Re: Medieval Home Automation

["David Buckley" <db@xxxxxxx>]

An interesting read, nice to see a project start at the beginning, so to
speak :-)

Anyway, I offer the following observations...

First: 110 (PDS) distribution blocks.  Just dont.  Several years ago, when
I
was a happy network consultant / installer / specifier / manager /
maintainer / operator for a number of large city institutions, it was my
enormous pleasure when upgrading whole buildings from cat3 (and coax, and
token ring, and all sorts of stuff which has now thankfully died off) to
cat5 to destroy 110 PDS panels.  They have no benefits over
"straight" RJ45
patching.  Actually, thats not quite true; they have one benefit - you can
share a pair or two pairs or three pairs of a cable using different width
PDS patch leads.  But in reality, this is natures (or rather, AT&T's,
PDS's
creator) way of telling you you your flood is not deep enough, and you
should have put in more wire when you had the chance.  If/when I ever
rewire
with cat5, I will try not fall for the insufficient flood, having fallen
for
it (and been persuaded to fall for it by people who talk athoritatively).

Thus, if you think you want two RJ45s per space, you know you'll need more.
With RJ45, termination is expensive, not cable, so pull at least twice what
you know you'll need.

And have I mentioned - forget 110 PDS punchdown blocks... :-)

Second: All that low voltage wiring - you have a node zero plus other
'nodes', but seem to be running a ton of copper back to innumerable cards
in
the node zero PC.  I'd suggest you look at distributing the I/O workload to
the nodes, using networked (which today means RS485) I/O cards at the
nodes.
The homevision folks are familiar with Sylva cards, there should be
something similar that works for your chosen solution.

Thirdly: Dimming, and 0-10V control.  D-A cards are expensive, as is all
that copper; There are digital solutions, which for 5.5K sq feet may be
worth investigating.

Fourthly - Audio, compression and voice cancellation; this technology is
well understood in the context of whole room audio and video conferencing.
Start by having a look at Rane,. http://www.rane.com for some ideas.  Its
non-trivial however, involving real time room modelling.  But it does work!
Also do a google search for "mix minus", which turned upside down
may
deliver a self-cancelling thing.

[quick digression to re-read the paper]

Fifthly - WHOA - Earthing - 10mm earth cable to each dis board, to
"improve..." and thus presumably in parallel with the 6mm or
2.5mm cable's
weedy earth? - Nope, not legitimate, if I remember correctly.  You cant
parallel earth coductors of different sizes, so just use the single
external
earth cable.  Make sure it cant come undone.

Electrics generally -  I see some traps for the unwary here:

1) Check you math for fault disconnection times, since you are calculating
correct circuit sizes for your sub-distribution.  Most electricians
over-wire, due to incapability of math and inability to understand the
wiring regs....

2) Circuit discrimination - If you have a socket protected by a 16A MCB in
your subboard, and the sub-board fed by a 32A MCB, then under gentle
overload conditions (say 35A out of a 13A socket :-), the breakers will
discriminate OK, and the 16A one should pop first.  However, under short
conditions (many hundreds of amps), its a lottery.  This may not be what
you
want to happen, or you may care not a jot.  If you do care, then you either
need massively differently rated breakers, or the main breaker needs to be
slower that the final circuit breaker, so the final goes first.

Audio - Ceiling mics - in fact mics in general - if they are both balanced
and low impedence then dont worry about the low level.  You'll probably get
away with shoving it over cat5, but a better choice would be balanced audio
cable.  Dont fuss too much about quality, after all, most recording studios
dont.....  As long as its twisted audio cable with an overall screen it'll
be fine.  Distance shouldnt be an issue.

Headphones should not really use line audio cable, the DC resistance of the
signal cores is likely to be too high.  Use Multicore.  Or better still,
use
local headphone amplifiers - folks like creek make nice ones.  Deliver the
audio over cat5 UTP at line level using KAT5?

IR - I personally use and highly recommend xantech - it just works.  And
isnt limited to just 40KHz.  But something is in the offing
"locally".....
Xantech (like most IR distro systems) is unbalanced, and so is not a great
choice for cat5 UTP, as it doesnt self cancel, so it radiates right next to
other stuff.  I also suspect the additional capacitance of cat5 dulls the
edges of the IR waveform, so I use standard four core from RS or CPC.   
The
xantech (and niles, and most other decent IR systems) allow you to set up
"zones", so you can choose what to repeat to where.  Look at
their website
at the 795-20 four zone amplified connecting block.

If fact, this wire comment applies to most single ended connected fixed
things you will install - they are not balanced, they just want wire, so
UTP
is not the best solution, if there isnt already some there.  Multicore, or
screened multicore is a better bet.  And its easier to tell the colours
apart!  This is widely available as security cable, and is perfectly good
stuff, but not for audio, video, or ethernet :-)  But for door sensors,
button pressing, PIRs etc, its entirely adequate.

ISDN - you should have the BT supplied box at node zero, and then extend
ISDN over cat5 to the study.  You'll need either a custom faceplate with an
ISDN terminator (blue), or better still, a little adapter cable with
ordinary RJ45 plug, and a blue terminated ISDN socket.   You can undo the
BT
supplied box, and put it on the other end of a twisted pair, but BT wont
like it......

CCTV - run video over UTP.  Either baluns (about 30 quid a pair IIRC) or
electronically balanced (KAT5?)

Distribution panels - I like the sound of these interchangeable breaker /
dimmer / relay panels; I'm not familiar with a specific example.  But a
point has been made elsewhere about using 13A sockets, and then dimming the
tele.  I have done just this (used 13A sockets on the end of as dimmer, not
dimmed the tele), but I use a patch panel (!) to go between the dimmers,
relays and permanent mains supplies and the radially wired sockets.  I'm
not
sure how legal this is but it does work, and is done safely.  And it is
flexible.  And when I leave, the patch panel and the dimmers go with me!!!

ESD - I think your biggest problem will be junk like earth loops, and
spikes
back to the HA equipment due to shorts causing the earth PD to jump.  Run
two of your 16mm earth wires to your Node 0, and use one for all the power
stuff, and another as a clean earth to which you connect your audio and
other gear to.  Stuff on the secondary side of power supplies.  And try not
to earth anything anywhere else.  Thus all your HA connected stuff should
stay at the clean earth potential.



----- Original Message -----
From: "Andrew Richards" <andrew.richards@xxxxxxx>
Newsgroups: tex.com.ml.ukha_d
Sent: 07 December 2001 17:47
Subject: [ukha_d] Medieval Home Automation


> Hi to all
>
> I've been an avid lurker on the UKHA and Comfort groups for a few
months
> now, picking up lots of useful tips.
>
> We are in the process of doing the self-build of a large medieval
house,
and
> I've completed the first draft of a schematic and a design document
for
> whole-house automation.  I'd really welcome some peer review,
particularly
> on the cabling proposed, as I'm about to start 1st fix on one part of
the
> house.
>
> The document is in Word format at the moment on the Files section of
the
> UKHA group (its around a 250k download).  The original schematic
diagrams
> were drawn in Turbocad, and cut and paste doesn't always seem to give
the
> right result (I can't get it to print the diagrams).  If you prefer
(and
can
> wait for the 'page' to load), then you can go to
www.progcons.co.uk/hav1.htm
> and get the full document - my apologies, it's just a Word dump to
html.
> Better web structure to follow.
>
> Happy reading: all feedback gratefully received.
>
> Andrew
>
> Kent, UK
>
>
>
> For more information: http://www.automatedhome.co.uk
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