Fwd: Alarms

[Sandy Duffy <sandyduffy@home.com>]

You said:
>To the question earlier regarding the protection of factory car alarms.
>
>As far as I know the only alarm company that makes an alarm that is 
>impossible to "code hop" is Clifford. 

As an ex-CodeAlarm rep, I can tell you they have an interesting "open" code
system.  Each time the unlock button is operated a series of randomly
generated prefix/suffix codes are sent around each of the various command
codes by the transmitter.  The receiver knows the available command codes
and the suffix codes that match with the various prefix codes.  Therefore
each actuation of the unlock button is a unique event.  It would be tough,
if not impossible, to code hop. (However remember Murphy's corollary:  What
man can encode, man can decode) 

HTH

Sandy