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URL:
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci953137,00.html
Broadband over Power Line (BPL) is a technology that
allows Internet data to be transmitted over utility power lines. (BPL is also
sometimes called Power-line Communications or PLC.) In order to make use of
BPL, subscribers use neither a phone, cable, nor satellite connection. Instead,
a subscriber installs a modem that plugs into an ordinary wall outlet and pays
a subscription fee similar to those paid for other types of Internet service.
BPL works by modulating high-frequency radio waves
with the digital signals from the Internet. These radio waves are fed into the
utility grid at specific points. They travel along the wires and pass through
the utility transformers to subscribers' homes and businesses. Little, if any,
modification is necessary to the utility grid to allow transmission of BPL.
This mode has not yet been widely deployed in the United States, but it has
been implemented in a few other countries, with varying results. The Federal
Communications Commission (FCC) is currently working on a set of rules
according to which BPL may be implemented in the United States. If it is put
into use, BPL will be an unlicensed service, and will be governed by rules similar
to those that apply to cordless telephones, television remote controls, and
other consumer electronic devices.
Some people say BPL represents an ideal solution for
people in rural areas. But many engineers, along with officials in the National
Telecommunications and Information Administration (NTIA) and the Federal
Emergency Management Administration (FEMA), fear that BPL will interfere with
fire, police, shortwave, land mobile, and other radio systems important to
national security. Amateur radio operators have voiced their concerns as well.
BPL subscribers may also be adversely affected by the electromagnetic fields
that radio transmitters generate in the course of their normal and licensed
operations. The utility power lines are not shielded, as is coaxial cable, and
some of the frequencies suggested for BPL operation lie within the spectra
assigned to essential wireless services.
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