This is conjecture on my part ...=20

The chip is probably a passive device with no storage of data in itself - =
apart from the ID code - a digit of maybe 64000 or more.

The reader most likely sends out an RF signal which is altered by the chip =
(uses perhaps a tank type circuit to scavenge power from the RF) and =
modulates it. The ID number is referenced in a central database which =
contains the appropriate data pertaining to the pet.

A good search on similar technology would be for "Wiegand wire" - even =
Microchip's RFID system (not sure if they need power or not - just checked =
- yes and no, depends on what ones you get, read here.

http://www.microchip.com/download/lit/pline/rfid/guides/51115e.pdf=20

Actually a very good document coving most of your questions.=20

You can buy the parts to do this kind of thing - I have used (from =
www.awid.com) a unit called "pcProx" - I did find a distributor of readers =
not in enclosure and serial interfaces, unfortunately I lost the link for =
them.

The passive ID tags with reader have the maximum range from what I have =
seen of 2-3 inches
Frequencies vary between manufacturers - 100 kHz up to 900 MHZ=20

>>> programmer1@HOTMAIL.COM 02/14/02 04:39PM >>>
Ok, does anyone know about the Identachip stuff?
For those who have not heard of it, it is the "microchipping of your pet"
stuff.
They inject a small transponder or something into your pet and it has a
number that can be looked up.
It is also used in Asset Tracking.

1. How does it work?
2. Is their a lifespan of the device?  Does it have a battery?
3. What is the frequency, range, and general limitations?
4. Is any of this technology avalible for OEMs?
5. How much data can be stored?

Some links to this type of stuff:
http://www.avidplc.com/assettrac/what.htm=20
http://www.hitec-id.net/=20
http://www.identichip.com/=20
http://www.homeagainid.com/=20
http://www.electronicidinc.com/=20
www.trovan.com  (this link looks dead, but the search pointed to it)

Best regards,
Giles

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