I don't think I'd use both methods though,
in this application it doubles the potential for failure, rather than becoming redundant (series vs parallel--and/or--nand/nor devices).
<font size="2" face="Verdana, Helvetica, sans-serif">Good point. The alarm module is actually a tone generator (GPS750). I agree, it probably best to stick with one method.

<font color="#FFFFFF" size="1">[ December 19, 2007 11:25 PM: Message edited by: Chadzero ]</font>