Tom..
I suppose then you would look at the rising edge like you said and just time
 shift
the overall ring envelope.  That ought to do it.  Or, you could use the ring
indicate opto circuit used in modems and do a similar thing.  But than again, I
can't even remember who started this thread.  Hope the originator gets some use
 from
it.

Chris Eddy
Pioneer Microsystems, Inc.

Tom Handley wrote:

>    Chris, the TCM1520A uses the ring cycles to charge a cap for the internal
 5V
> regulator so you don't need to (you can't) count cycles. By it's nature, it
> ignores the first ring while charging, then switches the output level after
 the
> ring burst.
>
>    - Tom
>
> At 11:09 PM 12/21/97 -0500, you wrote:
> >To mask off the ring, you could count off a few of the cycles, figure at 20
 Hz
> >(sometimes 30), there are 40 (60) cycles in that first ring.  Count off five
 to
> >make sure that the period is right and it ain't noise, and you could be in.
 A
> >crafty individual would then regenerate the ring back out and tack on the
 lost
> >five cycles.  You could then look at the hook status and kill the added
 ringing
> >cycles if the phone is answered.
> >
> >Chris
> >Pioneer Microsystems, Inc.
> >
> >Tom Handley wrote:
> >
> >>   <snip>
> >
> >>    Back to the original question, you could use one edge of the ring
 detector
> >> output to ignore the first ring.
> >>
> >>    - Tom
> >>
> >> At 02:02 PM 12/19/97 -0500, you wrote:
> >> >Do I sense defeat?  Tisk tisk.  Why can't you use that TI ring detect
> chip (I
> >> >forget the number, links a piezo to the phone line).  Then use a PIC (thus
> >> I did
> >> >not specify OT in the subject line) to detect the pulses, and based upon a
> >> > switch
> >> >on a pin that indicates ring/ don't ring, re-generate a piezo ring.  Then
> >> rig it
> >> >into your phones.  Ring signal is 2 seconds on, 4 seconds off.
> >> >
> >> >Chris Eddy
> >> >Pioneer Microsystems, Inc.
> >> >
> >
> >