Staff members of San Diego Gas & Electric Company (SDG&E) in California
announced during a February 23 presentation to the San Diego DX Club that
the utility plans to deploy multiple broadband over power line (BPL) test
sites in San Diego County. Locations for the BPL pilot projects have not yet
been specified. Several BPL equipment vendors are expected to be involved in
the trials, each with its own test area and frequency plan, and the first
system could be in place as early as this June, with others following soon
after.

The SDG&E staffers said they were unimpressed by early BPL equipment, but
were encouraged by a December visit to the Cinergy BPL system in
Cincinnati--said to pass some 50,000 homes reportedly without generating any
interference complaints so far. Cinergy has partnered with Current
Technologies in its BPL venture.

ARRL Lab Manager Ed Hare, W1RFI, says that while Current Technologies' BPL
equipment does reduce emissions in most spectrum used by Amateur Radio, it
operates at full strength on other HF spectrum--such as the international
shortwave broadcast bands--and it uses low-VHF on medium voltage lines.

"The Current Technologies' BPL HF emissions are from the 120/240 V wiring
only, so it is not likely that the signals will propagate along a line as
well as systems that put HF signals directly onto overhead medium-voltage
distribution lines," Hare said. But he added that even with the best
"notching" techniques, interference is still possible from a nearby BPL
system.

"ARRL's concern is that if the degree of protection this BPL equipment
provides proves inadequate for such circumstances and interference occurs,
there are no additional solutions to apply," Hare said.

Source:
The ARRL Letter Vol. 24, No. 09 March 4, 2005