Broadband Over Power Lines -- The Rest of the Story

In response to the article of March 5, 2006, "Broadband Over Power Lines for 21st Century Communities" which extolled the virtues of BPL, your readers need to know that there is another, darker, side to the BPL story -- radio interference. ARRL, the National Association for Amateur Radio, has participated in testing in a number of BPL marketing trials and has seen interference to radio reception on some spectrum in all of the sites their staff and volunteers have examined. Currently, only BPL systems that completely avoid the use of spectrum allocated to the Amateur Radio Service appear to have any promise at avoiding most interference that may occur to Amateur Radio. But simply moving BPL operating frequencies can still cause interference to other services.

George Steinert
One exception, Motorola's LV design for a system that uses only low voltage lines, looks very promising. By working closely with amateur radio in their development -- and by totally avoiding signals on medium voltage lines as used by most BPL providers -- the LV system significantly reduces the interference problems that plague most other manufacturers. Motorola has also added filters to their product to significantly reduce its interference potential.

Other BPL manufacturers, notably Current Technologies, IBEC and Corridor Systems have designed their systems without using spectrum allocated to the Amateur Radio service. This, too, has reduced their interference potential, although not quite as well as a system that uses additional filtering. BPL systems using equipment made by other manufacturers such as Manassas have active, unresolved complaints of harmful interference filed against them. In most other cases, BPL proponents may pronounce their marketing trials as being "successful," but to ARRL's knowledge, not a single BPL trial has included a thorough examination of interference issues if deployed on a large scale. It is premature to pronounce these tests to be a complete success.

Even former FCC Chairman Powell, one of the most vocal proponents of BPL, admitted the seriousness of the interference issues. Simply put, there is no way that radio frequency signals are going to stay contained in a wire designed to carry normal electric power. It will radiate and pollute the radio spectrum. The FCC's October 2004 Report & Order recognized this danger to communications and totally barred the BPL companies from using frequencies associated with aeronautics and some governmental agencies. Obviously, these concerns about interference and spectrum pollution were not seen as trivial or resolved by the FCC. For the rest of the radio community, there was the FCC promise that if a licensed system experiences harmful interference due to BPL in the area, the BPL provider must either fix it in a timely way or shut the system down. Many BPL trials have already closed after being unable to resolve the interference issues.

National Telecommunications and Information Administration (NTIA) studies have determined that broadband over power line creates a "high risk" of radio interference, and that harmful interference to public safety mobile radio receivers can be expected at distances of 300 feet from the power line where broadband over power line is in operation, and at distances of up to 1,500 feet from fixed stations, such as VHF police or fire dispatch communications facilities.

Many public safety agencies and support services, including emergency medical services, fire, and law enforcement, utilize Low-Band VHF (30-50 MHz). Thirteen states--California, Connecticut, Florida, Illinois, Indiana, Mississippi, Missouri, Nebraska, North Carolina, South Carolina, Tennessee, West Virginia and Wyoming--use the band for state police operations, while it's the primary public safety radio band in nine states.