[sclug] Powerline adapters

[Neil Haughton]

I thought you guys might be interested in my experiences with Powerline
ethernet adapters.

With PC upstairs and telephone-point/broadband-router downstairs and a ban
on any more cables around the house, and having struggled for ages to get a
wireless setup working with any degree of reliability, I eventually fell
back in despair onto using a (pink) cable running loose on the floor from PC
upstairs down to router downstairs. It didn't go down well with the
Management but at least she could get onto tinternet without much fuss, so
it bought me a few weeks' breathing space. In the meantime I stumbled across
the Powerline concept, which I hadn't come across before. So I took the
plunge and bought a DLink PowerLine kit. It came yesterday, a box containing
two plug-in air fresheners (or that's what they look like) plus two cables.
I plugged one air-freshener into the power socket next to the router,
connected it to the router with one of the cables and pressed a big button
on it until a light stopped flashing. Then I did pretty much the same thing
upstairs to the PC. Switched on the PC and oila! I had an internet
connection - and have had ever since. Brilliant! How painless can things be?

According to the LED colour-code I am geting at least 20Mbps between PC and
router (it could be as much as 85Mbps), which set against my 3.5Mbps average
ADSL download speed is more than enough - but out of interest, how can I
check the actual transfer speed between PC and router? Is the a Linux tool
that wil do this for me?

Lastly I have read some stuff about how these devices 'steal' shortwave
radio bandwidth (by making the unshielded household electrical cables a
large transmission antenna) and Have To Be Stopped. My radio engineering
knowledge is 30 years old now and could use some WD40, but I am at a loss
about how this can be because as far as I can see the Powerline devices are
superimposing a data signal onto a 50Hz carrier. The shortwave radio carrier
band is nowhere near this, being upwards of 3.5MHz. So how can the Powerline
system be occupying shortwave radio territory? Can anyone explain this?

TIA

Neil.