"Googler" wrote in message
om...
"Steve Nosko" wrote in message
...
"Googler" wrote in message
om...
I would like to interface the house security alarm with my 2m Tx and
my handheld. When the system is triggered, simultaneously with a local
sound alarm, I would like to receive a simple CW message ( no repeater
need to be involved)
Any ideas? Tnx in advance.
/M

I'd start with a "unique" Subaudible tone on the Tx them program that
tone
into the handheld & put it on CTSS receive. You could put any audio you
want on the TX. No CW required. Any time the squelch opens - alarm =
true.

Or if you really want CW, just get/build any CW IDer and key the TX &
IDer
with the alarm. Lotsa' PIC IDers around & In the various mags & QST.

How-zat?

Thank you. Yes, that would be very simple. I was thinking about CW
because one could create a different receptor points with the unique
identifiers.
In the more advanced system one could wish to send back a DTMF and
initiate an appropriate action. How to achieve this...the easiest way?
/M

Well, I'd go to a PIC chip like the 16F84 (since I used them in my
microprocessor basics class). There are (were) DTMF chips and the Pic could
easily send whatever they need. The DTMF decoder is a bit more complex at
the other end.

Another easier choice might be to simply use single tones and PLL (NE567 I
believe is the number) tone decoder chips. You should easily be able to fit
quite a few tones in the audio BW.
--
Steve N, K,9;d, c. i My email has no u's.