Subject: [NEXTEL-1] World's Broadcasters Join Anti-BPL Chorus

From: [email-masked]
Date: Sat, 11 Oct 2003 02:24:24 -0400

World's Broadcasters Join Anti-BPL Chorus
NEWINGTON, CT.
 Oct 9, 2003

A subcommittee of an International Telecommunication Union (ITU
http://www.itu.org/) panel of technical experts responsible for terrestrial
broadcasting issues has joined a growing chorus of concern about the
interference potential of power line telecommunication (PLT) -- better known
in the US as Broadband over Power Line (BPL). ITU Radiocommunication Sector
(ITU-R) Sub Working Group (SWG) 6E1 expressedthe view that interference
produced by systems employing PLT as well as by Industrial, Scientific and
Medical (ISM) equipment and short-range devices, would compromise broadcast
reception.

"SWG 6E1 is of the opinion that any increase in the amount of noise due to
these systems is unacceptable," said a statement from the group's chairman
to the chairman of Working Party 6E (WP 6E). "In particular, broadcast
services should be protected from unwanted emissions from PLT systems," the
panel asserted, "as these emissions are a byproduct of a system that is not
itself a user of the radio spectrum." The panel recommended the formation of
a group representing all users of the radio spectrum "to coordinate
development of limits to be imposed on the radiation from these systems."

WP 6E says it will continue to study the effects of PLT/BPL, ISM equipment
and short-range devices on terrestrial broadcasting and send the results to
ITU-R Working Party 1A, which is responsible for spectrum engineering
techniques. WP 1A is scheduled to meet in Geneva October 30 to November 5.

ARRL Chief Executive Officer David Sumner, K1ZZ, expressed strong support
and appreciation for the SWG's conclusions and the ongoing efforts of parent
Working Party 6E to study the issue. "Our studies have shown that the
broadcasters' concerns are fully justified," Sumner said. "If BPL is a
problem for broadcasters, it's easy to see that it would be a disaster for
us," he added, noting that broadcasters' signal strengths typically far
exceed those of radio amateurs.

Broadcasters themselves also have exhibited increased concern about the
potential of PLT/BPL to prevent their signals from reaching listeners. The
Research and Development branch of the highly regarded British Broadcasting
Corporation (BBC) has released a White Paper reporting on a brief trial in
Scotland (http://www.bbc.co.uk/rd/pubs/whp/whp067.html). The two competing
PLT/BPL systems in operation in the town of Crieff both interfered with HF
reception. Tests were conducted at four locations.

"The forms of access PLT that were tested in Crieff were found to have
demonstrable potential to cause interference to indoor reception of
broadcasting in relevant bands," the White Paper concluded. Before
commercially licensing PLT, the report advised, regulators need to undertake
further study of other PLT systems and, among other issues, look into
possible ways to make the PLT systems compatible with radio reception.

At the first location, a residence, interference from a Main.Net modem was
audible even on very strong broadcast signals. Reception was also
significantly impaired at a neighbor's house as well as at various locations
in the street between the residence and the substation serving it. This was
despite the fact that the main distributor cable was underground.

The BBC engineers described the interference as varying between "'annoying'
and a level sufficient to make the broadcast completely unintelligible."

At a retail shop where another Main.Net modem was in use, "reception of an
apparently strong broadcast signal was badly impaired when the PLT modem was
busy," the report said.

Ascom systems were in use at the other two locations. The BBC engineers
observed interference to HF broadcasting signals despite the system
designers' efforts to reduce emissions in the broadcasting bands.

Field strength measurements taken at three of the four locations showed
PLT/BPL emissions far in excess--by as much as 50 dB--of various proposals
for limits intended to restrict the degree of interference.

A report prepared by the Australian Communications Authority (ACA),
Broadband Powerline Communications Systems--A Background Brief,
(http://www.aca.gov.au/radcomm/frequency_planning/spps/0311spp.pdf)
concluded that "a potential risk to HF radiocommunications services from the
widespread use of broadband powerline communications systems" appeared to
exist. Citing BPL trials in the US, Europe and Asia, the ACA brief said,
"The results of these trials have not alleviated concerns over the potential
interference risk to radiocommunications."

The ACA report included the Australian Broadcasting Authority, the
Australian Maritime Safety Authority, the Department of Defence and the
Wireless Institute of Australia--that country's International Amateur Radio
Union member-society--as "stakeholders" subject to potential electromagnetic
compatibility (EMC) concerns.

 http://www.arrl.org/news/stories/2003/10/09/1/?nc=1

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