DTMF Decoder & CB Radio?

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CSL126

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Hey guys, have any of you attempted to place a DTMF decoder into a CB Radio? I was just wondering, because it seems like a good idea. You could just page your friend rather than having to monitor the busy channels.

What type of DTMF decoder would be best for a CB? I've seen several different models...
 

IdleMonitor

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Huh?

You mean you can't just call for a "Break" for a buddy, or annoy him any more by rambling off an echo mic. for 5 mins.

I could just see it now, paging your buddy now on the cb with a 2-3 tone burst then say "breaker breaker"
 

elk2370bruce

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NO. Have never heard a CB using a PL or DPL. Probably takes too much current away from the 5KW linears running into 15 element beams in the "free band" and diminishing the all important multiple channel splatter factor that gets the operator's progesterone flowing.
 

ReceiverBeaver

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Any "type" of decoder will work as long as it fits inside the box, or it could be external if it's large, and if it requires any voltage available inside the radio which is likely between 3 and 12 volts, which should be a standard thing for these devices.

Back to the other guy's comments about why one would even want to do this. Ditto here. Too much trouble and fairly pointless. It seems like you generally only have communication with this one friend. So pick a typically unused channel and monitor it. Or if ya'll talk on a group channel.....then you're both already monitoring it as it is.

Pager tones for the simple purpose of calling another party do seem silly. A tone and picking up the mic and calling them serve the exact same purpose so why not just keep your gadget money and pick up the mic. Numerous ham rigs have this feature, but the use of them has never caught on in the ham community. It's too nerdy even for them (us).

NO code tech for 11 years and still waiting for the FCC to get off their butts and drop the code.

RB
 

specman

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Can be done with audible tones and common equipment. Forget about any of the sub-audible stuff. Agree with the pointlessness of it though.
 

K2GOG

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the idea sounds alot like SELCAL used in aircraft who use HF. Since they use SSB radios, they will use a DTMF tone to break the squelch as well as alert them that a call is coming in for them.

I played around with adding SELCAL to two old AM Radioshack CB's a few years ago. It worked pretty good. All it did was just unmute the speaker when the proper tone was received. Many DTMF boards can be wired for this

or this TAPR kit woudl do what you need

http://www.tapr.org/kits_das.html

I do remember reading about an exension speaker with this function built in , but forget who sold it. i think it went for about 50 or so.
 

joefoss

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PL or sub-audible tones will not work with AM. You will have to modulate them to at least 85% modulation and that will take up all of you audio path. Most am modulators will not pass the low PL frequencies. DTMF may not decode well on am due to the noise on the AM signal as thw audible tones are combined and it tales a clean signal to hear the two combined signals in order to decode them. That is why single or mutable tones are used in the audible frequency range (500-1100 Hz) for best results.
 
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