Re: leviton vizia RF switches (Z-wave)

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

> Both Vizia and Intermatic's InTouch systems
> have only started shipping this month. Can
> you shed any light on why these second
> generation Z-Wave products cost so much
> more than the first generation products?

It is the same reason any new technology
initially costs more.  The manufacturers need
to recoop their investment in R&D.

> The few range figures posted here have
> been biased...

True.  The previous poster has repeatedly
posted short ranges based entirely on
supposition.  In fact Z-Wave does far better
than Mr. Houston alleges.

> Echelon published a whitepaper that
> included hands on tests of Z-Wave...

Speaking of bias, it is noteworthy that
Echelon is a competitor of Z-Wave.
However, their single test site showed
consistent successful transmission up
to 33 feet per hop.

Manufacturers routinely publish range
figures based on transmission in open air.
There's a good reason for this.  No two
building environments are alike so
testing indoors will yield very different
results from place to place.  A user who
reads that product X has a free air range
of 100 feet and product  Y has a range
of 50 feet will know that product X has
roughly twice the range of product Y.
This isn't linear though since each
frequency behaves a little different from
another in the same environment.  But
the published free air range does give
an indication of relative performance
between X and Y.

> (first generation) that indicated 20-30'
> reliable indoor range...

The test in the cited paper indicated
reliable performance up to 33 feet
with *some* locations functioning
reliably at up to 60 feet.  With early
release Z-Wave systems going four
hops and the controller centrally
located this would allow for a
theoretical installation covering
a structure over 260 feet in length.
That is far greater coverage than
what Mr. Houston claims.

> FCC rules allow higher power for
> systems that are primarily operated
> by a humanoid pushing a button
> and require reduced power for
> systems that send signals automatically.
> Automatic polling would appear to
> be a technical violation of the rules.

Since the FCC has granted acceptance
to these products obviously it is not.

--

Regards,
Robert L Bass

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