Power Line Based Home Automation

["Dr John Tankard" <john@xxxxxxx>]

Just seen this in W2K News and added it to the news page


Power Line Based Home Automation

You may ask yourself, what's that got to do with W2K? And as you will
see in a short while: everything. Engineers have been suspecting for
over a 100 years (really) it should be possible to use power lines for
communications. The good news is that chip technology has finally come
up to the level of sophistication to make it actually work.

It's been rough going. Power lines are notorious for many kinds of
noise. So, other networking technologies were developed that were easier
to deploy. Some examples are HomePNA which works through existing
telephone jacks, and the new Wi-Fi which is the wireless 802.11b
standard. But neither of these have been received warmly.

In the USA we have about 26 million homes with more than one PC, and
some 5 million+ are already networked. The vast majority is (90%) using
Ethernet because it's fast. But that's just PC's. How about all the rest
of the homes? Up to now there has been X10, which is fun, it works when
you install it correctly, but it is limited to short packet bursts (for
instance to switch devices on and off) with a maximum of
10Kilobit/second.

Envision a scenario where ALL devices in the home can be plugged into
your power lines, are able to communicate at 100Megabit/sec and are
aware of each other. Wouldn't that be something? Well, they have got the
networking part working. The trick is to make it reliable and fast as
the noise on power lines is deafening. Proof of the pudding is plugging
in a power drill right next to a power network adapter and your network
connection stays up.

The technology they have found to be workable took in mind all these
power line problems. There is a crowd of devices on these lines that
send spikes of static, the breakers filter and dampen signals, and
switching things on/off makes the resistance, voltage and current
fluctuate. (Think two people talking at their normal voice level but
trying to get across Times Square that way.)

The engineers had to go through several years of research to come up
with ways around all that. What turned out to work is using frequencies
above 4 Megahertz. But they used a very wide band of that spectrum
(4.5-21 Mhz) and split that up in 76 independent channels that ALL get
used to send the same data message.

The homeplug power line adapters have specialized chips in them that are
comparable to the complexity of an early Pentium. The adapters hook up
with each other, send test messages, define which channels are reliable,
encrypt on the fly and make the packets arrive correctly. The complexity
of this signal processing is awesome, and in about 2 years they will be
running this at 100Mb/sec.

Now it is of course waiting for the devices to become network aware. And
here is where Windows comes in. Universal Plug and Play is a very
capable technology to seamlessly stitch all of this together. The
existing television, stereo and other appliance vendors need to get on
the bandwagon as well and that is what MS usually is good at. An
advanced PC-like device would drive the whole house, with backward
compatibility to X10 devices and everything showing up in your "My
Network Places". Pretty cool.


http://www.homeplug.org/


John



For more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:  ukha_d-subscribe@xxxxxxx
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
List owner:  ukha_d-owner@xxxxxxx

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/