Re: House Access Help

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On 31 Jul 2006 11:12:51 -0700, joseph_stiehm@xxxxxxxxx wrote in message
<1154369571.193456.12140@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>:

>1) The iAutomate (Wavetrend) solution involves tags that are battery
>operated and have a lifespan of 5 years.  Are you aware of any good
>long-range proximity reader solutions which involves strictly passive
>tags that don't require their own power source (HID seems to fit the
>bill, but it doesn't seem to be marketed to home automation)?

See my other post in this thread.

>2) The setup I have envisioned has the reader installed in the house
>with the read envelope extending outside the house.  All the readers
>I've looked at seems to be omni-directional.  Any ideas on creating a
>hemi-spherical area of activation (on the outside of my house only)?  I
>looked at the front door this weekend with a tape measure.  In order to
>create a passive, transparent solution to opening the door I figured a
>radius of 36" around the doorknob (at wallet level) would be ideal.  I
>don't want to trip the front door reader from the inside so I figured I
>needed to do one of 4 things:
>  a - Shield the reader (using metal?) so it only detects tags from one
>direction. Is this realistic?

Can't see why not (but I have no hands-on experience). One conventional
approach is to triangulate using multiple readers. The G2 chip solution
using WIFI I cite in my other post in this thread would serve to keep the
'reader' costs way down and so allow for triangulation at moderate cost
(software permitting).

>  b - Set up the reader outside (ugly for a number of reasons) so that
>the envelope doesn't penetrate to the inside of the house

I don't think I understand this.

>  c - Use a reader and a second, fixed-location, tag set up
>asymmetrically and measure distance of the 1st tag against the distance
>to the second tag to determine whether the door should open (I don't
>even know if this is feasible)

Yes. This is a 2-sensor (1-D)  version of what I meant by triangulation (2-D
localization).

>  d - Get two readers (expensive) and set them up in conjunction to
>create a crescent of activation (tricky?)

Three points form a triangle.

>Again, I'm new to this so maybe my concern is due to naivete on my part
>(it may be that this is something HA folks simply "deal with"), but
>before I look to spend $700 on the venture I'd like to establish the
>feasibility of my concept.

So would I ;-)

... Marc
Marc_F_Hult
www.EControl.org