On Sun, Feb 19, 2012 at 17:33, George N. [email protected] wrote:
This was a super informative post, it’s really interesting to hear about
experience of actually building PLC in practice.
I haven’t seen very many
studies on it, but it seems like different buildings have greatly varying
profiles. I didn’t think of things like elevator motors in office
buildings, but that’s got to introduce a lot of interference.
Cheap switching power supplies (wall warts) are issues as well, if
they are plugged in close to the power coupler.
If you ever do this again, I would love to see some of the channels over
time. I ordered some basic PLC equipment, but all I really have access to
I’ll try to grab a spectrum analyzer plot from my lab. If I find time
I’ll see if I can get a channel sounding.
How do you actually get echoes in a PL? I never thought about this.
Any time there is a discontinuity in impedance on a transmission line,
there will be a reflection, including at the end of an open circuit.
Power lines have lots of open branches that signals can go down, get
reflected back from, and form a delayed sum with the original signal.
This can include, for example, traveling out to pole transformers and
One idea would be to measure the impulse response between two power
line endpoints, then use that as a baseline to detect changes which
could mean damage or unauthorized access.
It would be really cool to be able to hook up the USRP to a PL and
understand various channels in different types of buildings. Totally not
conducive to my dissertation, but I find it interesting.
Happy to distract you