I came across an article which says that an internet provider is using the incoming ac lines to piggyback their signal.Simply plug your computer in and you're online.

What would be the drawbacks to such an arrangement?

Russell

Can't think of any other than possibly speed, reliability and availability in all areas. Don't know anybody who has tried this so I couldn't compare to DSL or broadband. Certainly easy enough to install though.

One BIG drawback is spelled R-F-I.

Putting these high frequency signals over unshielded powerlines will play havoc with other uses of the radio spectrum. Shortwave, public safety, and amateur communications could be rendered just about impossible!

Lots more info on why BPL should never have gotten off the drawing boards:
http://www.arrl.org/tis/info/HTML/plc/

Unfortunately, now that MBAs are running the FCC instead of engineers, crap like this gets approved as a gift to the corporate interests that grease the wheels in Washington...

The first systems that came out behaved like NJwirenut describes. The manufacturers claim to have addressed the interference issue in later systems. It is mainly a solution for that "last mile" to the user with performance in the tens of megabits.

They CLAIM to have fixed the problems, but experiments in BPL deployment areas have proven otherwise. Watch the videos of the tests for yourself at:
http://www.arrl.org/tis/info/HTML/plc/#Video

I can't see how it could be POSSIBLE to "fix" the problem here, short of completely shielding the power grid or suspending the laws of physics. Putting RF signals onto long spans of unshielded wires by DEFINITION creates antennas which radiate the signals.

In addition to the RFI issues, such radiation creates the possibility for unauthorized access to the data stream by anybody with a scanner and a computer...

[This message has been edited by NJwirenut (edited 03-07-2004).]

How about: Lower the power used for signalling, make more sensitive receivers and improve the error checking and correcting.

NJwirenut

It seems you have already made up your mind on this.

Is there something you are not letting us know?

Like you are a Ham radio operator or something like that?

Maybe I am wrong, but your posts project a feeling of anger on this subject.

How about: Lower the power used for signalling, make more sensitive receivers and improve the error checking and correcting.

Lowering power might help a bit in the near field, but HF radio signals can propagate worldwide, even at low power levels. A BPL system here in the states could be clobbering radio communications on the other side of the world.

More sensitive receivers would only exacerbate the flipside of the interference issue--interference TO the BPL system by radio transmitters! In some tests, a simple CB or ham radio set near the powerlines was enough to totally disrupt the BPL connection. Improved error correction might reduce this, at the expense of connection speed, and increased radiated interference from the system (more hash as CRC packets bounce back and forth).

And yes, I am a ham radio operator. But it isn't just hams who are up in arms about this. FEMA, police/fire/ambulance, and aircraft comms groups have all filed comments against BPL with the FCC.

As far as "anger" over the issue, it is more frustration with what I (and many others) see as the FCC abdicating it's mission to maintain a usable spectrum for ALL users, in favor of giveaways to corporate interests. Comissioner Powell would much rather score points by promoting mega media mergers and raging against Janet Jackson's boobs than consider technical issues that might impact some corporation's IPO.

[This message has been edited by NJwirenut (edited 03-07-2004).]

Glad to see you are keeping an open mind.

Bob

Just wanted to add that the website NJwirenut linked to has a good list of references. It's not as biased as you would expect.

It seems to me that ADSL lines would have the same effect. Unshielded wires carrying a high frequency. Strangely, I haven't heard anyone complain about that yet.

The radio astronomers have a just cause: They aren't in control of the transmitters. "Hey, mr Spaceman, could you please go to UHF?"

What I don't understand is why special consideration should be given to radio amateurs? The cellphone operators have been forced to change band several times. The analogue TV network will be closed down to give room for digital. Even radio controlled model planes have been forced to change band. So have the police and other forces. This is a process that has been going on since the radio first was invented. Why not make the amateur radios digital? That should make them much less susceptible to interference.

Isn't this a little bit like the talk of computers being very sensitive, needing clean power and a shielded environment? When the elevator starts, the flourescent lights flicker but the computers couldn't care less. We have used electric welders next to the computers and, yes, the screens go 'boink' but no other problems are apparent.

{Edited to change tone a little}

[This message has been edited by C-H (edited 03-07-2004).]

ADSL lines are generally twisted pairs, which reduces radiation immensely. AFAIK, ADSL operates at lower frequencies and lower power levels than BPL, which also works to reduce interference potential.

The amateur bands are located where they are as a result of international treaties. It would literally take more than an "Act of Congress" to reallocate them. Domestic television and cell phones don't span the globe, and are primarily regulated at a national, not international level.

There are many digital modes employed in amateur radio. But mandating a shift to digital technologies here would eliminate much of the ability for hams to get on the air quickly in emergencies using low cost or even homebrew equipment. It would also price ham radio out of the reach of most youngsters. We would lose a lot when you could no longer communicate with a simple oscillator and crystal detector.

Besides, hams were here first!

C-H your post hit on something I was thinking.


First I have nothing against Ham operators, I know we have a few here at this forum and I certainly wish none of them ill will.

That said the few times I have read posts from ham operators the general feeling I come away with is that they "own" that part of the radio spectrum and anyone that might infringe on that is clearly in the wrong.

NJs posts just reinforce my view especially comments like this.


Now I know you said that with a smile but that is essentially the party's line.

What makes hobby radio any more or less important then the Internet, phones, TV, etc.

The one I do see is radio astronomy as CH pointed out you can't get them to change channels.

C-H I see the same things you do, it seems PCs can be very tolerant of poor power quality.

I worked at one place that had a 400 amp 480 volt unshielded DC motor drive that cycled from 0 to 350 amps every 20-30 seconds.

A PC was located right near this each cycle the screen did strange things but the PC never seemed to mind.

Ham operators, do not kill me, just an outsiders opinion, the kind of person you would have to convince to support you.

Hams aren't getting (or asking for) any "special consideration". Only enforcement of what is spelled out in the FCCs OWN REGULATIONS. BPL systems are Part 15 "incidental radiators". As such they are NOT ALLOWED to cause interference to ANY licensed users of the spectrum. This includes SW broadcasters, public service comms, and amateur radio. They also must ACCEPT any interference they receive from licensed sources. In short, if a ham or CB station wipes out the entire BPL system, there isn't a THING that the BPL provider can legally do about it!

When BPL manufacturers were unable to meet the RF emission limits of Part 15, they started pushing to raise the acceptable limits!

"Hobby Radio", as you call it, is more important than yet another internet service, cellphone service, etc. simply because amateur radio is among the LAST bastions of non-commercial "public access" to the spectrum. Most of the rest has already been sold off or given away! Amateur radio provides an invaluable emergency communications system, which, unlike internet, cellphones, etc., is independent of centralized infrastructure. When hurricanes or other disasters hit, ham radio is still there, when cell towers and power lines are down for the count!

Sorry but that does not dispel the idea you want special treatment.

Cell phones are proving to be quite a reliable resource in times of trouble.

Cell phones by their design are not centralized.

But do not get me wrong I do think Ham radio is another good source of communication, I just do not see what gives it "special" status.


What is not special about that?

I am not saying it is not an existing rule, just maybe it is time to reexamine that special treatment.

I just don't get it.

Just the opinion of a non ham operator, the kind of person you will need support from if you want things to remain unchanging.

Bob

Tell that to anyone who tried to use one in NYC on 9/11/01. A cell phone might be reliable for "individual scale" emergencies like a breakdown or reporting an accident, but when the excrement hits the impeller big time, cell phones aren't very reliable at all. The system is subject to overload even more than landline phones are...


All phones in a given area talk back to a central tower or "cell site". Take out that site, and all the phones in the area stop working. Same goes for the landline trunk cable feeding that site, or the telco central office at the other end. "Backhoe fade" kills cellphones too!


It is not "special treatment" of amateur radio. It is "special treatment" of UNLICENSED SERVICES that share our spectrum. Amateur radio is treated no differently than ANY OTHER LICENSED SERVICE. The same interference restrictions apply to broadcast stations, paging, mobile radio, or any other LICENSED user of the spectrum. BPL operates under part 15, and has to abide by those rules. Amateur radio is under part 97. Different rules apply.

If you want to protect unintentional radiators on the same basis as licensed services, get ready to pay a heck of a lot more for your garage door openers, WiFi equipment, and other wireless equipment. Each of these would have to have exclusive, assigned spectrum space, with no other users. There are only so many megahertz to go around!

You will need to have a license for that equipment, too. If your neighbor bought one first, tough luck!

Good enough I think we each made our point.

Mine was only trying to show what some outsiders think.

You gave the standard line as expected.

Back to the internet & a/c lines, I have had a discussion with the manager of the utility of Manassas, Virginia. they have installed this on their system, and have good reports. I will post a link tomorrow when I get back to office.

The way I understand it, it uses a fiber optic backbone, with some kind of transmitter located in the transformer, which is feeding the home, and then another unit that plugs into an outlet in the home. To this unit you plug in your computer (modem?).

Later.

More on the Manassas BPL rollout:
http://www.eham.net/articles/6803

As a ham myself, I am extremely concerned about BPL and the potential interference problems lurking. The listening aspect of shortwave (and longwave too) is, in my opinion, 90% of the fun. I do not like the thought at all of additional interference in the "basement" part of the spectrum, it's rotten enough as it is. We hams have suffered long enough from interference on our assigned bands too.

Assuming these problems were actually overcome, I wonder: is polyphase BPL faster?

...it is more frustration with what I (and many others) see as the FCC abdicating it's mission

Yup. Several months ago I took the same position as NJwirenut regarding RFI when the question of BPL was first came up here on this board. Apparently nobody cares so I didn't mention it above. Seems the FCC is more interested in big business interests than their mission.

I agree 100%. This is a stupid idea that never should have seen the light of day.

-Hal