"It Seems to Us . . ." Death by a Thousand Cuts

The American Radio Relay League ^ | 1 MAR 2005 | David Sumner K1ZZ

[Denver Ditdat]

Editor's note: Typically, only ARRL members get to read the "It Seems to Us ..." editorials that run each month in QST. We're posting this editorial that appears in the March, 2005 issue of QST in the hope that both ARRL members and nonmembers might appreciate it and find it informative.

Threats to radio amateurs' access to the radio spectrum come in several forms.

We can lose allocations, either at the international or the domestic level. The ARRL and the International Amateur Radio Union (IARU) devote a lot of resources to the protection and expansion of our international allocations through the International Telecommunication Union and regional telecommunications organizations. In its Washington-area Technical Relations Office the ARRL has four full-time staff pursuing the same objectives at the national level. Through the efforts of the ARRL and the IARU, outright losses are rare; gains are more common.

New sharing arrangements can be imposed on us that reduce the utility of our bands. The bands between 420 MHz and 24 GHz are especially vulnerable because our allocations are on a secondary basis, meaning that at least one and sometimes more services have primary allocations and therefore can claim priority over us. Historically, the biggest user of these shared bands has been the military. Their systems must be resistant to interference anyway, so we have been able to coexist pretty well. However, as new uses for this highly desirable part of the spectrum are developed, even the Pentagon has to accede to commercial pressures for reallocation--and commercial sharing partners may be much more difficult for us to live with.

The most insidious threat comes not from new allocations to licensed services, but from the proliferation of unlicensed radio frequency (RF) devices. We have always had to cope with some interference from incidental radiators, such as electric motors, that are not intentionally designed to generate RF energy but do so in the normal course of operation. Other kinds of devices intentionally generate RF energy, but the radiation of the energy is unintentional; radio and television receivers, computers, and power line carrier systems fall into this category. Still others intentionally radiate, but at levels low enough that the FCC does not regard them as significant interference sources (an issue on which we find ourselves in frequent disagreement). Finally, there are unlicensed personal communications devices that are confined to specific frequency bands and are subject to technical regulations designed to limit their interference potential to licensed services as well as to one another.

The public benefits greatly from many kinds of unlicensed devices. The garage door opener is a good example of an appropriate use for an unlicensed, intentional radiator. Commanding the door to open requires just a brief burst of RF, and commands are sent so infrequently that any resulting interference is insignificant. Few people who have garage door openers would want to give them up.

With careful selection of appropriate frequency bands and appropriate technical constraints, the public can benefit from further expansion of intentional radiators and personal communications devices. But the caveat is important. Some of these devices have high duty cycles, occupy large bandwidths, and operate at power levels that are sufficient to make them significant interference sources. While it is not fully utilized everywhere, all the time, the radio spectrum is fully allocated. Unlicensed RF devices are frequently incompatible with incumbent services and users.

On paper, licensed services always have priority. Operators of unlicensed devices have no rights. The devices themselves may only operate if no harmful interference is caused, and they must accept any interference that may be caused by the operation of an authorized radio station. When we licensees raise concerns about the proliferation of unlicensed devices we are told, "Don't worry. You're protected. Just look at the rules."

But reality is different. Enforcement action is rarely taken to protect licensed services. For more than six months the ARRL has been calling to the FCC's attention ongoing harmful interference caused by Broadband over Power Line (BPL) systems. The FCC has yet to pay more than lip service to its obligation to enforce its own "no harmful interference" regulation.

Or take the benign garage door opener, for example. For reasons that must have sounded good at the time, manufacturers decided to use frequencies in a military band. When the military began using a new communications system, garage doors stopped opening. On paper, that isn't the military's problem. But it is at minimum both a public relations headache and a distraction.

For years, the ARRL has fought a persistent and often lonely battle against the FCC's excessively permissive approach to unlicensed devices. We do so because the cumulative effect of an uncontrolled proliferation of unlicensed devices is to inflict "death by a thousand cuts" on licensed radio services. Every unlicensed emission in a band used by a licensed service diminishes the capability and the value of that service, sometimes at the risk of public safety. Every consumer device that is prone to interference is a potential neighbor-relations nightmare.

BPL is the extreme example. It is not a spectrum user because it is not an intentional radiator. To the extent that it radiates, it is purely and simply a spectrum polluter. And it will radiate, and therefore pollute, because power lines are an inappropriate medium for a high-frequency RF signal.

In the words of one unusually forthcoming BPL engineer, "This would be a lot easier if we could repeal the laws of physics."

[Denver Ditdat]

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