Gigabyte Modems over Electric Lines 194
Ryan Wilshere writes "C|Net has an article on so called 'Power Modems'. They claim they can do Gigabyte transfers over regular electrical line. Dallas-based start-up Media Fusion has won a U.S. patent on a process it says can send data, video and voice over electric wires at speeds thousands of times faster than current high-speed Internet access technologies."
They keep on trying. We keep on hoping.
yea yea (Score:1)
Would love one of these at home! (Score:1)
I own and ISP .... (Score:1)
scrap the wires (Score:1)
I dream of an inexpensive, wireless gigabit/sec connection!
Problems I see.... (Score:2)
I think this right here is just media hype. Ive seen cable modem, and dsl which both keep getting worse and worse. I would have to see some benchmarks and actually see this project completed and tested before I would believe that this works. Every technology has its flaws, and right now its too early to see what this products flaws will be. I know that Canada has a high speed network going on. Why doesnt the US or other countries for that matter follow what the Candians are doing?
Powerlines and Connectivity (Score:2)
If this works... (Score:2)
As long as the people involved in the implementation of this don't ruin it by adding silly usage charges, then we will finally be able to read
So, who's for a game of quake? I'll see you by the microwave.
Already been tried? (Score:1)
Here in the UK... (Score:1)
heh heh: they call it electricity :) (Score:3)
In other words it appears Media Fusion has patented an electronic signal on a metalic fibre called a wire. They must be so proud of their Intellectual Property
I just want.... (Score:4)
:) -Dan
Re:Already been tried? (Score:1)
:-)
Re:Problems I see.... (Score:2)
Nope, a different repeat story :-) (Score:2)
--
I've given up hoping! (Score:3)
Also, over long transmission lines signal tends to get spread out (smeared) as the velocity-of-propagation varies. AFAIK, Power lines were not designed with any consideration of Vp.
Patents do NOT impress me.
-- Robert
Re:Already been tried? (Score:1)
That all seems a bit vague, but the Computer Weekly search engine is even worse than the one in my head :-)
How does this technology work? (Score:1)
What if the power goes out? (Score:1)
Actually, in all seriousness, 2.5GB (is it Gb or GB they're bragging about? I can't see the pictures.) per second is great, but someone has to provide the bandwidth for all of the users. I guess this could work as a backbone-type technology, or maybe like a cable free-for-all.
One nice thing could be, since it would(should) use the existing electrical infrastructure, a company could bring high speed net access to rural customers just by making the equipment available on its power grid. Maybe I do like the thought...
Just wait 'til the day someone figures out a way to trip a breaker or blow a fuse in your house when you get fragged in Quake
Interesting technology but... (Score:1)
Then again, even if they have solved the broadcast problem, how do they deal with the random interference that shows up on power lines? After all, take a look at ADSL. AM radio signals can interfere with ADSL.
If they pull it off (and I'm not holding my breath on that score) and if it is not too expensive for deployment on a large scale (not holding my breath there either), it could prove interesting, though.
great (Score:1)
Monty
Old news, unlikely it's as hot as they claim (Score:1)
You can't provide long-distance communications over electric cabling because Live and Neutral are filtered at the substations and would remove any meaningful signal and the earth wire is local to each house. You could *possibly* set up local loops this way but you don't gain anything - it's the long-haul services and hardware that cost.
This *is* exciting! (Score:3)
Did anyone read the linked story from the weekend?
This is not about sending an electric signal over power lines. This is about manipulating the magnetic field which forms naturaly around a wire when you send an A/C current through it.
This is new. This is exciting.
Re:What if the power goes out? (Score:1)
Re:heh heh: they call it electricity :) (Score:3)
In other words it appears Media Fusion has patented an electronic signal on a metalic fibre called a wire. They must be so proud of their Intellectual Property
I guess the keywords you are missing are "at speeds thousands of times faster than current high-speed Internet access technologies". That does make a significant difference.
I only wish there was more information available on this - it sounds almost too good to be true, and the article is mostly marketing stuff. Can anyone with more EE/transmission-theory-background than mine share some information / references.
And btw, is "current high-speed Internet access technologies" the 34Mbit/s feed into this place? Then it's a darn fast thing they've come up with.
*waiting impatiently for more factual information*
Hey, would the powerlines BE the Internet (Score:1)
Anyhow, it could be neat - if everyone connected like that we'd have a pretty extensive topology for the web from day 1. All we'd need then is a S**tload of intelligent routers (that can stand 50KV) on the electrical poles.
If this turns out to be substratable we may end up with only one wire going into the home - carying power, phone, cable, internet, etc. Heh, it's nice to dream isn't it?
Re:Already been tried? (Score:1)
Re:Here in the UK... (Score:2)
I'm not so sure that the infrastructure is already there. Even if you get 1 terabit on a single segment of wire you then have to share that across all users on a CSMA/CD domain this could be 000s of users. On a CSMA/CD domain you also tend to only get around 30% of the available bandwidth, because of multiple user packet collisions.
You will also have to have effective "routers" and a backbone connection to distribute the data to the network proper.
As I see it there are quite a few changes to infrastructure required. The cable people didn't seem to have much probalem installing cable across the country and it is better suited than using existing old cables that might not be quite up to scratch. I'm sure there will be loads of incompatibilities with certain surge protection devices etc.. etc..
Competition is good (Score:1)
Re:Problems I see.... (Score:1)
But we shouldn't let that stop us from finding other forms of communication. Who knows, this might end up being faster.
Health and Saftey Issue? (Score:2)
Here in the UK their are health and saftey rules preventing power and data cables being put in the same coduit. I wonder if this would pose a problem for this kind of technology.
Re:heh heh: they call it electricity :) (Score:2)
I took high-speed Internet access technologies to mean a 9600 baud modem.
Re:What if the power goes out? (Score:1)
I can dial in now with my laptop when the power's out but the phone is up just fine.
If it works... (Score:2)
If Media Fusion's technology does work, it could radically shake the telecommunications market. Telephone and cable companies have invested billions of dollars to ready their networks for high-speed data transmissions.
That's a slight understatement. If the technology *does* work, look to see major U.S. Telecommunications companies go screaming to the FCC, demanding the regulation and taxation of the service in the same manner that their lines are. If that doesn't work, I'm not sure what they're going to do, because a technology like this could threaten to put them out of business.
How practical is it? Does anyone have more detailed information (perhaps information of a more technical nature) about how they're doing it? Is this just a vaporware announcement intended to scare the telcos?
While the details of actual implementation are vague, if it works, this may present yet another solution to the 'last mile' problem, which I personally see as the last major bottleneck before the true dawning of the (drumroll please) information age. Between this type of easy access to high speed broadband with existing infrastructure, and the high speed wireless stuff we read about a couple weeks ago, we might just get things *properly* wired sometime soon
Anthony
POPs are still the bottleneck (Score:2)
Access technology is worthless without the backbone to back it up, and right now the MAEs and other interexchanges, along w/ private peers and international cables, are our bottleneck points. You can't jam a gigabit pipe into a T1 and expect any performance.
Re:Problems I see.... (Score:1)
Re:scrap the wires (Score:3)
I dream of an inexpensive, wireless gigabit/sec connection!
Well, afaik some of the most high-end wireless consumer networks available at this time would be Hiperlan (23.5Mbps). Some information is available
here [inria.fr] and here [rwth-aachen.de].
There exists faster wireless networks, however then we're not in the "consumer end" any more.
Will this be a weekly event? (Score:3)
I mean, really.
A valid point was also raised about cost for this sort of service. When living in Canada, I paid CND40 for 24/7 CableModem service. Currently, in Ireland, I pay about IRP100 per month for heavy useage over a standard modem. This is because Eircom (formerly Telecom Eireann) was only recently privatised, and there is still little enough local competition. I believe there are a grand total of 20 cable modems in Dublin, all currently being tested (In Terenure, if any Dubs are reading.) At any rate (pun!), isn't there a threat regarding cost in the States? I'm not certain, but I thought the power grid was government property, and I can imagine how much they would enjoy the added revenue provided by fixed-cost high speed internet service. And I don't see an independent startup laying power lines in order to compete, personally.
This seems like little more than a pipe dream (pun!), particularly for those already enjoying the wonder of Cable Modems and DSL links. If anything, this new tech -- if it ever becomes new tech -- will up your prices and knock your smaller providers out of the market.
-l
This was tried in Britain (Score:2)
However, this is not a new idea. The transmission of electronic data over an electrical power line was first put forward in the mid 1940's, according to Wireless World. The idea was vetoed, at the time, because it was believed that this would allow a dictator absolute power over information. It was deemed essential that wireless methods of communication were predominant.
In this age of paranoia, suspicion and Government surveilance, I find it fascinating that cable-based communication is actually MORE popular than when the risks were merely speculative.
Re:Problems I see.... (Score:1)
There are many problems with cable connections due to interferance, anyone tried to use an appliance (ie a hairdryer) beside their cabled up TV? See what happens? That makes the current cable system fairly unworkable.
The one thing that is holding the internet back is that everything is expanding, growing and getting faster apart from modems. There will be many companies trying anything they can think of to develop faster access over the comming years, one of them is bound to get it right, perhaps this is it.
In the original article there is a mention of previous attempts to use electricity wires (they dont specify any in particular, but it must refer to the UK one from some months ago) this company says it will be different, who knows? But based on the amount of calls regarding access speeds that come into the ISP I work for every day, a solution is needed sooner rather than later. If no solution is found, the average consumer will give up on the 'net altogether.
Re:heh heh: they call it electricity :) (Score:2)
I think you are very quick to suggest this is not a worthwhile patent. Gigabyte speeds over cableing that was not designed for the purpose is an acheivement at any time. Getting a clear data single at high bit rate over a cable that caries mains electricity is nothing short of a mirical. Mains electricity is about as dirty as it gets with regard to noise, apart from the 50/60hz of the mains you have to contend with noise from just about evey appliance on the circuit.
I've read a few reports about this kind of technology before and I'd be interested to know if this has been tested in the field. Getting this kind of system to work well in a lab with high quility cable is one thing, getting it to work in the real world with cable wired in by evey man and his dog of questionable age and quality is another matter. After all, if you have to rewire an area to make it work it kind of defeats the purpose, you may as well lay coax at the same time and be done with it.
Re:This *is* exciting! (Score:1)
Sounds like just marketing misunderstanding the technology. You can't manipulate the wave surrounding the current without affecting the current. They may however use the wave to read from or modify the current which might be more sensitive than manipulating it directly.
One-way? (Score:1)
Re:Problems I see.... (Score:1)
The problem *I* see. (Score:2)
What *I want to know is. . . (Score:1)
Let's really solve this puppy: Wireless power, and Inyternet over the power grid!
We'll all have gigabit Internet connections for the two months before the civilized world drops dead from brain tumors. What a way to go.
-Omar
concept's been and gone... (Score:1)
Here is the actual patent... (Score:1)
it mentions a MASER but doesn't really explain it does anyone know what a MASER is?
Re:This *is* exciting! (Score:1)
Saw this in 96 (Score:2)
Re:Here is the actual patent... (Score:1)
Yeah.. I can imagine low noise would be a Good Thing.
Re:Old news, unlikely it's as hot as they claim (Score:1)
For my 4th year elec. proj, we're doing something similar (although not nearly the voltage level!). We're going to try to setup communication using frequency filtering over 120VAC house lines. The problems will likely include the stepdown transformer from the power grid. We'll likely setup some sort of freq. block to avoid feeding stuff out of the house. I think that X10 does something similar and I heard rumours of IBM having something similar. If the systems got really popular you'd have to block signals from feeding out of the house into someone elses.
Anyway, with ours we're hoping to setup some generic remote switching/status boards with some cheap front-end software. I'm assuming it wouldn't be too hard to allow control from the internet (hey there's always telnet
Now with their system I really wonder how they send any info at that rate over the power lines. I mean, the capacitance over long stretches of power line must be crazy. Could you approach it with FSK (frequency shift keying) at high-freq? I'm assuming that the noise and varying properties of the hydro lines would knock out any idea of phase-encoding (someone previously mentioned the idea of signal 'smearing' due to propagation effects). To avoid worring about amplitude drops, FSK is probably the better way to go. Unfortunately at high freq., any capacitance would act as a straight short, unless you balance it out by adding inductance to the lines. (Does anyone know (roughly) Z-angle of the hydro lines?) I know modems used to use QSM(? I think), which used amplitude + phase encoding.
Anyway, it'll be interesting to see how this works!
Re:Health and Saftey Issue? (Score:1)
It's using the existing power cable itself (more specifically, the magnetic field surrounding it if I understood their diagrams correctly), rather than adding any additional cable or wiring. So, there's actually no separate "data cable"...I assume it wouldn't pose a problem in that case, although I don't know anything about the UK law specifically.
Re:POPs are still the bottleneck (Score:1)
Media Fusion is a quack... (Score:4)
Go read the article, I'm trolling in the least. It's fucking ubelievable.
-
We cannot reason ourselves out of our basic irrationality. All we can do is learn the art of being irrational in a reasonable way.
Internet access via other utilities... (Score:1)
[Happosai]
Re:Problems I see.... (Score:2)
I don't think using power lines to transmit data will work. It has been extensively studied before by the British, and it flopped. Plus, the fact that the company did not even bother testing it on the actual power grid before letting out all the hype tells lots about the competency and the motive of the company. Had someone really discovered a feasible way of transmitting data over power lines reliably, VCs and bigger corporations would have queued to fund them.
--
BluetoothCentral.com [bluetoothcentral.com]
A site for everything Bluetooth. Coming in January 2000.
Re:heh heh: they call it electricity :) (Score:2)
As I have noted in other posts the Gigabyte speeds may have to be shared across thousands of users or perhaps even tens of thousands of users, and then you need a higher tier infrastructure to route the information to the network proper.
Because of this, I find the technology a waste of time and unlikely to get implemented. ISPs here in the UK tend to have an aggregate backbone bandwidth of around 15-25Gbps, not much point giving their users terabits to play with is there?
I guess I was trying to be funny, in light of the stupid patents that have been granted lately. No offence to the company involved...
How this (?doesn't?)works / Likely Problems (Score:1)
Unfortunately EM is one class I slept through and still got an A(I think it was the curve that helped me out).
However, there are some serious problems:
1) Even if everything works all snazzy, they still have discontinuities at substations/transformers which would require extra equpiment at each one. This might be okay because that would likely be a good place for routers anyway and a handfull of clip-ons to a powerline for ~100 mile 300 Ghz waveguide connection is VERY economical.
2) For microwave frequencies, they are obviously not sending the signal through the wire. It has to be either a) in between the stranded outer and solid inner wires b)around the wire(seems real lossy to me) c) in between the magnetic field and the wire(or in the magnetic field between wires). This last one jives with their patent, but I can see all kinds of headaches. These fields are going to spatially move with line transposing that is sometimes done and they will temporally move(wrt the microwave frequencies). This may require line sync/bursting and perhaps more "repeaters" along the line.
3) The last biggest hurdle that I see is survival in what is almost the harshest of environments. Control-house equipment(not on the line) is designed to survive 8kV, 500A/M, 35V/M, +85 to -40C, sometimes condensing humidity. All of these devices will need industrial-temp parts, conformally coated, magnetically shielded, to survive long. However, because of their sensitive nature, you may be shielding away the very signal you are trying to use.
I'll applaud them if they make it work, but I won't invest any of my money
Re:Media Fusion is a quack... (Score:2)
I have, too - and I'll give the secret away for free 8^)
Ever see that amateur radio support area in the Linux kernel? That's right! You too can manipulate the Earths electro-magnetic field for long range communications!!!
Spark-gap transmitters (while highly frowned upon), are also quite effective
Couple of wierd things. (Score:1)
They're also pretty vague about who's funding them and which companies are helping them etc etc... I think they're hiding too many things.
I'll believe it when my linux box is hooked up to it.
Re:Problems I see.... (Score:1)
Of course it was around the the conductor - all electronic signals are transmitted as changes in the magnetic/electric fields around a conductor - thats basic physics.....
Re:POPs are still the bottleneck (Score:2)
Patent number 5,982,276 (Score:1)
They are not exactly transmitting the data by injecting it into the line - that method is limited by bandwidth, SNR and regulations to a few megabits per second. They are using a MASER to transmit a microwave RF signal that uses the magnetic field AROUND the powerline as a waveguide. This will not work all the way down to your socket but powerlines hanging from pylons could be used by utilities to compete with fiber.
----
Re:Old news, unlikely it's as hot as they claim (Score:1)
I don't think their technology is based on this however, I think they've found something that's immune to "normal" filtering.
Re:POPs are still the bottleneck (Score:3)
Even with all the tier 1 ISPs hauling giant circuits, interexchanges are still hosed. This will be the limiting factor, I think.
Re:Here in the UK... (Score:1)
Information on the Media Fusion patent... (Score:1)
One should read the patent copy that's there at IBM's site before commenting upon this subject- it's interesting (and required for comments) reading for this subject.
I'll thouroughly examine the patent copy and post an analysis of the same later today...
Physics looks terrible (Score:2)
It is important to remember that for a patent to be valid, it must be detailed enough for one 'skilled in the art' (patent office terminology) to build the device based on the patent (i.e. it must be enabling). A patent (the word, of course, means open) is supposed to open up a technology... you can't simultaneously have something under wraps and patented. You either have a trade secret or a patent, not both!
I would consider myself to be reasonably skilled in the arts associated with this type of work (PhD in Physics, Caltech, 1983) but the patent is certainly not enabling.
Worse, I suspect that it isn't based on any real physics. The discussion of exciting atomic states in the magnetic fields surrounding a wire reads a lot like the kind of language one sees in perpetual-motion patents to try to cover up the complete lack of any real possibility of success.
If I were making investment advice, I would certainly not recommend buying into this one.
Two words: Radiation Losses (Score:1)
Since this is supposed to be a highspeed connection, the only way to keep it going over long distances is to have a zillion little repeaters. I'm not sure of the distances involved, but I'd be surprised if you could get more than a few kilometers under ideal conditions. Probably need them every 100 meters in big cities. Wouldn't that be fun to build and maintain....
MASERs are the microwave equivalent of LASERs (Score:1)
Re:heh heh: they call it electricity :) (Score:2)
As for my concerns about the actual technology - I have enough problems keeping the power clean in my house without there being lots of extra noise intentionally placed on the line. I'm one of those people who hates every power deviation that introduces noise into my stereo or video equipment. I'd liketo put a lot of effort into making sure that my 120vrms 60Hz signal is nice and clean, without a lot of spurious crap.
With that in mind - the isolation transformers, surge protectors, backup supplies (some which constantly filter the line), and other cute little wall warts which filter line noise would be detrimental to the aforementioned product - but a nice power spike from a vaccuum cleaner, fan starting/stopping or a garage door opener would probably not be in the best interests of the rx/tx section of this technology. There are many ways you can filter out the lower frequencies, but the spikes are inherently high frequency, with broad enough scope to disrupt the high-freq signal to the power-line modem (or whatever you might call it). Sure, you won't notice a brief
Not to mention repeated spikes just aren't good for electronics equipment...
I actually read the stuff on the site (Score:1)
Offtopic but true: Rear Admiral Grace Cooper invented the compiler. If this Admiral is half the person she was, we may see some innovation coming.
-Ben
Patent! (Score:1)
Patent! [164.195.100.11]
Looked different, I'll give it that.
---
Re:Two words: Radiation Losses (Score:2)
Seems backwards to me... Edison always wanted DC for power distribution, but AC wond out because it is far less lossy. For a really long wire (i.e. power distribution line), the DC resistance is *way* higher than the AC impedance. The electrons have to travel from point A to point B for DC (let say 1000km for this example), while at 60 Hz, the electrons bounce back and forth, going far less distance and losing less of their potential energy (read: voltage) along the way.
I haven't heard about the Pacific Intertie, but hey, they could be doing this... though I somehow doubt it.
Just my $.0004^.5
Re:Two words: Radiation Losses (Score:2)
Regarding DSL.... (Score:1)
All of this, and believe me, we are not the only country in this situation, is why there is so much interest in adapting existing conections into the home to avail of faster interenet access.
Re:I just want.... (Score:1)
Near-field interactions? (Score:1)
Re:Another word: Attenuation (Score:1)
Patent number is 5982276 (Score:1)
Like a waveguide... (Score:1)
Re:I've given up hoping! (Score:2)
The patent is for technology which transmits data
through the magnetic fields surrounding power
lines, NOT through the power line itself. From
what I could glean on the Net, the physicist who
invented this took a new approach and completely
bypassed the problems of transformers and filters
and everything else which affects the actual
electric signal.
Not being a physicist myself, I can't evaluate
the technology. Apparently, others on slashdot
are physicists who are intimately familiar with
magnetic fields/microwave interactions over the
power grid and should call this guy up and let
him know his idea is daft.
Of course, the whole thing could be a scam,
but what I've seen is consistent and doesn't
contradict what I do know about physics.
Bolie IV
Ownership (Score:1)
Re:Two words: Radiation Losses (Score:1)
The thing that matters for losses is voltage. The higher the voltage the less loss. AC won out early on because it is easier to convert AC to higher voltages and back again.
Today DC is starting to come back in because we now have technology to change voltages efficiently for DC, and very high voltage AC has a problem with arcing that is less bad for DC. A 1MV DC line
has a peak of 1MV while a 1MV AC line has a peak of 1.44MV and so can arc further.
Radiation losses are not an issue for AC power because the frequency (50 or 60 Hz) is so low. It is an issue for high-speed data transmission over power lines.
Re:Media Fusion is a quack... (Score:1)
Now, don't you feel stupid that you didn't patent it and use it to kill Microsoft and get the Nobel price
-
We cannot reason ourselves out of our basic irrationality. All we can do is learn the art of being irrational in a reasonable way.
How secure is this? (Score:1)
Re:Here in the UK... (Score:2)
Absolutely, the cable tech who came to my house to connect my cable modem was pretty clueless about how the whole thing worked, I got the impression that he'd basically gone to a couple of workshops the company (TCI now AT&T) put together. He really couldn't answer any of my questions about how it worked, and he didn't know what a cross-over cat 5 cable was.
I finally told him to run a cat 5 line to X point, plug in his laptop, let me make sure it works, then to leave and I'd take it from there. So he did that, I loaded Slashdot on his laptop (I was pretty sure this guy wouldn't have it cached) and sent him on his merry way. I set up my hub and ran some lines to my roomies' computers and was surfing half an hour later.
My point? This guy couldn't hook two computers to each other if he had to, he was a guy who knew how to hook up coax connections, and they gave him a laptop and taught him how to plug cat5 connections together. How hard would it be to get some people (college students?) with a basic understanding of networking?
---
Hand waving about the Transformer Problem (Score:1)
There also appears to be a problem with propagation control. Will this be pure broadcast? That might work more easily, but it will eat the bandwidth very quickly. I'll guess that even if they can use the magnetic fields of high tension lines as waveguides, they have a long way to go before they invent the MASER router.
Re:What if the power goes out? (Score:2)
---
It can be done. (Score:1)
I'm a little fuzzy on this stuff, it's been a while...
But what he is working on has more to do with the magnetic portion of the EM spectrum than the E part of it. If you read the article in the Dallas News, it basically states that the technology is based on the fact that a lightening strike can be 'heard' across the entire Power Grid of the United States Electrical companies (which are all connected to each other for power loading reasons)
If you are still a doubter, do some research on Tesla who had the same basic concepts outlined back in the 1920's. He was one smart cookie, but no one understood what he was trying to do. It's not about normal data transmission and it's not about quantum communications either..
Re:Two words: Radiation Losses (Score:1)
Seems backwards to me... Edison always wanted DC for power distribution, but AC wond out because it is far less lossy. For a really long wire (i.e. power distribution line), the DC resistance is *way* higher than the AC impedance. The electrons have to travel from point A to point B for DC (let say 1000km for this example), while at 60 Hz, the electrons bounce back and forth, going far less distance and losing less of their potential energy (read: voltage) along the way.
A little clarification here. The electrons don't have to 'travel' from point A to point B. The 'average' electron drift speed for say, a 1 AMP circuit is on the order of centimeters per hour. What 'travels' is the signal, and it travels just as fast(the speed of light) for an AC or DC circuit.
And, IANEE, but one of the BIG reasons they use AC current is because its ALOT easier to transform. The huge big wires you see have a tremendously high potential at low current, which results in less loss over the line. The high potential can then be easily transformed to high potential/low current for domestic use. I don't think DC is any more 'naturally' lossy than AC, in terms of impedendance.
There theres all this stuff about the capacitative/inductive effects of the circuit, and I think that might be another reason why they use AC, but again IANEE.
Re:The problem *I* see. (Score:1)
I'm Canadian, too, and he got me riled up until I actually want and read what he was referring to. He wasn't knocking the Canadian network, he was pissing on the excerpt from the Media Fusion ad.
It was Media Fusion's claims of high speed connections that he was comparing to 9600 Baug, not the Canadian high speed network.
Although granted, he could have made that a bit clearer...
--
- Sean
On basic physics. (Score:4)
Um, no.
Signals in most circuits are trasmitted as a flow of current _within_ wires, driven by an electric field gradient _within_ the wires (called "voltage"). Electric fields outside the wires try to move current between the wire and anything nearby, but this is an unwanted side effect, stopped by something called "insulation". However, the electric fields also result in capacitive coupling between nearby wires, which causes something called "capacitive cross-talk". This is minimized by keeping wires far apart and minimizing the amount of parallel surface area of conducting regions.
As a side effect of the current flow, a magnetic field is set up both around and within the wires. The current flowing within the wire and the magnetic fields around the wire are intimately connected; you can't have one without the other, and they interact very strongly with each other. You can't "transmit information in magnetic fields around the wire" without interacting with currents in the wire too - the magnetic field is _caused_ by local currents in the wire. In most systems, magnetic fields are an unwanted side effect. As there is mutual inductance between any two wires in a circuit, the magnetic fields caused by current in one wire will set up currents in other wires. This is called "inductive cross-talk". It is severe only for wires that are very close to each other, or that have a particularly vulnerable geometry.
For an excellent book on the basic physics involved, I recommend "Fundamentals of Physics, Fifth Edition", by Halliday, Resnick, and Walker. Another good reference is "Physics for Scientists and Engineers, Extended Version" by Tipler.
Magnetic fields are not waveguides. (Score:2)
This is bogus.
Electromagnetic fields do not interact with each other. They couple with charged particles, which couple back to the field. A "magnetic field" wouldn't be acting as the waveguide - the wire would. Over a single wire with no interference, this would work quite well. However, the actual power grid does not meet this specification.
This will not work all the way down to your socket but powerlines hanging from pylons could be used by utilities to compete with fiber.
The problems with this include, but are not limited to:
Power networks were not designed with eliminating reflections in mind, and were not designed for noise rejection. Cable - which is shielded coaxial cable - _is_ designed for both of these, and so has much higher ultimate bandwidth limits. It too behaves like a waveguide at high enough frequencies, and it's shielded. Optical fiber can beat both hands-down - it's a waveguide for an EM signal with a frequency _many_ orders of magnitude higher than radio and microwave signals.
Summary: Bandwidth limits and signal quality problems make this a not-very-useful technology.
Re:Here in the UK... (Score:2)
broadcast regulation. Isn't that the place where
every TV must be licensed, and there are actually
spooks who spy on people looking for unlicensed
TV's?
Maybe "turning street lights into antennas" is
something America would tend to tolerate.
We tolerate the sulfur lamps in the damned things,
after all. We'll even tolerate wasting millions of acres of woods for the poles.
Basic physics - again. (Score:2)
I'm afraid that this is a meaningless statement, most likely invented by their marketing departments. Click on "User Info" above to see my previous posts which cover this in more detail.
Re:This *is* a SCAM (Score:2)
When using even higher frequency-signals (even up to optical signals) there would be problems with the variation of the dielectric constants of material surrounding the wires. Some use platic insulators, some paper/oil, some use air, etcetera. These changes would diffuse or reflect signals. And once again it wouldn't pass the transformer.
What do they claim:
They claim they can use the electric utility-network to transmit signals in GBit/sec range over thousands of miles. (OK, this could be done by using the network as antenna and sending very powerfull radio-signals of several kW. Only one transmittor per continent: not very useful).
They claim to use the magnetic field, not the conductor. First ask yourself: what would happen when we have no current? No signal? (this happens 50 times per second, in USA 60 times). Why they claim this: because it is different and can even confuse the average EE that think in currents instead of magnetic fields.
They claim to have patents. Well, I'm not impressed. In USA even perpetual mobiles can be patented (see www.entropysystems.com).
They claim they will demonstrate their system somewhere in 2000 by sending HDTV-signals over thousands of miles of electricity-network. This will be done to find enough investors to make the 300 million dollars they need 'to speed up the development'.
Now I understand, poor investors.
Re:Magnetic fields are not waveguides. (Score:2)
There are several assumptions being made here that turn out not to hold:
- Firstly - EM fields _do_ interact with the atoms within them. This is what causes ordinary transmission of light, and is why light looks like it's travelling more slowly when it's passing through, say, glass. You also get the dielectric and magnetic permeability constants of materials from this kind of interaction. You're not going to get much more than this.
- Secondly - Magnetic traps only hold non-ionized atoms at _extremely_ low temperatures. A magnetic field strong enough to affect atoms in any unusual way (beyond just setting up normal paramagnetic/diamagnetic effects) would have to be ludicrously strong, and could not be generated by any terrestrial device (Prof Dawson: "Well, maybe in a degenerate star...").
In summary, everything that will happen when microwaves interact with normal matter is well-understood, and does not help with signal transmission in the way that you are looking for.
You seem to have an interest in physics, which is always a nice thing to see; click on "User Info", above. My first post on "basic physics" contains citations for two physics texts, which are very interesting and useful.
Re:I've given up hoping! (Score:2)
Magnetism and electricity are inseparable. You cannot manipulate one without changing the other. More to the point, electrical noise begets magnetic noise. Or put it is way, if they can separate electricity and magnetism, it's Nobel-prize winning, almost Unified Field Theory stuff. I'm highly suspicious.
Now, they may want to use the runner (steel support cable on mid-voltage lines) to carry signal to rural areas. If it isn't grounded, that may work at 1 Mbps but will have lots of induced noise from electrical transients. 10baseT ethernet will reputedly run over barbed wire!
-- Robert
DC power (Score:2)
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