Potential Spectrum Loss, BPL In Ham's Way

I was very disappointed with your "Beyond Technology" column in the 24 November 2003 issue of Electronic Design.

First of all, you only briefly mentioned in passing that the 682,000 amateur radio operators in the U. S. are part of the "Amateur Radio Service", designed to provide a necessary service of trained radio operators and communicators to the country in times of need, such as natural and man made disasters (which you didn't mention at all). You mentioned the word "ham" or "hams" at least ten times, but nothing about their contributions to the country, only their request for availability of spectrum, need for protection against power line interference, and certain Morse Code requirement changes.

Further, your column had essentially no technical information. Isn't Electronic Design supposed to be a technical journal for electronics engineers? While you did mention the number of licensed people in the amateur radio service you gave no idea of what any "possible loss of spectrum" might do to this service. Is it HF, VHF, microwaves, or exactly what portion of the spectrum, do they want to insure access to for future service needs? What are the competing needs? How much spectrum do other services require, and for what purpose?

In your "discussion" of the Broadband over Power Lines (BPL) you only mentioned the ARRL's concerns. What about the military, the FAA, the AM medium wave and short wave broadcasters, and numerous other users of the HF portion of the spectrum up to 100 MHz, who will potentially be affected by a much higher "noise floor"? What is this new noise "floor"? What are the proposed levels of interference from BPL, in microvolts/meter, for instance? How much will other services potentially be impacted? Is BPL the best, or even the most efficient method of delivering broadband computer access to homes? What about the "last mile" of fiber optics from the existing, or potential competing telephone systems, that could deliver more than merely data, but many channels of TV, etc.? Isn't that the "new" technology, and not merely attempting to greatly modify the 60 Hz power lines to try to deliver signals up to, say, 100 MHz? Don't the power companies have a difficult enough time in simply providing reliable, reasonably priced, low environmental impact, prime power to all of us? If they can't to their main job well, why should they attempt to get into another business when other alternatives may be better suited to the task?

Yes, your column was certainly "Beyond Technology," but in what direction "beyond"? Was it an attempt to educate your engineer readers about any technical aspect of the amateur radio service, BPL, spectrum management, reasons for the continued use of Morse code, or merely some other (hidden) agenda? If so, it failed.

The readers of Electronic Design certainly deserve more, as do the 682,000 members of the Amateur Radio Service.

The article was actually fairly positive, as these things go.

Unfortunately, BPL operates at the emissions limits in Part 15 -- 30 uV/m at 30 m from the radiating source. The laws of physics predict that a halfwave dipole or HF Yagi placed in a 30 uV/m field will pick up an S9-level signal (very strong signals). This will happen with any Part 15 radiator near that antenna. In most cases, however, the interference potential from a Part-15 device is local. We can and do hear devices in our neighbors' houses, but typically not the ones from several blocks away. Most Part-15 devices that generate "legal" signals do so on only a few frequencies, and most are not on 24 hours a day. So 30 uV/m at 30 m does help to limit the interference potential from Part-15 emitters.

How well can this apply to BPL? First, when a BPL system is built as large as entire community, all HF users within that community will have part of the BPL system "next door," or on the power lines outside his or her house. BPL systems don't just use a few narrowband freqeuncies, but occupy tens of MHz of spectrum simultaneously. From what ARRL has seen, they are not intermittent, but have some activity 24 hours a day. Trying to apply Part-15 to BPL would be like trying to live with the noise of the occasional airplane that passes overhead. What can be acceptable for a few minutes once in a while in only portions of town would be entirely unacceptable 24 hours a day at all locations simultaneously.

This is not just an amateur radio problem. BPL will use spectrum allocated to amateur radio; shortwave broadcast; commercial; military and into low VHF public-service communications channels. It will cause a change in ambient noise levels of up to 60 or 70 dB, or more in some cases where receiving antennas are located close to power-line wiring.

The Federal Emergency Management Agency just filed its comments about BPL with the FCC. An article about this is front-page on the ARRL web site at http://www.arrl.org. ARRL's BPL-resource page is at http://www.arrl.org/bpl. Ed Hare, W1RFI ARRL Lab 225 Main St Newington, CT 06111 Web: http://www.arrl.org/tis

It should be pointed out that BPL interference cuts both ways. Not only does it cause interference to the Amateur Radio Service (as well as other licensed radio services), it is also susceptible to interference from these same licensed services. Amateur radio operators in Manassas, VA and other suburbs near Washington, DC have shown how susceptible to interference BPL really is. In the HF spectrum, amateur radio transmitters are limited to 1500W PEP (peak envelope power). Informal tests with HF transmitters running as little as 100W (a very common power level for most HF radios on the market today) are able to disrupt, and in some cases completely disable, BPL network transmissions.

Rather than acting as an arbiter for competing interests, the FCC is unfortunately acting as a champion for BPL technology. The FCC is not acting with proper diligence in this matter, and is letting business interests get ahead of sound technical decisions. Incredulously, the BPL equipment providers have now asked the FCC if it would be possible to significantly increase the field intensity levels permitted under Part 15 regulations in order to make their systems more robust. Letting an unlicensed radio service knowingly interfere with licensed radio services simply turns logic on its head!

BPL is an ill-conceived communications medium that is not robust enough to effectively compete with other broadband services such as DSL, cable modems, satellite and licensed wireless services. BPL is the communications equivalent of shipping gasoline through sewer systems rather than through pipelines. Just because sewer lines are able to transport fluids and are commonly found throughout the country doesn’t mean that they’re suitable for transporting hazardous and flammable liquids! Similarly, BPL is a source of pollution in the HF spectrum and an unnecessary hazard to HF communications. I urge everyone to write their Congressional representatives and tell them that the FCC should dump its BPL initiative today!