Re: Z-Wave improvement

["Robert L Bass" <no-sales-spam@bassburglaralarms>]

> Intermatic announced their InTouch(tm)
> Z-Wave based system a year ago (March
> 2006) but it is just now starting to ship...

It is quite common in the industry for manufacturers
to announce new product designs some time before
they are ready to ship.  This allows distributors and
dealers to become familiar with the product in
advance so that they can build a market for it by the
time it actually ships.  Mr. Houston announced his
own products long before they were ready to ship.

> First, it increases the maximum number of hops
> a message can take from 4 to 8...

I think I said exactly the same thing.

> Given that Z-Wave devices need to be within
> 20-25 feet of each other to assure coverage...

That is misleading information.  The following is
from an article by Mikhail T Galeev of Embedded
Systems Design:

"Each Z-Wave network may include up to 232
nodes and consists of two sets of nodes:
controllers and slave devices. Nodes may be
configured to retransmit the message in order
to guarantee connectivity in multipath environment
of residential house. Average communication
distance between two nodes is 100 feet, and
with message ability to hop up to four times
between nodes, it gives enough coverage for
most residential houses."

Further, according to a study run by EURASIP
Journal onWireless Communications and
Networking, "The Z-Wave communication
protocol allows a maximum number of hops in
the network. Because of the protocol design,
it has to handle communications in a home
environment, and consequently, it does not need
to communicate data over long distances. The
communication range in a free line-of-sight
scenario is about 70m, but it can fall down to
15-20m in an indoor environment. However,
Z-Wave nodes belonging to the series 100
and series 200 allow a maximum of four hops,
so that the overall communication distance
which can be covered in an indoor scenario is
about 100m."

This study found that even the standard,
pre-Intermatic Z-Wave systems can handle
homes up to 330' long with the controller
mounted at one end.  With the controller in
the center, a Z-Wave system could handle
a home that is over 600' long.

> 4 hops severely restricted the size of any
> Z-Wave network and I considered it a fatal
> flaw in the Z-Wave system...

Actually, it is far from a fatal flaw.  The system
is far more powerful than Mr. Houston allows.

> 8 hops is a much more realistic figure...

Eight hops allows Z-Wave to service even larger
homes and office environments.

> Second, it employs what Intermatic calls a
> "server" which is in the base/charger for the
> handheld remote. It periodically polls all of the
> devices (including legacy Z-Wave devices) in
> the network and maintains a status table
> which can be accessed by other controls.

This answers one valid objection to Z-Wave
which several other participants have mentioned.
The system can now know which lights and
appliances are on, off or dimmed.

> I still have some questions and haven't been
> able to find in-depth technical details to answer
> them.
>
> 1. How often is the network polled?

> 1a. Can legacy controllers access the "server"?

The server will recognize signals sent by legacy
controllers to operate legacy devices.  However,
they will not be able to control the server.  That's
largely unimportant though, since the InTouch
server obviates use of legacy controllers.

> 2. It's not clear how legacy devices will deal
> with the increased number of allowable hops.

Legacy devices can travel 4 hops.  InTouch
devices can go 8 hops.

> Intermatic says they've applied for patents
> so their approach may or may not show up
> in other Z-Wave systems.

The Z-Wave protocol is licensed by InTouch
and over 100 other manufacturers.  Using
Z-Wave protocol, anyone can develop a
system that handles 8 hops and polling.

> Prices for InTouch(tm) devices are approximately
> 3x those of comparable devices in Intermatic's
> HomeSettings(tm) line of legacy Z-Wave products.

Better products cost more.  However, you can
expect online discounters to keep prices in line.

> Intermatic has started a forum where those
> interested can get answers to their questions.
>
>     http://www.intouchcontrolsforum.com/forums/

The forum is brand new.  There's only one
2-message thread in it as of this writing.

> Finally, I don't know how microwavable it is
> - it uses the 900MHz band in North America.

Set the microwave on medium for 30 seconds
with the turntable set to OFF.  Be careful to
remove aluminum foil from the product before
turning on the microwave.  :^)
--

Regards,
Robert L Bass

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