Dave Liquorice wrote:
On Wed, 22 Jun 2011 20:04:12 +0000 (UTC), Nick Leverton wrote:

The mains network shouldn't be affecting the WiFi. The WiFi is on
2.4GHz, pretty sure the mains network things are less than 1MHz.

Couldn't be arsed to google when I wrote that and that particular
memory cell seems have suffered a failure.

"Which frequency range is HomePlug AV using? Does HomePlug have any
plans to use higher frequencies (e.g. above 30 MHz) and if not, why?

HomePlug AV uses frequencies in the range of two to 28 MHz. The IEEE
1901 standard extends this range optionally to 50 Mhz. HomePlug AV2
will utilize additional frequencies above 30 MHz to increase
throughput."

http://www.homeplug.org/about/faqs/

That would be a neat trick, given the published data rates.

If you are thinking that to carry 100MBps of data you need a 100MHz
carrier think again. Each transition can carry more than one bit of
information and these are spread spectrum transmissions as well.
Something approaching 1000 individual carriers in the case of
Homeplug.

You possibly missed the bit where I said that not using frequencies
above *1MHz* would be a neat trick, and the published spec in your link
goes to 28 times that, with an option to go to 50MHz. Each carrier may
have a bandwidth below 1MHz, but the aggregate contains frequencies up
to 28 or 50 MHz.

Multiple bits per transition is not a new trick, it's been used since
the days of 56K modems, if not before.

Reads specification It seems that the homeplugs are carrying 200MBps
of data. They say they use between 2 and 28MHz. If they're using spread
spectrum, then the bandwidth of each carrier can be reduced, but the
overall bandwidth stays the same, surely?

I'm glad that I don't use LW, MW or SW AM radio nowadays. Homeplugs have
been reported as wiping out reception of weak stations for quite a
distance from the installation. Twisted pair ethernet doesn't,
especially the shielded stuff.

--
Tciao for Now!

John.