From: Watson 'Atto Parsec' Name
Subject: Re: Single / Multitone Detector (Not DTMF)
X-Newsreader: MicroPlanet Gravity v2.60
Date: Wed, 15 Jan 2003 03:52:48 -0800
NNTP-Posting-Date: Wed, 15 Jan 2003 04:53:34 PST
Organization: InReach Internet
In article ,
> Thanks for suggestions; I'm looking at some of the
> selcall stuff.
> The 567 is one-tone-at-a-time and I have made stuff
> with several of them in the past; they aren't the
> most stable possibility, but would probably work.
> I was hoping that a decade of silicon development had
> some up with my fantasy chip :-)
I've used the 567 PLL, and it's kind of slow to lock if you use the
value of caps that they show in the data sheets. I've reduced those,
but then it has a wider bandwidth. But it's a good chip for picking
tones out of the noise.
> 1: I have several inputs from handheld FRS and/or GMRS
> radios, which have several 'calling tone warble'
> options, one of which sounds like a typical electronic
> phone. I was hoping to be able to pick two tones
> from each of these, and to be able to identify which
> user was calling. I MIGHT be able to pick one tone,
> and detect the time-domain pattern. Hmmm.
> 2: Maybe I have just carrier-detect from handheld radios.
> 3: I have DTMF from amateur radio and the phone system.
> My hope is to come up with a PIC based system that I can use
> and which might be able to be used by others for similar
I think that with fast tone bursts, you're probably better off using
something like a prefilter to let the whole band of tones thru, then
clip them and then look at them with your microcontroller and firmware.
If the tones are consecutive with no gaps between, that should make it
more resistant against false 'talkoff'.
> My application is for access to my home control system and
> communications systems from FRS radios used by family members,
> and from the phone system. My most immediate need is to
> be able to turn on the "road" lights when arriving late at night.
> But once I get into the system, lots is possible.
I think this would be a good job for a garage door remote or the X-10
(yuck, damn pop-up ads). Also you could probably install a security
light with the PIR sensor that detects people or cars, and the lights
would turn on automatically for a minute or two. And where I live, in
So. Cal, the security lights were dirt cheap at Wal-Mart, I guess
because the power companies want to get people to install them to save
> This time of year we end up often walking down the hill thru the snow
> from 800 to 1200 feet, depending on what got plowed by whom. The
> town doesn't plow OUR road. I have 120V lights up covering most of
> the first 800 feet, but I hate to have them on from sunset until
> EVERYONE gets home, especially with older kids who may not get home
> this night at all...
> The rest of the logic and interfacing will be OK, but this funny
> tone-detect stuff is problematic right now...
> Thanks for the help!
> > Are you stuck with specific tones? or can you make
> > them anything you want.
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