Re: Re: HA Holy Grail #1: Occupancy Detection

[Lehane Kellett <lehane@xxxxxxxxxxxxxxxxxxx>]

Try putting the RFID  tag in your shirt pocket and then try
reading it from behind you.........2-3ft? Add a GSM cellphone in a call
nearby and it may decrease some more. A single reader in a room is
going to have lots of problems and full coverage is too expensive (unless
your name is Gates).

Using 2W (ETSI EN 302 208) may give more range. Of course, in the
US they can use more power.

The antennas are typically serpentine pattern - this shows it quite well:
http://www.plitek.com/images/Inlays-sm.jpg

For HA occupancy detection  I'd still stick to PIR's for the next few
years but RFID is great for access control.

Lehane


noel_pilot wrote:
>
> Hmm careful here, not completely sure that's right. If the bit about
> the aerial length is correct then the aerial can be wound up within a
> casing.
>
> I've just been reading tags the size and thickness of a post it note
> from a distance of 8-10 feet with a handheld pda reader. All passive,
> no silly power outputs, just 869MHz with 0.5watts of power from the
> reader.
>
> --- In ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>,
> "Michael" <michaelhims@...> wrote:
> >
> > But are you talking about active or passive tags? Passive tag
> readers need an ariel the same length as the distance you wish to
> operate them from. Active tags have a greater range, and so you can
> get away with less readers.
> >
> > I must admit I havn't looked at the cost of them, but I can't
> imagine they would be that bad...
> >
> > Michael
> > ----- Original Message -----
> > From: Malcolm Surgenor
> > To: ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
> > Sent: Wednesday, August 23, 2006 8:06 PM
> > Subject: RE: [ukha_d] Re: HA Holy Grail #1: Occupancy Detection
> >
> >
> > >>Still think an Active (would give greater range) RFID tag
is the
> way to
> > go.....
> >
> > I have to agree but each time I've looked at it I just can't
> justify the
> > expense. Too often people see tags at just a few pounds but from
> what I've
> > seen those are the ones that you need to run past or hold close
to the
> > reader to get any movement sensed. All the tags I looked at were
quite
> > bulky and expensive. I also calculated I wouldn't get away with
reader
> > covering the whole house either. Originally I wanted to put a tag
> in my car
> > but to get a reading I was going to have to stick it in the
middle
> of the
> > windscreen to get any use - I thought I could hide it behind the
> grille
> > somewhere.
> >
> > Certainly there are quite a few UK based HomeSeer users
> successfully using
> > RFID but I just can't justify the expense - yet!
> >
> > Malcolm
> >
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> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
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