Power Line Communications : SUBVERTING THE IMPOSED LIMITATIONS AND NETWORKING OVER POWER LINES
Allright, I recently got my hands on some Power Line Communcations adapters, those wall warts with ethernet plugs on them that let you network over your 110 power lines in your home, yeah those, and I got to thinking and decided to do some testing. I plugged the things in all over the house testing throughput etc, etc. And the results were consistant housewide, no matter where I put them.
The adapters had lights on them to indicate "Sync, Activity, and Power" So I figured it was time to test and see if these things could be used to setup a link between homes. I started with the neighbor to the left of me, who didnt mind being a guinee pig, I ran an extension cord from their house and hung it over my side of the fence for easy access during testing. What I found was interestingt to me, no link, the sink lights didnt come on at all, they just blinked as if there was only one adapter present, so apparently they couldnt see eachother at all.
So, I went to the next nieghbors house, across the street, whos power line I can see hanging over the street, connected to the very same pole as our house. The results were different this time, the Sync light on the PLC device was rock rolid, indicating it detected something, unsure if it was the other device it had detected. But the activity light didnt work, checked dhcp on a laptop connected and even tested this way on both ends, no dice, not even with a static ip, couldnt ping my server or anything.
I thought it was interesting that while it didnt work at ether location, I did get different results. So I did some looking into this, there is documentation on PLC communications readily available on the web, and I wanted to know how to network with my nieghbors over the power lines. Considering what we can learn about PLC, It SHOULD be possible. What I discovered was that the power company actually uses this same technology to transmit data across their own power lines, and like wifi have a limited number of freq or channels to work with, four channels or frequencies to be exact,
The bandwidth that can be carried by the power lines is considerable, now how that scales across large distances on the power line network, I do not know. But what I do know, is that the power company has gone out of their way to lock each home into its own frequency, staggering them from 1 through 4 of these channels, perhaps if I knew which homes on the block were using a particular frequency, the same as my home, I could have had success with this device. I do not know.
SUBVERTING THE POWER COMPANIES FREQUENCY LOCK: AND NETWORKING OVER POWER LINES
(this is my opinion based on my own limited, amatuer experience with PLC devices, I could be wrong, but my data and intuition has lead me to these conclusions)
Your power meter appears to take its orders from the power company, and this appears to be how they set the frequency your home is on. There are also documents available that detail how it is possible to bypass this, and yes , almost all the methods I found were ILLEGAL. Either by subverting your existing power meter or replacing it with an after market , modified meter.
However, your PLC devices that you buy from bestbuy or w/e you get them, ALSO appear adhere to the PLC standard by getting its 'orders' from your power meter, and I presume, this is how your PLC device knows which channel to function on, there are, I have read, PLC devices that do not Adhere to the PLC standard as set by the FCC, or you could modify a cots plc device for this, and manually specify the channel the devices run on, thus, making it possible to bypass the power companys imposed frequency lock without going to prison or becoming toast trying to jury rig your home power meter. And thus, network across the power lines.
I will follow up this thread with links to the materials I have found and look forward to discussing this topic further with anyone whos interested.
Personal Note: Perhaps somebody with the technical expertise and/or resources could take this to the next level to reveal what is potentially achievable, might make a great paper/talk.