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Why use DTMF? Use caller ID circuits. Higher data rate, easier to modulate, and inexpensive.msovais said:apart from home automation...i need some ideas which i can implement using dtmf concept...
DTMF is slow, maybe you can get 10 codes a second... I might be on the low side here, butit is something I was looking into recently.mramos1 said:How about using DTMF over RF to turn things on and off?
cadstarsucks said:DTMF is slow, maybe you can get 10 codes a second... I might be on the low side here, butit is something I was looking into recently.
Caller ID signals are just an old fashioned 1200BPS modem link.
Dan
Very common, even today, in the two way radio field to use DTMF to enable/disable link transmitters on repeater sites. DTMF pads are common on a lot of commercial two way radio's and are used for exactly these purposes. Another common use is to use DTMF over-dial on a touch tone phone to access such things as paging terminals, security systems, etc.I thought RF since no one has hear the tones as he sends them and I am sure someone has done that in the past (google.com maybe). Or an IR version. Just some carrier to ride the two tones over.
Yes, it's called CTCSS and DCS coding. Primitive but effective for eliminating unwanted signals being received but the 'privacy' word was just a marketing ploy used by Motorolla and others.I think FRS radio's in the US use a tone decoding (maybe not DTMF but at least related to it) as 'privacy' codes
That would work and I would not know what is used in those situations. I do know however that DTMF is a bit more complicated to generate and decode that simple the FSK that is used in caller ID, as well as being much slower.kchriste said:Very common, even today, in the two way radio field to use DTMF to enable/disable link transmitters on repeater sites. DTMF pads are common on a lot of commercial two way radio's and are used for exactly these purposes. Another common use is to use DTMF over-dial on a touch tone phone to access such things as paging terminals, security systems, etc.
Yes, it's called CTCSS and DCS coding. Primitive but effective for eliminating unwanted signals being received but the 'privacy' word was just a marketing ploy used by Motorolla and others.