Hi Dave, Timothy,

> (although anyone can jam a rf based secirity system easily unless the
> transmitters are spread spectrum.)
>
> > I've been contracted to design an inexpensive home alarm system using
> > miniature transmitters (inside each sending module) and a matching

This has been done a few times.  By some others that are on the PIClist
in the past as well.

There is a company C&K Systems that makes a very nice range of
SpreadNet (R) alarm components that put me off designing anything
for my own use as I could never get close to the quality that they
have achieved.

If you want to keep costs down use the 8pin PICs.

Cheers
--
Kalle Pihlajasaari   kalle@ip.co.za   http://www.ip.co.za/ip
Interface Products   P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750   Fax: 402-7751    http://www.ip.co.za/people/kalle

DonTronics, Silicon Studio and Wirz Electronics uP Product Dealer