Re: Sensor locations ...

["David Gumbrell" <david.gumbrell@xxxxxxxxx>]

I like ceilings because you rapidly learn to ignore them - you are not
likely to be staring at the ceilings much (except in bed), I think walls
are
much more aesthetically sensitive. The new Idratek PLH module reduces the
module count to 2 for fairly sensor extensive coverage. If you mount them
quite near to overhead of typical sitting positions then they will be more
likely to be outside your usual field of view when you are looking at the
TV
or your dining companions, for example. Also turn off the tell-tales so
that
the blinkenlights don't attract attention.

Interestingly, this weekend I had visitors and the lighting automation was
noticed, but not the sensors enabling it until I pointed them out.

I think temp sensing (for comfort) is better at human height in theory due
to vertical differentials and near to usual sitting position due to
circulation currents. So possibly a MFP/DFP near to favourite sitting
position might be best. But I am working on the basis of not worrying about
the absolute temperature setting relative to the sensor, but discovering
the
correct sensed value to create comfortable conditions. I guess the
completion of my heating control scheme will test whether that is true.

I'm not sure about humidity - where I am using it for control (in the
bathroom) it seems to me that steam rises so ceiling is better.

PIRs have to be placed according to the sensor pattern, they are most
sensitive to heat sources crossing the pattern, but you also have to take
into account whether you want them to see through open doors into corridors
or not. So aesthetics has to loose to function, but I think ceiling offers
best freedom of choice in positioning.

Light level sensors need to be away from light sources such as bulbs, seems
obvious, but I screwed up. They can also be fooled by bright/dark objects
in
their field of view. Arguably they would be better  seeing horizontally
onto
a representative wall that is not going to change much, unlike a ceiling
position where they could be affected by people moving around underneath.
Having said that, the only time I have fooled them was when I lined a
baking
tray with tin foil in the kitchen once. I mean I fooled it once, not that I
lined a baking tray once.

I think CCTV best done with covert cameras looking through hidden apertures
such as coving or cornice or maybe cupboards if available. You also have to
think about how they are being used. If you just want to be able to monitor
activity then ceiling may give best viewpoint. But it would be unlikely to
capture sufficient identification features for evidential purposes. The
crims have learnt to wear hoodies and peaked caps against high level
cameras, so I guess head height or lower positions might work better.
However, if in home cameras become common expect the return of the face
stocking.

IR is interesting, I guess habit means receive should be in the wall above
your equipment - it is very natural to point the controller at the thing
being controller, but then the TX would rely on reflections, or an external
repeater. I compromised and fitted them into the ceiling as well !

Cheers

David

On 8/25/07, Chris Hunter <cjhunter@xxxxxxx> wrote:
>
>   for good & effective HA, 'seems we'll be needing lots of sensors
...
> PIR, temp', humidity, CCTV, etc, and plenty of them ... but where to
> mount them ... wall, ceiling ... perhaps even in light-fittings, and
> on the sides of cupboards ... but, 'wondered if anyone had found any
> one better than any other ... or, better-still, if anyone had worked-
> out any good guidelines, or things to avoid ... and how to keep SWMBO
> on-side - aesthetics being the issue - ceiling-mounting would be
> good, but 'not sure SWMBO would be keen !
>
> Chris
>
>


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