The day the D.C. Circuit decided ARRL v. FCC (the broadband-over-power-line case), I posted a brief summary of the decision.

The following is a more complete account, including background on past disagreements between the unlicensed-device industries and the amateur radio community.


On April 25, an appeals court sent parts of the Broadband-over-Power-Line (BPL) rules back to the FCC for a second look.  The challenged rules remain in force in the meantime.

So-called Access BPL, the form at issue here, is a technology for delivering broadband, including high-speed Internet, to homes and businesses over the electrical power lines.  (Another kind, In-House BPL, distributes signals within a home or office.)  The power companies like Access BPL, not only as an additional source of revenue, but also to read customers’ meters remotely and for system-related communications.

Amateurs vs. BPL

Amateur radio operators opposed BPL from the beginning.  BPL works by sending radio-frequency signals along the power lines using frequencies anywhere from 1.7 to 80 MHz.  The useful part of the signal is conducted along the lines, much as voice signals are carried along a telephone line.  But some of the BPL signal leaks off in the form of radio waves.  With access to eleven different frequency bands over 1.7-80 MHz, the amateurs are concerned about that leakage as a source of interference.

Much of the dispute in the BPL proceeding turned on how much leakage there is, and where it comes from.  The amateurs claim that every BPL power line emits energy over its entire length, thus turning a BPL-equipped city into a giant, miles-wide antenna.  The BPL companies disagree.  They say the emissions come only from specific points — from gadgets on certain power poles — and are not much stronger than the stray radio emissions from an ordinary PC.

The American Radio Relay League (ARRL) is an association of amateur radio operators dating back to 1914, with a long record of looking out for amateurs’ interests before the FCC.  It fought BPL throughout the proceeding with a certain amount of rhetoric, but also with reasoned analysis and empirical data.  ARRL mobilized its individual members, who participated by the thousands, though by and large with a lot less reason and data than their association.  (There were a dozen or so notable exceptions.)  For some amateurs the battle against BPL took on the fervor of a religious crusade.

And indeed, the amateurs won a substantial victory.  Although the FCC authorized BPL in the amateur bands, it required BPL operators to undertake unprecedented measures to cure any interference they cause.  But the amateurs wanted more.  They wanted BPL completely off their frequencies.  When the FCC refused to go along, ARRL went to court.

The Part 15 Problem

BPL devices, both on the power poles and in customers’ homes, are treated as "unlicensed devices" under Part 15 of the FCC rules.  The same is true of all other digital products, such as laptops and iPods, and also a host of low-power transmitters such as Wi-Fi, Bluetooth, and cordless phones.  All such unlicensed devices are regulated as to stray radio emissions, among other properties.  Manufacturers and importers must establish compliance before marketing.  Once they pass the required tests, the devices can be purchased and used by anyone without an FCC license.

There has long been some tension between the amateurs and the Part 15 industry.  Most of the higher-powered Part 15 operations occur in bands shared with the amateurs.  In some of these bands, Part 15 power can exceed one Watt — 10 million times higher than the limit elsewhere in the spectrum.  As Part 15 devices proliferate, the amateurs are exposed to increasing risks of interference.  The amateurs routinely oppose expansion of Part 15 in the shared bands.  Starting about fifteen years ago, those oppositions began including a stock footnote suggesting that Part 15 might be unlawful under Section 301 of the Communications Act.  That section can be read to say that any device emitting radio waves must be licensed by the FCC.  If that were the correct reading, then the statutory language would leave no room for unlicensed devices.

In 2001, the FCC approved one more in a string of Part 15 power increases in shared amateur bands.  ARRL sought reconsideration, and this time argued head-on that the FCC’s action violated Section 301.  The FCC’s reasoning went something like this:

1.    We think Section 301 requires licensing only for devices that actually cause interference.  Harmless devices like laptops and PDAs and musical greeting cards are exempt — and would be impossible to license anyway.  (ARRL agreed.)

2.    And we, the FCC, get to decide which devices cause interference.  (ARRL agreed again.)

3.    We now decide those higher-power Part 15 devices you oppose are non-interfering.  That makes them lawful under Section 301.

ARRL promptly filed an appeal.  But it withdrew the appeal shortly afterward, giving no reason for the change of heart.  Observers at the time thought ARRL, to prevail, would need a case having better facts.

From ARRL’s point of view, the ideal set-up for a challenge would have the FCC authorizing a Part 15 device that the FCC itself conceded could interfere with amateur radio.  But that seemed unlikely, to say the least.  The FCC had always been careful about limiting Part 15 emissions to make interference to other users a very remote possibility.  But it took only three years for the planets to align.  In the BPL rules, the FCC seemed to give ARRL everything it needed to contest Part 15.

Mobile vs. Fixed

There are two kinds of amateur stations.  Fixed stations are typically installed in a building such as a residence or club; mobile stations are usually in a car.  Fixed stations tend to have better antennas and receivers, and so can receive weaker signals.  That makes the fixed stations more sensitive to very weak levels of interference.

The FCC at first adopted the same BPL rules as to fixed and mobile amateur users.  If an amateur reports interference, the BPL operator must "notch" (turn down) the signal on that frequency by either 90% or 99%, depending on the band.  If that does not resolve the problem, the operator has to completely shut off the offending BPL unit.  In addition, the BPL industry must maintain a publicly accessible database showing the frequencies in use and details on the equipment at every location nationwide, with phone numbers and email addresses to report interference.  All of this added up to a major victory for the amateurs, far beyond anything else in Part 15.

In a reconsideration order, the FCC made a small but significant change.  The rules remained the same for fixed amateur users.  But on a complaint from a mobile amateur, the BPL operator must only effect the 90 or 99% notch; it need not turn off the unit.  The FCC acknowledged that intermittent interference might remain after notching, but it absolved the BPL operator of further obligations.  The mobile user could escape the interference by relocating, the FCC noted, and besides, the public benefits of BPL justified "a small increase in instances of disruptions" to mobile communications.

No party had asked for this particular ruling.  But a look through the 8,000 filed comments turns up a possible motivation.  A few of the more zealous amateurs had said they planned to drive around looking for interference, report it, and thus shut down BPL "one pole at a time."  Eliminating the shut-down requirement as to mobile users ended this threat to BPL.  But it stirred outrage in the amateur community.

ARRL thought it finally had its case.  The FCC had admitted possible interference from a Part 15 device.  ARRL went to the U.S. Court of Appeals for the D.C. Circuit.

Is Part 15 Lawful?

ARRL’s central argument turned on the Section 301 licensing requirement.  If a device can cause interference, said ARRL, it must be licensed, according to prior FCC rulings, and therefore is ineligible for authorization under Part 15.  At the very least, ARRL insisted, the FCC should be required to explain its departure from precedent on this point.

The FCC answered by saying, yes, while BPL may cause minor and intermittent interference, that does not constitute harmful interference.  Because Part 15 must protect amateur radio only against harmful interference, BPL is therefore proper under Section 301.

(The FCC could have made a different argument.  Another rule, much older than BPL, requires any Part 15 device to shut down if it causes harmful interference to any licensed user.  If that rule applies to BPL and mobile amateurs — and there is no reason to think otherwise — then BPL complies with the long-standing, non-interference interpretation of Section 301.  But the FCC did not raise this point.)

The Part 15 community was concerned about the case.  Any Part 15 device is a potential source of interference — even harmful interference — under some conditions.  Wi-Fi, for example, sometimes interferes with amateur radio.  A court ruling that barred the FCC from authorizing arguably interference-causing devices under Part 15 could have thrown the legal status of the industry into doubt.

But the court accepted the views of the FCC that BPL would not cause harmful interference to mobile amateurs.  This means the missing shut-down requirement would never have to be invoked, so its absence from the rules does not run afoul of Section 301.

The FCC must realize that it had a close brush.  Going forward, it is likely to be more careful in framing its rules to ensure that licensed devices are well protected from Part 15 interference.  And yet, as the role of Part 15 in the economy continues to grow, Part 15 becomes increasingly hard to contain.

Other Issues

While affirming the FCC on the Section 301 issue, the court found fault with other two aspects of the BPL decision.

First:  Among the many technical studies that played a part in the proceeding were five carried out by the FCC itself.  The FCC placed these in the public docket, but blacked out some passages it said were "preliminary or partial results or staff opinions."  It claimed not to have relied on those passages in reaching its conclusions.  And ordinarily an agency need not share its internal deliberations with the public.  But the court, having reviewed the missing material, suspected it might contain evidence that could call the rules into question.  For that reason it ordered the FCC to publish the material and to receive public comment on it.

The other ARRL victory (at least for the time being) concerns an "extrapolation factor" that the FCC carried over from earlier Part 15 rules.  At frequencies below 30 MHz, the permissible emissions are specified at a distance of 30 meters, or almost 100 feet.  That requires an inconveniently large test set-up.  The FCC allows measurements at shorter distances, which are then corrected to 30 meters by a factor of 40 dB/decade.  Translating:  for every factor of ten change in distance, the actual measured values are divided by 10,000.  For example, measurements taken at 3 meters can be 10,000 times higher than the published limit at 30 meters, and still comply.

ARRL insisted throughout the proceeding that 40 dB/decade is too high:  that the factor should be 20 dB/decade, or division by 100 for each tenfold increase in distance.  Using ARRL’s figure, a BPL device measured at 3 meters would be allowed only 1/100 of the emissions it could have under the FCC’s approach.

Ordinarily the courts tend to side with the agency on a complex technical issue.  Here, however, the court found that the mathematical models used to justify the 40 dB/decade value relied on measurements from other, non-BPL technologies that might not accurately reflect BPL.  The court also wondered why the FCC had disregarded British studies, placed in the record by ARRL, showing that 20 dB/decade was closer to the mark.  The court did not invalidate the 40 dB/decade factor, but it ordered the FCC either to justify it in terms of the record, including the British studies, or else to pick a different number and justify that one.

The last issue went to the FCC.  Equipment made by one leading BPL vendor uses only the frequency band 30-50 MHz, where the amateurs have no operations.  If one vendor could do it, ARRL reasoned, so could all of them.  It asked the FCC to limit BPL to just those frequencies, and when the FCC refused, complained to the court that the FCC had brushed off a good idea.  But the court found enough reasoning in the FCC’s order to support the rejection.

Back to Work

The next step in the process will be a request for comments from the FCC, certainly on the redacted studies, and probably on the 40 dB/decade issue as well.  Considering the great interest in the original BPL proceeding, the FCC is bracing itself for this new round, which promises to be at least as contentious.  The amateur community is unlikely to pass up another opportunity to express its displeasure with BPL.