Re: DTMF dead?



Nico Coesel wrote:


The sort of wiring hasn't been nailed down yet, but at this moment I
would prefer a system with 2 wires which carry both power and
communication.

Is it a two way or one way communication?
If it has to work in one way, the simplest way to transmit is by inversion of the polarity of the power.

low baud rates. Also, the communication comes from a UART. Using a
transformer on DC biased signals is not a good idea.

It is not a problem to make a UART signal to be DC-balanced. You just have to encode the data to equalize the number of zeroes and ones.

It also seems an NXP LPC2101 ARM micro is even cheaper ($1.65) than a
NXp LPC935 8051 based micro ($1.82) so I think software FSK -which
I've build before- is not out of the question. DTMF is a whole lot
more complex to decode than FSK.

Indeed PSK is even simple then FSK. Any microcontroller would do.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com



.

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