Re: leviton vizia RF switches (Z-wave)

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Sat, 17 Mar 2007 15:18:57 GMT, "Dan Wright" <No_way@xxxxxxxxxxx> wrote
in message  <BFTKh.21981$PF.12156@attbi_s21>:

>
>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:45fcb433.140411640@xxxxxxxxxxxxxxxx
>> "Dan Wright" <No_way@xxxxxxxxxxx> wrote:
>>
>>>I am yet to find a range/hops issue, even in the large installation.   I
>>>have not done formal tests, but my current attitude is that it is good
>>>enough up through the 3500 sqft range/single story, depending on layout.
>>>Homeseer offers a tool that does Z-wave network analysis which would
>>>help with any  network issues..  It requires their Z-troller primary
>>>controller.
>>
>> What's the distance between nodes? Does Vizia use 4 max hops?
>
>ViziaRF says it use up to 4 hops.
>
>Roughly the longest distance between nodes is about 25 feet.  Furthest
>node from the primary controller  is about 65 feet.

Welcome (back) Dan. Your experience-based comments and advice are always
appreciated.

Both PLC- and RF-based lighting are aimed partly at the retrofit market. So
the dimensions of the typical existing (eg) US home are of interest when
discussing applications of technology that may be limited by geometry and
size of homes.

Years of looking at topo maps tells me that the vast majority of existing
US homes could work with a primary controller, adjacent nodes and at most
one additional hop. In this configuration, each node can communicate
directly with every other node (using even only 25 feet is used as the
maximum distance). IOW, four-hop "limitation" really isn't.

node<--25'-->node<--25'-->node+controller<--25'-->node<--25'-->node
Outside wall <---------------100 feet ---------------> Outside wall

100 x 100 x 1 floor  = 10,000 square feet
100 x 100 x 2 floors = 20,000 square feet !

And a 75-foot-long home with a garage 75 feet away (using a conservative
75' free air range is also accommodated. A square one-acre lot is 209 x 209
feet, so a 50-foot-long home in the middle allows coverage of even an
entire one-acre lot.

node<--75'-->node<--25'-->node+controller<--25'-->node<--75'-->node
          Outside wall <---- 50 feet -----> Outside wall
Lot boundary  <---------------200 feet ---------------> Lot boundary

( IIRC, the U.S.Geological Survey (USGS) 7-1/2 minute 1:24,000 topographic
maps show the actual dimensions of buildings once they reach 40 feet x 40
feet. This is  the most common modern paper scale, and a common source of
digital/ized maps. This spatial resolution is different than the accuracy
of the _location_ of an object. So a square, one-story buildings greater
than 1600 gross square feet and two-story homes greater than 3200 gross
square feet are shown to scale. (Although in built-up urban areas,
individual residences are typically not shown; a red/pink shading for the
urban areas is typically used. )

According to the [fact-free, gratuitous bashing of guvmint bureaucrats and
public servants typically included here in comp.home.automation] US Census
Bureau, the median square footage of new one-family US homes has slowly,
and not monotonically, risen from 1525 square feet of floor area (1973) to
2227 (2005). The regional differences are typically less than 10% although
homes outside the Metropolitan Statistical Areas tend to be about 15%
smaller than those in MSA's. The range for multifamily units is roughly 1/2
the sq footage of single family homes. A majority are =>2 stories.

http://www.census.gov/const/www/charindex.html

In other words (allowing for a ~25% reduction from gross areas to net floor
area (eg 20,000 --> 15,000sq ft) the median one-family US home is only ~
1/4 (single story) to ~1/8 (two-story) the area that can be handled by a
simple configuration in which each node can communicate directly with every
other node (using 25 feet as the maximum distance).

So Dan's experience would seem to be overwhelming the rule rather than the
exception.

IMO, constant and unwarranted attention by some in this newsgroup to huge
McMansions that are statistical outliers (and where Crestron and AMX rule
anyway) distorts the discussion and advice given.

... Marc
Marc_F_Hult
www.ECOntrol.org