 |
 |
|
|
|
|
|
|
||||||||||||||||||
|
|
|||||||||||||||||||
|
|
|||||||||||||||||||
|
|||||
|
|
 Previous: Youth@HamRadio.Fun: A Journey of Nothing But Fun |  Next: Amateur Radio on the International Space Station Logs 100th School Contact |
By Rick Lindquist, N1RL
ARRL Senior News Editor
June 19, 2003
Broadband Over Power Line (BPL) technology poses significant interference potential to HF and low-VHF spectrum use between 2 and 80 MHz.
 Power lines used as conductors for RF signals at HF and low band VHF create the potential for interference from radiated emissions. |
The BPL NOI In a Nutshell
On May 23, 2003, the FCC published a Notice of Inquiry (NOI) in ET Docket 03-104 asking how it should regulate the delivery of broadband services to homes and businesses using electrical wiring to conduct high-speed digital signals. The FCC calls this technology "Broadband over Power Line" (BPL)--a technology also known as Power Line Carrier or PLC. This article briefly explains the NOI and what amateurs should know so they can make informed comments to the FCC.
BPL uses building and/or overhead power lines to conduct HF and VHF digital signals to network computers. There are a number of ways people can obtain broadband services--from cable modem to digital subscriber line (DSL) to satellite. The FCC views BPL as a competitive Internet access point, and the utilities view the technology as a means to use existing infrastructure to generate additional revenue from something other than power generation and distribution.
The NOI asks how BPL should be regulated and states that the FCC wants to remove regulatory hurdles to its deployment. Present rules already permit BPL right now at significant power levels. Utilities would prefer that the FCC authorize even higher power levels.
As of mid-June, nearly 1000 comments already had been filed. It is worth your time to become informed by reading the NOI itself and this article and to make your views known to the FCC. Amateurs should outline the important uses they make of Amateur Radio and the impact strong interference from BPL might have at HF and low-VHF amateur frequencies.
Electric utility companies will operate many, if not most, BPL systems. ARRL members who have had experience dealing with power line interference and utilities' responses to complaints can describe those experiences in their comments to the Commission.
Information on how to file comments is at the end of this
article. An ARRL white paper, "Calculated
Impact of PLC on Stations Operating in the Amateur Radio Service."
provides a more detailed presentation on the technical aspects of this issue.
The ARRL's Broadband
Over Power Line resource page contains links to worldwide
studies and resources to help Amateur Radio with BPL issues.
 How will the radiation from BPL wiring affect other systems, such as telephone or cable TV? |
What to Tell the FCC
Amateurs filing comments to the FCC NOI might want to consider including words on these topics and points as part of their comments to the FCC:
A BPL Tutorial
The BPL industry claims that the infrastructure to accommodate this technology already is in place. In many field trial areas, however, the BPL purveyors have had to run optical fiber cable throughout the service area to serve as the Internet backbone for the few hundred trial subscribers. Other BPL systems use overhead medium-voltage wiring, with digital "repeaters" installed every 2000 feet or so along the way. This widely spaced, unshielded wiring radiates a strong BPL signal to nearby areas. Still other BPL systems use IEEE 802.11-protocol wireless equipment to make the connection to homes and businesses.
A number of BPL system types are in use or in development. Each employs different techniques and architecture, but all are carrier-current systems--a term describing systems that intentionally conduct signals over electrical wiring or power lines.
There are two major categories of BPL: Access BPL and In-Building BPL
 ARRL Lab Manager Ed Hare, W1RFI, is investigating the potential for BPL to cause interference to HF and low-VHF users. |
What Present FCC Rules Permit
The NOI is not asking if BPL technology should be permitted. Under existing FCC rules, BPL systems may be built and used in the United States right now . The FCC is asking how the rules might be changed "to promote and encourage new BPL technology," in the words of the NOI.
Present FCC rules say that carrier-current systems--this includes BPL/PLC--need to meet the general radiated emission limits for unlicensed "intentional emitters." An intentional emitter is one that transmits a radio signal as a part of its normal operation. At HF, BPL systems are permitted a radiated field strength of 30 uV/meter measured at 30 meters from the signal source. At VHF, they are permitted radiated emissions of 100 uV/meter measured at 3 meters from the signal source. In most cases, the source will be the electrical wiring within a building or the electric-utility lines that pass close to residences and businesses in the US.
The FCC Notice of Inquiry
The FCC NOI asks a number of specific questions about BPL and how it should be regulated and tested. BPL systems under development and in field trials right now use spectrum between 1.7 and 80 MHz, but the NOI is also asking whether BPL should also operate on other parts of the spectrum. Amateurs are encouraged to read the NOI in its entirety and answer those questions from an Amateur Radio perspective view. Many amateurs have significant professional credentials and experience and this represents an opportunity to use that amateur experience to help the Commission make a difficult decision.
The NOI asks additional questions than we cover here, but these are the ones of greatest interest to most amateurs:
 NTIA Administrator Nancy Victory has praised the FCC's BPL initiative but cautioned the Commission to take interference concerns into consideration. |
No Harmful Interference
FCC Part 15 rules require that the operator of an unlicensed emitter not cause harmful interference to authorized radio services. The absolute emission limits and the non-interference rule work together to allow most unlicensed devices to operate without causing widespread interference.
BPL is different from point-source emitters, however. Access BPL systems are not local in nature. They are expected to occupy entire communities. BPL systems do not create "birdies" on specific frequencies. They create radiated emissions at the FCC limits on entire swaths of spectrum.
If interference occurs from localized "unintentional radiator" sources such as power line noise, solutions exist. For example, power companies can change cracked insulators. The FCC has been able to enforce these rules when necessary. Indeed, a number of electric utilities have received letters from the FCC, as have the neighbors of hams who own and operate noisy Part 15 devices.
In the case of access BPL, if an amateur doesn't have the broadband system installed in his or her own house but experiences interference from signals radiated via the overhead electrical wiring, the only real solution could be to turn off the BPL system in entire neighborhoods. As a practical matter, that is unlikely to occur.
BPL Field Trials
A number of field trials have been conducted overseas. In many cases, International Amateur Radio Union (IARU) member-societies have carried out tests in the trial areas. In Austria, video recordings were made of some of the field trials.
Field trials are just getting under way in the US. To date, none of them have specifically included Amateur Radio nor have any incorporated interference studies. Typical field trials include from a handful to a few hundred homes in suburban neighborhoods.
ARRL has identified active field trials in Briarcliff Manor, New York; Cape Girardeau, Missouri; Cullman, Alabama; Emmaus, Pennsylvania; Hyde Park, Ohio; Manassas, Virginia; Potomac, Maryland; and Raleigh, North Carolina. In addition, the FCC has granted experimental licenses to BPL equipment manufacturers or utilities in a number of other states. To ARRL's knowledge, actual field trials have not started there yet.
Immunity
To ARRL's knowledge, no field trials have studied immunity. What will happen when amateurs operate their stations in areas where BPL is deployed? ARRL recently petitioned the FCC for a tiny amateur LF allocation in the vicinity of 136 kHz. The electric utility industry claimed in comments on the ARRL's petition that its PLC devices--operating on an unlicensed basis on frequencies below 490 kHz--would suffer harmful interference from 1 W effective isotropically radiated power (EIRP) amateur stations. The FCC agreed and chose not to grant Amateur Radio the LF allocation it sought.
Yet the same utility industry, in consortium with BPL manufacturers, is making the claim that on HF and low-VHF--frequencies where power lines make better antennas than they do on LF--BPL signals can coexist with amateur stations that may be running more than 10,000 W EIRP.
Hams are generally very concerned about immunity, because they understand and appreciate the social problems that might result when a neighbor's broadband access doesn't work because the amateur is on the air.
 One technical issue involves the best method to bridging or bypass the typical step-down pole transformer to deliver BPL from the power grid into an office or dwelling. |
File Comments
Comments are due on or before July 7, 2003. Reply comments are due on or before August 6, 2003. The FCC now is accepting electronically filed comments via its Electronic Comment Filing System (ECFS). Under ECFS Main Links, click on "Submit a Filing." In the "Proceeding" field, enter "03-104" and complete the required fields. Comments may be typed into a form or you may attach a file containing your comments. Comments also may be submitted via e-mail per instructions on the ECFS page. The FCC has created a Web page that offers more information about filing comments. There's also a mailing address for those wishing to file comments by postal mail.
Supporting ARRL's Efforts on the BPL Issue
The ARRL has initiated an important Spectrum Defense Fund campaign to support activities to educate government officials on the potential threat that BPL poses to Amateur Radio. "Although this technology is already allowed, the industry wants the limits to be relaxed--with greater interference to your ham radio operation," notes ARRL CEO David Sumner, K1ZZ, in an appeal that went out recently to ARRL members. "The staff at ARRL is already hard at work on this issue."
To find out more, or to support ARRL's
efforts in this area, visit the ARRL's secure BPL Web site.
| Previous: Youth@HamRadio.Fun: A Journey of Nothing But Fun | Next: Amateur Radio on the International Space Station Logs 100th School Contact |
