Internet via transmission lines.

[lord loh.]

I read an article in the newspaper some years ago that a prototype to deliver internet access was being developed via transmission lines.

If this were to be done, could high speed data be transfered on a 50 Hz / 60 Hz carrier ?

If the line frequency were to be rised to a few KHz or MHz would it not act as an antena ?

I think (If I still remember it correctly) the article said that it was causing interference with Ham radio and since the govt. of US protects the Ham radio frequencies, the ham operators were planning to challenge the projects.

 

[spuffock]

It will cause considerable interference to HF radio, but the amount of protection you get from the authorities depends on how much MONEY you have. Since the internet people have much more MONEY than the radio amateurs, I think it safe to conclude that the amateur HF bands are a thing of the past.

 

[Phasor]

The power co. I work for is doing some trials with PLC (Power Line Communication). I don't know any specific details (as I am not involved with the research), but I believe that they are having difficulties in passing the high freq signals through the distribution transformers, which are only designed for 50Hz, and effectively filter high freq signals.

We already have difficulties passing the audio frequencies (between 492 and 1050Hz) used for off peak switching, to some areas, never mind MHz!

 

[stevez]

BPL or Broadband over PowerLine is one of the ways to describe that service. It scatters the data over a wide frequency spectrum (HF)with the claim that a low power it will do little harm. In actual practice it's quite noisy. FCC claims that amatuers are protected - complain and the BPL provider is supposed to address that by notching. Apparently that does little to solve the problems. As already suggested, the folks with the money get the protection. Amateur radio service is only one of many services that are impacted. When they ran BPL testing in Penn Yan, NY I could hear it all over my shortwave radio - 40 miles away. It would seem that if the use of BPL increases that the noise floor of the overall HF spectrum will be incredibly high.

ARRL websites have lots of info and as you'd expect, quite biased against BPL. The pro-BPL people suggest it's a big deal about nothing.

From my point of view BPL is a messy, sloppy approach and there are plenty of other systems/technologies that are economical and reliable. Power companies like it because they can get into that market too.

 

[lord loh.]

BPL provider is supposed to address that by notching

What is notching? Same as shielding ? Can the problem be resolved if the transmission lines are shielded ?

 

[Nigel Goodwin]

BPL provider is supposed to address that by notching

What is notching? Same as shielding ? Can the problem be resolved if the transmission lines are shielded ?

No, notching is removing the interfering frequency with a sharp sided filter, so you 'notch' a particular piece of the spectrum out.

How could you shield all the electricity transmission lines?, it would be an incredibly expensive job - particularly with the voltages involved!.

 

[stevez]

It is my understanding that sheilding would defeat the purpose in some instances. The idea is to provide wireless connections - wireless implies radiation at some point. An advantage is supposed to be the use of existing power transmission infrastructure which is not sheilded. If you had to replace the lines you might as well just use cable or fiber optics. Sheilding high voltage lines would be quite a task.

Apparently the system requires what I'll call 'jumpers' or repeaters across things like transformers. I understand it's not as simple as just hooking up at the power station and then everyone gets the service. When you take a look at the equipment requirements it seems like it's not such a simple system. I suppose one could make the argument that if there are no other services to an area that the BPL eliminates the need for extra wiring.

 

[lord loh.]

Notching sounds like a band-reject filter.

Wireless? I though it was to provide internet to all devices that are plugged in to the mains.

A parallel discussion is going on **broken link removed**

 

[atferrari]

Something evident...

It is also that xmtr & rcvr should be plugged to wiring fed by the same phase. In big buildings that's a concern.

Buena suerte :!:

 

[lord loh.]

Re: Something evident...

In big buildings that's a concern.

How ?

There are three phases... Surely all three phases shall have BPL.

 

[samcheetah]

i think he was talking about an inter-building network in which there is one transmitter and a some recievers. in that case both the transmitters and the recievers should be on the same phase.

but in the case where internet data is coming from somewhere out of the building, all three phases will have the data. in that case there would be no problem of being on a different phase. the problem will be how to efficiently transmit the data to that building in the first place :lol:

 

[atferrari]

think he was talking about an inter-building network in which there is one transmitter and a some recievers. in that case both the transmitters and the recievers should be on the same phase.

but in the case where internet data is coming from somewhere out of the building, all three phases will have the data. in that case there would be no problem of being on a different phase. the problem will be how to efficiently transmit the data to that building in the first place.

Yes. I just wanted to stress that for any practical purpose each phase is a separate circuit and needs to be fed by a xmtr.

 

[Pyroandrew]

I remember reading a quite in-depth article about this. The carriers intended for BPL WILL cause interference with short wave radios. There is a wide spread concern that the emergency radio bands were due to become engulfed by the noise floor being raised so far that you would need a power station to transmit a signal strong enough. The Tsunami that hit Asia and Africa recently highlighted the need for sanctions to be put in place to protect the short wave radio bands. Immediately after the tsunami, news spread very fast due to the use of small short wave radios. They were the most important piece of equipment in the aftermath because there was no other way of communicating over the vast distances involved. BT are currently working on a system that confines the emitted noise to frequencies that are not suitable for long distance communication. As you know the optimum carrier for short wave radio varies throughout the day, BT plan to have what has been dubbed "ionosphere watch" to make sure their power line noise does not interfere with the vital emergency short wave radio bands. Another advocate of sanctions against such noise being allowed is the BBC. Strange? maybe not if you consider that the "World Service", listened to by millions of people across the world, uses short wave radio. Rest assured, there are plenty of people doing real work to preserve short wave radio, The only real problem is the situation in America, last thing I heard was something like the service providers didn't really care and are going ahead regardless. Short wave radio does not play a large role in the every day lives of Americans, 'so that means that no one in the whole world needs it'. Like carbon emissions, America doesn't really care that it's actions affect the whole world.

 

[lord loh.]

The Tsunami that hit Asia and Africa recently highlighted the need for sanctions to be put in place to protect the short wave radio bands. Immediately after the tsunami, news spread very fast due to the use of small short wave radios. They were the most important piece of equipment in the aftermath because there was no other way of communicating over the vast distances involved.

They might still be in case of emergency.... :lol: :lol: :lol: :lol:

Since, in case of emergency, the BPL might be one of the first communication systems to be knocked off. So the noise floor shall fall low...paving path for the short wave radio.... :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

 

[Pyroandrew]

That's a nice thought, nice if it happened that way . But the shortwave noise rendering radios useless on the otherside of the world would also affect the radios trying to be used. It's a shame that we can't find some other way to implement BPL. Shortwave noise is a *****, because it goes around and around the world, even if all the power lines stopped BPL there would be a cooling time before low power radios were useable again . Depending on the noise floor level, this could take hours, days in exceptional conditions. After early high altitude nuclear bomb detonation tests, the temperature of the noise was so high that HF radio communications were rendered useless for al least half an hour across almost half the world, weeks later the noise was still present.

 

[lord loh.]

...But the shortwave noise rendering radios useless on the otherside of the world would also affect the radios trying to be used.

Can you explain me why this happens? I thought shortwaves were limited to a line-of-sight.

And I also thought the only way of using shortwave radio over large distances was by use of repeaters.

 

[Nigel Goodwin]

Can you explain me why this happens? I thought shortwaves were limited to a line-of-sight.

You thought wrong :lol:

VHF and above is line of sight, shortwaves bounce off the layers in the upper atmosphere and travel round the world. Coverage varies with time of day, and the frequency in use.