MadSci Network: Computer Science
Query:

Re: Internet Access through power lines

Date: Tue Sep 7 18:25:04 1999
Posted By: David Taylor, Staff, programming, Testronics
Area of science: Computer Science
ID: 936554902.Cs
Message:

Is it possible to send an email through a power line? How much can go 
through it?

Yes, data can be transmitted through power lines. You can buy PC LAN (Local 
Area Network) cards that transmit data over the power line. Last I heard, 
they cost about $200 per node. Standard 10Mbps Ethernet cards (these use 
dedicated network wires) can be had for about $20 each. The expense pretty 
much limits power line LAN cards to places where stringing another wire is 
simply impractical.

Power lines are meant to carry power - data is strictly an afterthought. 
Power lines are very noisy, and the transmission characteristics of the 
power line vary wildly with what is using power at a given instant. Many 
appliances dump noise into the power line. Anything that receives data over 
a power line will need to have very robust noise tolerance. All that noise 
limits just how fast data can be transmitted. I'm guessing that a $200 
power line LAN card would be somewhat slower than a $20 10Mbps Ethernet 
card.

Data transmitted over a power line doesn't make it through utility company 
transformers. Since Utility transformers usually power only a few houses 
each, your data isn't going to go very far.




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