W1RFI
join:2003-05-12
Burlington, CT
| ARRL and Motorola
I usually respond to posts individually, but this may be a good opportunity to make a number of points all in one place.
In the fall of 2004, motorola approached ARRL, wanting information about Amateur Radio and feedback on how they could design a bpl system that would not have major interference problems. After a non-disclosure agreement was signed, ARRL and motorola worked closely, discussing needs and solutions. Although ARRL has had some discussions with some bpl manufacturers, not all of them are willing or able to work cooperatively with radio users, and to this date, none have communicated as throughly as motorola nor have others done as much in actual joint work together on EMC issues.
The end result was motorola's PowerLine LV system.
ARRL had analyzed the design and tenatively concluded that it should not pose a major interference risk to Amateur Radio. This was outlined in a story on the ARRL news crawl:
»www.arrl.org/news/stories/2005/05/23/1/
ARRL and motorola both wanted to see this in practice, so more or less together, engineers for both organizations came to the conclusion that motorola should install one of its systems at ARRL HQ.
»www.arrl.org/news/stories/2005/08/29/1/
The motorola system uses its Canopy wireless as a backbone. This does, of course, eliminate those overhead wires as antennas. It also offers the system immunity to radiated and conducted signals. While fully "wired" bpl needs repeaters every 2000 feet or less, the Canopy system, under line-of-site conditions, can go a few miles between hops, if needed.
They then couple onto LV secondary wiring (240 volt) into homes and businesses. They use HomePlug modems into the premises. By standard, HomePlug notches the ham bands.
»p1k.arrl.org/~ehare/rfi/HomePlug···ARRL.pdf
motorola has added hardware filters to increase the depth of it notches.
Their design does have some interfernce potential to shortwave listening. At this time, the only solution to that would be for motorola to go wireless all the way to that individual location, which it can do.
As an aside, other wired broadband services and devices such as HomePlug, the VDSL systems and the Home Phone Networking Alliance have all deviced standards to notch the ham bands. Although some in the bpl industry, such as motorola, Current and IBEC have designs that completely avoid the Amateur bands, other companies such as Ambient and Amperion are literally leading the industry push not to have such standards for the bpl industry. Although even some of the other companies may be seeing some light at the end of the tunnel, as many of the entries into the FCC-mandated bpl database indicate that many Amperion and Mitsubishi systems are now also voluntarily notching the ham bands.
It is pretty evident that the companies that have designs that avoid most interference issues are the more successful in the marketplace -- Current in Cincinatti and Texas and IBEC in the rural areas. Frankly, the industry reluctance to address interference head on is one of the factors holding it back. They have an opportunity to do so through the IEEE standards process, but even there, their choice is specifically NOT to address compatibility with radio services in their standards in any way other than by specifying test methods.
Back to the point, though. The motorola bpl system installed at ARRL HQ didn't use the electric utility wiring, but was installed on a wireless link from our HQ building to the W1AW station across the parking lot. A simulated "drop" wire was installed and the bpl system mounted on one of the W1AW towers. An example of how the station is configured is seen in some of the pictures at:
»www.arrl.org/news/stories/2004/06/21/1/
In general, the antennas are clustered all around the building.
When the motorola system was fired up, Dick Illman and I monitored each of the ham bands in turn. We only heard their bpl signal on one band, just above the noise, on only one antenna, pointed right at the building. All other bands were clean. (A minor design change subsequently made by motorola is expected to reduce the emissions level somewhat from that level.)
The W1AW station transmits simultaneously on seven Amateur bands, using 1000 or more watts for each transmitter. When the W1AW bulletins came on at 4 PM, the additional filtering in the motorola system allowed it to continue to operate unimpeded, by the tests we did at the time.
All in all, the combination worked well from an EMC point of view. motorola will have to sell itself in terms of reliability; speed and utility applications; ARRL can speak only to EMC issues.
What I find ironic is that some in the bpl industry have convinced themselves that Amateur Radio is a "dying breed" or that its "mere hobby" status should not offer it any protection. Read the following and decide for yourselves:
»p1k.arrl.org/~ehare/bpl/emcomm.html
»www.arrl.org/hamradio.html
Some have also convinced themselves that ARRL is anti-bpl and that what it says is politically driven. ARRL has worked closely with any bpl manufacturer willing to do so. Over the years, it has worked with the VDSL industry, the cable industry and groups like the Home Phone Networking Alliance on interference issues. In general, those companies that can address bpl interference are willing to do so; those whose designs cannot do so adqequately claim that the victim is to blame.
What is ironic is that, to date, the most successful bpl companies are building on the work done between ARRL and HomePlug. The most successful broadband industries are the ones that address their interference issues responsibly. I see no reason to think that this won't apply to this industry as well.
In an EDN article on bpl, I was quoted as saying that my goal is to help bpl be successful. By helping this industry address its EMC issues, I will be doing just that. The article is at:
»www.edn.com/article/CA6280032.ht···yid=2282
ARRL's bpl resource page is:
»www.arrl.org/bpl
It contains, among other things, a list of bpl articles done by the press that are NOT the quick press-release yay-rah articles. There is a lot of good reading there. The page also has links to Amateur-Radio articles, business-case studies (pro and con) and a list of the cities where bpl is deployed.
Ed Hare, W1RFI@arrl.org, ARRL Lab |
