What about interference that interrupts BPL?
This only addresses transmitted interference from BPL to other licensed services; what about receiving interference from licensed radio services? Whether you choose to believe it or not, tests by certified electrical engineers have shown that very small amounts of high frequency RF power in the proximity of a BPL installation on a power pole or even in an underground entrance in a neighborhood can render that BPL system inoperable, sometimes for a few minutes, but sometimes permanently.

Completely legal licensed operation of a radio transmitter could shut down a part or all of a BPL installation, and there is absolutely nothing the BPL operator can do about it. The BPL industry has chosen to go the unlicensed route under Part 15 rules for the same reasons the baby monitor and garage door industry has -- it's cheap. Cheap to design and cheap to build. But cheap might just be the undoing of the BPL industry, as more and more licensed radio transmitters are coming online, or being used in a mobile environment, and these could disrupt BPL systems on a wide scale.

This radio interference is no exaggeration, either. I am a technologist first, a ham operator second. I make my living on things technical (both RF and wire line communications), and I certainly wouldn't chance my VoIP service, or my company's, on BPL, knowing the shortcomings it has relating to receptive interference.

Hams have not made a big point of this because, to the uninitiated, logic would make it seem that the transmitter of the interfering signal would be the offender. But because these BPL devices fall under Part 15, it's the other way around; they must accept any interference from licensed services.

But what of unlicensed services? While they have no legal standing, unlicensed services like illegal CB operation, using exceptionally high RF power amplifiers, are a fact of life. For example, if a CBer with a 500 watt (illegal) CB amplifier is driving within a few blocks of a BPL installation, it is highly likely the BPL system will be severely adversely affected. Legal or not, the BPL is still affected, and this is something the BPL providers won't address, because it would require a lot of money be spent to "harden" their equipment. They made a choice to go the Part 15 route in the first place to save money; it isn't likely they will spend money after the fact to harden their systems and equipment.

This isn't late-breaking news to the BPL providers, they simply didn't do their homework before putting money into the technology initially.

Had they done so it would have been obvious that their 3 to 30 MHz band of operation would quite likely give, and more importantly to this discussion, almost assuredly get interference.

This could have easily been avoided if they had built their technology to operate wide-band further up the radio spectrum, like maybe in the 2 to 10 GHz range. It would have been slightly more expensive to build, but virtually impervious to outside interference. So much for advance planning. I hope you have an opportunity to research this before your next installment; the ham community would very interested in how the BPL consortium responds.