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Subject: Re: Single / Multitone Detector (Not DTMF)
Date: Tue, 14 Jan 2003 11:43:51 +0800
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On Mon, 13 Jan 2003 11:12:02 -0500, Terry King
>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.
If the warble is AFSK the use something like an XR2211 for
a detector and decode it with a micro
>2: Maybe I have just carrier-detect from handheld radios.
You can use a sequence of carrier on/off keying to trigger.
This is used quite often for turning on landing lights at
remote unmannned airstrips. The processor has to allow for
a wide variation in on and off times. For instance send
three one second (approx) on, one second (approx) off carrier
and detect with a micro. The micro would look for times between
say 0.8 and 1.2 seconds each on and off.
>3: I have DTMF from amateur radio and the phone system.
Use a DTMF decoder (8870 or similar) with a micro or with some
logic. You can use lock codes and unlock codes to prevent
unauthorised use. Here's one that we manufacture:
http://jenal.com/dt8.htm that might give you some ideas
(or http://jenal.com/pdfs/dt8prg2.pdf for more details
>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.
With the right system you can switch things on and off remotely.
Manufacturers and Suppliers of HF Selcall
P O Box 1108, Morley, WA, 6943
Tel: +61 8 9370 5533 Fax +61 8 9370 5106
Web Site: http://www.jenal.com
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