Re: DTMF dead?
- From: Vladimir Vassilevsky <antispam_bogus@xxxxxxxxxxx>
- Date: Sat, 07 Jul 2007 16:09:34 GMT
Nico Coesel wrote:
I have an upcoming project in which I might want to use dtmf
transceiver chips as a simple means of communication. However, it
seems that dtmf transceiver chips are quite hard to get these days.
Even Digikey stocks none. Anyone knows a source that keeps making dtmf
transceivers for the years to come?
It is possible to encode and decode the DTMF with pretty much any microcontroller. For example, you can do this:
http://www.abvolt.com/research/Multitone%20detect-IEEE.pdf
However, if the goal is the communication, I would rather implement a PSK or FSK modem using a microcontroller. It would be much better and even simpler then the DTMF.
I was hoping to use the analog front-end which is usually quite good
(reception downto at least -30dB). Its hard to beat that with a
microcontroller implementation (been there done that).
It depends mainly on the incoming SNR, not the absolute signal level. It is quite possible to over perform the standard 8870 decoder if the micro does have the internal ADC.
PSK / FSK is also an option. I just need something cheap and reliable
that will communicate over a 2 wire system carrying both communication
and power.
Been there, done that :) Perhaps, the most straightforward solution is running the UART over the power. There could be several possible ways to do that, depending on your system.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
.
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- From: Nico Coesel
- Re: DTMF dead?
- From: Vladimir Vassilevsky
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