as Southern recommends, does not 
cover the installation as a whole. Accordingly, we will keep our 
proposed in-situ requirements for including and testing all components 
of an Access BPL system. We also find that our measurement procedure 
for testing Access BPL systems in-situ at three typical underground 
locations along a number of radials consistent with testing other part 
15 carrier current devices. The selection of three typical underground 
installations is a streamlined procedure, compared to testing each and 
every installation, as recommended by some parties; therefore we do not 
agree with Main.Net that only one underground location should be 
tested. We discuss below the issues with respect to measuring radiated 
emissions from Access BPL systems on overhead power lines.
    39. Measurement Distance. Despite the stated aversion of NTIA and 
ARRL to distance extrapolation, we recognize that at many in-situ test 
locations, it may not be possible or practicable to measure at the 
proposed fixed distances of 10 and 3 meters. If a 10-meter distance 
places the measurement antenna on a roadway, safety may dictate 
increasing the distance to, e.g., 14 meters in order to position the 
testers out of harm's way. Hence, we expect that distance extrapolation 
will be necessary for in-situ testing. We note that NTIA's latest 
computer modeling results show that the variation of field strength 
with distance is consistent with the existing part 15 distance 
extrapolation when used with the slant range distance to the power line 
as was proposed in Appendix C of the NPRM. We also note that although 
the ARRL and ARINC recommend the use of a 20 dB per decade 
extrapolation factor rather than the existing 40 dB per decade in part 
15 for frequencies below 30 MHz, Ameren states that it has determined 
the characteristics of the fields near the line support the case for 
assuming a 40 dB per decade decay rate of the field away from the line 
and recommends the use of the existing 40 dB per decade extrapolation 
factor. Given the lack of conclusive

[[Page 1369]]

experimental data pending large scale Access BPL deployments, we will 
continue the use of the existing part 15 distance extrapolation factors 
in our rules, but with the slant range rather than horizontal distance. 
If new information becomes available that alternative emission limit/
distance standards or extrapolation factors would be more appropriate, 
we will revisit this issue at another time.
    40. Receive Antenna Height and Correction Factor. NTIA expresses a 
possible need for ``adjustments'' to measured data due to three 
factors: (1) Effect of antenna height, (2) effect of distance 
(extrapolation methods), and (3) effect of using an H-field sensing 
antenna to predict E-fields in the near-field region. However, NTIA 
initially provided a specific recommendation regarding only one of 
these issues--correction for the effect of antenna height. Our modeling 
suggests that there is a linkage between these factors. We believe that 
all three areas must be considered together in order to develop 
appropriate measurement procedures. Furthermore, NTIA's recommendation 
for a 5 dB correction factor is based on a constant measurement antenna 
height of 1 meter. On the other hand, for frequencies above 30 MHz, our 
current measurement guidelines require varying the receive antenna 
height from 1 to 4 meters, hence higher peaks at a higher antenna 
height would