Subject: Re: Single / Multitone Detector (Not DTMF)
Date: Tue, 14 Jan 2003 10:27:05 -0800
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I've been trying to do similar stuff with a
and tone detecting in sw. Have lots of ram and
horsepower do correlation.
With a pic, you don't have either. So I'm
thinking about doing what
amounts to a pair of switched capacitor filters
in sw off the PIC a/d.
Remember the Timex computer from 20 years ago?
There was an application
that did voice recognizion by looking at zero
It worked amazingly well for what they had to work
Terry King wrote:
> > The most vexing problem with using what's built into the radio is that
> > anyone with another radio and a little patience and good ear can
> > duplicate the tones and bingo! turn on or open your whatever.
> Thanks for the suggestions. Actually, I am in a VERY interference
> free area, probably the darkest point in New England except
> northern Maine. That's for all frequencies from Light down to
> the maximum skip frequency. I only get interference from
> ONE TV station, but I almost always just turn the set off and
> do electronics instead. I've been monitoring for days on a typical
> FRS channel and heard no-one. If I pick a CTSS frequency as well
> I expect the risk is real low of anyone even knowing I exist.
> I plan to have my existing system talk back, as of now, but
> I'll probably set up some simple log-in sequence to validate
> It's US. Hmmm. I can also disallow certain actions from this input,
> but there's nothing that can 'blow up the house', although the
> backup heating level can be changed. Mainly I just want to turn the
> doggone lights on from 1000 feet away, so we don't have to try to
> walk down a snowy road in the dark while loaded down with Groceries.
> Yes: there SHOULD be a flashlight in everyone's car...
> TECH issue: I had a suggestion that I may be able to detect these
> signals accurately enough by just looking at Zero Crossings with
> the PIC. I'll probably get to try that some, today. Anyone done
> that, or similar approach? Signals SEEM to be actually single
> tones, with several "warble - bleep" variations in frequency.
> Thanks for the help...
> Regards, Terry King ...In The Woods In Vermont
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