🚀 go-pugleaf

In article <205@nbc1.UUCP>, abs@nbc1.UUCP (Andrew Siegel) writes:
> I've been wondering for a while about those card-keyed door locks
> that you find in newer hotels.  I have three questions:
> 
> 	1) How are they powered?  (I can find no evidence of wires
> 	   running to the door itself.)
> 	
> 	2) What is the means by which they are reprogrammed?  Is
> 	   it done using RF?  Carrier current?  Microwaves?
> 	
> 	3) If they are battery powered, what kind of batteries
> 	   are used, how often must they be replaced, and how
> 	   does one open the lock to replace the batteries?
> -- 
> Andrew Siegel, N2CN		NBC Computer Imaging, New York, NY
> philabs!nbc1!abs		(212)664-5776

When I stayed at the Hilton in Anaheim I was told that the registration
desk punches a new card for each guest.  The number on the card comes
from a random number generator located in the computer at the registration
desk.  The microprocessor in the door lock has the same random number
generator software.  When a card is inserted into the lock the numbers
match and the doorlock micro then computes the next number in the sequence
and savesthis number away.  As long as the numbers for the current random
value match the hotel guest can use his card key.  When a new guest
arrives, his card will contain the next number in the sequence (which
the door lock has pre-computed), and when he inserts his card into
the door lock the number of the previous guests card is invalidated
and a new "next number" is calculated from the random number generator.
The problem is that sometimes the registration desk computer gets out
of sync with the door lock computer and a security person has to reset
the door lock with a "master key".  The locks use lithium batteries
and are replaced periodically.  Most of the power consumption is during
card reading (optical) and door opening (selenoid magnet).  The door
processor is probably low-power CMOS logic.

That's all I know.

Charlie Thompson
Motorola DSP Operations

Disclaimer: Lock pick at your own risk....Moto and I are not
responsible for anything said.