Reply to: Networking over mains wiring

[MPwannadecentincome]

In the interest of balance I feel I should point out some quirks and limitations I have experienced with the Devolo plugs:

Firstly, it doens't take much of a knock to put them out of action. I used to just have 2 and moved the 2nd one around quite a bit depending on which room I wanted to use the laptop from. After a while it just stopped working and I guess maybe it dropped or something. It was just outside its warranty period though it was a few years ago and the warranty periods are longer now.

Secondly, the older model does not like re-connecting the network after resuming from standby or hibernation. It only happens about 40% of the time and what happens is the 'limited connectivity' message in XP. This can be cleared by switching the devolo on and off or, by doing a repair on the network client. I don't get this problem with the newer models (the old ones were ethernet only, the new ones have both USD and ethernet.

Anyway I'm going to buy some more - the Wii has a USB port into which can plug in a Ethernet port and an old laptop will be cobbled into service - if I can get it to boot - as a kids play machine.

[MPwannadecentincome]

Aye, i was surprised at this, i've just brought my Devolo Homeplugs back into service after moving my office to a room with a duff phone point.

Had read somewhere they dont work with gangs or surge protectors and all my PC kit runs off a fancy 8 gang surge protector. Feared the worst but it just plugged in and worked.

Dont see why these things aren't more popular as they are speedy, just work and dont fill your head with cancer rays like wireless.

I've never had a problem with gangs or extension reels, I often sit in the garden plugged in like that - doing that now in fact :-)

I've not tried to plug in after the surge protector, I've always had a spare socket to plug into.

[VectraMan]

One end of mine is plugged into a gang socket, plugged into another gang socket, which is then plugged into the wall. No problem at all. It also doubles as the router power supply, which is nice.

And it means you can use good old fashioned wired ethernet around the house, which is more reliable, faster and less of a drain on the machine than Wifi. I did a test copying large files from my Vista laptop to XP desktop, and with it plugged into 100Mb wired ethernet it was about 7 times faster than 54Mb WiFi.

[Moscow Mule]

All swimming along nicely now.

Do not mix water with mains electricity!!!

[NotAllThere]

I guess they're mainly a European thing. US houses are made of wood, so maybe wireless works better for them. Without the US market, I suppose they're just not that well known.

Got my duff one replaced (got a credit note, picked up a replacement, to find that the price has dropped by 10CHF! which was nice ).

All swimming along nicely now.

[xoggoth]

Threads like this should go into a useful CUK bits page somewhere.

[Durbs]

they even work fine over gang sockets.

Aye, i was surprised at this, i've just brought my Devolo Homeplugs back into service after moving my office to a room with a duff phone point.

Had read somewhere they dont work with gangs or surge protectors and all my PC kit runs off a fancy 8 gang surge protector. Feared the worst but it just plugged in and worked.

Dont see why these things aren't more popular as they are speedy, just work and dont fill your head with cancer rays like wireless.

[PDCCH]

BPL Comms

What happens if the next house on the same phase (three doors down?) are also running ethernet comms over the mains. Does the system address the signal so that it only uses the local data, and not the one down the road? Will the signal clashing be enough to corrupt the data? So, house number 1 puts data 0101 on the bus and house number 7 puts 1010 on the bus (the mains cable) at the same time. I assume it is modulated on top the mains signal. Not a comms expert - in fact pretty poor comms knowledge, hoping one of you wise lot know the principles.

Probably not an issue as not many people own them at present, but just a hypothetical due to curiousity.

Hullo,

One of my areas of expertise (radio & wireless) - the system is essentially two OFDM endpoints (http://en.wikipedia.org/wiki/OFDM) utilising the live / return wires as the medium instead of airborne spectrum.

The principals of the above as well as the coding scheme in use (normally QAM-1024 in the Devolo units) ensures a high degree of symbol (ie: signal element) seperation, redundancy and throughput.

Regarding phase and seperation - from what I understand, given the technical documentation, the manufacturer indicates that the signal will not pass via ferrite couplers or other isolators / switching units. However, thinking about this in retrospect (and from anecdotal evidence to the contrary), it seems apparent that the carrier baseband can jump phase and go past couplers / step-downs. Devolo have actually had the foresight to include AES-128 encryption in their product to mitigate any unexpected behaviour however (no shared key? No broadband for you)

The standard has already been cracked and documented as such - but requires some degree of dedication to effect any sort of succesful intrusion outside of passive traffic analysis. URL : http://hackaday.com/2008/12/28/25c3-...communication/

Bloody clever stuff all in, and cheap as well - the radio equivalent to do speeds like that costs a mint and is still at the prototype / testing stages. Currently using mine to stream AV to a media-mac in the living room :-)

Cheers,

PDCCH

[vlc]

Network over power-lines works! I've been using HomePlug AV 200Mbps system for about a year now... faultless, quick, convienient, simple, all good. I got two types of access-point units...because I didn't know what performance to expect. Wired and wireless/wired... both work perfectly.

[NotAllThere]

Solved the problem. I have three adapters. I swapped them around. And discovered one is duff.

[NotAllThere]

Just put some devolo devices in. Yesterday evening all three devices could see each other but now, the two on the same circuit can see each other, but not the one plugged into the router in the cellar.

I'll troubleshoot that this evening, but otherwise, it looks like a fantastic solution!

Re: the question of phases. The website says

Question:
My house has three separate phases. Can dLAN also establish a connection from one phase to another?

Answer:
Yes. This is known as phase coupling, and in dLAN devices, it works without the need to install an additional phase coupler. This means that you can also establish network connections via two or three phases.

So looks ok.

[TykeMerc]

You are right not many people own these at present, certainly not as much as wireless. I can see many wireless networks from my house, I do not see other people's mains LAN devices.

Same here.

As mentioned configuring security is a doddle.

[MPwannadecentincome]

What happens if the next house on the same phase (three doors down?) are also running ethernet comms over the mains. Does the system address the signal so that it only uses the local data, and not the one down the road? Will the signal clashing be enough to corrupt the data? So, house number 1 puts data 0101 on the bus and house number 7 puts 1010 on the bus (the mains cable) at the same time. I assume it is modulated on top the mains signal. Not a comms expert - in fact pretty poor comms knowledge, hoping one of you wise lot know the principles.

Probably not an issue as not many people own them at present, but just a hypothetical due to curiousity.

Apparently the meter blocks the signal or at least severely degrades it. Even if the signal did cross between the houses through the meter the manufacturers recommend using encryption which actually is very easy to set up.

You are right not many people own these at present, certainly not as much as wireless. I can see many wireless networks from my house, I do not see other people's mains LAN devices.

[PerlOfWisdom]

What happens if the next house on the same phase (three doors down?) are also running ethernet comms over the mains. Does the system address the signal so that it only uses the local data, and not the one down the road? Will the signal clashing be enough to corrupt the data? So, house number 1 puts data 0101 on the bus and house number 7 puts 1010 on the bus (the mains cable) at the same time. I assume it is modulated on top the mains signal. Not a comms expert - in fact pretty poor comms knowledge, hoping one of you wise lot know the principles.

Probably not an issue as not many people own them at present, but just a hypothetical due to curiousity.

I imagine they use a similar system to wireless internet.

[ASB]

apparently it was £3.14159265358979323846p