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Electric Plug 14Mbps Spec Agreed On 102

Tei'ehm Teuw writes: "From this article on EDTN the effort to establish a standard for power-line-based home networking will take a step forward this week when the HomePlug Alliance announces it will adapt technology from Intellon Corporation for its specification. The 36-member alliance will release a complete specification based on Intellon's technology, with its 14-Mbit/second raw data rate. In Europe, meanwhile, the HomePlug Alliance has established formal liaisons with two groups working on power line home networking: the European Telecommunication Standards Institute and the International Powerline Communications Forum. Neither has defined a technology to date, but it would be possible for them to adopt the same technology as the HomePlug Alliance, even though the European power line access technology is different there than in the United States. (The European power line delivers 220 volts at 50 Hertz; in the United States, it's 110 V at 60 Hz.) The overall forecast for power-line-based home networks is now beyond the 32 million nodes initally projected."
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Electric Plug 14Mbps Spec Agreed On

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  • Compare it to water, and think of volts as volume and amps as velocity.

    Well, that's ass-backwards, but yeah. Voltage is actually the electrical pressure - rather like kinetic energy, whereas amperage is the actual movement of electrons.

    It's the volts that jolts but the mills that kills

    A simple application of ohms law will yield the maximum safe voltage. Ohms law is E=I/R, or voltage = amps * resistance...

    So, we know most people's skin, when dry, has a resistance of about 1.5k if they are NOT grounded. If they are wet and grounded.. well.. let's just say they have about as much resistance as a hunk of 4ga wire. Anyway.. plug this into the formula...

    E = 0.005 * 1500

    .. which yields a voltage of: 7.5

    That is your maximum "safe" DC voltage. This means that anything under 7.5 volts you can sneeze at without worries. :)

  • by gmhowell ( 26755 )
    How is this going to work with X10 modules? How will X10 modules work with this?
  • by Anonymous Coward
    Find and dandy, but did ECHELON agree to this spec?

    Not a troll, seriously, how secure is this compared to say, modem/phone, cable modem, etc...

  • The transmission of data over power lines has had a lot of press in the UK, a prominent voice being the RSGB, (U.S. equiv = ARRL who eventually got the testing stopped. The upshot is that the technology could not provide a service without interference to other services. Check out the RSGB's comments at It also mentions a press release on the subject ...but I could not find it ! I would hazard a guess that the same technology is being used in the U.S. but as for the comment about it being transferable to Europe.... it would not get approval ...
  • If it works half that fast I'll buy it though. I don't want to wire up through 2 stories in my house with cat5. I doubt it'll touch 14Mbps at all, but I don't care. Slow is good enough for me, I just want to print on my mommmy's computer :)

    Mike Roberto ( [mailto]) -GAIM: MicroBerto
  • but only 14mbps? this may serve okay for gaming over home-based networks, but as we've seen, electric-plug networks can't touch good old 10baseT/cat5. i know electric plug is neater, but it costs a lot more, is not user-serviceable, and is held back by lack of bandwidth.

    What costs more, ripping up a three or four story Victorian house with mint-condition woodwork to run standard structured cabling, or buying into a scheme like this? For new construction or serious tear-aparts it's tough to beat a structured cabling scheme, but for existing construction where there are severe limits on where and how you can run cables, this seems really nice.

    As far as speed goes? 14MBit is ideal for controlling your VCR from your satellite box, monitoring your fridge/AC/furnace from the PC or any of the other home automation things. Even better this may enable 'smart' device application-layer interfaces (think SNMP for home applicances, but without the annoying which-MIB-is-supported grief) common across vendors, applicances or other devices.

    Even if it remains a computer-only interface, think of printing without any cable other than a power cable, etc. Hell, it would beat playing doom over arcnet..

  • Similarly, AFAICR the electricity meters in the UK get their timing from a medium-wave radio signal carried by one of the BBC Radio channels.

    They use that time signal to switch back and forth from 'Economy' rate overnight...I assume other countries use similar systems? Anyone?

  • You could probably just plug a compatible laptop into an
    outlet in a house's backyard and gain access to their
    network. I can imagine lots of problems like:

    - turn off that noisy stereo (air conditioner, washer, etc)
    - gain access to the DSL link, send spam or
    incriminating email
    - gain access to a computer

    I wonder how many houses will be set up with a filter
    on external outlets?
  • I have no idea where you're getting this 1.5k ohms as body resistance. Hell even wet (spit, a great conductor) 1" of skin measures about 800kohms.

    First off, you don't say for how much skin. The more skin between the probes, the more resistance.

    I've got an ohmmeter on me right this minute and I can't get below 12M on my fingertips. My arms won't even register so it's above 4000Mohms (Fluke 87 III making the measurements).

    Also remember that AC resistance and DC resistance are completely different. I may be over 4000Mohms with the ohmmeter but you feel a lot more if you hit yourself with 240VAC. Part of it is skin effect (the AC will travel along the skin, but I imagine 60Hz will penetrate the skin more than straight DC along the surface since it is probably a little more conductive *in* the skin rather than just *on*). I work in industrial power electronics and have been bitten a few times by 575VAC. 90A breakers have a lot of let-through before they trip, and the only reason I'm still here is because the bulk of the current wasn't through me. One of our sales critters got a blast of 4160 when he tried to measure the width of the stacks with a metal measuring tape and my old manager (he's alive, just in a different department) got 4160 across the chest through a power factor capacitor.

    Perhaps the weirdest feeling I ever had was when load-testing a 1200A starter. We took a big 50 gallon plastic barrel and filled it with cold water. Then we put the resistor bank in. Our power source was 208 going down to about 8V through one of our big step-down transformers for load testing. a 208:8 transformer would allow us about 5000A of current.

    Needless to say the water got pretty warm pretty fast. The neat part was when the president grabbed me and said "Put your arm in it!" When I did so I didn't feel anything at first but when I stuck your arm in the warm water (about 40 degrees C) up to about my elbow, all the muscles in my arm (fingers, wrist, forearm, all of them) started to flex and unflex because of the current flow.

    Where was this current flow? From my arm, through my body, through my shoes and to the concrete floor. I was AC-coupled. Very poorly but it was definately one of the weirdest feelings I've ever had. If you know what you're doing it's definately worth doing just to feel it.

    Anyway I just meant to comment on your human body model. The most common I've heard is a 1Mohm resistor to ground, not 1500 ohms.

  • Time for IPv6? Or do we just put every toaster, refrigerator and light bulb in the house on an unroutable domain and handle the translation in the router/firewall/proxy built into the fuse box?

    Only if you want the outside world to be able to talk to your lightbulbs and fridge! All those kind of devices can live in a non-routed IP class; if they really need to be externally managed then only the 'main' control system would need a real IP.

  • Gee.. they basically bypassed the transformer using an optocoupler and a pair of bandpass filters Yippie.. that's definately patentable. *groan*
  • Except that when you are being electrocuted, even with a low, non-fatal current, the longer you are exposed to the current, the more the resistance of your body drops so the more current flows through you.

    That may be due to the capacitive effect the body has, but I doubt it would have a significant impact. Besides, by the time you start pumping serious amperage through someone they're already dead.. so capacitance doesn't mean much now does it? :)

  • Hey John! :-)

    Security is solved doing what wireless does now: encryption. Take it a step further (or sideways, depending on how you look at it) and incorporate it right in Layer 2 in hardware, a la GuerillaNet.

    Bandwidth is bandwidth. There'll never be enough. Once this progressed to a switched-style network (this is a neat concept in and of itself) it'll alleviate both problems by providing "virtual" point-to-point networking.

  • I've already got an investment in the phoneline stuff--the 10mpbs works great for Home Networking (obviously not suitable for offices or really high-traffic networks), gaming, filesharing, etc.


    There's still no driver support for HomePNA under linux. Not 1.0 (1mpbs) or 2.0 (10mpbs). So I'm stuck using a Win98 box as a mixed-media router! I looove having a firewall that crashes once a week and needs nightly reboots!

    Can someone point me towards a driver (ANY driver, beta, alpha, I don't care) so I can use my HomePNA 2.0 cards under Linux?

    (and no, I can't rip up my house to install cat5; we're about to sell it)
  • I have no idea where you're getting this 1.5k ohms as body resistance

    1.5 kohm sounds about right. That's *body* resistance, measured with a good connection to internal fluids. Of course, most of us don't implant electrodes to measure this. ;-) You were measuring *skin* resistance, which depends on many things, including saltiness, moistness, skin thickness, and skin composition. With small electrodes on dry skin, it measures anywhere from 100 kohm to >100 Mohm.

    Try repeating your measurements, but with reduced skin resistance. Make each electrode a big wire, one of which is squeezed in each hand. And drench the contacting skin with salt water. I just did this and got 20 kohm. And the skin is *still* a significant impediment to current. So a 1.5 kohm body resistance is reasonable.

    ... 60Hz will penetrate the skin more than straight DC along the surface ...

    Nope. The skin effect (unrelated to human skin, BTW) is mostly negligible at 60 Hz. At 60 Hz, it's only important for huge generators dealing with thousands of amps of current.

    "Put your arm in it!" When I did so I didn't feel anything at first ... all the muscles in my arm (fingers, wrist, forearm, all of them) started to flex and unflex because of the current flow.

    Stupid, stupid, stupid. It's things like this that earn Darwin Awards. A portion of the current was certainly flowing through your heart. It just wasn't enough to cause immediate cardiac arrest. And this is the most dangerous situation possible, because your heart may have been silently damaged. Plenty of people have gotten shocked, counted their blessings for not being killed, gone home at the end of the work day, and quietly died in their sleep from delayed heart failure. A quick trip to the friendly emergency room cariologist will show any subtle injury to the heart -- the heart's electrical waveform usually changes significantly when it is seriously injured (AFIK).

  • If the homenetwork is on the Internet, how does this prevent other people with the same ISP from accessing the network?

    See how your question makes no sense?

    It is all about configuration and doing it correctly.

  • Actually, it's not as bad as you'd think. One similar system in the UK was the Rediffusion system (circa 1960), which placed analogue video on a (essentially) mains carrier. Still some places that have it in. TV would be plugged in, and got power and everything from the one plug (the 'video signal' was 110VAC peak-to-peak ;). Audio was in there too. Picture quality was fine.

    However, Rediffusion installations generally used a dedicated network. So it might be that all networked things need to be on their own circuit, etc. Not beyond the realms of possibility, but if you start talking dedicated networks you may as well be installing CAT-7...
  • 1.5k is a little low I think, with 30mA being lethal as you say that would mean 45Volts...

    I should be dead several times by your standards since I have touched 220V outlets several times....Funny fealing BTW


  • It has been 230V in almost every eu country for years.... not that it matters much, the difference is well whithin the minimum tolerance for electrical appliances


  • Noise isn't a function of the frequency or modulation.

    Yeah, but I was saying if you want to dampen a signal with a cap, the frequency has an impact on the capacitive reactance of the cap.. sorry, perhaps that wasn't clear 'nuff..

    The supply and cap would be fighting each other, hence a recreation of the big bang.

    If you're stupid enough to not to properly rate it.. or use an electrolytic on it! Otherwise, all it does is create resistance in the circuit.. I was thinking of something like a tank circuit / band pass with the capacitor to have the lowest impedance at 60hz. Presumably the frequencies you want to block are in the Mhz range, and hence would be highly attenduated through the circuit!

    Quite how this system works in conjunction with UPS's, though, is the interesting question...

    When a UPS detects a drop in the line voltage, it usually trips a relay inside it .. hence your UPS will never "bleed" energy back into the lines..

  • by DG ( 989 ) on Wednesday June 07, 2000 @06:31AM (#1019477) Homepage Journal
    Technical and security challenges aside for the moment, the really killer app for this technology is the seamless networking of otherwise non-networkable appliances.

    Not everybody wants an ethernet jack on their toaster, but _everything_ has a power jack.

    Imagine the following:

    - buy a new VCR/DVD Player/Alarm clock? Plug it into the wall, and watch it set the time on itself to the same time as all the other devices in the house.

    - Self-monitoring appliances that are syslog() capable (or something similar) and report faults to a central logging facility

    - Appliances that export network APIs to provide scriptable control

    ...and a host of other Really Neat Stuff possible if you have a standardized network in every home.

  • I said maximum safe current.. 30 mA is the threshold for lethality for a cross-body shock, but I'm not an expert on this... I just recall that from reading a book on applied math with electronics and it had a little chart in it with a cute symbol labelled "You" as part of the circuit and a lightbulb for your head.

    Obviously putting your finger across an electrode while you are ungrounded would have significantly less impact than a finger from each hand and putting the charge across the heart.

    btw - don't let that "funny feeling" last too long.. internal / RF burns suck. REALLY suck. No, no, I don't think you understand: THEY ARE THE MOST PAINFUL THING YOU CAN POSSIBLY IMAGINE.

  • I was just logging in to ask about this very subject.

    I've been wondering how far this sort of thing would work in an apartment complex (on USA power lines, if it matters). Could people in several apartments form a "clandestine network" on the existing powerlines to communicate with each other, and if so, how close would the apartments have to be to one another? Also, could someone build "repeaters" to boost the signals from the other end of the apartment complex, or a signal amplifier (much like the "long range FM radio antenna amplifiers" that occasionally get advertised) that would amplify and clean up the incoming signal, to boost the effective range?

    Somebody (perhaps more than one somebody) in one of the other stories (one of the "perversely wealthy corporate bastards with rabid legal department stomps all over internet freedoms" stories, I can't remember which one) made a brief comment along the lines of 'maybe we should form our own internet'...could this be a way to do it?

    Joe Sixpack is dead!

  • Flouescent lights, refridgerator, space heaters, air conditioner, microwave oven... got em all.

    Yeah, but your house does 250 amps, I bet.. the building I'm sitting in right now I betcha does over 2000. That, umm, kinda makes a difference. :)

    I don't string my cat5 anywhere NEAR my power cables

    You can do that all day long if you run them at 90 degree angles relative to each other - that way you get minimal interference between them. Worse though is leaving them all coiled up - inductance can cause some serious problems over long lengths of cable.. like what you might find behind a patch panel.

    We'll have inferior bandwidth at home, subject to all the power line noise you described. And don't expect the house to be sold/built any cheaper for the lack of a real cat5 network either.

    I already resolved, like many of my geek friends, to live only in neighborhoods with high speed options available.. they'll come around - it is all a matter of market demand and as people become clued about this it'll become alot more prevalent.

  • Heh, I'm not sure you've ever designed an anti-RFI mains filter ;) It's a little more complicated than a cap - varistor, suitably small caps (0.22 microfarads, ish). You also need to consider where the caps are placed. You can actually buy these in IEC packages, for easy drop-in replacement.

    As for the UPS, I was talking more about how they expect the signal to get through it.. and it also depends whether you have an active or passive UPS. Most good ones completely separate the mains going into the UPS from the mains going out - they're completely isolated. Hence, no data :)
  • >Yeah, but your house does 250 amps, I bet.. the
    >building I'm sitting in right now I betcha does
    >over 2000. That, umm, kinda makes a difference.

    Yeah, but the building I work in is n SF's SOMA district and was renovated two years ago specifficly for the purpose of housing technology companies. Plus, my home circuit is all ME. At home I prolly use more amp/person than the office does w/ one refridgerator split between 40 people, etc.

    Plus, I live in an OLD house. You'd be supprised how old some of these homes in SF are. I don't even want to imagine what kind of spec my home electric wiring is up to, or how old it is.

    Some big streaches of SF are in need of some MAJOR urban renewal. But the city planning board makes it INCREDIBLY difficult to demolish and redevelop ANYTHING.

  • Actually this was from one hand, across my heart to my other hand so my shoes would have little to do with it.

    You are correct, though, that much more current would flow if I was wet. With moist fingers I can get the resistance down to 50k Ohms or so, or 180 microamps from a 9V battery. I personally wouldn't even worry about taking a 9V battery into the shower with me.

    Hey, a lot of people stick 9V batteries on their tongue to see if they're dead or not.

    The European safety standards specify about 30V (it might be 32 or 35 or so) as the "safe" voltage level. Any voltages used in your product above 30 or so volts have to be protected from coming in contact with anything (i.e. a finger) but below 30V no protection is required.
  • Does this not assume that one computer is connected in between the ISP and the home network? What you are doing with the power network is sharing the same physical layer as everyone on your power grid. Kind of like running an ethernet cable to all the other people on the ISP, in your example. Unless youplace a filter on your breaker panel or fuse box, any signal you place on your power lines will be transmitted back through the power network to your neighbors. It's the same piece of copper. If you filter your power distribution box, the problem disappears. No signal will get through the filter to the neighbors. My question is, does this work across phases? Most houses have two phases whose hot lines are not connected. Only the common is connected. How does the A phase talk to the B phase?
  • ... its bad enough worring about power surges blowing out your equiment. Now, everything on the network gets blown apart. I dunno, seems like an intersting idea, but, something is bound to go wrong.
  • I had some X-10 units in my house. Then one day I got this Isobar, power filter/surge protector strip. Suddenly the X-10 units started to act flakey; sometimes working, sometimes not. It seems that any kind of AC noise filter will work on both sides of the line, filtering the power to the equipment and filtering "noise" on the rest of the house wiring, including desired line noise, like X-10 signals and not ethernet signals. Also won't EVERY transformer operated devide suppress some high frequency noise from the line. How many wall warts are in your house?
  • Ok. This is strange. The FIRST post was moderated as "Troll". The SECOND post, complaining about the moderation of the FIRST post, is moderated to "Off Topic". I'm afraid the /. moderators have gotten into Granpa's moonshine stash again. Or perhaps they just scored a really nice big, fat bag of crack.

  • Assuming this is setup, with that high of a voltage, I wouldn't want any physical connection between the dsl modem and my computer. Let them convert it to optical and run a fiber line into the pc (fiber nic in pc) or maybe use an infrared or other wireless technique. No physical connection electricity can travel in though-not me... :0

  • of course it will slow down like a cable line when the neighborhood is online, so you'll see DSL advertisements where some drunk redneck in South Carolina is running out of his mobile home in his underwear screaming how he is going to lynch ya'll bastards fer slowin' up his sister/wife's apple ][e as he cusses about spillin' his natural light 40oz beer just seconds before being electrocuted at the top of a service pole while trying to cut the power lines to the rest of the trailer park with a rusty pair of bolt cutters.

    that has to break a run-on sentence length record somewhere...
  • by Detritus ( 11846 )
    According to the technical specs [], it meets FCC Part 15 emission standards. Still, it is transmitting in the 4.3 - 20.9 MHz frequency band over non-twisted, non-shielded, copper power wiring. This has the potential of trashing important shortwave broadcast and amateur radio frequency bands. Widespread deployment of these devices could be a disaster for HF radio users. Noise is already a severe problem in many places.
  • I just grabbed my multimeter and see about 1.5M Ohms, so the max. current that would flow from a 9V battery through me is 6 microamps, even though the battery will probably deliver at least an amp into a short circuit.

    Only on a good day, most of the time it would be substancially less.

  • How much will a "card" cost? This might be ideal for making networked appliances (no not your toaster, but probably all your lights and clocks your A/V), but only if the incremental cost is small. I'll get excited if someone starts producing a cheap (~$1) Electric Plug addressable switch. X10 is still just too expensive.

  • How hard would it be to eavesdrop on something like this? Easier than a cat 5 connection? Would you have to worry about your neighbors potentially tapping into your data connection.
  • but only 14mbps? this may serve okay for gaming over home-based networks, but as we've seen, electric-plug networks can't touch good old 10baseT/cat5. i know electric plug is neater, but it costs a lot more, is not user-serviceable, and is held back by lack of bandwidth.
  • I've been looking recently for a solution for home networking.. I want to be able to use my laptop to surf from the living room and I don't want to run wires if I don't have to. Electrical outlets would be perfect. Wireless could work to? What products exist today that do this? I know intel has a product but I don't think it uses ethernet?
  • Yeah, but it'll still be much better than the 5 kilobytes/second download rate you get from a modem on a good day, even if the 14 mbps is shared bandwidth.
    Cable modem or ADSL aren't user-serviceable beyond the plug in the wall either...

  • by Stskeeps ( 161864 ) on Wednesday June 07, 2000 @05:33AM (#1019497) Homepage
    That I can make my own personal organic echelon by plugging my fingers into the electric sockets? ;)
  • Don't know what the bandwidth was but they were modulating the carrier to send data over power distribution lines.. company was Energis I think. They failed for a number of reasons.. EMF emissions being a security risk and the sheer' dirtiness' of the carrier signal were the main problems they didn't manage to overcome.

    Oh.. and it's 240v at 50 Hz in the UK.... BTW.. which, as *everybody* knows, ain't strictly Europe.

    t o b e
  • How well does it scale? How many nodes will we be able to have on a single circuit? How well will it deal with electrically noisy circuits? Will it be possible to isolate my network from my neighbor's?

    This sounds pretty sweet, but... There is no heaven on earth... Things are not usually as perfect as they seem...
  • Cable modem and wireless LAN are encrypted, and I see no reason why this wouldn't be, too. The encryption isn't very strong (40 or 56 entropy bits RC5, or something like that) but it's enough to keep the neighbor from tcpdump'ing one's connections, at least in real time.

  • From what I understand the trial systems in the UK ended up retransmitting the network signal using any meta object. For example every street lamp on the road.

    This is not good for EMF and for security of course.
  • Sure.. but I think you'll be getting messages from God before you decrypt the signals...
  • by Signal 11 ( 7608 ) on Wednesday June 07, 2000 @05:37AM (#1019503)
    'tis important that people note this is for home networking, not for general distribution between an ISP and your home.

    The reason that an ISP->user connection will never be feasible across powerlines is due to transformers - the moment you put a signal through a transformer you get garbage out the other end.. that's the downside of transformers - and why you can't use load coils with xDSL. The second problem I see with this is that because of the high voltages involved, it is quite possible to kill yourself.. well, the voltages don't kill, but use alittle ohms law and you'll figure out why high voltages are a problem (for reference, your body is about a 1.5k resistor and your max safe current is 5mA with lethal at 30mA).. anyway.

    I also think the technology will be limited SOLELY to the home market - if I was IT manager I wouldn't let my company even *think* about deploying it.. you have all kinds of nasty things in commercial/industrial settings on those wires that just make it totally unreliable - a blown circuit breaker takes out your network, phase shift from flipping on the refridgerator, all those flourescent lights severely throw the phase out of whack - you're left with anything *but* clean energy in a commercial setting.. this is why power strips are so VERY VERY VERY VERY important.. and UPS' on anything worth a damn.

    So, uhh, don't expect this to be any kind of "long term" tech - it'll be around for about 10 years tops.. most new buildings these days have cat5 and coax drops just per default.

  • by Anonymous Coward
    Will this be Compatible with X-10?
  • How well does it scale?

    Not very well. At best it is essentially a massive hub. At 1.5MB/s, that means that you will never break 700k/s with more than a couple nodes chatting.. just like you would with any other half-duplex hub.

    How many nodes will we be able to have on a single circuit?

    I'd peg it at 5, tops.. and that's optimistic.

    How well will it deal with electrically noisy circuits?

    That is a function of the frequency and the modulation.. I cannot answer that.. however I would assume the error rate would be fairly low - maybe 1 per 10^9 ?

    Will it be possible to isolate my network from my neighbor's?

    Practically speaking, no. You can use different frequencies, of course, but the signal still gets there. A sufficiently large capacitor could remove enough of the signal.. but without knowing the frequency I can't tell you what size cap you'd need!

  • the max. current that would flow from a 9V battery through me is 6 microamps

    Assuming you're wearing rubber-soled shoes and are dry. Obviously if you get out of a shower and hook yourself up to a 9V battery you'll be in for a suprise. :}

  • The first thing I did was try to compare the value of a system based on electric wiring over Ethernet. I can immediately see two advantages; the network cables are already there, and any number of nodes could exist without the added complexity of hubs and switches.

    Now of course immediately, the usefulness in networking is with computing devices, most of which are pre-equipped with Ethernet capability, and most of those at 100bT. But perhaps the real future here is in other kinds of networked devices. As it becomes more feasible to network your coffee maker, lights, microwave, alarm clock, and other household appliances, I can definitely see the value in using existing network architecture rather than installing a whole new one.

    The one technology I see as the killer here is wireless communications. If we're talking intra-unit communications, the advantage easily shifts toward 11mbps IEEE 802.11b. Yes, it's slower. I'm getting a good deal less than 11mbps (more like 2), but it works. It's shipping; it's here. And I predict that by the time we see a working system based on this new technology the bugs will be worked out in the wireless sector. That would effectively make the power-line-based system obsolete before it's even a reality.

    All we need is bandwidth comparable to today's Ethernet (100bT, not necessarily Gbit) and a range increase on an order of about 2-3x (can almost get this now with an external antenna). I could easily see running an entire household worth of appliances off of such a network, and possibly hook a few personal computers in as well.
  • The biggest problem I can see with this system is that, unlike the slow old systems, this one is into radio frequencies (4-20MHz), which must surely cause problems for something.

    Every frequency across the board will have problems because the transmission lines are so long. The trick is lowering the output to the point where the FCC doesn't complain, and maybe making it broad-spectrum... considering this is only feasible for home use we're talking maybe 1/8 watt transmission.. it's not like it has to go very far!

  • I have half an idea of taking an ADLS connection (it's 640 Kb download, 128 Kb upload, ~1.2 KEURO x year ) and share it with the owners of other flats of the same building ( I live in a building with >20 apartments ). This would bring to all us involved internet connectivity at least at the same rate of a fast modem, but 24 hour per day and without telephone bills (yes, here flat-rate internet connections are still a dream for many ).

    One major hassle would be connectivity in the building. Mainly for the social engineering needed to persuade non-geeks to put another cable in their walls. Solutions like this could help, if they mature soon enough.

    I also though of using inter-phone lines. I know there are products meant for offices internal phone lines. Anybody knows aho fast/good they are?

  • by panda ( 10044 ) on Wednesday June 07, 2000 @06:39AM (#1019510) Homepage Journal
    Ok, thanks for correcting my analogy. I had a suspicion that I migh have had it backwards.

    You said, "If they are wet and grounded."

    Yeah, if you're grounded you're in deep trouble. A guy I used to work with has this bumper sticker: "Electricians' kids are never grounded."
    Yeah, I did electrical work to pay my way through college. I don't have a degree in physics but I know enough about electricity to be safe.

    As for the wet part, isn't it the salt(s) in water that conducts electricity? I recall doing some labs in high school physics class that showed that distilled water makes a lousy conductor. Of course, water loves to dissolve salts, so your distilled water quickly becomes "contaminated" and a good conductor if you do something silly, like stick your hand in it. Again, correct me if I'm wrong.
  • This would be a very similar situation to the one I had in my college dorms. We had 10baseT in the building without switching. Naturally, privacy was more or less a joke unless you encrypted everything, but on the other hand most people on your segment didnt have much of a reason to eavesdrop.

    Bandwidth was not a problem due to the fact that the universities outbound line was the real bottleneck. However, I could see this becoming a problem in a large building where everyone has different providers. Perhaps this could be solved by apartment buildings leasing their own frame relay lines and including power line networking in the lease.

    The security issue is really the reason that people need to move towards encrypted layer 4 protocals (authentication is nice too). TLS sounds like a great solution for this, as you dont need to worry what is being sniffed (it is like tcp but fully encrypted).

  • Even if the bandwidth was significantly less, this opens a huge door for "smart" homes and appliances. The "average" consumers are more likely to buy a fridge that doesn't require an ethernet cable snaking around their home. I can't see my dad wiring cat5 in his house, but I can see him plugging in a home monitoring system that knows when he left the oven on.


  • by Anonymous Coward
    Last I heard, yes, you can run both signals. They're different enough that it isn't an issue, and each is very tolerant of noise.

    The real question is: When will the price drop to X10-like levels? Using this for simple off-on control is massive overkill, but if chipsets are cheap and can be hooked to PICs, well, why not?

  • Look at what you just said. "14mbps ... can't touch good old 10baseT." Hmm... 14mbps can't touch 10mbps? And most people really don't need 100mbit for what they would use this for. 10mbit is enough to share files reasonably, do usable remote control via VNC or X, or whatever your program of choice is, and to play games. And that is about all someone is likely to do with a home network. Most people don't videoconference within their house.

    Cat5 might be cheaper on the endpoints, but you have to consider the cost of getting the wires in. Most people's homes don't have Cat5, and I would question anyone who says that any more than a small percentage of new homes are getting Cat5 in them. Most people don't have multiple computers strung about the house, nor do they care enough about their computer to get extra wiring put in for it.

    If you just want connectivity between points in your house, this is undoubtedly much cheaper than ripping your walls out to put Cat5 in.
  • 'tis true that mineral water is a good dielectic. Unfortunately it is not suitable for use in electronics as it is very acidic and will eat away your PCBs and stuff. Worse, the acidic nature of it will eat away the plastic in many electronics which will either destroy it (like if it is a capacitor) or change its electrical characteristics. The worst part about this though is that that newly dislodged plastic floating around in the dielectric will create INCREDIBLE static charges. 3M has some very good low viscocity dialectrics which are very cool.. they are made out of strings of florocarbons IIRC, and I suspect they have some which don't do stupid things like eat electronics. :)

  • I get several 120V AC shocks each year (and a number of 60VAC (120Hz) shocks, too)... of course, the number has gone down quite a bit, and most of them only run through one hand (or foot - now that feels really funny), so it's not quite so dangerous... if you get current running through your trunk or head... that's another story.

    In one finger and out the other causes some cool muscle spasms, though. One downside of electrical shock is that it can tense your muscles, strenthening your grip on the item that is shocking you, causing better contact... etc... don't grab lines with your palm...

    I've only once suustained a burn, and that was about 3-5 seconds of contact (seems like forever, though...)
  • Only if you want the outside world to be able to talk to your lightbulbs and fridge!

    Good point. Very few household devices would need to talk to the outside world. Although perhaps more than at first glance. Your fridge might want to talk to its manufacturer (or vice versa) for software updates or service calls if it detects a problem, for example. Your blender might want to conduct an email love affair with that cute toaster oven it sat next to on the store shelf. That sort of thing. :-)

    Meanwhile, how long before somebody builds a webcam into a light bulb?
  • i did not say 14mbps can't touch good old 10baset i said "but only 14mpbs?" and on a different thought said "but as we've seen, electric-plug networks can't touch good old 10baseT/cat5." cat5 was included in that, which includes 10 and 100 baseTX. gosh. rip it apart on semantics, why don't you.
  • They should probably have some sort of password and encryption scheme much like 802.11 wireless has. This is to prevent the above mentioned problem, as well as having the ability to have "multiple" mini-lans in the same home... (kids network for internal fileshares vs. access to internet capable network)

    Amarillo Linux Users Group []
  • it will probably have the same limitations that things like the home control systems have (like the x10 firecrackers). The control singnal is limitied to within a master circuit breaker... (ie: within the same phase loop)... So unless your neighbors share the same electric meter, they should not be able to see your network traffic...

    Amarillo Linux Users Group []
  • Raw data.. do they define what they mean by this?
    You wonder why I ask....

    In 10Mbps ethernet, the 10Mbps refers to the capacity of the ethernet as a single, baseband channel. at perfect 100% usage, the channel will contain 10 million bits/second.
    In practice, the maximum amount any single host can transmit, (full sized 1518 byte frames, smallest legal inter-frame gap (9.6uS, or 96 bits) equals about 9.9Mbps. Accounting for ethernet framing, fcs, plus ethernet headers, plus ip & tcp headers, and accounting for tcp acks... the max throughput on ethernet between two hosts doing ftp is about 9.8Mbps.
    Fine you say... close enough. True.
    T1 = 1.544Mbps, raw data rate. This translates to near 1.3 mbps (or higher, I forget) after PPP framing and whatever else is in there.

    However... take many wireless networking protocols. Using whatever proxim's protocol (whatever they use in their rangelan-II radios)... a raw data rate of 1.6Mbps translates to a max uni-directional broadcast of about 800Kbps. About 600-700Kbps in normal TCp operation.

    I've seen 11Mbps wireless gear that only does 5Mbps in useful throughput....

    so.. in other words... be wary when someone says 'raw data rate' or 'throughput'... you (and they) will probably be unsure of what you mean.

    Also..for any given medium, one has to take into account latency due to (c), the fact that there really IS no such thing as throughput.. a more relevant profile of a link is...
    How many of what size packet can our setup move with what latency?

    10Mbps ethernet again... it's a good example, because aside from the (frame+header)/(data) ratio changing with the size of (data).. it's efficient.

    Many wireless devices I've tested aren't so lucky. Some of them perform just great trying to bridge 1518 byte packets, but then you get down to 64 byte... and they drop *way* off (processing bottleneck or something..). In other words... small packets take up much more than their fair share of resources in some devices... so in a common office ethernet, where 75% of the packets are 200bytes or smaller (not 75% of the total data.. 75% of the packets)... perhaps you don't get the throughput you think?

    Why am I on this rant?
  • Our IBM 3090 mainframe had a neat system for eliminating external RF interference and power glitches. The power from the electric company was used to turn a motor, which in turn drove a generator, which supplied nice, clean AC power for the computer. A large, heavy flywheel was also attached to the common drive shaft to keep the AC nice and smooth.

    Gotta love mainframe technology overkill!
  • Think of the havoc you could play with an EMP weapon. The refering article says that the inventor thought of this when he found that you could "hear" a lightning strike in Miami from LA. Our current grid keeps outages local. When you have equipment designed in a way that they bypass the transformer problem then they are not protected by those transformers. Something that currently would take out 30 Km could now take out an entire grid. Network security also becomes an issue fiber is nice for long range comms. becouse it is nearly imposible to remotely tap. With this new system an inductance tap becomes not only possibable but easy (think RPM counter for a car). Anyone plugged into any point in the national power grid can moniter anyone else. # of adresses for use Q. When there are no private networks and every elec. apliance is networked how long are the IP adresses. A. Way too damn long =-=-==-=-=-=-=-===-=-=-= | Think Fiber : -=-=--=-=-=-=-=---=-=-=-
  • by Anonymous Coward
    ... a beowulf cluster of wet anonymous cowards, plugged into the wall, holding hands?
  • germany and austria (which i know of for sure) have 220. as per the post above, the british have 240. and the netherlands 230. good ole europe. YES, ITS TRUE: we can never agree on anything!
  • Stupid is right. I've personally gotten nailed by 220VAC and it hurt bad. Believe me, where I work there are tons of ways to kill yourself with electricity and I do my best to make sure everything and everyone stays safe. That's why, knock on wood, we've never had a serious electrical accident. We have a sister company that has not been so lucky, but they do it to themselves. A bunch of engineers and scientists running around playing with stuff, defeating interlocks, and not using grounding rods to really check and make sure that cathode is off. 90 Kilowatts or even 120 with Niobium DC would not be cool, and has jumped from 4 different people standing next to the idiot that latched on to it. Your president must be a clown if he told you to stick your arm in it.
  • Wow. That's simply beautiful. sorta reminds me of an article I saw in a recent Wired where instead of a battery-powered UPS, energy was stored in giant, incredibly high-speed fly wheels. Sorta has a high-tech-retro kind of feel to it... I like :-)
  • The standard voltage all over Europe is now 230 volts @ 50 Hz.

    Some years ago it was 240 volts in the UK and 220 on the continental Europe.

    A world-wide guide to plug and voltages around the world can be found here:

  • Search for Powerline communications on this page

    Ascom is/will start field trials soon.
  • The simple diagrams I've seen have all contained the idea of separating the network signal before transformers. If you have plenty of houses/apartments behind the same transformer you can just separate the network in the transformer room and send it off on another line. It still saves piles of wiring. After all this is what at least Elisa Communications (my local telco) does with xDSL. As the other end has to be at the local telephone exchange anyway, they move everything onto an IP network at the exchanges. That way the xDSL lines for the whole city form a single network which they call Arenanet. It has some neat high-bandidth applications. And of course they can build the separate network from the transformer room onwards into the same ducts as the power cables. At least Sweden is going to build the backbone of their national high speed network onto existing power pylons. -Late
  • by panda ( 10044 ) on Wednesday June 07, 2000 @05:57AM (#1019531) Homepage Journal
    Remember, it's not the volts, nor the amps that kill you. It's the two together. It's basically the wattage, or the amount or work (ie heat) done by the current. You can survive quite a lot of volts if the amperage is extremely low, just as a relatively small number of volts would kill if the amperage is really high. Compare it to water, and think of volts as volume and amps as velocity. That's generally how I visualize it.

    Other than clearing up something that might be a bit confusing, I agree with pretty much everything the previous poster said.
  • oh, well atleast I get some messages by it ;) "Plug your fingers in your electric socket and hear from god soon after!"
  • I believe we moved over to 230V a few years ago, along with the rest of Europe.

    We still have different plugs, though, and (unless they've made some significant changes to the ones on the other side of the Channel) long may it remain so...
  • and 230v 50Hz in belgium (they have been upping the voltage slowly in the last ~10 years from 220v to 230v)
  • This isn't for your external connectivity. It's for internal home networking -- plug your laptop in on the patio and access your server, for example. Or access your toaster, fridge, etc.

  • That was a trial, run by Norweb Communications (an offshoot of the private company that used to be the North Western Electricity Board), of a system to provide bandwidth into the home. This system is simply to move data around the home over power lines, which has been around for years (though at much slower speeds) - you can even get hobbyist kits to build yourself.

    The biggest problem I can see with this system is that, unlike the slow old systems, this one is into radio frequencies (4-20MHz), which must surely cause problems for something.
  • You can survive quite a lot of volts if the amperage is extremely low

    Exhibit A: The Van-de-Graaf Generator, which is incredibly good fun, but produces extremely high voltages.

  • Hmm... Just like Compuserve used gifs based on Unisys' technology, or mp3[*] is based on Fraunhofer's technology? I would be very careful to find out if the technology is encumbered by any current or pending patent claims before making it the standard. Whether or not the company says that it won't charge for the use of the technology, once enough people move to the new standard it starts looking real attractive to a corporation to go back on that agreement. Don't get fooled again.

    [*] apparently Fraunhofer believes that their mp3 compression patent is broad enough that it is impossible to create mp3s (using any algorithm) without infringing on their patent.

  • The overall forecast for power-line-based home networks is now beyond the 32 million nodes initally projected.

    Time for IPv6? Or do we just put every toaster, refrigerator and light bulb in the house on an unroutable domain and handle the translation in the router/firewall/proxy built into the fuse box?

    More seriously, this ain't bad. Speed is comparable to 10base Ethernet, but I'll still run Cat 5 cable in my new house (faster, and for now cheaper, since I already have the NICs and hub). One nice thing about signal-over-AC is that you don't need a separate cable to the device -- the power cord is the network cable, very convenient for appliance-type devices.

  • by HomerQPeabody ( 102137 ) on Wednesday June 07, 2000 @06:07AM (#1019540)
    1. Inari (formerly Intelogis []) has been shipping a 350 Kbps powerline networking kit for 2 years. You can purchase it at Fry's, Office Max, CompUSA etc. It works in about 80% of the outlets in an average home. There are GPL'd Linux drivers for it on SourceForge []. It's good for no more than about 10 nodes. It uses encryption to keep your neighbors from sniffing your data. Sure it is slow, but it's faster than your dial up connection.
    2. 14 Mbps is really impressive on a power line. (Lots of reflections, lots of noise, dynamic line conditions). I wonder if it really runs that fast? Has anyone seen a demo?
    3. Intel's home networking product is a phone line product based on the HomePNA [] (Home phone network association) spec.
    4. Wireless is still more expensive than powerline and it has its own set of problems.
  • The previous poster meant the amperage when there is no other resistance involved.... Which is (kind of) the case with electrical wires.
  • The rest of Europe has 230v
  • by johnlenin1 ( 140093 ) on Wednesday June 07, 2000 @07:10AM (#1019543)
    They look promising [] in this area. Peep this article [] for more info.
  • Indeed. I've got at least two 120V shocks in my life, and I'm still here. Mind you with one of them, the current presumably passed across my body (it went from one hand to the other), and I nearly blacked out, but all's well that ends well.

    It's important to note that the amount of damage a current will do depends entirely on where the current goes. IIRC, it only takes one or two milliamps (or maybe less?) across the heart to stop it. Current going from one knuckle to another on the same finger will probably not do anything more than "weird out" some of your nerves and maybe give you burn.
  • well, actually, it can go very far. do a search sometime for 'qrp' on the net. it's sort of an amateur radio sub-culture. i routinely work the continental united states at 500mW, and there are people running microwatts as well. output power is only a small part of it. the length of the antenna and frequency in question contributes more.

    basically, they will need to do a lot with ensuring compliance of the electrical wiring in homes to minimize interference with licensed users of radio spectrum. i routinely find spurious emmisions from all kinds of household devices (including home networking stuff) all over the shortwave band, and occasionally up into the vhf band as well.

  • IANAEE, however I can attest that my simple home intercom that does FM over the house wiring is in the clear out to the transformer. We had what amounted to a party line with an unidentified neighbor in one house that we lived in. Then we changed frequencies (the box has a A-B-C switch).

    My new house has Cat-5 in the walls. I'll stick to that, thank you.
  • Cable modem and wireless LAN are encrypted, and I see no reason why this wouldn't be, too. The encryption isn't very strong (40 or 56 entropy bits RC5, or something like that) but it's enough to keep the neighbor from tcpdump'ing one's connections, at least in real time.

    umm, that is not neccessarily true. a lot of early wireless lan products, and quite a few on the market today, are _not_ encrypted. the newer, forward thinking products, fortunately, are.

    you'd be amazed at how insecure wireless data systems actually are. when you are reading the specification for something and you run across the statement "the technical knowledge and equipment neccessary to intercept and decode this system is out of reach of the average person, making this an extremely secure system" it makes you scratch your head. this was [paraphrased] from the mobitex specification, which requires a handful of parts from radio shack and a bit of software.

    be wary of _any_ wireless data product that does not implicity state it uses encryption, and states what the encryption algorithm is. a lot of protocols use something called 'bit scrambling' to maintain data integrity, and the marketing types always confuse this with encryption.

  • Everything you said plus more bakes this a *BAD* idea for HOME networking as well as office networking.

    Flouescent lights, refridgerator, space heaters, air conditioner, microwave oven... got em all.

    I'd bet good money that the power signal in my HOME is just as "dirty" as at the office. Moreso I'd bet, actually. And yep, everything important is on a power strip/surge supressor, and the cpu boxen are all on UPSs. And I don't string my cat5 anywhere NEAR my power cables (actually, it's not even IN the walls, it's duct taped to the ceilings, walls, and floor OUTSIDE the walls).

    >most new buildings these days have cat5 and
    >coax drops just per default.

    Most new HOMES have this too, at least according to an article in the Mercury News a while back. And this is EXACTLY why this is a horribly *BAD* idea for home networking as well.

    What happens when real estate developers and builders find out about something like this? They'll think, "well, we can still sell a 'network ready' house, but skimp on all that cat5/coax cost". We'll have inferior bandwidth at home, subject to all the power line noise you described. And don't expect the house to be sold/built any cheaper for the lack of a real cat5 network either.

  • Am I the only person that's sitting here thinking that although this is a great sounding idea, the fire hazard that's involved here, I mean there's all of this power running over every cable, and let's say you're like me and have 4 computers all networked at times, running wires through the attic, don't you think things would be likely to catch on fire if a cord frayed? I've never been zapped by a Cat5 though...
  • Just a random thought, but what happens if you're using a technology like this in, say, an apartment building? Is it even feasible? Assuming that it is feasible, two things that immediately come to mind are:

    • Security: Could someone in another apartment sniff my packets?
    • Bandwidth: How many people would have to be in the complex before the internal network became saturated?

    Security might not be a big deal to most people, but I'm sure bandwidth would be. Things to think about....

  • actually 230 V, not 220.

    At least, in the Netherlands, that is.

  • by dustpuppy ( 5260 ) on Wednesday June 07, 2000 @06:10AM (#1019553) Homepage
    Image if someone performed a Denial Of Service (DOS) attack via a powerline-based network?

    All those ping packets of x volts combined - boom!


  • by mistered ( 28404 ) on Wednesday June 07, 2000 @06:10AM (#1019554)
    Actually, it is the amps that kills you.

    Here's a link [].

    The reason you don't get hurt by a 9V battery (which, in fact, can deliver quite a healthy current) is because of Ohm's law. The resistance from one of your hands across your heart to the other is quite high. I just grabbed my multimeter and see about 1.5M Ohms, so the max. current that would flow from a 9V battery through me is 6 microamps, even though the battery will probably deliver at least an amp into a short circuit.

  • Noise isn't a function of the frequency or modulation. It's a function of how many cheap electrical devices you have plugged into your system. This is why we have filters. Why your amplifier goes pop when you turn on the hoover. Etc.

    And no, a sufficiently large cap wouldn't remove the signal. A sufficiently large cap would blow up the sub-station - mains is AC, caps hold DC charge. The supply and cap would be fighting each other, hence a recreation of the big bang. (Actually, it's far more likely the cap would go, and yes, they do explode). I think you're thinking of DC power supplies there. But anyway, you can filter the mains, for about 20 UK quid (30 dollars) at most. And I can tell you the frequency easily: 50/60Hz band-pass. Pretty obvious, huh? Quite how this system works in conjunction with UPS's, though, is the interesting question...
  • by Ed Avis ( 5917 ) <> on Wednesday June 07, 2000 @06:14AM (#1019557) Homepage

    The voltage is still 240V in Britain and 220V on the Continent. The new European 'standard' is 230V, but with a wide enough tolerance to cover both. See this page [].

How many surrealists does it take to screw in a lightbulb? One to hold the giraffe and one to fill the bathtub with brightly colored power tools.