NEWINGTON, CT, Aug 21, 2003--The ARRL says Broadband over Power Line (BPL) proponents failed in their comments to the FCC to substantiate their claims that the technology will not cause widespread interference. In reply comments filed August 20--the FCC's deadline to receive comments in the proceeding, ET Docket 03-104--the League said that if the FCC is going to rely on industry statements in making decisions on BPL deployment, the industry should back up its assertions with technical studies and hard data and make these public.
 ARRL Lab Manager Ed Hare, W1RFI, in his "BPL-mobile," specially equipped to monitor for BPL signals. Hare used a typical HF transceiver--in this case a Kenwood TS-440--to listen on HF for BPL interference and other receiving gear to take field strength measurements. |
"Unfounded assurances that BPL will not cause interference are no substitute for real-world measurements," the League declared, "and the FCC should rely on documented test results and an impact of interference potential based on scientific, not marketing, criteria." Generalized conclusions drawn about BPL's interference potential in industry comments "are premature and meaningless," the League said.
A form of power line carrier--or PLC--technology, BPL would use existing low and medium-voltage power lines to deliver broadband services to homes and businesses using frequencies between 2 and 80 MHz. Some BPL proponents--primarily electric power utilities--already are testing BPL systems in several markets and want the FCC to relax radiation limits.
"Power lines are ubiquitous, and attempts by
the BPL industry to obtain relaxed emission classifications based on operating
environment are obviously illogical and frivolous," the ARRL said, noting BPL
would impact not only hams but public safety low-band VHF systems and other
mobile systems.
 BPL would use low and medium-voltage lines like these in a typical business-residential area to distribute broadband services. |
In contrast to the BPL advocates' "blanket statements" of no interference from BPL field trial sites, the ARRL said its own field tests "lead inescapably to the conclusion that BPL will, if deployed, create widespread harmful interference." It predicted signal levels of up to 30 dB over S9 on a typical amateur transceiver, "well beyond what would preclude amateur HF communications entirely."
To dramatize its point, the League urged the
Commission to view video shot during
recent ARRL test-and-measurement forays to BPL field trial communities in four
states. The ARRL said the type of degradation expected from BPL would transform
20 meters from a band with worldwide communication capabilities to one of
limited regional communication capability.
 The calculated reliability of a station in a typical "residential" noise environment at 14 MHz. The station in this model is using a 3-element Yagi to receive signals from worldwide stations transmitting at 1 kW. The man-made noise level is just starting to have a significant effect on the capability of the station to establish reliable worldwide communications. Modeling was done using VOACAP software. (The curves represent the percentage of time that the signal-to-noise ratio is greater than the SNR required for reliable communication over a given path. Red is greater than 75 percent. White is less than 20 percent.) |
"ARRL has, in fact, done what the BPL industry should have done--brought an amateur station to the trial area," the League said. "When it did so, the interference was manifest and widespread and would be so even to an untrained observer."
Noting claims by Main.net that it had received no reports of harmful interference in its worldwide trials, the ARRL countered that the tests had resulted in "strong protests from Amateur Radio operators." Austrian amateurs documented "massive interference" on video, and, in an unusual move, the Austrian Experimental Transmitters Union (OeVSV) filed comments in the BPL proceeding. BPL proponents argue that the European power distribution system differs from that in the US.
The League said measurements and testing
should be done when the BPL systems are heavily loaded, treating the system's
entire emission as a single device. "If all of the appropriate measurement
factors are applied," ARRL said, "no access BPL system would be found in
compliance with FCC Part 15 regulations."
 The calculated reliability for a noise environment at the present level of Part 15 radiated emissions for carrier current (PLC) devices. The range and reliability of this station on 14 MHz have been reduced to the point where this frequency range is no longer useful for DX communication. |
The ARRL characterized some industry comments regarding the interference potential of BPL as "wishful thinking" and based on flawed premises. It said the League's own technical exhibits--attached to its initial and reply comments--show that BPL signals do propagate well and that overhead power lines make excellent radiators of HF signals.
The League also noted that comments in the proceeding so far have been silent on the interference susceptibility of BPL to ham radio signal ingress. The League predicted that even as little as 250 mW of signal induced into overhead power lines some 100 feet from an amateur antenna could degrade a BPL system or render it inoperative.
The ARRL called on the FCC to stop acting like a cheerleader for BPL. "It is past time that the Commission acted in its proper role as a steward of the radio spectrum and recognized the interference potential of BPL to the sensitive incumbent licensed services in these bands," the League concluded. "The Commission cannot stretch the Part 15 regulations as far as would be required to accommodate BPL."
The League's complete reply comments and technical exhibits are available on the ARRL Web site. See also the article "BPL is a Pandora's Box of Unprecedented Proportions, ARRL Tells FCC". Additional information and video clips are on the ARRL "Power Line Communications (PLC) and Amateur Radio" page.
To support the League's efforts in the BPL
fight, visit the ARRL's secure BPL Web site.
 Previous: Ham-Concert Pianist-Jogger Completes 880-Mile Charity Run |  Next: The K7RA Solar Update |