FEMA says power line broadband threatens its radio system
- By Joab Jackson
- Dec 17, 2003
Responding to a Federal Communications Commission inquiry, the Federal Emergency Management Agency has warned that sending data through power lines could disrupt FEMA's National Radio System.
The Homeland Security Department is responding to a notice of inquiry (http://edocket.access.gpo.gov/2003/03-12914.htm) issued last May by the FCC on whether, or how, the agency should regulate an emerging technology called broadband over power line, or BPL.
BPL systems use live utility company power lines as a conduit for data transmission by modulating radio frequency signals that are coupled with electricity transmissions. The technology could be offered to consumers as an alternative to cable modem and digital subscriber line service. Although no services are now offered, several companies have introduced products that let users send data over the power lines within their own homes.
The FCC asked for more information on what effect power line radio signals would have on other licensed radio technologies using those same frequencies.
FEMA responded (http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6515292045) earlier this month to the inquiry, stating that it had 'grave concerns' about how the technology would affect its National Radio System
The radio system, which works with shortwave radios, is FEMA's backup command and control communications media, and was designed to interface with the radio systems of other agencies during times of disaster.
'By design, BPL systems use radio frequency energy on unshielded, unbalanced transmission lines, resulting in the unavoidable radiation of [radio frequency] energy,' the response read. This unintentional radiation will create harmful interference to licensed radio services throughout the [high frequency] and lower [very high frequency] spectrum.'
Alan Shark, president of the Power Line Communications Association, said that FEMA's concerns were overblown. Most first-responder radio systems work in the 800-MHz range, far above the usual operating range of power line equipment, which can run from 1 MHz to 300 MHz.
Shortwave radios, also called high-frequency radios, do operate in about the same range as power line equipment, he said. Not surprisingly the National Association of Amateur Radio, whose members volunteer their services during times of crisis, are also protesting (http://www.arrl.org/tis/info/html/plc) the BPL technology.
Shark said that BPL equipment vendors have done studies on whether additional interference comes from their products, and have failed to find any interference beyond what the power lines themselves cause. Both the FCC and the National Telecommunications and Information Administration also are conducting studies to measure interference levels.
Joab Jackson is the senior technology editor for Government Computer News.