Making Waves: BPL Comes Home

What happens when you suddenly find your dipoles surrounded by BPL couplers? I’m about to find out.

The Broadband over Power Line (BPL) pilot project continues in San Diego. The test observation committee set-up by SDG&E power systems engineer Terry Snow, of which I am the token broadcasting representative, met last during the recent NAB Convention, but Terry was kind enough to forward a copy of the meeting minutes. 

{mosimage}So imagine my surprise when I looked at an enclosed map to see that the third vendor pilot would surround my University City home. The system power-up is scheduled for this week, and the amount of activity in the neighborhood has been very high. Truck crews have been installing wireless receive antennas and data couplers on poles and electricians have put data modems in a test  home…which happens to be a next-door neighbor.

I won’t comment much on the BPL pilots to date except to say we haven’t found any measurable interference to the broadcast bands that you care about. I’ve agreed with SDG&E to patiently await results of spectrum analysis tests before drawing any conclusions. There is something a bit childish about berating a scientist as he’s performing his experiments, whether you agree with the science or not.

It appears as though Terry and his co-workers are genuinely interested in getting feedback on interference caused by their BPL pilots, and they are studying similar pilots around the country for experiences with interference. In fact, they added a vendor to their pilot series that was known for reduced interference. There are at least three of us on the committee who are licensed ham radio operators. Whether the board at Sempra Energy takes their, or our, final recommendations to heart is another matter.

I have to believe that my neighborhood was chosen because it was one of the last with overhead electrical lines, and due to the lack of CC&R’s, it has has a higher incidence of ham radio operators than later built neighborhoods. If Terry chose specifically to surround my house, that’s very funny Terry. Very funny.

As a ham radio licensee for 35 years, I haven’t been very active for the past few years. I have enjoyed 6 meter E-skip operations from time to time, but that’s about it. I have a dual 10 meter/40 meter dipole and a decent collection of 40-year-old Drake equipment, so I’ll be firing that up to make sure there the HF interference characteristics haven’t changed. It’s been amazingly quiet here considering the urban nature of the neighborhood. I hope it remains that way, but the future’s not bright. 

One of the surprising findings on a previous pilot project site test was that the primary radiators in the fake home office was a plasma TV generating a big, raspy signal on the upper portion of the AM broadcast band. When we turned that off, we found another device radiating in the middle frequencies of AM–this was the power supply of the BPL modem, not the power lines themselves. We saw a heterodyne on channel 6, but turning off the BPL system made no difference. 

Ever played Whac-a-mole at Chuck E Cheese?