homeplug

[Alma J Wetzker]

Man-wai Chang wrote:
> I am no EE guy. So the sginal is still supposed to be transmitted inside 
> the wire, right? Just that the amplitude is larger than normal so it 
> interferes with other radio equipments?

You don't really need to be an EE guy.  Would you try to use phone 
hookup wire instead of cat5(6) to make a 100BASE-T run?  Probably not. 
All wires are not created equal.  Things like signal loss per meter, 
noise immunity, and generating interference (signal loss of another 
type) are important.  You can use any wire to do anything, but design 
makes a big difference in the quality of the result.

The power system is old and cranky (reference the northeast blackout a 
wile back).  Some types of equipment generate quite a bit of "noise", 
and some types of "noise" are easier to deal with than others.  Spikes 
are the worst because they spread out to so many other frequencies. 
Changes in digital states are, essentially, spikes.  Commercial power 
users are heavily fined if they put too much noise on the power grid. 
(They also get in trouble if they need power to keep something going, 
but don't use the power and let it reflect back to the grid.)

It gets worse, there are usually two power legs in a residence.  The 
wanted signal is, usually, only put on one leg.  So you only get the 
signal you want in half the house, and you do NOT get to pick which half.

     -- Alma