A court decision last year ordered the FCC to revisit certain technical aspects of its rules on Access Broadband-over-Power-Line (Access BPL), a technology that carries broadband services over electrical power lines. The FCC has now responded with a defense of its earlier decision, combined with a willingness to rethink one of the more controversial details.
Our earlier summary of the dispute is here.
Access BPL has lost much of its gleam in the five years since the FCC adopted the rules that were at issue in the 2008 court decision. Back then, BPL was heralded as the “third pipe” for broadband, a viable competitor to DSL and cable, and a promising solution for hard-to-serve rural communities. Now, few utilities still offer BPL broadband services to end users. Most new installations are used only by power companies themselves, for reading customers’ meters and system-related communications.
BPL works by transmitting radio-frequency signals over the power lines. Some of that energy leaks off, in the form of radio waves, potentially interfering with radio reception. The question is, how big is the interference threat?
Really big, say the amateur radio operators, who have long opposed BPL. Pretty small, said the FCC in adopting rules, although it mandated interference safeguards from BPL operators not required of any other industry.
The amateur radio operators’ association, ARRL, asked the FCC to tighten the rules further, and when the FCC refused, took the agency to court. ARRL raised four issues. In the April 2008 court decision, here, it lost on two: a claim that the Communications Act bars the FCC from authorizing BPL as an unlicensed service, and a request that the FCC limit BPL operations to the 30-50 MHz band, which the amateurs do not use.
But ARRL won on two other counts.
The first was a claim that the FCC had improperly withheld information that would have shown the FCC knew all along of a serious interference threat from BPL. The court ordered the FCC to release the information and to request public comment on it. The FCC has now done so – and, to be on the safe side, also released a lot of other information the court did not ask for.
The second point concerned procedures for measuring the radio-frequency energy emitted from BPL equipment. The FCC specifies the permissible emissions as if they were measured 30 meters from the equipment. The actual measurements can be taken closer in, which naturally gives higher readings. The FCC rules include a formula that adjusts the close-in readings down to what they would be at 30 meters, for comparison with the specified maximum. At certain frequencies, the formula is based on a correction factor of 40 dB/decade. (For what that means, read toward the end of this post.) ARRL thinks the formula should use 20 dB/decade instead. Under typical conditions, the ARRL’s numbers would limit BPL devices to much lower levels of emissions. The dB units are a logarithmic scale, making the difference between the numbers much greater than it might appear. For measurements taken at three meters, for example, the 40 dB/decade value allows emissions to be 100 times higher than does 20 dB/decade.
The court did not exactly call the FCC wrong for specifying 40 dB/decade, but it did question the FCC’s handling of the available data, particularly its brusque treatment of studies offered by ARRL. The court’s ruling ordered the FCC either to do a better job of justifying its number, or else to pick some other number and justify that one.
The FCC has now tried the first and begun the second, in its July 17 “Request for Further Comment and Further Notice of Proposed Rule Making.”
The FCC duly offers a defense of the 40 dB/decade value, but a reader senses the FCC’s heart is not in it. The FCC lists the many variables that can affect experimental results, criticizes the studies cited by ARRL for ignoring most of them, and cites later studies as supporting its own views. Throughout, though, the FCC emphasizes that the truly definitive study, taking all relevant factors into account, has not yet been done. The FCC seems to be saying, “The numbers are all over the map; the right answer is not known; and 40 dB/decade is as good a guess as any other.”
Doubtless sensing this approach might not survive a second pass through the court, the FCC immediately moves to a Further Notice of Proposed Rulemaking. That portion of the document requests the following:
- Information on other studies, if any, that bear on what the distance correction factor should be.
- Comment on the use of “slant range” measurement. The BPL rules figure the measurement distance on an upward slant to the power line. The default FCC approach would take the measurement distance horizontally, to the base of the pole. Compared to the horizontal method, slant range measurement effectively pushes the correction factor well below 40 dB/decade, especially for close-in measurements.
- Comment on an alternative factor of 30 dB/decade, or any other number the commenter wishes to propose and support.
- Comment on a proposed procedure that would compute an individualized correction factor for any particular site, based on multiple measurements at that site.
- Suggestions for other correction procedures, particularly for cases where conditions require working close to the pole. The FCC emphasizes that any such proposals require technical support, and must not unfairly burden BPL manufacturers or users.
Comment due dates have not yet been announced.
With commercial interest in BPL fading, one might reasonably expect to see the controversy dying down as well. But that is not how things work in Washington. Once fired up, a regulatory dispute can stay active long after the underlying issues have ceased to matter. The BPL proceeding, even after six years, still has lots of life in it.