Mixed Conclusions About Powerline Networking vs. Ham Radio
Barence writes "Since writing about the success he's had with powerline networking, a number of readers emailed PC Pro's Paul Ockendon to castigate him for recommending these products, such as HomePlug. They were all amateur radio enthusiasts, claiming the products affect their hobby in much the same way that urban lighting affects amateur astronomers, but rather than causing light pollution they claim powerline networking causes radio pollution in the HF band (otherwise known as shortwave). Paul's follow-up feature, 'Does powerline networking nuke radio hams?' documents his investigation into these claims, which found evidence to support both sides of an intriguing debate."
It's a volunteer emergency communications organisation.
Do not mock my vision of impractical footwear
I doubt any EM leaked out of that house.
Except out the power lines that are good at radiating RF outside the house just like they are good at carrying RF inside the house. At least until they reach a transformer.
Frequency planning is an area you would need to study further before you could make sensible statements about it. Sorry, and good luck if you do decide to look into it.
Bruce Perens.
If there's any question about HAM operators on the Internet, just check any of the wikipedia articles on radios. You'll easily find lots of (well cited from multiple sources per sentence) stories about how HAM operators invented modern electronics and have saved the world multiple times from disaster. In fact, you'll wonder how any country could get along without them!
another point of confusion: HomePlug devices are regulated under "Part 15", which basically means it must suffer any and all interference and must not itself cause any interference to licensed stations.
Licensed stations include: Shortwave broadcasters, TV/AM/FM broadcasters, Private commercial stations (Taxis, Couriers, etc.), Government stations (Local and Federal), and Amateur Radio Operators ("Hams"). (previous list not exhaustive)
Like it or not, the "asshole with the fugly antenna" had it right.
If you look in the manual that came with your TV, you will see a little bit of small print talking about "FCC part 15 regulations". These essentially say that your TV cannot unintentionally radiate a signal that will disrupt any licensed radio service, and, more importantly, that your TV viewing IS NOT PROTECTED against interference by licensed radio services, as long as said stations are operating within their legal requirements (power output, spectral purity, etc.).
In short, you don't have a license to watch TV, but the ham DOES have a license to transmit up to 1500W of RF on various frequencies, whether it screws up your TV or not. If you don't like this, you are free to buy a better quality TV receiver, that incorporates all those "frivolous" features like proper shielding and filtering, that usually get "value engineered" out in order to sell the set for fewer bucks at WalMart.
A good summary of FCC Part 15 available here:
http://www.arrl.org/tis/info/part15.html
BTW, you could be subject to FEDERAL charges for damaging a federally licensed radio transmitting station, , if your "asshole" neighbor wanted to press things. Generally, hams are more than willing to work with their neighbors to resolve interference issues (even if not legally required to), but when said complaints become abusive or threatening, we are fully within our rights to tell you to take your cheap Chinese TV set and stick it where the sun don't shine. And the FCC will back us up, every time.
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For a wire to not be an efficient RF radiator, typically it has to be 1/4 wavelength or longer. For the freqencies we're talking about (up to 30MHz), 1/4 wavelength can be as short as 2.5 meters (since 28MHz is around 10 meters).
14 MHz is only 20 meters, so a piece of wire 5 meters long (or even a combination of wires that are segmented together through a panel) can become a radiator (aka transmitting antenna).
You can see where this is going. It's hard to get the frequency low enough where the typical wire layout in even a small home won't tend to transmit RF energy. The lower the frequency, the smaller the frequency spread. You can't transmit as much data in 2-10MHz (8 MHz of total RF spread) as you can in 2-30MHz (28 MHz of spread), and so the throughput rate of the device would be so small that it would no longer be a viable product.
They're caught between physics and the market.
There are other services in the HF band between 1.8 MHz and 50 MHz than just Ham operators and shortwave radio stations.
The spectrum is also used for aviation, particularly when commercial aircraft are over the ocean and out of line-of-sight to a shore station. Most ships at sea use HF radio for communications from ship to ship and for ship to shore communications. The military still uses HF communications for a great many systems, including the broadcast of EAM (emergency action messages).
Someone will say "so what, they are way up in the air or in the middle of the ocean" but they fail to realize that the shore based stations are subject to interference while trying to receive signals from aircraft and ships.
There are still radio navigation systems that operate in the HF bands, weather bouys in the ocean sending back data by HF and many other overlooked systems of lesser renown.
Having spent a significant amount of my professional life hunting down interference sources to communications systems I can say it is NOT a good idea to put a thousand low powerline network extenders across a city. There WILL be harmonic interference, intermodulation and an overall decrease in performance. Look at how badly screwed up the 802.11 a/b/g/n, Bluetooth and ZigBee are? The 2.4 and 5.8 GHz devices at least have the decency of being line-of-sight and range is limited by buildings. As soon as you attach something to the wiring system of your home you create something that is impossible to manage (resolving interference issues).
Give this one to the Hams and to those of us who still own and use shortwave radios.
Tisha Hayes
Truth. Not only that but there are people still coming into this. I'm working towards my amateur here in Canada, and I'll be glad to get it. For those of us who live in the middle of no where, this stuff is our only lifeline when everything else fails(see ice storms, blizzards, and other natural disasters like floods).
Om, nomnomnom...
Minor nitpick: just tested for my ticket last week, and they were charging $15, so I think your $10 figure is old. But I fully agree on the non-elitism; you can't usually get a netbook for less than $200, and anyone can get a license (even at $15 for the VEs) and a 2m or 440 HT for $85, and get started for less than half that.
jesus christ, you have no fucking clue about how electricity works. This isn't the result of "poor wiring" at all, and circuit breakers DO NOT act as isolators (why the hell would you think they would?).
That's curious. My meter will not block anything. The TRANSFORMER provides some isolation, but for many of us in the US, that's on a utility pole up to 100' from the house. Since the lines from the transformer to the house are usually strung overhead, they make very effective radiators.
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.